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TW125 Misfiring + Spluttering


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Hi All

Last week my TW125 started to misfire and i can't find out why,i have changed the plug,cleaned all the wiring and sprayed all the connections with WD40 to make sure there are no wet connections,I have checked the HT lead and it looks fine.

Is there anything else i should check before i strip down and clean the carb . it feels like the bike is not pulling up to top speed with the throttle open and splutters a lot.

HELP

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Update

Ive stripped and cleaned the carb but it's still spluttering,i rode it with the air filter and cover missing and it went fine :blink: is the mixture wrong ?

Help

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What type of filter is it? is it the corrugated paper type? if so try blowing it clean with compressed air, or replace it!

Hi

Nope it the foam type,iv'e cleaned it in petrol and reoiled it but it still splutters :huh:

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Hi

Nope it the foam type,iv'e cleaned it in petrol and reoiled it but it still splutters :huh:

It runs fine without it and youve cleaned and oiled it, it must be too oily, place it between newspaper and squeeze it to remove excess oil, replenish with new papers, dont wring it...be gentle, should be ok after that... :)

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It runs fine without it and youve cleaned and oiled it, it must be too oily, place it between newspaper and squeeze it to remove excess oil, replenish with new papers, dont wring it...be gentle, should be ok after that... :)

:o Done the filter again and it still splutters,could the valve clearance affect the performance :blink: i cleaned the carb again and can't find anything wrong with it,the fuel is flowing fine out of the pet tap ,iv'e replaced the throttle cables as i noticed they were starting to fray.

Ive spoke to a couple of mechanics,the first said i need to replace the filter as i shouldn't had washed it in petrol,the next one said thats rubbish as long as i spray it with a light oil (3 in 1 type )after cleaning it it will be fine.

I think i will try the valve clearance tomorrow and see if that makes any difference,any other ideals ...........

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Getting desperate now,the suns shining and im stuck in the car :angry: Iv'e done the valves,drained the tank and flushed it out,refilled with new petrol and checked the fuel tap and it still splutters.

If i leave the cover and the foam filter out it's noisy but rides fine,if i put the cover back on without the filter it still splutters so it can't be getting enouth air :blink: is that right or when the filter and covers back on is it not enouth fuel :blink:

The local bike shop is busy and can't look at it for at least 1 week so what do i try next :huh:

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I am presuming that you had it running fine at sometime in the past!

It runs fine with the filter and cover off so it sounds like fuel/air mix.

Take the filter out but replace all of the air box. If it runs fine then it will be the air mix.

Change the filter. If it runs fine - no problems.

Cake the carb off and check the carb fitting to to cylinder. There is an O ring. is air being sucked in here?

I would also reclean the carb with carb cleaner. Carb holes are very small and it onlt takes a small amount of grit to block a jet.

Don't run the bike for long periods with the filter off but it seems the the mix is better when the airflow is stronger (no filter = less resistance) so a blockage of air or the filter is not coping. If the resistance of air is too great (filter on) it is sucking in air from somewhere else (maybe via the O ring on the inlet).

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I am presuming that you had it running fine at sometime in the past!

It runs fine with the filter and cover off so it sounds like fuel/air mix.

Take the filter out but replace all of the air box. If it runs fine then it will be the air mix.

Change the filter. If it runs fine - no problems.

Cake the carb off and check the carb fitting to to cylinder. There is an O ring. is air being sucked in here?

I would also reclean the carb with carb cleaner. Carb holes are very small and it onlt takes a small amount of grit to block a jet.

Don't run the bike for long periods with the filter off but it seems the the mix is better when the airflow is stronger (no filter = less resistance) so a blockage of air or the filter is not coping. If the resistance of air is too great (filter on) it is sucking in air from somewhere else (maybe via the O ring on the inlet).

hi

Its been running fine up to a couple of weeks ago when on the way home from work it started struggling and it still struggles with the air box on without the filter.

