40 hp / 2cyl / 1 carb run rough at idle ?

[kergoat]

hello

My motor mercury 2001/ 40 cv / 2cyl / 1 carburator walbro doesnt like to be under 1000 rpm in forward speed under this the motor sounds a bit rough.

I ve never solve this i check en re check timing(8 degrés at idle) , try different settings for the idle mixture screw nothing to do the motor is very rough at 750 in forward speed!

So i put forward speed at 850-900 in forward low speed, it's a just a little bit better tan 750 rpm!

Is there a solution to solve this problem or is it normal for this 2 cylinder / 2t motor to be very rough under 1000 rpm?

thanks

 

[Texasmark]

Re: 40 hp / 2cyl / 1 carb run rough at idle ?

No. Realizing that you only have 2 cylinders, alternate firing, but they do fire every time they come up, it's not going to run like a sewing machine, and the power impulses are obvious in the engine as it will be shaking somewhat, but the rythm is solid and it shouldn't die.

Dieing is fuel starvation and you need to fix that as high idle rpm's are very hard on your shifter mechanisms in the lower unit.

Try a decarb and clean out your fuel tanks. Do a search for the decarb process. Worked for me; might work for you.

My low speed jets are 1 1/4 open for the factory setting. Currently running 1 1/2 open. If you screwed your low speed jet it too tight you may have damaged it (them). Take it out and look at it. It should have a perfectly smooth conical tip. If there are any rings on the tip it is damaged (from overtightening) and you will need a new one before it can do you any good.

Mark

 

[kergoat]

Re: 40 hp / 2cyl / 1 carb run rough at idle ?

Do you think i must decarb? My motor must have 100-150 hours of run max !

My motor work at 750 rpm in slow forward, but the power head is shaking, but never stall. I think it's the way this motor work?

So i must re set it to 750 to prevent shifter mecanism ?

your idle screw mixture is set to 1.5 turn ?
for the 40 factory preset is 1.5 turn +/- 1/4
mine is set to 1.5 tr i can find/heard any difference at 1 1/4 or 1/3/4 !

thanks for answer, excuse my english i m french from Brest