Fredrik

Hi guys!

Need some expert help here on tuning engines!

When my engine has been on full throttle for more than 20 sec, the rpm slowly decreases until it dies when I put the throttle down to idle. After full throttle for less than 20 sec the rpm also decreases but then increases again to a stable idle. I think the full throttle setting are at the rich side. Any ideas? I would be most thankful! By the way, the engine is quite new so it might not be fully broken in yet.

Best regards/ Fredrik

smitty70

My Feedback: (5)

sounds too lean to me.......Do a pinch test. pinch the fuel line very quickly. If the rpm decrease or the engine dies, it is too lean. If the engine rpm increases alot then it is too rich. When the needle is set right the engine rpm should increase slightly when the fuel line is pinched quickly. Do this with the engine running at full throttle.

downunder-RCU

Sounds lean to me too. An engine that's running rich will hold a stable RPM all day long. It also seems to me that maybe your fuel is a bit low on oil content unless it's very lean. Richen the high end until it's obviously rich and see how it goes. If it still does the same thing then try another plug or fuel.

Fredrik

Ok! I'll try that, Thanks a lot!! This forum i fantastic!

/Fredrik

ossie

Yes I agree that the engine sounds like its running too lean.
SC's when new take a little time to run in.
My SC .75 took around 20 X 16oz tanks to fully run in, a really strong and reliable engine now.
Hope this helps.
Cheers
Ken

ossie

Oh yes, and use a No. 8 OS or colder plug.
Ken