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Timing / carb issues. Any ideas.

950 views 8 replies 4 participants last post by  duke416ex 
#1 ·
Just rebuilt my TRX 450 R with a 470 kit. 96 mm piston. It was running great before with huge bottom end power. I don’t know what cam it has but I know it doesn’t have the stock cam. The cam has a number three engraved in the gear side with no notches on the other side, and Had a big valve head. Now have a stock head. Original jetting was 180 Main 55 pilot. And stock carb. And I already had the 470 kit to begin with. Now with stock head it acts as though you’re hitting the rev limiter around mid RPMs with wide open throttle.Any ideas would be greatly helpful please.
 
#2 ·
My first question is why did you go back to a Stock head?

1. Are you running an Air Box Lid? If so remove it...

2. Might have to big of jetting go down to like a 168 (= to a 152 DynaJet) or like a 170 (= to a 154 Dynajet)

3. What brand jets are you using? If it's DynaJet that's equal to like a 205 Keihin jet seems way to big in my opinion. Remember richer is not always better.

To me sounds like your fuel mixture is way to rich.

Check to make sure your cam timing is correct. At TDC you wanna have the Intake Cam Lobes pointing to the back of the quad and the Cam Sprocket Screws directly up and down
 
#4 ·
Thank you for your input. Really do appreciate it and I found a big part of my problem. A/f screw was missing an oring. Replaced it and now it’s running but still having issues. Running great but having a strange blog about quarter throttle while pulling. Free revs great with no hesitation from idle to rev limiter. And after running for about 15 minutes it all of a sudden decides it doesn’t want to crank.
 
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