New pump cover and it still cuts out!!!

24 replies to this topic
  • Ga426owner

Posted May 10, 2005 - 10:37 AM


I'm way ahead of you thumpalot, I completely took my carb apart and cleaned it out. It was spotless before I even did that. I inspected everything and it looked great but I figured since it was apart that I would hose it down in carb cleaner and blow it out with my compressor. Anyways that did nothing. :worthy:

I'm gonna try a richer pilot. If my valves are out of adjustment will that have anything to do with throttle response off the bottom. :) :D

All I can say right now is that I feel absolutely no effect from boyssen's pump cover. I'm sure its not there product, but all my fault for not having the bike tuned right. :D

What about needle height? Anyways I'm gonna check my valves, if there good then I will try a richer pilot. If that does nothin then I will move the needle. :D If no luck there then I will get a YZ250 :) :D

you are giving up too easy.........did you make sure that you installed the diaphram right side up - a common mistake. Set the AP duration with the gauge it is the starting point - stock level
The fuel screw should be set 1/4-1 turn out -
Valves have nothing to do with this - but check them for adjustment

  • dunecj2a

Posted May 10, 2005 - 02:09 PM


The diaphram should be right, looks just like the picture. The spring should sit in the little seat right?

One side has a little metal ring that looks like its a seat for the spring? Also doesnt the lip of the diaphram needs to sit in the pump cover?

Do you think I need to fool with the Timing squirt? Its set with that guage boyssen gives.

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  • dunecj2a

Posted May 10, 2005 - 02:16 PM


What pilot are you running now? If the fuel screw didnt change anything, go down one size, not up.

Hey fastest
You think leaner is better than richer?? Plug is a little black but doesnt look to rich. Its been a bitch to start lately when its sat for a couple of days. Thats kinda why I was leanin towards a richer pilot. :)
Oh ya its a 42 pilot.

  • Fastest1

Posted May 10, 2005 - 03:09 PM


Plugs are deceiving without doing a real plug chop. They have to run through every RPM and there are transitional throttle changes that wont necessarily be spot on in all conditions. I always gravitate towards lean because throttle response and power are when the mixtures are leaner. I recommended the leaner pilot due to your statement that the fuel screw made no change. These carbs are infinitely adjustable and there is always changes to be made if you are patient. Good Luck and I would check and adjust the timing squirt if needed. Also is this bog only on the stand? or when underway?

  • Scotty426

Posted May 13, 2005 - 10:33 AM


When I put the Boysen cover on, I became rich during accel pump operation until I did the BK mod and reduced pump timing. Now shes sharp and nice.

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