I've got a problem with the carburetor on a TT-R50E. Since removing the airbox, installing a foam air cleaner, GYTR jets and Leo Vince full pipe, the bike kinda falls on it's face for a split second going from idle to throttle. There's a pause (or a bog) right as the throttle opens. If the idle speed is low enough (like it sometimes just drops a few revs for whatever reason) and you crack the throttle at that exact second, the bike will stall completely. If you 'gently' feed in the throttle it's fine, no drama. And the mid-range and top end pull great. But when the gate drops and he hammers the throttle WFO, the bike just sputters a little and really hits the track coughing. Is this a needle clip position thing? Or more like a fuel-air screw position thing? I don't have a clamp-on tach to set the idle/fuel-air screw, so I just used the recommended settings in the shop manual and although the bike works great everywhere else, the start is pretty important and so far we've stalled in the gate 1 out of 4 chances, and came pretty close another time. How do I fix this and not hurt the performance everywhere else in the rev range?
Probably needs a slightly larger pilot to compensate for the removal of the airbox. If you can't change the pilot maybe raise the float height a little. Those are both swags Howard...someone with a bigger brain than mine may say different.
Also, it's not a CV carb. When you twist, it opens everything up right away since the cable hooks right tot he slide. It doesn't wait for the pressure to lift the slide. You can hammer it open and dump fuel before the air can start flowing through. Tell him to rev it up a little and hold the brake. Maybe that would help out.
We've tried that. We'll continue to work on it. It seems his throttle control is still a little lacking, because he pushes the front wheel, locked, when he twists the throttle that little bit. I tell him to give it a little less, but he can't hold it still enough to be useful on the gate. I guess I'll try raising the idle speed. I'm just afraid the increased RPMs may cause the auto-clutch/trans to drag a little at idle. Then he'll have to ride the brake on the gate. I would have thought it could be dialed out with a different size jet or a needle adjustment, though.
That setup is only going to be optimal at WFO. Why not put the airbox back on? If he's really only ever WFO then get him more cc's!
Because the jet kit for the header & silencer call for an open filter. I have other mains that came with the jet kit, so I just installed the "middle" one. I don't believe it came with different pilot jets, though. The bike really is better everywhere, except off-idle. I just assumed I hadn't properly dialed in the jets, yet. So before I went screwing around with it, I figured I'd ask in which direction I should go.
I'm not trying to nitpick your work Howard. I put a similar setup on my XR50 and ended up feeling that the Uni filter had killed my mid-range which is what I needed to get off of turns. But I have no idea how this setup effects a TTR. I do think if you're trying to squeeze more power out of the TTR then a KTM isn't far away.
Nah, I didn't think you were, I just meant that we ditched the airbox 'cause the directions instructed me to, not 'cause I know what I'm doing or anything! I can't get a KTM or more cc's right now. Ultimately, I'm trying to get him the fastest 50 (or at least an equally fast 50) in his stock 50 beginner 4-stroke class. Some of these kids absolutely rail on their bike, I mean they rocket out of the turns and easily clear the doubles & table tops on the straight-aways. I'm dumb-founded. Unless they're running 88 kits (which I doubt)... but something's going on. Anyway, it's not really about all out monster power at this point, I was just looking for better throttle response and a few more MPHs at WOT. But it turns out that getting that "squirt" on top has lead directly to a 'fart' on the bottom. :down:
There's a lot of info here (http://www.thumpertalk.com/forum/search.php?searchid=11652925). You may have to join to see any pics. I've been tinkering with a bigger carb (26mm vs 20mm) on a ttr125 I picked up recently. I agree with a larger pilot jet and maybe even raising the float level 1 or 2 mm after a pilot jet change. There's lots of drivability problems with the stock carb on ttr's like mine because they're so lean stock. Probably holds true for the 50's. I'm nearby so if I can help, let me know. Dave
