A forum for owners of Yamaha TTR250 trail and enduro bikes!

yamahaTT250R · Veteran Member

Low rpm stuttering

barra8 · Guru

What method of cleaning did u use?

The holes in the side of both the main jet and pilot jet need to be spotless aswell as the main hole. (see pic below)

Also spray carby cleaner or similar around the rubber intake boot (bolts carby to motor) and around the top of the carby (making sure its reletively clean first) while idling bike. If you notice a change in revs then you have an intake/vacuum leak.

The float needle should be removed being carefull not to snap pin support (like it did ''see repaired pic below'' lol )and cleaned and seat (where float needle sits inside) needs to be either blown out or squirted through with carby cleaner aswell as any holes ie. two air holes at back of carby,air fuel mixture screw hole,fuel line ect.

Give the slide and slot a light oiling (synthetic two stoke preferably)for a snappy responce

Before refitting (with bottom carby screws out and holding bowl in place) connect fuel line to carby check that the fuel level is about 10mm from top of bowl (roughly just over 3/4 full)

If it's not the right level either the float needle is not shutting off at the right point (ie.wrong float level) or it has dirt in it

You can also check the float level by taking note of what angle the float shuts at. It should be closed (ie no fuel coming through float needle) when the line on the float is level with the carby (horizontal)

To adjust the air-fuel mixture idle bike and turn fuel-air mixture screw in until it nearly stalls. It is then 1 and a half turns out (roughly). NOTE: one turn is a full revolution of the screwdriver line.

Questions..

Did you try dropping the circlip on the pin (needle) down one slot?? NOTE: to do this obviously the circlip would go one higher on the pin settings.

What does your plug look like when removed??black??white??normal??

Tried a new spark plug?

Are you still using #147 main jet??

-- Edited by barra8 on Saturday 1st of September 2012 12:52:32 PM

barra8 · Guru

#147 main will be fine.

Your problem won't be main jet

Have you done all of the above?

I can't help if you don't tell me what you have tried and not tried.

-- Edited by barra8 on Wednesday 22nd of August 2012 01:27:11 AM

barra8 · Guru

Try all mentioned and let me know what your spark plug looks like....

Also how is your air filter? Is it standard?

Does your needle still have a nice sharp point on it? Wear?

-- Edited by barra8 on Wednesday 22nd of August 2012 02:05:01 AM

yamahaTT250R · Veteran Member

the needle looks fine, its got a twin air filter, my spark plug looks a little better than before i raised the needle, slightly black not too much though.

-- Edited by yamahaTT250R on Wednesday 22nd of August 2012 05:28:00 AM

barra8 · Guru

It is a possibility of course although if it does it straight away after cleaning maybe not.

Flush and drain tank and check filters inside petc0ck valve if you think it's dirty fuel. Installing a fuel filter would be an idea.

If you have'nt checked all i mentioned above this mesg do so and get back to me with the verdict.

-- Edited by barra8 on Wednesday 22nd of August 2012 07:18:28 AM

yamahaTT250R · Veteran Member

yes i am still using the 147 main jet and it seems to be working fine.

yamahaTT250R · Veteran Member

ok ive changed the needle position 1up on the clip and acceleration is much better than it was but it still sputters in low rpm acceleration.

barra8 · Guru

Glad you found your problem

Sounds like your needle is a bit worn,may go better with a new one but depends if it still has a cone shaped point to it.

My needle was still sharp but did'nt have a cone shaped point. I dropped it two needle settings and it went well like that but in the end the needle broke cry

The standard needle was aluminium and had seen better days

I fixed the problem by using an xr250 needle that is brass so should last longer bleh

It fitted perfectly to my suprize

Also fitting the new needle has given me heaps more responce when given revs all of a sudden aww

-- Edited by barra8 on Wednesday 22nd of August 2012 11:36:39 AM

yamahaTT250R · Veteran Member

could it possible be dirty fuel?

yamahaTT250R · Veteran Member

ok i have found the problem.....It was the needle jet i lowered it down 2 on the circlip and now the bike is fine! thanks for the help

BM Steve · Guru

barra8 wrote:

I fixed the problem by using an xr250 needle that is brass so should last longer

-- Edited by barra8 on Wednesday 22nd of August 2012 11:36:39 AM

Hey Jarrah, good solution, any particular XR250 needle ? if I need one in the future ?? Do you need the XR clips or the TTR clips OK ??

Funny I thought they were all brass

Thanks

Steve

-- Edited by BM Steve on Sunday 2nd of September 2012 12:29:04 PM

barra8 · Guru

BM Steve wrote:
barra8 wrote:

I fixed the problem by using an xr250 needle that is brass so should last longer

-- Edited by barra8 on Wednesday 22nd of August 2012 11:36:39 AM
Hey Jarrah, good solution, any particular XR250 needle ? if I need one in the future ?? Do you need the XR clips or the TTR clips OK ??
Funny I thought they were all brass
Thanks
Steve

Hey Steve,

I'm not sure what carby it was out of but i could let you know in a few days (maybe) Will let you know when i can though.
It was identical & i used my TTR clips
Mine was alluminium standard so not sure if they all come like that

.........................................................................................................................................................................................................................................

Jarrah.