Tuning Help!

[The_Bill]

hello all

i have been having an issue with the high end of my motor. I cannot keep it at full throttle. It doesn't die but kinda cuts out/lowers rpms and gurgles... it seems to be tuned right, up till full throttle. can a small air leak cause this? bad plug? i have looked this up all over and on this forum to, but cant find my exact problem

 

[nitrocat]

Sounds to rich if not it's to lean but I'd bet to rich

 

[The_Bill]

which needle do you think? they both seem to be set, it runs great all day but won't hold WOT, it will hit the high end then back off a bit by its self

 

[Revolauncher]

Verify carb. is W.O.T. and servo is travelling correctly, then make sure the carb. bolts are tight, then see if your fuel line needs replacing. The stock 5ive T fuel line for instance is black and you can't see the air bubbles going into the carb. when the fuel line is leaking air. After replacing my stock fuel line with 3/16 tygon (yellow clear) (chainsaws use it) it then tuned and ran like a champ, top to bottom. Rule out the simple things first would be my advice before you start replacing gaskets, carbs. etc...

 

[tallgoldguy]

I had the same problem. Low end had all the power but once I hit top end, it fell on it's face. I started with a new carb because I did find an air leak, like everyone told me about at the throttle lever. Well, new carb and still had the problem. Thing is, even new carbs have the same air leak from around the throttle lever. Replaced the clunk, all fuel lines with the chainsaw yellow line. Did not resolve the problem. Turns out that the velocity stack and filter I bought, well, it did not filter anything. Dirt and debris took out the chrome plating on the cylinder. OBR 4 bolt Zen head and 36mm piston and it's a monster now. I hope you don't have the same problem but unless you have a Redcat with that crappy clone carb, you may need to look at the cylinder.