Stator test readings

[seedy]

Why not use proper crimps and a plug? Was it soldered from the factory?

Good point to consider.

The problem with solder - while it is fine for stationary applications - in a mobile environment it in effect makes the braided copper wire into a solid wire. All of the flexibility is gone. If you solder, make sure that the soldered joint is mounted to a solid clamp - like a Adell Clamp - that will not allow it to move. If is shakes-rattles-rolls it will put stress on the transition between soldered and unsoldered wire and cause it to break.

In the marine environment soldered joints are not allowed. Crimp and place in conduit, or speedy sleeve, and fasten with clamps as above. This will allow the wire to move with the ship - or car - or bike.

[AllanB]

This is a hobby of course, as I only work in the UK and during the summer, so my time is irrelevant. So far I have spent about 15k on the bike, including tyres, bearings, brake pads, oil and odds and sods, on a bike that cost me 65k, so money isn't an issue either and I am learning stuff from various sources, including here, thanks.

Only solder tinning the end to swell them slightly and ensure grip/continuity for crimps, so loss of cable flexibility is not an issue.

Now for the issue of stator output and this is odd, I get 8 to 11vac at almost any rpm, if fact the volts drop as I rev the engine. But my battery is fine, engine always cranks, horn and lights all work and the engine runs. Heat sink on my rectifier is warm, so that is working too. I even checked the DVM on the mains and it reads 225vac as it should. So I very surprised the bike runs at all.

[AllanB]

A neighbour of a mate of mine says he can rewind the stator for me, so that's good if a replacement is unavailable, so draining the oil (after a flush) ready for the strip down in the cool of the morning tomorrow. So fingers crossed this is it.......and that the job is easy.

I wonder about the damage to the stator cover ally casing, so will check and make good.

A guy on Youtube who was changing a stator on a big CBR said some high performance bikes need a new stator every 12k miles, especially in hotter climates, mine has 62k km on the clock.

Edited February 4, 2014 by AllanB

[yankee99]

Sorry I have to ask you do have the stator disconnected? Basically the wires come out of the stator and at that plug is where I would be checking. Also if the voltage is the same at all rpm then maybe it is not spinning (possibly a broken pin).

[AllanB]

Sorry I have to ask you do have the stator disconnected? Basically the wires come out of the stator and at that plug is where I would be checking. Also if the voltage is the same at all rpm then maybe it is not spinning (possibly a broken pin).

Everything appears okay, no sign of burning on the stator itself, so tomorrow morning will take it over for testing at my mates house and an expert's opinion.

The stator is mounted on the damaged casing, so a possible misalignment problem, which will be a bugga as a replacement casing is unlikely on such a rare bike.

[AllanB]

Update....

Flushed and drained oil and removed the stator, all was well with no sign of damage, but we did find burning of the 3 phase wires when they were reconnected to the loom.. So a slight issue there.

One thing I did discover which was not explained is that you get 50-60vac with the stator out of circuit and only 10vac in circuit, so all was apparently fine from the start. We got 12.43vdc from the battery engine off, 14.05vdc at 3000rpm, so all okay there too.

Anyway inclipped all the connectors in the charging circuit and cleaned them, plus we added an earth lead from battery minus to the bike frame, this was because the only earth was from battery minus to the starter solenoid.

Got a new tacho drive cable so now I can see the engine rpm.

I have to say that when I rode the bike I thought it was fixed, but not so, the bike certainly runs better and revs better, but under hard acceleration it does misfire. The hot start problem is improved too, as when the bike stalled while I was opening my gate it did restart after only a few seconds.

So is this progress, perhaps, but not a result? I am starting to feel something approaching the 43bhp from the engine and it will rev to 9,000rpm, if the load is lowered.

Will look at the CDI unit next, but think that it either works or doesn't.

[Woodsie888]

Update....

Flushed and drained oil and removed the stator, all was well with no sign of damage, but we did find burning of the 3 phase wires when they were reconnected to the loom.. So a slight issue there.

One thing I did discover which was not explained is that you get 50-60vac with the stator out of circuit and only 10vac in circuit, so all was apparently fine from the start. We got 12.43vdc from the battery engine off, 14.05vdc at 3000rpm, so all okay there too.

