70 Tech Help! Boggs under throttle

[VABCH350X]

Sorry for the long post, but this thing has been kicking my butt. TRX70 starts and runs well, but boggs when given WOT. It will wind out if given throttle slowly, but seems to lack power.

Takes WOT on choke, which might indicate a clogged jet, but both jets have been replaced and carb cleaned multiple times, all passages clear. Also installed a carb rebuild kit, and swapped out carb bodies with another used one. No joy.

Exhaust smells rich, and plugs sometimes carbon-foul, but the fact that it takes WOT on choke should indicate a lean condition. I'm kinda confused and hoping someone else has conquered this problem on the Honda 70 and can help.

Timing looks good, and valve lash is set properly. Is it possible that a valve seat is bad or compression is low? Would either of those conditions cause these symptoms? Thanks a lot for any help.
-Paul

[TravEX]

You need to bump up the main 1 or 2 sizes. Both of mine did the same thing till I put bigger mains in.

[Yamada]

When you say to put a one size bigger jet, let say that the current jet is a 110 is the bigger one 111 or 115?

[VABCH350X]

I think the current main is a #62, I'll see what I can find at the Honda shop. This would explain the fact that it feels starved for fuel. Any idea why it would carbon-foul the plug?

[VABCH350X]

I think the current main is a #62, I'll see what I can find at the Honda shop. This would explain the fact that it feels starved for fuel. Any idea why it would carbon-foul the plug?

[Preddy05]

Are your points set?

[VABCH350X]

CDI Ignition on the TRXs. Got a handful of jets from my friendly local Honda dealer and set to work. Went up to a #65 (from 62) with a new pl;ug, and the bike ran horribly, fouled the plug in the first 30 seconds. I went back to the stock setup (#62) and blasted out all the carb passages yet again, and the bike runs OK. If it's hot (e.g: after blasting down the road wide open) it will take throttle off idle, but not otherwise.

All the jets I grabbed at the dealer were bigger...perhaps I should be goiing smaller. Thoughts?

[KASEY]

have you looked at a jetting chart? changing the main does NOTHING for the lower spectrum of the throttle position,,,, and thats where you are probably starving for fuel,,,, try 2 sizes larger pilot and raise the needle... your probably not getting enough fuel in the midrange to run right ,,,,,,,,,, i just rejetted a trx70 tonight and it runs PERFECT ... the needle had to go up 3 notches to run so i did a little reshaping of the taper to get a little more midrange fuel.... it was way to lean,,,,