I must have the cleanest carb on a TW anywhere,i have cleaned it 3 times (3 tins of carb cleaner ) just in case i missed something so i will give up on that,i will check the seal tomorrow and check for other air leaks. (fingers crossed ) :o

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hi

Its been running fine up to a couple of weeks ago when on the way home from work it started struggling and it still struggles with the air box on without the filter.

I must have the cleanest carb on a TW anywhere,i have cleaned it 3 times (3 tins of carb cleaner ) just in case i missed something so i will give up on that,i will check the seal tomorrow and check for other air leaks. (fingers crossed ) :o

Seals and everything fine and i have had some success :rolleyes: i have adjusted the float level and the bike runs a lot better now but i have also snapped off one of the legs the float pins sit in :angry: ,i have use chemical metal to stick it back together and so far all it holding it together and the bike is running fine (upto the last bit of throttle anyway)

So i will get another carb asap but at least i can still ride the bike to work for the moment :D

I don't want to take it apart again incase i break the leg again.

Thanks to everyone who gave advice of what the problem could be :hail:

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Seals and everything fine and i have had some success :rolleyes: i have adjusted the float level and the bike runs a lot better now but i have also snapped off one of the legs the float pins sit in :angry: ,i have use chemical metal to stick it back together and so far all it holding it together and the bike is running fine (upto the last bit of throttle anyway)

So i will get another carb asap but at least i can still ride the bike to work for the moment :D

I don't want to take it apart again incase i break the leg again.

Thanks to everyone who gave advice of what the problem could be :hail:

I had to take it apart again as it still isn't pulling right,i have reset the float again but it still pulls better without the air filter.

I am going to try a aftermarket cone air filter to see if that evens up the over fueling,any recomendations ?

Can you get replacement jets for this carb as i cannot find any on the web,will a carb from a TW200 improve the performance ?

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I had to take it apart again as it still isn't pulling right,i have reset the float again but it still pulls better without the air filter.

I am going to try a aftermarket cone air filter to see if that evens up the over fueling,any recomendations ?

Can you get replacement jets for this carb as i cannot find any on the web,will a carb from a TW200 improve the performance ?

Iv'e took apart the air box and have fitted a foam air filter straight onto the tube from the carb and it works ( its a bit louder :blush: but no more chugging,i now have to fit a crank breather as that ends in the old airbox.

Im not sure what this has done to the fuel consumption but i assume i will use more fuel :glare: but at least i will have my bike back :D

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  • 2 weeks later...
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Right i am now trying to rejet the carb as it's getting too much fuel.I could leave it like it is but it's too loud .

I dont understand this statement, how do you know its getting too much fuel, it will be louder without the original airbox and filter

i am now trying to rejet the carb as it's getting too much fuel.................. no acceleration at the top end so i am assuming not enouth fuel getting through

Bit of a contradiction here? The removal of the filter has likely made it run lean, may require a bigger jet now or risk overheating and possible engine damage but i'm not convinced you suddenly developed a carb problem with this bike

Any other idea.

Heres an easy one to try...Replace the spark plug, check the gap in the plug fitted at the moment too, and also replace the HT cap with the correct resistance replacement before any more tinkering with the carb. ;)

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Iv'e took apart the air box and have fitted a foam air filter straight onto the tube from the carb and it works ( its a bit louder :blush: but no more chugging,i now have to fit a crank breather as that ends in the old airbox.

Im not sure what this has done to the fuel consumption but i assume i will use more fuel :glare: but at least i will have my bike back :D

Right i am now trying to rejet the carb as it's getting too much fuel.I could leave it like it is but it's too loud ,i cannot get Teikei jets anywhere but did read that Mikuni jets fit but there might be a difference in hole size ( anyone know about this ) i have tried a Mikuni 130 (original Teikei 134) the bike runs but not very fast with no acceleration at the top end so i am assuming not enouth fuel getting through,the next size i can see is 132.5 but no 134.

Any other ideal.

