When I bought the bike (130 hours) It bogged off the bottom a bit, so I installed the stronger AP spring and put a #60 leak jet in. I was happy with the results but lately the bike doesn't feel it's quite as snappy on off the bottom. (230 hours now) Does anything in the carb wear that can cause this? Is my motor just wearing out? Maybe I'm just used to the power and trying to ride it harder off the bottom? Its not at the point where I wanna start pulling the carb out and swapping leak jets etc. But I thought it could be worth a discussion to see if you guys had any insight. Cheers, Jack
Dunno... my te250 is acting the same way. My bike seems a bit more sensitive to jetting these days - but I really have not spent the proper time to sort it out. I did need to replace the float valve because it leaked on the floor when not riding if the fuel was left on, and after that the required jetting seemed to be a lot different for some reason..
Don't plan on rebuilding it anytime soon, motor still seems really strong, valves have hardly budged, oil always come out clean. Guess I'll just deal with it for now and if it gets any worse I'll start looking at jets.
I did ask another rider about the main jet, he said the needle should never wear because it does not contact anything because the fuel has to travel around it. However a rich condition does seem logical for the problem I am having. Perhaps a needle inspection is required. Is it possible to pull the needle out without removing the carb? Only time I've hard the carb apart was when I removed it, which is kind of a pain. Also my weight has dropped
http://www.factorypro.com/tech/needle_jet_wear.html All needle jets wear while being used, at varying rates. Needle material and surface finish DO affect the needle jet wear rate. Needle Jet material and surface coating affect the wear rate. Unplated brass wears quicker than nickel plated brass. Stainless Steel needle jets KILL aluminum and titanium needles (yes, we tried it!) Sadly, titanium is a quirky material material to use for needle jets, as you have to be careful about what needle material you - or - somebody else, down the road, installs. A stainless needle in a titanium needle jet will hollow out the ti orifice in a few 100 miles. Riding habits affect wear rate. http://www.amr-of-tucson.com/carb_facts.html Needle Jets - The most wear prone item in the carburetor besides the throttle valve (Slide, to most of us) is the needle jet. Because of the relatively small internal surface area of the brass jet in contact with the stainless steel throttle needle which is constantly moving up and down with the slide, a high degree of wear is inevitable. While opinions may vary, it has been our experience that most needle jets are worn beyond specification in 10,000 miles or less. Remember, a mere .001 of wear changes your #106 jet to a #107.
You will not visually see any change, though if you have an 'optical comparator' you could compare it to another. At least I cannot personally see those tiny changes. As an experiment, you might get some information by opening the hotstart or choke a bit while riding. It could be as simple as a slightly plugged leak jet or AP spring not being as snappy as it used to be - you could put an o-ring on the AP arm as an experiment. On my 2006 te250 I can loosen the band clamps and rotate the carb and get enough access to take the float bowl off or take the top off & have access to the needle. I vaguely recall the TE450 being even easier to work on because the cylinder is slightly taller but am not sure.
Thanks for the info guys, now I have a few things to try and see if it alters the way the bike behaves. I'll have a play around this weekend
I know this is an old post, but, I'm working through a carb clean now on my 07 510. Learned on this forum, via a George post I think, that removing the carb is very easy if you loosen all of the rear subframe bolts and pull the assembly back an inch or two. Be careful with wires and exhaust mounts. I just removed the spring on the muffler. Plus less chance of damaging the boot. Cheers.
