Peeps, decided to tap into the vast engineering knowledge to help me fix my buddy's, daughter's Yamaha ttr125 dirt bike.
The problem - overflows at the carb bowls; but runs well, idles wellish, but takes ages to return to idle once revved in neutral.
Things I've tried and or discovered:
I can already hear the chorus of float heights. However, i did clean the gunk out the carb, which was easy having only one simple unit to deal with. Jets are clean, etc and I set the float height from a utube vid on the bench using the tube/fluid level method.
But it still overflowed. So I stripped the needle valve assembly and dremel polished the needle valve itself and the brass seating to mirror level using a Qtip and metal polish.
The cone on the needle looked good - no grooves - so I became confident that the needle valve was working and the floats were set at the right height.
With great flourish, it was put back on the bike - I expected it all to run perfect.
Alas - same thing on testing - drips from the bowl overflow, poor return to idle.
SO - the bike rides ok, but I don't like that vague throttle shutdown since my buddy's daughter is a learner.
Andy
Hi Andy.
I am not familiar with a ttr125 but if I had To guess....Could it be that O'ring 32 is perished and leaking around the float valve assembly?
I have had this problem on ny FJ.
(http://cdn.boats.net/diagram/yamaha/MCY/2005/TTR125LT/IMAGES/CARBURETOR.png)
Cheers,
Jeff P
Here's an article about a carb upgrade...
http://motocrosshideout.com/ttr125-mikuni-vm24-carb-swap-best-bang-for-your-buck/ (http://motocrosshideout.com/ttr125-mikuni-vm24-carb-swap-best-bang-for-your-buck/)
Cheers,
Jeff P
Good call Jeff. My thoughts exactly...knackered float needle seat o ring, same as our FJ's. :good:
just fixed the same problem on my bike thanks to pat and George and company.
that stinkin' needle seat o-ring
Thanks for the link Jeff - looks like an easy upgrade and a tried and tested one as well.
Come on Yamaha, don't muddy the waters by cheaping your customers on important parts.
Andy
And thanks fintip for my first and cheapest option. Much as the replacement unit sounds like a winner, i like the simple o ring idea.
Andy