Wide Open throttle question???

[Coolector]

Hey guys, just rebuilt the old 81 KDX250 and its working pretty darn well. Only question I have is that at wot the bike seems to flatten out on the power. I would expect it to pull better in the high revs. Could it be a main jet or needle position adjustment.
Its jettet to stock now and cliped in the middle
55 pilot (Rich eh)
160 main (Rich eh)
no plug fouling yet
32/1 gas.
thanks
Andy

 

[cicone]

coolector---No over rev could be a number of things. I would make sure the exhaust is not restricted---heat the pipe with a torch or cook on the grill for a while...when cool you might fill it with heavy duty oven cleaner and then rinse. Also check the silencer and the packing---clean and replace if needed. Could be the timing is too advanced. That would kill the top end as well. Another thing might be too LEAN on the main---not enough fuel at high RPM. Could be other things at work, but these are cheap and easy first steps.

 

[canyncarvr]

Yep, quite a number of things. From the standpoint of 'everything is OK, it's a jetting question,' it's still a bit iffy.

High revs with lack of power is probably lean, a 'flattening' effect (that would be not revving correctly) is likely rich.

Obviously you don't want to be doing a whole lot of WOT running if there is a question of being too lean.

If it's stock jetted (and mechanically sound) it's almost certainly rich.

The mixture ring at the base of the insulator is the way to gauge air/fuel mixture.

Under the heading of 'experiment', you could try some 20:1. If the condition improves you've shown the bike to be rich.

 

[JasonWho]

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[Coolector]

Thanks for the info all , Jason i'm not sure about the model # in my book though The pilot is actually a 60, main 162.5. I would imagine its way to rich because i fouled a plug yesterday. Temp was 20c.