Jonsered 451

[Mutley]

I've put my hand on a 10$ 451E that was supposed to be dead. I've managed to get it going quite easily and I have now some questions about it. On the chainsaw collector corner, they claim that this model should use a 25:1 fuel ratio. Now, I've made severals search about that subject, and usually people here are recommanding between 32:1 to 40:1 fuel ratio. I've used 40:1 fuel ratio to get it going, but I'm concerned about keeping it this way.

Also, I'm kind of a newbie when it come to 2 stroke and carb stuff. There's 2 small screws on the top to adjust the carb, and a bigger one just below them. The first two one are probably for Idle (L) and WOT (H) . The other one I don't know. I would like to know how to adjust these. The carb is a Tillotson HK-12, but I don't really know how to adjust these. If I turn the screw clockwise, I guess I'm letting less fuel to pass by, and vice-versa? How should I adjut the Low and High? Also, what's the purpose of the bigger screw just below the 2 small screw?

Thanks for your help

 

[TimberPig]

The bigger screw is the idle speed adjustment. The others are for the low and high speed air/fuel mixture adjustments. In (right) on the mixture screws leans it as you guessed. In on the idle speed screw raises the idle speed.

 

[Mutley]

Thanks for your help. I've managed to get a perfect idle but adjusting the L and IDLE screw, but as soon as I WOT , the motor want to die (too much fuel I guess) . I try with the H screw all the way IN with no improvement. What I should look for in the carb? What exactly a good cleaning of the carb require?


Also, anybody is aware of which fuel ratio I should use?

 

[lostone]

richen up the L screw and turn the idle screw in some so it wont die, then try to wot it and see what happens, sounds like you are to lean on the L screw. Run a search on carb adjusting on here there are several links that will help you out. Madsens has a good page on adjusting carbs.