Stumbling engine

[DarrellT]

Stas first.
1986 Honda XL250R
RFVC engine with dual carbs.
I just replaced the manifold unit from the carbs to the head with a new one from Honda to replace the old one that had a couple cracks and vacuum leaks.
I figured this would solve my serious lean out condition when cracking the throttle quickly from idle to 1/2 or more throttle...No dice it seems to be the same. If I crack it fast to 1/2 throttle the engine just dies if held at 1/2 throttle for more than a couple seconds, if I close the throttle the engine will recover and idle...but a little slower.
My Clymer manual says the primary carb has a accelerator pump yet I can't find anything about it in the exploded technical views in the book.
Can anyone shed any light on this for me?
Thanks
Darrell

 

[Ol'89r]

Darrell.

If I remember correctly, :) , your primary carb does not have a accelerator pump.

The primary carb has all of your low speed jets and the secondary carb has the high speed jets.

I would suggest taking your carbs apart and cleaning them. Also, the correct adjustment of the linkage between the two carbs is very important. Try adjusting the linkage to where the primary carb opens further, before the secondary carb opens. If the secondary carb opens too soon, it will give too rich of a condition. Your manual should show you how to bend the little tab on the linkage to correctly adjust this.

Many XR owners adjust this tab the wrong way thinking that by opening the secondary carb sooner, it will give them better throttle response. Actually, it works quite the opposite.

No matter how well your carbs are adjusted, they will never operate as good as a pumper carb when you snap the throttle open. Just the nature of the beast.

Just my $ .02

 

[IrishEKU]

Ditto!

Cleaning usually clears up the problem or clues you in the right direction.

Phillip