810 build fuel issues. jets? petcock?

I have been riding my just finished 810/gpz build and have been very satisfied with it. I decided it was time to see what she was capable of and completed a few drags against a friends well built harley. First and second gear seemed great, but at high rpm in 3rd then through to fifth, it seemed like there was no power there. The only thing i can think of is that it is running out of fuel. I am still using the stock petcock, should i be running a pingel? Also, my jetting right now is 140/70. These are the jets i have had in since it was stock with pods and a header w/no baffle. Do i need to jump up in main jet size?

Id do the petcock change first then test ride it and go from there with the jetting

what carbs are you running? did you cange the cams?

Hey Jordan. Maybe I am missing something here but I would think that the engine uses the same amount of fuel in the same high rpm range in any gear. If you are not starved at 9 grand in first or second gear, then you shouldn't be starved for fuel at 9 grand in fourth or fifth gear. I would be looking somewhere else for your problem like ignition.

Anyhow, I am not sure what carbs you are running but I found the 28's I had on the bike didn't feel right on my top end. I am still running a stock fuel petcock with my 650/810 and haven't been starved for fuel at high rpm's. If I recall, the 650/750/900 and 1000 all had the same petcock but a quick scan of www.buykawasaki.com can clarify this point. Incidentally, I am now running Mikuni 29 Smoothbores from Wired George and have the 650 top end modified with GPz innards and there is no high rpm stumble.

If you are running 24's or even 26's they might be a bit light under high rpm and I am suspect on whether you can increase the main jet size enough to overcome this problem.

Wired George would probably be the best to offer an opinion on the carb-jetting side.

Cheers-Colin Firth-Ontario Canada

1977 Kz650 Custom - 14,000 original miles, bought new by brother in 1977. Current re-incarnation includes- 810 Wiseco, WG Mikuni 29 Smoothies, 750 GPz cams, intake valves, modified head, Dyan ignition and coils, plus too much more to mention. Painted Moon Dust Silver to re-create factory paint scheme. Not much can keep up with this old girl up to 70 mph. This bike will never be sold and probably passed on to my teenage son when his testosterone levels off!

1982 Ferrari 308 GTSi. 3.0 litre, aluminum V8 Four Cam Engine with a sweet shifting five speed. Rosso Corsa Red with tan leather interior. 56,000 miles. Looks and rides like it just came off the showroom.

2007 Toyota FJ Cruiser. The yellow tank that will go anywhere-anytime!

1998 Jeep Wrangler TJ - 6 Banger with a five speed.

2007 Chevy Uplander (for my bride)

140/70 sounds like a Keihin CV34 set up for pods and aftermarket exhaust and works very well. I expect it would work well on a punched out 750. The symptoms he describes does sound like the bike is running out of gas. The symptom will show in higher gears as it revs to redline in 1st and 2nd very quickly where in 5th gear, it has to pull and this shows up fuel delivery problems. The jetting described sounds good so I would guess perhaps other issues such as petcock, fuel line, fuel filter, vacuum lock, etc.