Anyway inclipped all the connectors in the charging circuit and cleaned them, plus we added an earth lead from battery minus to the bike frame, this was because the only earth was from battery minus to the starter solenoid.

Got a new tacho drive cable so now I can see the engine rpm.

I have to say that when I rode the bike I thought it was fixed, but not so, the bike certainly runs better and revs better, but under hard acceleration it does misfire. The hot start problem is improved too, as when the bike stalled while I was opening my gate it did restart after only a few seconds.

So is this progress, perhaps, but not a result? I am starting to feel something approaching the 43bhp from the engine and it will rev to 9,000rpm, if the load is lowered.

Will look at the CDI unit next, but think that it either works or doesn't.

Are you 100% sure it is not leaning out for some reason Allan. Your description of the misfire is a characteristic of this.

What seems like an obvious electrical problem, can in fact be intake/fuel related.

You appear to have been very thorough with your checks so far. Perhaps it's time to back track a little?

[AllanB]

Update....

Flushed and drained oil and removed the stator, all was well with no sign of damage, but we did find burning of the 3 phase wires when they were reconnected to the loom.. So a slight issue there.

One thing I did discover which was not explained is that you get 50-60vac with the stator out of circuit and only 10vac in circuit, so all was apparently fine from the start. We got 12.43vdc from the battery engine off, 14.05vdc at 3000rpm, so all okay there too.

Anyway inclipped all the connectors in the charging circuit and cleaned them, plus we added an earth lead from battery minus to the bike frame, this was because the only earth was from battery minus to the starter solenoid.

Got a new tacho drive cable so now I can see the engine rpm.

I have to say that when I rode the bike I thought it was fixed, but not so, the bike certainly runs better and revs better, but under hard acceleration it does misfire. The hot start problem is improved too, as when the bike stalled while I was opening my gate it did restart after only a few seconds.

So is this progress, perhaps, but not a result? I am starting to feel something approaching the 43bhp from the engine and it will rev to 9,000rpm, if the load is lowered.

Will look at the CDI unit next, but think that it either works or doesn't.

Are you 100% sure it is not leaning out for some reason Allan. Your description of the misfire is a characteristic of this.

What seems like an obvious electrical problem, can in fact be intake/fuel related.

You appear to have been very thorough with your checks so far. Perhaps it's time to back track a little?

Do you mean running too lean, had no idea this could lead to misfire, if so I am sure this is the case. I was thinking of trying to raise the needles, any idea how much? I understand that the fuel/air mixture screw only affects the throttle up to 25% open.

Unable to get an air filter, I cut the paper out of the old one and replaced it with sponge, thought that may be the problem, but removed the sponge and nothing changed.

Thanks.....

Cut 1 cm off the burned wires from the stator and found clean metal, tinned the ends and reconnected. Another fault sorted.

Edited February 9, 2014 by AllanB

[Woodsie888]

Update....

Flushed and drained oil and removed the stator, all was well with no sign of damage, but we did find burning of the 3 phase wires when they were reconnected to the loom.. So a slight issue there.

One thing I did discover which was not explained is that you get 50-60vac with the stator out of circuit and only 10vac in circuit, so all was apparently fine from the start. We got 12.43vdc from the battery engine off, 14.05vdc at 3000rpm, so all okay there too.

Anyway inclipped all the connectors in the charging circuit and cleaned them, plus we added an earth lead from battery minus to the bike frame, this was because the only earth was from battery minus to the starter solenoid.

Got a new tacho drive cable so now I can see the engine rpm.

I have to say that when I rode the bike I thought it was fixed, but not so, the bike certainly runs better and revs better, but under hard acceleration it does misfire. The hot start problem is improved too, as when the bike stalled while I was opening my gate it did restart after only a few seconds.

So is this progress, perhaps, but not a result? I am starting to feel something approaching the 43bhp from the engine and it will rev to 9,000rpm, if the load is lowered.

Will look at the CDI unit next, but think that it either works or doesn't.

Are you 100% sure it is not leaning out for some reason Allan. Your description of the misfire is a characteristic of this.

What seems like an obvious electrical problem, can in fact be intake/fuel related.

