Engine Misfire In Mid Rev Range

[wana]

i have a Tiger Boxer 250 thats been serviced only last week and its got a weird engine misfire in the mid range of every gear ,its not bad enough to stall the bike but when it coughs and then fires properly you can feel the surge of power

kick in

it happens about half way up the rev range (thats a rough guess because it doesnt have a tacho )

clean oil was put on saturday along with a new spark plug and throttle cable when i got it serviced

it only runs on benzine 91 because i dont like using gasohol if i can help it

anyone know what might fix this problem ? id rather not bring it back to the dealer but i will if i have to

[iono]

Sounds like a carb issue, I've had similar issues (and more) with my bike (not a boxer), mine came down to replacing jets and eventually a carb....however what I would suggest is buying a fuel additive that will clean the carb at the same time look for some spray for cleaning the carb (Tesco or Big C should sell the additive)...for the spray if you can find it, just take off the air filter start the bike and spray as what you are attempting to do is clean clogged jets...I've heard that sea foam is the way to go, but not available in the land of mediocrity....

Edited September 15, 2011 by iono

[wana]

its particularly noticeable when going up hill+ with a passenger ,you change gear and feel the power steadily increase until the misfire ( somewhere around 5000rpm i would guess ,the engine kinda stutters for a second ) then it fires properly and bursts forward and goes smoothly up to the top of the rev range

it does the same thing in every gear but its most noticable in 2nd ,3rd ,4th and especially up hills you notice any loss of acceleration that much faster so its more apparent when power comes back on

i have seen those fuel cleaners and boosters in the supermarkets before but ive never tried any of them before ,it would be great if that cured it but maybe replacing the carb jets would be cheaper in the long run than using fuel additives

i dont really "need" the boxer on a daily basis so i could drop in to the service centre and let them have a crack at it

i would like rubber dampers put between the engine mounting brackets and the frame to ease the handle bar vibrations also so maybe they could do both when its in

[KRS1]

Sounds like an overtightened sparkplug, too close to the piston and indexing the exhaust ports.

If it's an NGK the washer shouldn't be flattened out completely, if it is you'll probably need another plug. If its a Nippon Denso the washers are already flat.

Tighten with fingers as much as you can, then tighten with tool 1/4-1/2 turn. It shouldn't be dead tight, when it gets heated it will expand and tighten.

If you look on the box the sparkplug came in, you will see an illustration, stick to it. The NGK will have a picture of the washer in relation to turns and washer flattening height.

Change it yourself, its hard to explain in thai and is simple to do.

Edited September 15, 2011 by KRS1

[wana]

Sounds like an overtightened sparkplug, too close to the piston and indexing the exhaust ports.

loosen it, then retighten with fingers as much as you can, then tighten with tool 1/4-1/2 turn. It shouldn't be dead tight, when it gets heated it will expand and tighten.

If it's an NGK the washer shouldn't be flattened out completely, if it is you'll probably need another plug. If its a Nippon Denso the washers are already flat.

If you look on the box the sparkplug came in, you will see an illustration, stick to it. The NGK will have a picture of the washer in relation to turns and washer flattening height., the ND will have a picture of the turns since its already flat.

they didnt show me the box and i didnt ask to see it ,i dont know what brand of plug they changed on saturday ,probably the cheapest they could get their hands on or whatever was lying around the shop on a saturday morning

[KRS1]

If it is the plug, they probably had good intentions, just didn't know.

[wana]

there is a tool kit under the seat which includes a plug wrench ,but in traditional thai fashion ,you need tools to remove the seat to get access to the tools

all my tools is at a friends home in pattaya but i might buy a socket set and a few bits n pieces to keep in the condo in bkk for small jobs like this

[KRS1]

LOL... i keep the seat bolt loose on my CBR so i can access the battery and fuses quickly.

[wantan]

there is a tool kit under the seat which includes a plug wrench ,but in traditional thai fashion ,you need tools to remove the seat to get access to the tools

all my tools is at a friends home in pattaya but i might buy a socket set and a few bits n pieces to keep in the condo in bkk for small jobs like this

The tool kit for the Tiger Boxer 250 should be under the plastic cover on the left side (cover battery). You just need a screwdriver to open it.

