Stator test readings

[Spoonman]

Have you ruled out the Gasohol yet ?

[AllanB]

Yes, you are right, the CDI units 2 off, are AKBZ07 (131.100-3553, 12v MF5) which are also fitted to the VT500, so they are obtainable, just. However, with both units in good condition and having to order from the UK, http://www.ebay.co.uk/sch/i.html?_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XAKBZ07&_nkw=AKBZ07&_sacat=0&_from=R40 I will leave that for now. There is a German guy in Pattaya who has one, but I have lost his phone number...I bought the coils from him.

Next on the list, after I have the 2nd coil fitted correctly, still needing a longer HT cable 60cm would be just enough, is to try some petrol/benzin. I have my doubts, but "after you have eliminated the impossible, whatever remains, however improbable, must be the truth."

[KRS1]

can you list the sparkplug number please?

[paz]

can you list the sparkplug number please?

Wrong sparkplugs don't cause major misfire. Neither HT cable or gashol do, but let the OP chase ghosts his own style.

[AllanB]

can you list the sparkplug number please?

Wrong sparkplugs don't cause major misfire. Neither HT cable or gashol do, but let the OP chase ghosts his own style.

The sparkplug is the good old dash 9, the DPR8AE-9 to be precise, fitted to nearly all Hondas, got it from the Jap website. Not sure about the gap though, most are 0.9mm (35 thou), but I think it should be 0.6mm (25 thou), so settled for 0.7 and a bit (about 29 thou), nothing made any difference anyway. But it would nice to know, one day.

Managed to get some HT lead, it is orange, but mostly hidden under the tank, will worry about aesthetics after it is running 100%.

Ghosts eh, well this is Thailand, perhaps a few bits of well placed string may be the answer.

........Just had a thought, how do the float chambers breath?

[KRS1]

my 3 hondas in the past did not have those sparkplugs

the gap for that plug is speced at 0.036" as you mentioned, but since its on gasohol.....its going to run hotter so maybe try a colder plug.

on the cbr 250 the stock plug (SIMR8A9) is an '8' which is 3mm shorter than a '9' plug (CR9EIX or CR9EGP))...from my experience on a cbr 150 in the past an '8' caused misfiring compared to a '9'.

[seedy]

The NGK -9 plug means 0.9mm gap. Google NGK part decoder and get the whole part number breakdown. Just be aware that a higher number in NGK means a colder, not a hotter plug like all the other mfg's. BR9ES is colder than 8ES.

Carb float bowls breath thru a vent hole, usually with a small diameter hose attached for when the bike falls over or crashes the raw fuel is directed away from the pipes, etc.

[yankee99]

can you list the sparkplug number please?

Wrong sparkplugs don't cause major misfire. Neither HT cable or gashol do, but let the OP chase ghosts his own style.

Exactly correct

[AllanB]

The NGK -9 plug means 0.9mm gap. Google NGK part decoder and get the whole part number breakdown. Just be aware that a higher number in NGK means a colder, not a hotter plug like all the other mfg's. BR9ES is colder than 8ES.

Carb float bowls breath thru a vent hole, usually with a small diameter hose attached for when the bike falls over or crashes the raw fuel is directed away from the pipes, etc.

Thanks for that, dash 9 obvious I guess, so I will set the plug at 35 thou, as the Japanese website who sell spares for this home market only model, specify that and so did the guy in our big bike shop.

So I guess if that hole is partially blocked in the float chamber/s, the slight vacuum effect could cause fuel starvation when flow is at it's highest under full load. Easy to get to and worth a look, but didn't see an over pipe/s.

[seedy]

Maybe rotted off. Will usually be in the casting forming the top of the carb body, not the float bowl itself.

If they are partially plugged, may cause fuel starvation I guess. Never heard of it but still have lots to learn.

What brand carbs - Kiehen ??

[KRS1]

can you list the sparkplug number please?

Wrong sparkplugs don't cause major misfire. Neither HT cable or gashol do, but let the OP chase ghosts his own style.

Exactly correct

yes it will can

Edited February 16, 2014 by KRS1

[AllanB]

Can anyone tell me whether these two float chamber levels are okay. I am used to carbs being upright?

