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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> TTR running a bit rough
Post Info TOPIC: TTR running a bit rough
matador


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TTR running a bit rough
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I only recently brought my TTR on a private sale, good clean bike but, it would only run on choke but the engine sounded ok so I brought it. I found it was so clean due to over pressure washing water and some sort of cleaner had got into the carb via the air box. I stripped and cleaned out the carb, drained cleaned the fuel tape and refilled the tank.

It runs ok but under load it pops & bangs as it the plug is failing under pressure - changed the plug but it still pops and bangs under load - it revs freely ok. I suspect the ignition coil or ht lead - any ideas, as I can't test out the parts and don't want to buy new parts that may turn out to be ok.

Many thanks in advance. I will do my 'hello' bit tomorrow as my head is full of petrol fumes and my 'nursey wife has given my a prescription of a couple of cans



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TTRfan


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Welcome to the forum!

What colour was the plug you took out as popping and banging can be an indication of a weak mixture?

I am assuming that when you stripped and cleaned the carb, the jets were clean.

If my theory is correct then maybe air is leaking in through the carb inlet manifold? It is not uncommon for the rubber rear section to part company from the front metal section.

Brian



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matador


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Many thanks Brian, originally the plug was black but that was due to the mucked up carb. the 'glunk' that got in from pressure washing needed the air filter to be washed in parrifin, I used solvent to clean the stripped out carb, I tried to clean out all the jets, but will re-strip it again tomorrow plus check the rubber connector. I took it out earlier for a 10 mile ride so will check plug colour in the morning

I assume the fault is from the original 'glunk' so will try again in the morning, the bike is an 07 model with black alloy rims and only 3k miles, the motor engine noise sounds ok - just this fault.

I will get this fault cleared than order up some upgraded parts.



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matador


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Finally fixed it and running well. I don't mind problems but when you find somebody has 'had a  go ' first then it means sort multiply problems - it did. thanks again.



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matador


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Just thought I would expand on the problem and what I found as it may be of interest. The engine was misfiring under load - so assumed it was the plug failing under pressure, but the plug worked fine in my XT660R.

After the normal strip 'n' swear session over a few days, I'm sure I found the problem (plus it didn't come back) as with all trail bikes, mud is flicked up onto the engine and around the plug and under the plug seating from a few removals when the dirt wasn't blown out. This along with some carbon on the plug thread caused some resistance to the plug circuit - I pushed a piece of plastic pipe in the plug hole and carefully scrapped the plug seating, blow out the dirt around the tube and removed the pipe. With the same plug back in, and the engine warmed up I ran it up a few hills under power - no problem. I had stripped the carb down a few times but I'm sure it was plug seat resistance

I had similar problems on the old Cortina engines with oil getting on the back plug, I used to clean it with a 22mm pipe brush.

The problem tracing these type of faults is it could be one of many, I recently had a problem with a chainsaw that run rough and cut out at times - stripped the carb down a few times but it turned out to be the electronic ignition unit.

I have a saying for these types of faults after a few attempts, it's either something so simple I missed it or really complex and normally expensive - this time basic.

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Cubber


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Great description. I agree that tracing bad running can be a PITA. hmm

I advocate doing one thing at a time - then testing.

If it fixes it then OK - if it doesn't then try another thing.

Eventually you're bound to fix the problem. aww

If you tackle many facets of the same symptom and cure the trouble you can't then put your finger on which cured it. You still have to do the lot next time without knowing what the cure is! confuseconfuse

Martyn



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matador


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Cheers Clubber - prob is I was past the 'methodical phase' of applied logic after 3-days.

Years ago my brother came out of the garage and asked if I was any good at fixing radios? walking out, why I asked? well I was trying for the 5th time to assemble the gearbox selectors in my Rocket A10R when a 'carp record' came on - that was when I flipped and put a  2lb hammer through the radio.

My son had a rattle in his SV1000 - only just found it. The guy before had 'lost' 4 nuts in the handlebars trying to fit bar ends.

I'm pretty sure is was dirt under the plug as it's running ok now - just though I would pass on another tip on.



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