Is the spark plug connector sitting tight? Ignition cable broken? Did the do something on the carb at the service (cleaning, adjustment)?

You should check the intake rubber too. I mean the rubber part between the carb and the engine intake. It easily gets broken on the Boxer and can create weird symptoms depending on the engine vibration (rev). Is the bike starting easily?

[wantan]

wana, do you use gasohol? I had to replace the Teikei carb on my Boxer because it was broken by gasohol. The problem was the long time the bike was standing (repairs, previous owner) with gasohol in it. The gasohol eats up the plastic parts in the carb. I had symtoms like you and wasted a long time trying to clean the carb and adjust it properly. I had to replace the carb and now the bike is running fine. Hope its not the same with your bike.

[hedonist44]

wana, do you use gasohol? I had to replace the Teikei carb on my Boxer because it was broken by gasohol. The problem was the long time the bike was standing (repairs, previous owner) with gasohol in it. The gasohol eats up the plastic parts in the carb. I had symtoms like you and wasted a long time trying to clean the carb and adjust it properly. I had to replace the carb and now the bike is running fine. Hope its not the same with your bike.

I agree.

[wana]

i dont like gasohol and only put benzine in older design engines like the boxers and the last guy told me he used red 91 whenever he could as well ,but he also said he rarely used the bike for months since he bought a new car so there is a possibibilty gasohol has been left eating away at the rubber components

it was difficult to start last week week but since the service it starts easy with the electric and the kick starter and i wil only put red 91 in it whenever possible

[VocalNeal]

50% RPM or 50% throttle?

You have a new spark plug and they had to take the slide out of the carburettor to install a new cable.

First rule of fault finding is "What has changed"

1) Spark plug is the wrong one or faulty.

2) The rubber plug on top of the spark plug is not properly seated or tight.

3) someone decided to do you a favour and change the needle height to save fuel or whatever.

a third but outside chance would be a wire in the ignition circuit momentarily shorting against the frame at the frequency caused by 50% rpm. This was distrubed when they replaced the spark plug.

If dealer is close simply go back. If not change the plug yourself and that eliminates one problem. If someone else with a 250 can tell us the stock needle height then you can check that also.

Generic picture of needle clip position

Whacky idea. On the stand rev the bike to 50% in the dark and see if you can see any sparks.

Edited September 15, 2011 by VocalNeal

[wantan]

i dont like gasohol and only put benzine in older design engines like the boxers and the last guy told me he used red 91 whenever he could as well ,but he also said he rarely used the bike for months since he bought a new car so there is a possibibilty gasohol has been left eating away at the rubber components

it was difficult to start last week week but since the service it starts easy with the electric and the kick starter and i wil only put red 91 in it whenever possible

If you (or the mechanic) do a carb cleaning than you should look for signs of broken plastic parts. On the picture you see my old carb. There is a lot of the black plastic float missing in one corner. The whole missing plastic has to go through the jets and can block the jets at any time. But this was not my only problem. The whole system of vacuum chamber and enrichener circuit diaphram was affected and rough running. I am sure my problems with the carb were caused by gasohol.

But this is only a wild guess. Maybe your problem is something completely different.

VocalNeal is right, the height of the needle is affecting the power when throttle half open. But if noone has changed it it should be OK. Normally they should have told you if they have opened the carb, so i hope they did not

[wana]

50% RPM or 50% throttle?

You have a new spark plug and they had to take the slide out of the carburettor to install a new cable.

First rule of fault finding is "What has changed"

1) Spark plug is the wrong one or faulty.

2) The rubber plug on top of the spark plug is not properly seated or tight.

3) someone decided to do you a favour and change the needle height to save fuel or whatever.

a third but outside chance would be a wire in the ignition circuit momentarily shorting against the frame at the frequency caused by 50% rpm. This was distrubed when they replaced the spark plug.

