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3W 106 strange behavior

Bill Vargas

Bill Vargas

50cc
The other thing about 3W engines is they have more compression than most other engines. They always run best when tuned on the rich side of the house. A sag is lean condition just like that infamous Holley 4 barrel bog when you stomped on the gas. Burbly is obviously rich, it catches after it cleans out and goes. There you would want to tune the engine to be just above that. A new set of plugs wouldn t hurt either.

Tune for flight,,, not the ground :)
 
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thurmma

thurmma

150cc
I know it has been a while, but we have been rained out for a couple of weeks here. The last trip to the field after a full rebuild and leveling of the aluminum reed cage and carb mount was very encouraging. I have it just about fully tweaked and it will knife edge both directions again :) I really think there was a slight air leak that would rear it's ugly head when the plane was in a ke from left to right due to what I found when leveling the surfaces of the reed cage and the carb blocks.

When going from right to left, the fuel may have been enough to seal the air leak because the warp was at the bottom, but when going from left to right, the warp was at the top, so no fuel to seal the slight air leak, thus running lean :) Strange things happen to great people just to make them burn more brain cells!
 
Kevin-Young

Kevin-Young

70cc twin V2
you couldn't have something simple like the clunk in the fuel tank getting hung up on the side or back of the fuel tank, could you? Try and look at the simple things first like tank or fuel lines and cross them off the list before you get into reed valves, chipped reed petals, carb blocks and such.
 
thurmma

thurmma

150cc
@Kevin-Young, I went through everything twice with a fine tooth comb before digging in to the engine. Once I had no other alternative, I pulled the carb, carb block and reed block off and went through all of them and it appears that the issue has been resolved :) Thanks for offering alternatives :)
 
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