[seedy]

Hard to tell from the pics. Is vertical the top of the foto ???

I see what you mean that there is zero room - tight in there !!!

[seedy]

What make and model carbs ?? I will investigate and see what info I can uncover.

[AllanB]

Hard to tell from the pics. Is vertical the top of the foto ???

I see what you mean that there is zero room - tight in there !!!

I tried to keep the camera straight and the bike was upright.

The carbs are no too bad actually, the tank comes off with one bolt (plus 2 m6 seat bolts) and I can get the carbs off in a couple of minutes.

I assume the overflow doubles as a breather on the Keihins

[VocalNeal]

Float in the chamber pivots so the carb doesn't need to be vertical if designed that way.

That screw in the centre of each picture is the mixture adjustment have you done the "increase idle speed, adjust mixture to get idle right, then decrease idle speed, adjustment on each carb" to get the mixture correct?

Just wondering?

Edited February 20, 2014 by VocalNeal

[Woodsie888]

Float in the chamber pivots so the carb doesn't need to be vertical if designed that way.

That screw in the centre of each picture is the mixture adjustment have you done the "increase idle speed, adjust mixture to get idle right, then decrease idle speed, adjustment on each carb" to get the mixture correct?

Just wondering?

Looking at the wear on the screw slots, I'd say those screws and been fiddled with more than a boy in a Catholic Boy's Home.

[VocalNeal]

Float in the chamber pivots so the carb doesn't need to be vertical if designed that way.

That screw in the centre of each picture is the mixture adjustment have you done the "increase idle speed, adjust mixture to get idle right, then decrease idle speed, adjustment on each carb" to get the mixture correct?

Just wondering?

Looking at the wear on the screw slots, I'd say those screws and been fiddled with more than a boy in a Catholic Boy's Home.

Agreed but doesn't mean that Allan did?

[AllanB]

I know where all the adjustment screws are, they have all been set up including the balance, I just need to establish what level the fuel in the float chambers should be. On a vertically mounted carb, it is quite easy, just below the level of the top of the bowl, but these are mounted at an angle.

As far as I can see the overflow doubles as a float chamber breather and the breather outlet is at a high level, so if the bowl is too full it will flow into the overflow, without spilling out, but will block the breather.

If the breather is blocked (by fuel) it will create a partial vacuum and could be the cause of the misfire under full power due to fuel starvation.

The level in one of the bowls is slightly higher than the other, so maybe I should adjust that down?

I assume all V twins have their carbs mounted at this angle, a semi downdraft i believe it is called.

Edited February 20, 2014 by AllanB

[VocalNeal]

If you suspect a lean mixture I would adjust the other one up first and see what happens. If they are so different then you should see it in the colour of the plugs?

Just a thought. Have you run the bike on each cylinder separately to ascertain if it is one cylinder misfiring or both?

Edited February 21, 2014 by VocalNeal

[AllanB]

If you suspect a lean mixture I would adjust the other one up first and see what happens. If they are so different then you should see it in the colour of the plugs?

Just a thought. Have you run the bike on each cylinder separately to ascertain if it is one cylinder misfiring or both?

The back cylinder plug is a little leaner than the front, but with a straight through exhaust and a sponge air filter, lean is what I would expect. So I am considering raising the needles to compensate.

Did another measurement of fuel levels in each chamber, this time using a spirit level and they are both the same, give or take a mm.

Anyway stripped the carbs down yet again and found nothing untoward, the vent is right up the top of the float chamber, almost 50mm higher than the fuel level, so bang goes my latest theory. If anything the fuel level could be higher but the floats are correct, being just below topping out on the carb body.

The misfire only occurs under full power, so difficult to test one cylinder under those conditions, I am thinking of getting hold of a digital tacho the type that pick up on the plug HT, that would tell me whether the misfire was electrical or not and if so which cylinder. At least I would be closer, but haven't seen them for sale here, which may mean getting my sister to ship one to me.

http://www.ebay.co.uk/itm/Spark-Plugs-Engine-Digital-Tach-Hour-Meter-Tachometer-Gauge-/321234666271?pt=UK_Motorcycle_Parts&hash=item4acb14031f

Anyone seen these here?