If dealer is close simply go back. If not change the plug yourself and that eliminates one problem. If someone else with a 250 can tell us the stock needle height then you can check that also.

Generic picture of needle clip position

Whacky idea. On the stand rev the bike to 50% in the dark and see if you can see any sparks.

its hard to tell without exactly without a tachometer but the boxer is not a hi -revving bike the cbr 150 so the power/torque is lower down (not sure where the red line is )

by sound/feeling alone id estimate the misfire kicks in about 5000-6000rpm and when you give it more gas it carries on through the rev range when it fires properly again

the dealer is only 10km away so il let them have another crack at it if the spark plug adjust doesnt work

[VocalNeal]

so il let them have another crack at it if the spark plug adjust doesnt work

That is a very good point that I missed. One always assumes... It is almost 100% that they took the plug out of the box and installed it without gaping it. This is critical on some small 2T scooter but maybe also is on Tiger.

Spark plugs are cheap so better of with a new one. Buy a replacement gap it correctly and then install.

[wana]

this is the new plug they installed just a few days ago ,looks way too black ,maybe need to get the carb checked out or replaced

by the looks of things the mix ratio is too rich

tiger service centre ,here we come!

[KRS1]

the dealer is only 10km away so il let them have another crack at it if the spark plug adjust doesnt work

make sure you use a new plug because the washer may be too flat now. You can change the washer if you have another old plug thats known to be good, but you need vice grips and a wrench that will fit the plug to remove the over flattened one.

plugs are only 80 baht...but 120 for platinum and 350 for iridium.

[wana]

the factory manager have just agreed to take it back and fix all the issues that the showroom were unable to rectify on saturday

not sure how long it will take yet though but il update the thread when/if they bring it back

[KRS1]

Good god that plug looks nasty !

No need to replace whole carb, floats and jets can be purchased separately. If you do get a new carb, sell me your old one please if its bigger than 28mm

Edited September 15, 2011 by KRS1

[wana]

Good god that plug looks nasty !

No need to replace whole carb, floats and jets can be purchased separately. If you do get a new carb, sell me your old one please if its bigger than 28mm

the spark plug is only a few days old and its covered in thick black soot ,neutral gear just doesnt want to engage ,the back brake caliper is loose

(if they give me a new carb you can have the old one for free )

if you think the plug is bad check this

the front fender bracket was so brittle it cracked while driving over the rama bridge well over 100kmph and scared the shit outta me when i heard this clanging banging noise of the fender bouncing off the forks

when it came loose

[KRS1]

One day is all it takes for that soot to accumulate, are you going to try a new plug, not overtightened or are you just going to give it to Tiger to sort out?

I had the same exact problem on another bike, and it was just the plug being to far down.

Man i would hate for the front fender to come flying off over 100 kph. Probably wouldn't endo, but it would still most definately suck !

Edited September 15, 2011 by KRS1

[wantan]

the spark plug is only a few days old and its covered in thick black soot ,neutral gear just doesnt want to engage ,the back brake caliper is loose

(if they give me a new carb you can have the old one for free )

if you think the plug is bad check this

the front fender bracket was so brittle it cracked while driving over the rama bridge well over 100kmph and scared the shit outta me when i heard this clanging banging noise of the fender bouncing off the forks

when it came loose

Hope they can fix your bike soon. How long do you own your Boxer 250?

Problem with neutral gear is part of "the Tiger Boxer 250 character" some people say. Nearly all have this problem, me too. Maybe the mechanic can adjust it to make it better. But i never heard that they were able to fix it completely.

Is something broken on the back brake or are the screws loosen? You should check every screw by yourself when receiving the Boxer. Also better check if the hose (brake fluid) for the back brake is layed in a way that it will not crack someday (moving swing arm). This is very common too.

Broken holder for front fender is a bad thing, but the holder is not stable enough, it will break one day from shaking. I tightened it with some nylon cable ties to the down part of the fork and stabilised the thing with a rubber part that i clipped between the holder and the fork. This works pretty well and now my front fender is not shaking anymore. There is plenty of space on the down side of the fork to fix the bracket, so i ask myself why Tiger hasn't designed this more stable.

