Has anyone ever built a 686 Raptor and had it run worse after the larger piston and cam was installed?

A friend of mine put a pipe, filter, pro-flow adaptor and jet kit, along with modifying the air box on his Raptor. The head was also ported, and a 3 way valve job was done as well. After these simple bolt-on mods, the quad ran great. Much better than stock.

Sometime later, he also installed a 102mm piston and a Webcam camshaft (the one requires the springs, etc).

I believe he is running the DynoJet jet kit, with 148/150 mains and no lid (K&N filter).

After these mods, the quad is slower than it was with stock cam and piston.

The timing on the cam has been check, and it is correct.

Just wanted to throw this out and see if others have had similar problems. We would like to get some ideas on what might be the problem.

Thanks.

Rog

 

There is no way that jetting can be right

 

He is only running 148/150 mains with that much work done?
I'd say he is WAY lean. I have a yoshi full exhaust and the pro flow adapter with no lid..and I run 146/148 DJ mains. He is one jet size above me and has a hell of a lot more work than I do. I'd reccomend jetting way up. Has he ever done a plug test? His plug must look like an albino child.

 

I've heard that once you go "bigger" (bore), that everyone finds the stock needles and larger Mikuni jets work better.... Now I am a FIRM BELIEVER in the DynoJet kit!!! I absolutely love it in my Raptor! But it is stock bore too.

I just thought I would throw that out there...

"TOID"

 

we have 2 dj kits not being used any more. We switched back to mikuni jets and needles. You need to go up as mentioned above to at least 180/185.

 

I guess I would have to dis-agree. My 686 runs perfect on the Dynojets, of course you have to order the larger jets special from Dynojet, but once you've got the right size it works perfectly. I run 155/160 Dynojet mains and 25 Pilots with the standard needle setting(I Believe its #4). No Lid and no problems, smooth to 8000+ rpm's.

 

That is good to hear!! I'm glad to see that it can be successful - I never want to get rid of my kit!!

 

Zrwhat, where did you order the larger dj jets from an how much for each one. All I could get a hold of was the 150 that came with the kit.

 

RaptorRRC: I just ordered mine from Dynojet. They are very inexpensive, except I needed them the next day, so I paid more than the jets cost just to have them shipped. I can't recall, maybe a couple bucks a jet. Dynojet mains are sold in increments of 5 after 150, example 150, 155, 160, 165.......

 

RaptorRRC

www.dynojet.com

DynoJet web site.

Click on jet kits once there. Then on the next page click on jet assortments. You need the DJ style jet.

Or just click here to go to the page I'm talking of.