[Woodsie888]

If you suspect a lean mixture I would adjust the other one up first and see what happens. If they are so different then you should see it in the colour of the plugs?

Just a thought. Have you run the bike on each cylinder separately to ascertain if it is one cylinder misfiring or both?

The back cylinder plug is a little leaner than the front, but with a straight through exhaust and a sponge air filter, lean is what I would expect. So I am considering raising the needles to compensate.

Did another measurement of fuel levels in each chamber, this time using a spirit level and they are both the same, give or take a mm.

Anyway stripped the carbs down yet again and found nothing untoward, the vent is right up the top of the float chamber, almost 50mm higher than the fuel level, so bang goes my latest theory. If anything the fuel level could be higher but the floats are correct, being just below topping out on the carb body.

The misfire only occurs under full power, so difficult to test one cylinder under those conditions, I am thinking of getting hold of a digital tacho the type that pick up on the plug HT, that would tell me whether the misfire was electrical or not and if so which cylinder. At least I would be closer, but haven't seen them for sale here, which may mean getting my sister to ship one to me.

http://www.ebay.co.uk/itm/Spark-Plugs-Engine-Digital-Tach-Hour-Meter-Tachometer-Gauge-/321234666271?pt=UK_Motorcycle_Parts&hash=item4acb14031f

Anyone seen these here?

Allan, I'm surprised you're still 'considering' raising the needles to richen the mixture since I raised the possibility some time ago after your disclosure of exhaust/intake mods and the number of posters who subsequently suggested the same since then.

Mechanics is a whole lot more to do with practicality and experience than 'theory' and it seems there are a few posters here who have a lot of practice. The self taught enthusiasts sit in another basket where a little knowledge is a dangerous thing.

Why don't you richen it as suggested and then report back on the result in order to move on?

Please don't think I'm being rude and if you think I am, I do apologise.

You know the Nike tag line 'Just do it'.

Forget the mixture screws as they only effect the idle circuit which does actually still operate at surprisingly high rpm's but not full power.

[AllanB]

If you suspect a lean mixture I would adjust the other one up first and see what happens. If they are so different then you should see it in the colour of the plugs?

Just a thought. Have you run the bike on each cylinder separately to ascertain if it is one cylinder misfiring or both?

The back cylinder plug is a little leaner than the front, but with a straight through exhaust and a sponge air filter, lean is what I would expect. So I am considering raising the needles to compensate.

Did another measurement of fuel levels in each chamber, this time using a spirit level and they are both the same, give or take a mm.

Anyway stripped the carbs down yet again and found nothing untoward, the vent is right up the top of the float chamber, almost 50mm higher than the fuel level, so bang goes my latest theory. If anything the fuel level could be higher but the floats are correct, being just below topping out on the carb body.

The misfire only occurs under full power, so difficult to test one cylinder under those conditions, I am thinking of getting hold of a digital tacho the type that pick up on the plug HT, that would tell me whether the misfire was electrical or not and if so which cylinder. At least I would be closer, but haven't seen them for sale here, which may mean getting my sister to ship one to me.

http://www.ebay.co.uk/itm/Spark-Plugs-Engine-Digital-Tach-Hour-Meter-Tachometer-Gauge-/321234666271?pt=UK_Motorcycle_Parts&hash=item4acb14031f

Anyone seen these here?

Allan, I'm surprised you're still 'considering' raising the needles to richen the mixture since I raised the possibility some time ago after your disclosure of exhaust/intake mods and the number of posters who subsequently suggested the same since then.

Mechanics is a whole lot more to do with practicality and experience than 'theory' and it seems there are a few posters here who have a lot of practice. The self taught enthusiasts sit in another basket where a little knowledge is a dangerous thing.

Why don't you richen it as suggested and then report back on the result in order to move on?

Please don't think I'm being rude and if you think I am, I do apologise.

You know the Nike tag line 'Just do it'.

Forget the mixture screws as they only effect the idle circuit which does actually still operate at surprisingly high rpm's but not full power.

