I need some help my plugs have a nice light tan but I think the topend is lacking for what was done.

Big gun pipe
K&N no lid
Cam
10.75 to 1 piston
port polish cleaned up to improve flow

What size jets do you think?

Doc

180/185 should be your starting point on the mains. if you don't have the dynojet kit you may want to get that

I use 180/185 when I am @ Glamis and it runs great, You should be using a lil bigger jets w/the work on it.

If the plug looks good, then you might just be expecting too much. I'm not trying to be mean, but the plug tells all for top end/main jetiing.

The Raptor is deceptive. I don't have a tach, but I thought the same thing, the engine isn't revving to max rpm. But after seeing a few well tuned Raptors, I think they sound a lot lower rpm than other motors simply because it's a thumper.

Regards, Steve

Lets put it this way a stock predator beats me on a hill. I had to order jets so I haven't tried new jetting yet. The gains above A stock raptor is not much to talk about. The bottom grunt to 5gs is great then no gains noticed above that. The jetting I am running right now is 165 170 which is less then CT with lid removed no mods that they recomend.

Doc

Doc, the "problem" with the Big Gun system is that it falls flat on top. The dyno curve has a higher low and mid range, but topend was just about stock. I'm running 170/175 27.5 pilots and mixture screws at 3 and 2 3/4 out I'm right on for my elevation (3000 ft), but I needed to go at least 2 steps richer on the mains at G. Too bad it's such a pain in the rear to change jetting on the reptile. If you want a more definitive answer, I'd recommend atvconnection.com go to the forums click Yamaha then search for Big Gun If it's out there for the Rap, this site has something posted on it. The good thing about your powerband is you can drop a tooth on the front now and pull 3rd gear up the hills. Hope that helps. Haz