Stalling @ high rpm

[zgjttgd]

I installed a 30mm OKO (Keihin take off) on my son's blaster with a Shearer pipe and vforce 3s. The carb was off of a KX85 if that helps. I am running a 155 main jet and a 52 slow jet. The plug looks good and I am running 32-1 fuel mixture with Maxima oil. Start up is fine and it run's smoothly until he tries to go full throttle in 4th and 5th gear. The motor won't maintain full rpm for more than 3 or 4 seconds before it stalls out. It will then restart and do the same thing all over again. I was wondering if anyone has had this problem before. I was reading and article on the site about seizures, and I noticed in one scenario my same problem was listed. Here is the description.

"As many people already know, a larger size needle and seat must often be installed into a carburetor to contend with the increased fuel demands of a moderately modified engine. If a modified engine is operated at full throttle with a stock size needle and seat, it will usually carry full rpm for about 2 or 3 seconds and then shut off as if someone hit the kill button. When the machine comes to a stop, the driver re-starts to see what the problem is.
The engine, no longer in fuel deficit caused by the undersized needle and seat, unexpectedly starts right up. This instant high speed shut off is caused by the carburetor literally running out of gas."

This sounds like my problem, if you agree let me know. I am not sure what size needle and seat I should be running. Any help would be greatly appreciated. Thanks in advance.

 

[blasterfreek30]

lol before u posted that quote....i was gonna say it sounds like the carb is running running out of fuel

 

[stephen12091985]

so maybe try to put a bigger main in there

 

[zgjttgd]

Thanks guys. I am not sure what the fix was, but I installed his Project Blaster Air box today, went up on the main jet and set the needle clip up two positions. Problem fixed, it's a little rich because I only had a larger size jet, one size down and it will be perfect. Thanks for the help, the PB air box really opened this thing up, it sounds a lot different. Now that he's set up I had a hard time getting away on my YFZ in the woods, I am shocked at how strong this thing is now.

 

[tyler1blaster]

Thanks guys. I am not sure what the fix was, but I installed his Project Blaster Air box today, went up on the main jet and set the needle clip up two positions. Problem fixed, it's a little rich because I only had a larger size jet, one size down and it will be perfect. Thanks for the help, the PB air box really opened this thing up, it sounds a lot different. Now that he's set up I had a hard time getting away on my YFZ in the woods, I am shocked at how strong this thing is now.

so u liking the pb airbox? was it hard to fit?

 

[zgjttgd]

Yeah we love it, I ran the Shearer without it and then with it installed and there really was a difference. It was not hard to install at all, took me about an hour to take everything off, do the mod, and put it all back together. Once this thing could finally breath it woke up a lot. The Shearer is awesome, my son's buddies have FMF and LRDs and there is no comparison.