You appear to have been very thorough with your checks so far. Perhaps it's time to back track a little?

Do you mean running too lean, had no idea this could lead to misfire, if so I am sure this is the case. I was thinking of trying to raise the needles, any idea how much? I understand that the fuel/air mixture screw only affects the throttle up to 25% open.

Unable to get an air filter, I cut the paper out of the old one and replaced it with sponge, thought that may be the problem, but removed the sponge and nothing changed.

Thanks.....

Cut 1 cm off the burned wires from the stator and found clean metal, tinned the ends and reconnected. Another fault sorted.

Yes, I do mean running too lean at higher rpm's and under load.

If it was my bike, I would make absolutely sure, the fuel/intake system is 100% correct.

Have the carb's, intake, cams or exhaust been modified in any way?

The sponge will let more air thru, hence leaning it out. Try blocking the air intake partially, although it is quite doubtful this will be your problem.

[AllanB]

Update....

Flushed and drained oil and removed the stator, all was well with no sign of damage, but we did find burning of the 3 phase wires when they were reconnected to the loom.. So a slight issue there.

One thing I did discover which was not explained is that you get 50-60vac with the stator out of circuit and only 10vac in circuit, so all was apparently fine from the start. We got 12.43vdc from the battery engine off, 14.05vdc at 3000rpm, so all okay there too.

Anyway inclipped all the connectors in the charging circuit and cleaned them, plus we added an earth lead from battery minus to the bike frame, this was because the only earth was from battery minus to the starter solenoid.

Got a new tacho drive cable so now I can see the engine rpm.

I have to say that when I rode the bike I thought it was fixed, but not so, the bike certainly runs better and revs better, but under hard acceleration it does misfire. The hot start problem is improved too, as when the bike stalled while I was opening my gate it did restart after only a few seconds.

So is this progress, perhaps, but not a result? I am starting to feel something approaching the 43bhp from the engine and it will rev to 9,000rpm, if the load is lowered.

Will look at the CDI unit next, but think that it either works or doesn't.

Are you 100% sure it is not leaning out for some reason Allan. Your description of the misfire is a characteristic of this.

What seems like an obvious electrical problem, can in fact be intake/fuel related.

You appear to have been very thorough with your checks so far. Perhaps it's time to back track a little?

Do you mean running too lean, had no idea this could lead to misfire, if so I am sure this is the case. I was thinking of trying to raise the needles, any idea how much? I understand that the fuel/air mixture screw only affects the throttle up to 25% open.

Unable to get an air filter, I cut the paper out of the old one and replaced it with sponge, thought that may be the problem, but removed the sponge and nothing changed.

Thanks.....

Cut 1 cm off the burned wires from the stator and found clean metal, tinned the ends and reconnected. Another fault sorted.

Yes, I do mean running too lean at higher rpm's and under load.

If it was my bike, I would make absolutely sure, the fuel/intake system is 100% correct.

Have the carb's, intake, cams or exhaust been modified in any way?

The sponge will let more air thru, hence leaning it out. Try blocking the air intake partially, although it is quite doubtful this will be your problem.

The carbs are in A1 condition and look totally original, I could easily blank off half the air filter, or oil the sponge. This is a lot of horsepower from a 400, which means highly strung and sensitive... and I have buggard about with the exhaust (now straight through), after someone else had, so that is not original at all.

[Woodsie888]

The carbs are in A1 condition and look totally original, I could easily blank off half the air filter, or oil the sponge. This is a lot of horsepower from a 400, which means highly strung and sensitive... and I have buggard about with the exhaust (now straight through), after someone else had, so that is not original at all.

Yes, I do mean running too lean at higher rpm's and under load.

If it was my bike, I would make absolutely sure, the fuel/intake system is 100% correct.

Have the carb's, intake, cams or exhaust been modified in any way?

The sponge will let more air thru, hence leaning it out. Try blocking the air intake partially, although it is quite doubtful this will be your problem.

I suspect you have answered your own question.

