Jetting, Timing, What's The Deal? Need Help!

[gmacker007]

OK, here it is:

 

I have a '91 Banshee that I have dumped a bunch of $ into: welded crank, dune porting, advanced timing plate, T5's, Trinity Stage IV head (18cc domes, running 32:1 VP red only), Kehein 28mm carbs, v-force reeds, etc. Also, flywheel has been lightened.

 

After all this money, it screamed like a bat out of hell (for 2 rides). However, it has ran poorly since. Loses power on top end, can't seem to get the jetting right after buying and trying about every possible jet size.

 

Last ride it blew up. I've rebuilt the top end at .30 over and re-assembed the bike. Still can't get it jetted right.

 

I have clean power at idle through 1/2 or 3/4 throttle right now. It really screams through 1/2 to 3/4 throttle. However, from 1/2 or 3/4 throttle to WOT, I can't get it to jet properly. No amount of changes yields a satisfactory result. With all the mods, I figure I should be at 165 mains at msl. I've used main jets from 155 through 175 to jet the bike. At WOT, it seems to either have no power (seems lean) or will gurgle (seems fat). But the results are sporadic.

 

Anyone have ideas as to my next step?

 

Trying to dial in my bike at sea level for now. At sea level, I have the jet needle on the 3rd clip from the top and the mains are at 158. I've advanced the timing back to about 3 or 4 degrees (originally running at 7 degrees advanced).

 

I'm curious if anyone has had similar experiences w/ the Kehein carbs? Any recommendations regarding jetting. Also, could it be the timing? Please provide any help you can.

 

Thanks.

[Banchetta]

Timing could be a problem, but shouldn't. The race fuel needs a little more advancing then low octane. I'd think the +7 would work nice but try the +4 and go from there....I'd start w/ a 175 main at 60 degrees and even higher for colder temps...Some people have run a 185 mains w/ the porting.....what do your plug look like when you do a wot test run in 6th gear??That'll tell you....you could also have a bad wire connection on the plugs...try the timing and go from there...