I have received advice from a number of sources, including a old Team Suzuki mechanic who, along with others are convinced the misfire is electrical fault. He has suggested the needles need lifting too, just to correct the mixture.

So far I have been going through the possibilities in order and then testing and have found and fixed a number of faults along the way, some of which have improved the overall engine performance and at the moment the misfire is much less noticeable than it was.

An over lean mixture is/was considered an unlikely source of the misfire, but as we eliminate more of the probables, the less likely becomes more likely. We spent a lot of time playing with the silencer baffles including one which was highly restrictive and nothing made any difference and that steered us away from mixture being a probably culprit. When I bought the bike the silencer was the only thing that was none standard, actually failing the MOT on excessive noise and the reason I have a sponge air filter is because I can't get an original, so I removed the dirty paper element and installed some foam.

I don't think you are being rude and thank you for your contribution, this problem is becoming rather annoying, though I am getting to know the bike rather well and luckily it is quite easy to work on.

With so many differing opinions from the many sources, I merely use my mechanical engineering experience to prioritise a course of action in trying to solve this. So far it seems I have been wrong as the solution is yet to be found.

Anyway tomorrow morning the needles go up.

[seedy]

You will find that inline v-twins usually have the rear cylinder running a little hotter. All the heat from the front cylinder flows back, so they have to deal with this extra heat too. Once you got ér running sweet, try bumping up one main jet size on the rear to see if it makes a difference.

My old Kawa 3-cyl middle cylinder was the worst in my experience. Went up two main jet sizes if I remember to compensate for it running hotter.

In those days of regular gas spark plug reading was much easier, ceramic color was uniform. Now with unleaded gas I need to use a lighted magnifier to look into the ceramic and see what is going on.

Could be old eyes too.

[AllanB]

An early start, daybreak.....Actually I remember why we didn't enrich the mixture up until now, the needle height is non-adjustable on the this Keihin VD carb, which means either new needles or a bodge, which involves putting a small 3mm diameter washer under the needle.

I tried one washer, but raising a needle with such a fine taper by only 1mm will make very little difference.

Looked on the web to find info about this carb and interestingly http://www.felesgrata.dk/VF/VF1000F2/4-Fuel%20System.pdf has a diagnostics section which says "Misfiring under acceleration" -"faulty ignition system"

Anyway I checked float levels against spec and they are both spot on at 7.5mm.....so one more thing ticked off but we are still no closer.

It has been suggested that to compensate for the higher air flow through the modified filter, I should blank off part of it, so I may do that and lose 30% of the filter area. This is easy to do with a piece of cardboard.

[AllanB]

Sorry, it's me again. After all the work including fitting coils tested on another bike, the hot start problem is back and although the under-load misfire is better, it is still there.

I had wrapped the rubber fuel pipe which touches the rocker cover up in tin foil, but left that off during the latest strip down, so a vapour lock may be the issue, but I have a question.

I read on another forum that some bikes have a temperature sensor feed to the ECU, does anyone know if the Steed had such a sensor? Or does this only apply to fuel injected bikes?

Anyway the foil is back so we shall see.....

[seedy]

I read on another forum that some bikes have a temperature sensor feed to the ECU

Nor familiar with your bike, but you probably have a temp switch to tell the cooling fan when to cut in, if you have a cooling fan on the back of the radiator.

[AllanB]

I read on another forum that some bikes have a temperature sensor feed to the ECU

Nor familiar with your bike, but you probably have a temp switch to tell the cooling fan when to cut in, if you have a cooling fan on the back of the radiator.

That is more of a thermostat, rather than an analogue sensor feeding an ECU and no, I have a simple manual type fan switch. What I am referring to is a sensor in addition to other sensors like crank position and perhaps oxygen sensors, etc. which are required for electronic fuel injection systems.

Maybe that was not available back in the early eighties..?

[seedy]

Does your bike have an ECU, or is it just a CDI ignition system ??

[VocalNeal]

Allan,

Have you checked other stuff like valve clearances or even cam timing. Maybe someone other than you has been "playing" and if one cam timing on one cylinder was one tooth off?