No back pressure = misfire under load at higher rpm.. (Straight through)

Solution = Richen the mixture. (Not via the mixture screw which is effectively only the idle circuit)

[AllanB]

We did have the misfire before we opened up the silencer. When it failed the MOT on noise levels we had a very restrictive baffle put it, which sapped the power/torque and made the exhaust run hot, that is why I went for a straight through box. The sound was a consideration too and there was a lot of twoing and throwing, but always that misfire and hot start problem.

Now we also get a lot of popping (forward firing) on deceleration, which again would denote a weak mixture.

[Woodsie888]

We did have the misfire before we opened up the silencer. When it failed the MOT on noise levels we had a very restrictive baffle put it, which sapped the power/torque and made the exhaust run hot, that is why I went for a straight through box. The sound was a consideration too and there was a lot of twoing and throwing, but always that misfire and hot start problem.

Now we also get a lot of popping (forward firing) on deceleration, which again would denote a weak mixture.

The hot start problem and misfire at higher rpm are likely to be separate issues.

[AllanB]

We did have the misfire before we opened up the silencer. When it failed the MOT on noise levels we had a very restrictive baffle put it, which sapped the power/torque and made the exhaust run hot, that is why I went for a straight through box. The sound was a consideration too and there was a lot of twoing and throwing, but always that misfire and hot start problem.

Now we also get a lot of popping (forward firing) on deceleration, which again would denote a weak mixture.

The hot start problem and misfire at higher rpm are likely to be separate issues.

That would be a bit of a bugga.. It is the hot start issue I would like to fix, I don't rev the bike that much, quite happy to use the torque and cruise at 80kpa, all day.

So what about the hot start problem? Run for about half an hour, at the lights the bike revs drop and eventually it stalls and for 2-3 minutes won't restart.

[Woodsie888]

We did have the misfire before we opened up the silencer. When it failed the MOT on noise levels we had a very restrictive baffle put it, which sapped the power/torque and made the exhaust run hot, that is why I went for a straight through box. The sound was a consideration too and there was a lot of twoing and throwing, but always that misfire and hot start problem.

Now we also get a lot of popping (forward firing) on deceleration, which again would denote a weak mixture.

The hot start problem and misfire at higher rpm are likely to be separate issues.

That would be a bit of a bugga.. It is the hot start issue I would like to fix, I don't rev the bike that much, quite happy to use the torque and cruise at 80kpa, all day.

So what about the hot start problem? Run for about half an hour, at the lights the bike revs drop and eventually it stalls and for 2-3 minutes won't restart.

Is cranking speed when trying to start in these conditions normal, or is the starter struggling to turn the motor?

[AllanB]

We did have the misfire before we opened up the silencer. When it failed the MOT on noise levels we had a very restrictive baffle put it, which sapped the power/torque and made the exhaust run hot, that is why I went for a straight through box. The sound was a consideration too and there was a lot of twoing and throwing, but always that misfire and hot start problem.

Now we also get a lot of popping (forward firing) on deceleration, which again would denote a weak mixture.

The hot start problem and misfire at higher rpm are likely to be separate issues.

That would be a bit of a bugga.. It is the hot start issue I would like to fix, I don't rev the bike that much, quite happy to use the torque and cruise at 80kpa, all day.

So what about the hot start problem? Run for about half an hour, at the lights the bike revs drop and eventually it stalls and for 2-3 minutes won't restart.

Is cranking speed when trying to start in these conditions normal, or is the starter struggling to turn the motor?

Cranking speed is 100% normal, but it won't fire, then after a couple of minutes, it just about fires up and then runs. At no time is the coolant temperature more than it should be and the cooling system has been flushed, however, I have never noticed any real pressure in the cooling system..

[Woodsie888]

Cranking speed is 100% normal, but it won't fire, then after a couple of minutes, it just about fires up and then runs. At no time is the coolant temperature more than it should be and the cooling system has been flushed, however, I have never noticed any real pressure in the cooling system..

Is cranking speed when trying to start in these conditions normal, or is the starter struggling to turn the motor?

That would be a bit of a bugga.. It is the hot start issue I would like to fix, I don't rev the bike that much, quite happy to use the torque and cruise at 80kpa, all day.

The hot start problem and misfire at higher rpm are likely to be separate issues.

So what about the hot start problem? Run for about half an hour, at the lights the bike revs drop and eventually it stalls and for 2-3 minutes won't restart.