:)

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I dont understand this statement, how do you know its getting too much fuel, it will be louder without the original airbox and filter

Bit of a contradiction here? The removal of the filter has likely made it run lean, may require a bigger jet now or risk overheating and possible engine damage but i'm not convinced you suddenly developed a carb problem with this bike

Heres an easy one to try...Replace the spark plug, check the gap in the plug fitted at the moment too, and also replace the HT cap with the correct resistance replacement before any more tinkering with the carb. ;)

Surely if the bike runs fine without the air filter the mixture must be better which in my mind means that with the standard filter on (less air flow) the bike will not run properly so there is too much fuel to air (i expect i am thinking wrong)

As above surely if i put in a bigger jet the bike will get more fuel and bog down more ? if it's not getting enouth air now will it be better with a bigger jet :blink: (it runs fine with the mod but i want to get it to run with the original filter)

I have done the plug and gap,but why will the bike run fine without the air filter or with the mod i did with a foam filter fitted straight onto the carb if the fault is else where. :unsure:

Is my thinking wrong somewhere ?

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You post started with, 'Last week my bike started to misfire' thats a good reason to check the plug in my book, I've seen it before all manner of fiddling with the carb and then it turns out to be an ignition issue. You seem to have solved it though with removal of the filter and replacing it with something, personally I wouldnt be happy with that and would have fitted a new filter. be careful with reducing the jet sizes though.

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You post started with, 'Last week my bike started to misfire' thats a good reason to check the plug in my book, I've seen it before all manner of fiddling with the carb and then it turns out to be an ignition issue. You seem to have solved it though with removal of the filter and replacing it with something, personally I wouldnt be happy with that and would have fitted a new filter. be careful with reducing the jet sizes though.

Hi

My first thought was the ignition so i changed the plug,this made no difference,i cleaned the tank + petrol tap ,then adjusted the valve's ,none of this made a difference but when the bike had no foam filter and no filter case cover fitted it ran fine.

I tried it with the case cover on but no filter and it still chugged which made me think the problem was the carb so i stripped it down and cleaned it several times but it still wouldn't run with out chugging.

I then adjusted the float and tried it with the filter and cover on and it ran without chugging but no power (wouldn't go over 40) i then took the cover and filter out and it ran fine.

I then fitted a foam filter direct to the carb,so it was sucking filtered air straight in not via the box and snorkel and it ran fine but a bit loud (no box to dampen the noise)

I then tried several different size jets but none would work with the original filter and cover on (would run but no power)

the problem is i cannot find anyone selling the original Teikei 134 jets ,so i have to try to get a compatable jet and the only one i can find which fits the holder are Mikuni jets but apparently they are 2 sizes smaller,i have tried a 132.5 and a 130 (they go up in 2.5)but it still struggles.

I think my only option is to run the bike like it is and wait for a carb for sell on ebay.I have my eye on a cdi unit just in case the problem is still electrical and will let you know how it works out. :rolleyes:

Oldgitonabike thanks for your help :hail:

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Honestly mate what your'e saying does not compute...it runs fine with no filter and filter lid removed, yet it chugs with no filter and lid re-fitted...thats incredible...either that or something is blocking the airway into the filter box, have you checked this? perhaps theres a dead mouse in the snorkel... :P

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Just read the last couple and I think that the engine is running rich because you are covering an air passage on the carb.

So with filter etc, removed it runs OK and when you refit, it runs bad. So it has something to do with that.

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Honestly mate what your'e saying does not compute...it runs fine with no filter and filter lid removed, yet it chugs with no filter and lid re-fitted...thats incredible...either that or something is blocking the airway into the filter box, have you checked this? perhaps theres a dead mouse in the snorkel... :P

:lol: that was one of the first things i thought ,so i ran a wire from the snorkel up through the air box and it comes out under the seat :lol: when i decided to fit the air filter straight on to the carb i stripped the air box down and still didn't find a mouse :smash:

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