Low RPM

[herb]

I have an /02 Viper, Ekholm tunnel, drop and roll, 151-2 1/4 track, mnt viper gearing, hc clutch kit, silver sec spring, and 8 tooth drivers. I put a set of cpr pipes on this week and seem to have an rpm problem. While doing my plug checks today, I noticed the PTO plug was black, the other 2 were brown and on the wot test, rpm's went to 9000 then slowly dropped down to 8000 rpm. When I checked the plugs, the pto plug was wet and the other 2 still brown. The weights are set at 4.8 heel, 0 0. Is clutching the issue here?

 

[herb]

The jetting is 150 mains 50 pilots groove 4 washer top and bottom 2.5 turns out not vented to airbox.

 

[mrviper700]

what helix are you using in this combo?

the pto is probally too rich, if you have the stock head its got lower comprssion in the cylinder so it most likely isnt going to need as much fuel, its the mag cylinder that likes to be rich with a stock head viper, the mag cylinder runs the hottest from the junk head design, so you have to keep it extra cool with fuel.

 

[herb]

Stock helix 110 twist. Can excess fuel cause it to drop rpm on wot?

 

[mrviper700]

its the stock helix is why, the 47 degree helix is ok on the start but way too steep on the finish angle with heel clickers, you need to find something like a 50/40 helix, it will run alot better and not drop off the rpm then, youll be able to add some weight to the middle hole and get a hold of the belt some more.

There is a couple heel clcicker/clutching write ups I did in the tech FAQ section on this site.

http://www.totallyamaha.net/forums/showthread.php?t=22939