RPM's dropping whilst idling and difficulty restarting would normally indicate a fuel/intake/carb problem.

I do understand you have checked this though and a myriad of other possibilities.

[AllanB]

Cranking speed is 100% normal, but it won't fire, then after a couple of minutes, it just about fires up and then runs. At no time is the coolant temperature more than it should be and the cooling system has been flushed, however, I have never noticed any real pressure in the cooling system..

Is cranking speed when trying to start in these conditions normal, or is the starter struggling to turn the motor?

That would be a bit of a bugga.. It is the hot start issue I would like to fix, I don't rev the bike that much, quite happy to use the torque and cruise at 80kpa, all day.

The hot start problem and misfire at higher rpm are likely to be separate issues.

So what about the hot start problem? Run for about half an hour, at the lights the bike revs drop and eventually it stalls and for 2-3 minutes won't restart.

RPM's dropping whilst idling and difficulty restarting would normally indicate a fuel/intake/carb problem.

I do understand you have checked this though and a myriad of other possibilities.

You are not kidding, just taking a break from cleaning up all the electrics, surprised to find 2 CDI units, happy to discover they are not unique to this bike in case I need one. However, I think they either work or don't, so will leave that.

Only a few earth issue found so far to rectify, but cleaning may do something you never know, it is running better since I added a chassis earth, but after four maybe it is playing tricks with my mind.

Half the people I speak to say fuel, half say electrics, so wait and see, hopefully not another 4 months. The thing is we have found dozens of faults and corrected them, but nothing fixes this particular problem. Perhaps it is time for the spiritual approach, question is whiskey or vodka?

Oh one thing I forgot to mention, a month or so ago, I hit the wrong part of a speedbump a bit hard with a thum and everything went off, engine, lights, the lot, 10 seconds later it was all back to normal.

[KRS1]

get the bike into 'wont start' mode...then pull the plugs and see if its getting any spark. Ground it to the head.

i had a tzm 150 with the exact same problem, culprit was a faulty cdi.

[AllanB]

get the bike into 'wont start' mode...then pull the plugs and see if its getting any spark. Ground it to the head.

i had a tzm 150 with the exact same problem, culprit was a faulty cdi.

Thanks for that, hadn't heard of CDI being faulty, only working or bust. I always felt that when it won't start it is only one cylinder missing, now I know I have 2 CDIs a fault on one could explain that.

[seedy]

Oh one thing I forgot to mention, a month or so ago, I hit the wrong part of a speedbump a bit hard with a thum and everything went off, engine, lights, the lot, 10 seconds later it was all back to normal.

Sounds like a bad connection - at first guess a bad ground (earth)

Good news re: the CDI

Edited February 12, 2014 by seedy

[yankee99]

Heres a idea! Take your plugs out and post good photos of the electrode and insulator this can eliminate some problems. Also when were the plugs last replaced?

[KRS1]

get the bike into 'wont start' mode...then pull the plugs and see if its getting any spark. Ground it to the head.

i had a tzm 150 with the exact same problem, culprit was a faulty cdi.

Thanks for that, hadn't heard of CDI being faulty, only working or bust. I always felt that when it won't start it is only one cylinder missing, now I know I have 2 CDIs a fault on one could explain that.

you may have two problems that create a larger one, check to see the plugs are the correctly specified heat range.

after multiple removals the plugs crush washer will become over flattened and throw it into a different operating temperature range. This happened to me on a cbr 150 with iridium plugs, and caused backfire.

[bigdod]

get the bike into 'wont start' mode...then pull the plugs and see if its getting any spark. Ground it to the head.

i had a tzm 150 with the exact same problem, culprit was a faulty cdi.

Thanks for that, hadn't heard of CDI being faulty, only working or bust. I always felt that when it won't start it is only one cylinder missing, now I know I have 2 CDIs a fault on one could explain that.

you may have two problems that create a larger one, check to see the plugs are the correctly specified heat range.

after multiple removals the plugs crush washer will become over flattened and throw it into a different operating temperature range. This happened to me on a cbr 150 with iridium plugs, and caused backfire.

