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

ttr250slw · Veteran Member

speed limiter?

TT-R250M · Super Guru

Check your carb manifold pipe for cracks. Also, have you tried cleaning the carb? Is there good fuel flow?

It could be just that you have a large sprocket and small 13T front and you are hitting the rev limiter but I would think that it would not do that at that speed.

Is there any other symptoms that go with it?

Andy_C · Veteran Member

Now thats an interesting comment, I run 13/52 sprockets, its been rejetted and has the air box mod and a fmf powercore exhaust.

It pulls well and usually off road don't even bother with 1st gear but it seems to hit a barrier where it doesn't rev any higher and I change gear.

Could you give me more information on this "rev limiter" in case I'm missing something, is this rev limiter controlled by the cdi? can it be adjusted?

Don't get me wrong the bike works well off road but hitting the "rev wall" just feels weird.

Thanks

Andy

TT-R250M · Super Guru

The rev limiter is in the Cdi and cannot be adjusted. You can buy an aftermarket Cdi like THIS ONE, to derestrict it.

However, it should not ''kick in'' unless you over rev it flat out in lower gears without changing properly. It is hard to notice but it is there.

As mentioned there is a problem somewhere that is making it hit this rev limiter. A rich or lean condition will not help this but it should not be hitting in high gear.

Of course, the easiest solution is it is NOT hitting it and there is just something wrong.

We need more info.

Jarrah

ttr250slw · Veteran Member

its not the revs that are the problem its like a cars speed limiter like when you hit 185 in a magna it does the exact same thing as my ttr was doing at 90kmph

TT-R250M · Super Guru

TT-R250M wrote:
Check your carb manifold pipe for cracks. Also, have you tried cleaning the carb? Is there good fuel flow?
Is there any other symptoms that go with it?

If we cannot narrow it down we have not much chance of helping.

ttr250slw · Veteran Member

yea sorry about that

um well the carby is immaculate and there is no fuel smell so i wouldn't think that there is a crack and it doesnt have a problem in any gear at any rpm until it hits dead on 90kmh

Phil · Member

I don't know what the CDI rev limit is but with 13/52 final drive gearing at 90 kph you will be doing 6831 rpm. To get to 100 kph you would need to do 7590 rpm.

Is the max RPM 7000? This would give a max speed of 92.2 kph.

I used the following calculator:

http://woodsware.aciwebs.com/gears/

Type 'ttr250' into the filter to load the TTR250's gear ratios that I saved.