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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> NEED HELP WITH RUNNING ISSUES
Post Info TOPIC: NEED HELP WITH RUNNING ISSUES
mudkrab


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NEED HELP WITH RUNNING ISSUES
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Hi all, long time fan of the site!

Alot of u guys seem to  have an amazing amount of knowledge on these bikes so im hoping someone can help me out!

i recently bought a 2008 ttr250, got it very cheap not running. fresh fuel and a new plug later and it was going. however this leads to a new problem. bike starts and idles fine you can even putt around at very low throttle openings and its ok, however anything more than about 1/8th throttle and it just dies off, like a lean condition. if you go to 3/4 to full throttle it usually clears and goes ok. on free rev though it just pops and farts and kinda sound like a rev limiter but at alot lower revs. 

the problem to me ( auto mechanic) sounds and feels like an electrical fault like spark breaking down or something.. its really ON/OFF if you know what i mean where in the past fuelling problems have been somewhat gradual ( for want of a better word) in the symptoms e.g. surging where as this is almost like a switch in how it pops and carries on

I have had the carb completely stripped and blown out and clened every little jet/passage etc, the accelerator pump seems to be working correctly and float level is ok

i have also changed the coil with no luck, air filter is clean and valve clearances are 0.12mm intake and 0.14mm exhaust which seems OK to me

the plug is showing signs of an overly rich condition but i think this may be just due to all the missfiring its doing

ANY HELP IS GREATLY APPRECIATED THANKYOU



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TTRfan


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Hi there!

I know you have had the jets cleaned but your symptoms are exactly those of a blocked or partially blocked pilot jet.

These jets have a very small opening and are notoriously difficult to clean. Even ultra sonic cleaning doesn't work on them and carb cleaner is also ineffective. The only sure way is to ream them gently with a piece of suitably-sized copper wire - or fit a new one wink

Brian



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mudkrab


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Thanks for the reply brian, isnt the pilot jet for idle? i will pull the carb again tomorrow and check it though.

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mudkrab


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also cant find any sizing on the jets in there... maybe time for a full rejet? what jets would people recommend? all stock except air filter??
TIA

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TTRfan


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mudkrab wrote:

Thanks for the reply brian, isnt the pilot jet for idle? i will pull the carb again tomorrow and check it though.

The pilot jet on the TTR fills the gap you have between idle and the main jet cutting in wink



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TTRfan


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mudkrab wrote:

also cant find any sizing on the jets in there... maybe time for a full rejet? what jets would people recommend? all stock except air filter??
TIA

Loads of information here http://ttr250.activeboard.com/f611253/carb-stuff/

Jetting recommendations will depend on what airbox/exhaust mods have been made to a TTR and the altitude it gets ridden at.

It is easier as you say yours is standard apart from the air filter. What filter are you running?

Brian



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mudkrab


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TTRfan wrote:
mudkrab wrote:

also cant find any sizing on the jets in there... maybe time for a full rejet? what jets would people recommend? all stock except air filter??
TIA

Loads of information here http://ttr250.activeboard.com/f611253/carb-stuff/

Jetting recommendations will depend on what airbox/exhaust mods have been made to a TTR and the altitude it gets ridden at.

It is easier as you say yours is standard apart from the air filter. What filter are you running?

Brian

 

twin air also the snorkel is no longer there. ill take a look at that link and let you know how i go with the jet tommorow, thansk for your help!

 



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