Good luck

[wana]

if a new spark plug was the only issue i wouldnt bother but................. the spark + broken fender mounting + vibration issue (they forgot to install rubber dampers between the engine mount and the frame on this one ) + unengageable neutral gear +loose rear brake caliper + possible carb damage i think its better to let the factory do their their stuff

this is the last warranty year as well so the best option would be to let the factory fix it since they should know their own bikes better than me and the local somchai ,in 6 months when there is no more waranty then i can start fixing things myself

[wantan]

if a new spark plug was the only issue i wouldnt bother but................. the spark + broken fender mounting + vibration issue (they forgot to install rubber dampers between the engine mount and the frame on this one ) + unengageable neutral gear +loose rear brake caliper + possible carb damage i think its better to let the factory do their their stuff

this is the last warranty year as well so the best option would be to let the factory fix it since they should know their own bikes better than me and the local somchai ,in 6 months when there is no more waranty then i can start fixing things myself

Vibration is also normal. I also do not have dampers. But you get used to it, at least i did

But i saw some police Boxers with dampers. Maybe this is part of the special version Tiger has sold to the police.

May i ask who has sold this bike to you and when? Your front fork looks very old and outworn. Someone did not took much care of it imho.

[KRS1]

Then by all means get the warranty !

[wana]

if a new spark plug was the only issue i wouldnt bother but................. the spark + broken fender mounting + vibration issue (they forgot to install rubber dampers between the engine mount and the frame on this one ) + unengageable neutral gear +loose rear brake caliper + possible carb damage i think its better to let the factory do their their stuff

this is the last warranty year as well so the best option would be to let the factory fix it since they should know their own bikes better than me and the local somchai ,in 6 months when there is no more waranty then i can start fixing things myself

Vibration is also normal. I also do not have dampers. But you get used to it, at least i did

But i saw some police Boxers with dampers. Maybe this is part of the special version Tiger has sold to the police.

May i ask who has sold this bike to you and when? Your front fork looks very old and outworn. Someone did not took much care of it imho.

tiger sachs forum says vibrations CAN be cured by looser engine mounts with rubber dampers between engine and frame !

gear box is fixable somehow (the factory have done it for people in the past apparently )

i bought it last week to play with because i have wanted a boxer 250cc rs for some time and i couldnt wait for the fuel injection version to be ready (might take years,nobody has any idea )

it came from a private seller btw

there was about 7000km on the clock ,and it 2+ years old

i will take a few pics when i wash the dirt off it ,i was out riding in the rain the last few days so it would be a crime to put pictures up right now :Dbut when cleaned mine is

more or less identical to this one

[wantan]

tiger sachs forum says vibrations CAN be cured by looser engine mounts with rubber dampers between engine and frame !

gear box is fixable somehow (the factory have done it for people in the past apparently )

i bought it last week to play with because i have wanted a boxer 250cc rs for some time and i couldnt wait for the fuel injection version to be ready (might take years,nobody has any idea )

it came from a private seller btw

there was about 7000km on the clock ,and it 2+ years old

i will take a few pics when i wash the dirt off it ,i was out riding in the rain the last few days so it would be a crime to put pictures up right now :Dbut when cleaned mine is

more or less identical to this one

Sure vibration can be cured with dampers. But i never heard that Tiger is doing this for free as a warranty service. I would be interested in this too. Please tell me how it worked for you.

Gear problem may depend on how bad it is in your special case. On my Boxer neutral is sometimes hard to find. Some times i need long time to find neutral (10-15 seconds) and have to move the bike and/or release the clutch in this time. They have tried to adjust it at Tiger factory but weren't able to make it better. Some people have reported that the oil is important. But always taking expensive synthetic oil just to be able to find neutral?

Your Boxer is comparable to mine in age and mileage. Mine is 2 years and 10,000km. Yes, show a picture when you have cleaned it. Would like to see it. The Boxers are really nice bikes