Yamaha Rhino Forum banner

Jet size for these engine mods

1646 Views 5 Replies 4 Participants Last post by  CamShaw
I just rebuilt my 660 after it threw a rod and busted a baseball size hole through the cases. So I thought now is the time to go all out. Here's what I did to it. New cases of course, hot rods stroker crank and rod, bored to 101mm with wiseco 11:1 piston. Hot cams stage 2 cam and ported head with kibble white double springs. Dynatek fs cdi, custom air intake and exhaust. It also has a machined sheeve and electric fuel pump. I sent my info to 6sigma jet kits and they sent me a kit that they recommended. They gave me four main jet sizes from 170-185 a new pilot and some other things to increase throttle response. They suggested starting with the 175. So I did. I've been running it about a week now and it runs great. It seems like it has more torque but it just seems a bit sluggish also. Just doesn't have that rip it response that I expected. The AF screw is at 2 1/2 turns out. My question is do you think the 175 is too much fuel making it feel a bit boggy? What are your suggestions for the engine work I have described above? Anyone have the same work done? Thanks for reading.
1 - 6 of 6 Posts
There's no exact science for jetting, but 170-175 is usually about right.
Is the air box opened up?
What does the plug look like?
Yeah the air box is custom made by me : ) its wide open. Haven't looked at the plug yet. I'm gonna try the 170 hope its good I don't have a 165.
the only real way to be super safe is a air fuel meter guage , you might want to consider one makes tuning through the entire power band a breeze
Thanks I'm gonna get one and give it a try
what carb and intake and exhaust set up do u have, thats probably why it aint ripping...
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.