Problem with the iridium plugs is that iridium is a crap conductor of electricity and the electrodes are just too small. I heard reports of guys all over back home cooking those plugs. I've never had any issues with NGK plugs and I've had them in all sorts - even used them in a turbo engine and only had to drop to a colder plug when I was racing, rest of the time was standard heat rating & standard gaps...

Engine popping on the over run is coz you've lost the backpressure in the exhaust, learn to live with it coz it wont go away til you put baffles back in.

The misfire sounds very indicative of a low float height in the carbs. This will lean off the mixture and will be most noticeable at around 4000rpm. Will also cause your bike to run hot, but shouldn't be such a big issue if its liquid cooled. Also with it flowing too much air, I don't know, but if you cant get a hold of the proper air filter, this coupled with the open pipes is really going to mess up your fuelling and a re-jet will likely definitely be on the cards. If you do that, I'd also recommend picking up a set of O rings for the carbs because it sounds as though you've had them off and on a few times now - if a couple of those have flattened off and are bleeding air in, you'll chase the problem all day and never see it. One more thing to look at in detail is the bleed holes from the pilot circuit into the venturi - basically those little holes just near the slide - that's where the air fuel mix gets in when your throttle's closed. The fuel over here with the alcohol in it holds moisture in, unlike 'proper' fuel which separates out from water, and its pretty well known that the tanker drivers all tap a little bit off for themselves and top it up with water, so when your bikes lying in the shed for months on end with this stuff in the carbs, the fuel evaporates of and leaves the watery shellacy gunky crap in yer carbs to work its wonders on the aluminium. That stuff doesn't shift easily. its worth using fuel stabilisers or even better still draining the carbs and blowing them through if you can before you store it. You'll have to mess around with carb cleaners and solvents and high flow compressed air to shift that stuff if you suspect it.

Hot starting - if your fuel line from the tank is a pretty much straight run with no up & downy "u - bend" sections in it, and of course your carb breathers are clear, then its unlikely to be vapour locked. Honda were renowned for producing decent bikes with $hitty electrics around that period of time and yes, some of the faults do turn up when the bikes hot coz hot stuff flows electricity differently from cold stuff, pity the only way to rule a part out completely is by changing it.

Good luck....don't let it beat you

[AllanB]

get the bike into 'wont start' mode...then pull the plugs and see if its getting any spark. Ground it to the head.

i had a tzm 150 with the exact same problem, culprit was a faulty cdi.

Thanks for that, hadn't heard of CDI being faulty, only working or bust. I always felt that when it won't start it is only one cylinder missing, now I know I have 2 CDIs a fault on one could explain that.

you may have two problems that create a larger one, check to see the plugs are the correctly specified heat range.

after multiple removals the plugs crush washer will become over flattened and throw it into a different operating temperature range. This happened to me on a cbr 150 with iridium plugs, and caused backfire.

Problem with the iridium plugs is that iridium is a crap conductor of electricity and the electrodes are just too small. I heard reports of guys all over back home cooking those plugs. I've never had any issues with NGK plugs and I've had them in all sorts - even used them in a turbo engine and only had to drop to a colder plug when I was racing, rest of the time was standard heat rating & standard gaps...

Engine popping on the over run is coz you've lost the backpressure in the exhaust, learn to live with it coz it wont go away til you put baffles back in.

The misfire sounds very indicative of a low float height in the carbs. This will lean off the mixture and will be most noticeable at around 4000rpm. Will also cause your bike to run hot, but shouldn't be such a big issue if its liquid cooled. Also with it flowing too much air, I don't know, but if you cant get a hold of the proper air filter, this coupled with the open pipes is really going to mess up your fuelling and a re-jet will likely definitely be on the cards. If you do that, I'd also recommend picking up a set of O rings for the carbs because it sounds as though you've had them off and on a few times now - if a couple of those have flattened off and are bleeding air in, you'll chase the problem all day and never see it. One more thing to look at in detail is the bleed holes from the pilot circuit into the venturi - basically those little holes just near the slide - that's where the air fuel mix gets in when your throttle's closed. The fuel over here with the alcohol in it holds moisture in, unlike 'proper' fuel which separates out from water, and its pretty well known that the tanker drivers all tap a little bit off for themselves and top it up with water, so when your bikes lying in the shed for months on end with this stuff in the carbs, the fuel evaporates of and leaves the watery shellacy gunky crap in yer carbs to work its wonders on the aluminium. That stuff doesn't shift easily. its worth using fuel stabilisers or even better still draining the carbs and blowing them through if you can before you store it. You'll have to mess around with carb cleaners and solvents and high flow compressed air to shift that stuff if you suspect it.

