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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Engine bogs on high rpm
Post Info TOPIC: Engine bogs on high rpm
honda15i


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Engine bogs on high rpm
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one of mine ttrs bogs on high rpm around 6500-7000. It seems like I hit rpm limiter, engine doesn’t reach full power.

My second TTR reach top high rpm without bogging. I took these parts from second ttr and installed on first:

1. Carb with fuel hoses and one way valves

2. Cdi

3. Ignition coil

4. Spark plug

5. Voltage regulator 

6. air filter

7. Exhaust muffler

Another part Im thinking to take is alternator.

I did google people suspect valves ie. bad clearance, leaking gas, soft springs

Any other ideas?

 



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learning to ride on 1993 TTR 250

Ex 1997 and 1998 Honda XR 250
mossproof


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You have covered nearly all the external stuff there! Carb-to-engine rubber ok? I would be suprised if the stator/alternator was the cause try valve clearances and check the timing first I think.
Has it always been like this or just started to be a problem?
Well done getting the header off by the way. That looked nasty!

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ttr steve


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My Wrf bogged at full throttle, someone had removed the snorkel, put it back on and it runs perfect.

Hope that helps

Steve



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TTRfan


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Timing chain jumped a tooth on a sprocket? Shows similar symptoms....



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honda15i


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I forgot to mention, intake rubber is also taken from second TTR.

Second TTR is running fantastic without snorkel. It even has three holes around 3-5 cm made in the air filter locking door!
I tried inserting/removing snorkel on the first one that did not help.

If I recall correctly the first one started to run badly last year. I thought this is a problem with carburetor. Then I bought Chinese Koso carb and surprisingly it was running OK, however Chinese carb had a problem, it was leaking the fuel.

So, I replaced to original back. Then I bought the second TTR, that has only 6 BAR of compression on cold engine. However, it runs great! Then I started swapping parts and searching the cause of the problem on my first TTR.


I will keep you updated soon. Next will be valves clearance inspection ( I recall I did this last year and it was OK).



-- Edited by honda15i on Wednesday 24th of April 2019 08:09:28 AM

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learning to ride on 1993 TTR 250

Ex 1997 and 1998 Honda XR 250
ttboof


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Mine had a flat spot after doing everything ended up standard main jet dropped needle clip one notch and went up one size on the pilot jet now perfect 



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honda15i


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Since, I'm now using the same carb on both TTRs I don't think it is related to the carb issue.

I think if one TTR running perfect with same carb adjustment then other one should be running perfect too.



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learning to ride on 1993 TTR 250

Ex 1997 and 1998 Honda XR 250
ttboof


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True  every bike Mr Yamaha has built for me has had very ordinary valve seating usually found and fixed at the first rebuild 

Very rare but moisture and dirt in the kill switch can cause some weird stuff but usually after being wet 

 

Will keep an eye on what you find . 

 

 

 

 



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honda15i


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Finally I got this problem solved.

Replacing entire left side engine cover (alternator) did not help.

Then I opened valves top engine cover and found incorrect timing set and chain was a little bit to loose. After correcting both intake and exhaust sprockets it runs perfect now.



-- Edited by honda15i on Wednesday 8th of May 2019 06:26:14 PM

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learning to ride on 1993 TTR 250

Ex 1997 and 1998 Honda XR 250
mossproof


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Good news!
Thanks for letting us know.

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