Surging at crusing speed (70 to 80 MPH)

Hey Guys,

I have one question and hoping that some could help me with that. I ride Monster 900 and just to give you some overview these are the modes I have done to the motor (Stage 2 Jet kit, pod K&N air filters, slip ons, high compression pistons (12:1), light flywheel, aluminum clutch basket). I live in Great Lakes area and is really hot and humid in the summer, therefore the bike is not set up too reach (main jet is 170). For couple of seasons now I have noticed the bike is not running 100 %. At cruising speed (70 – 80 MPH) the motor doesn’t run smoothly, what I mean by it is that there is a surging (jerking) effect at these speeds. When I am taking off or go full open everything seems to be fine, bike got power and torque. Any idea what may be causing this? I realize that is difficult to diagnose problem of this nature over the Internet, but maybe some of you have had similar problem. Your thoughts and advise in this matter would be greatly appreciated.

Thanks


Modified by Monster 900 at 10:12 AM 4/7/2005

What octane gas are you using? I had something similar w/ my s4 when running on 91 oct. I dropped to 87 and the problem went away.

I usually use 94 wherever available. Because of high compression I am warring about pinging.

How come Canada has high octane grade gas? I've noticed this on trips to B.C. Maybe in L.A. you could find 93 but nowhere in Washington-91 is the highest. I have a friend with a real 429 Shelby Cobra that won't run on 91 Maybe he needs to move to Canada

i'd guess warn needle jets. does it blacken the plugs if you cruise around?

I put a brand new needle jets last season so I don’t think this is the case.

if the needles are scratched they'll chew out a new set of needle jets in less km than a tank of fuel. we polish any jet kit needles if we replace needle jets.

If that would be the case what are my options?

new needle jets, new needles. you'll probably need to buy a complete jet kit as dynojet and factory both won't sell the needles individually in my experience.

Go for the 41mm Kehins instead of throwing good money after bad.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by brad black &raquo;</TD></TR><TR><TD CLASS="quote">new needle jets, new needles. you'll probably need to buy a complete jet kit as dynojet and factory both won't sell the needles individually in my experience.</TD></TR></TABLE>

Maybe the emulsion tubbes as well?

I thought that surging meant it was running lean in that range.??