Hot starting - if your fuel line from the tank is a pretty much straight run with no up & downy "u - bend" sections in it, and of course your carb breathers are clear, then its unlikely to be vapour locked. Honda were renowned for producing decent bikes with $hitty electrics around that period of time and yes, some of the faults do turn up when the bikes hot coz hot stuff flows electricity differently from cold stuff, pity the only way to rule a part out completely is by changing it.

Good luck....don't let it beat you

First of all the "forward firing" is a nice sound and I like it, so I am fine with that.

The float chambers were checked and both okay.

I looked on a couple of Japanese websites, through Google-Translate and the plugs are right for the model and year, they were the first thing I replaced when I got the problem, so all new. I then tried a combination of 5 coils, all secondhand, then on to carbs, all the things you would associate with the symptoms.

The carbs don't have o-rings, they have rubber tubes and hose clips and all is well.

I am working on checking and cleaning up all the electrics at present, found a lousy connection from the ignition switch, a little burned at the junction end, found clean wires, tinned and reconnected and added another earth anchor at the front, which I will run back to the battery. Cleaned up all the connectors, so when I have finished, I should have good electrics to tick off.

Tried to get a photo of a spark plug, but after 20 photos, none look like the plug in terms of colour, they look good though, terracotta electrodes and a tiny amount of soot around the threads.

Heat wise the engine runs as it should, though it is cool here in Isaan, but I have only ever used the fan in traffic, even at 38degc ambient.

The next thing to do is switch to benzin, get a couple of tankfuls in it and see.

Thanks...

[AllanB]

Well, that's the entire electrical system checked and renewed where necessary, excluding the instrument panel, which was looking a little fragile to risk dismantling. The ignition switch is not the best, but it works and all the other faults are now 100%.

Anyway, I now have the tacho working, which gives me a bit more information and this morning went out testing.

Ignoring the hot start problems, which I assume still exist, I found this.

After I warmed it up, I still had the misfire.

At over 2000rpm at full open throttle..misfire.

At 3-4000rpm at partial throttle..misfire.

At 6000rpm any amount of throttle would cause a misfire, so the bike will not go over 6000rpm, on the flat.

On the driveway, I can get 7000rpm

The bike produces max power at 9000rpm and peaks at 10,0000.

This would lead me to believe fuel starvation...any other ideas?

Edited February 15, 2014 by AllanB

[VocalNeal]

Is it both cylinders? Do a two-stroke type plug chop to find out. Warm the bike up go for a ride, induce the missfire at full throttle, then simultaneously pull in the clutch and hit the kill switch. By the roadside remove each plug and see if either is different.

[paz]

This would lead me to believe fuel starvation...any other ideas?

That, as said many times already, you have a faulty CDI or timing pick-up.

[AllanB]

Some success,..... I think.

Knowing that Steed coils are better than the original NV coils, I borrowed two from my friend's Steed and the bike runs much better and after a long thrash, the bike still ticked over okay and restarted every time. We rode around town and still it re-started.

I already have one Steed coil and bought another for 500baht, so I now have to mount them properly making a couple of brackets. I plan on fitting an ally heat shield under them as they are directly above the engine and trapped in the void under the petrol tank.

I also need some HT cable and will be starting another thread to find a supplier, otherwise buy it in the UK and get them to ship it here.

As for the under-load misfire, the next thing is to raise the needles in the carbs and perhaps try some petrol, but I can live with that for now, as I don't ride the bike hard.

The bike has two CDI units, so I don't suspect those at present, as the fault only occurs under load and even if I did I cannot get replacements.

[seedy]

In post #48 you said CDI units not unique to your bike. Still no luck sourcing replacements ???

Sure wish there was some way to get past the epoxy filling on these things, and expose the 3 dollars worth of parts inside !!!