Engine Trouble Will not Idle, At All!

[Greg58]

24 mph is really low, sometimes on a unmodified engine the smaller sprocket keeps the engine from reaching the needed rpm to produce the maximum horse power. The guys that reach the higher speeds have a good bit of improvements done to theirs. Just as a example I have a straight plug head on one of my 48cc engines that has been shaved .040, ports cleaned up and the piston skirt trimmed to clear the intake port at tdc, it will do 30 plus on flat roads with a 44 tooth rear sprocket. I have another engine that has a angle plug head with a nice squish band with porting and piston trimmed that has reached 32 mph on the same bike.

 

[Hello Moto!]

I resurfaced the head and made a new gasket and I still don't feel like my engine is running 100% I'm almost wondering if my crank case has a minor leak. There's a spot where the gasket isn't seated right. Not sure but I can only get to about 27mph and it seems boggy any where after 15mph. Maybe our problem is similar lloyde.

 

[crassius]

some motors are just slow - I'm thinking bad port timing by some factories, or highly polished cylinders not getting a good seat of the rings - a lot of the old H2 motors were that way

never forget to check case bolts and suchlike for seepage tho

 

[Lloyde]

have you checked the head for flatness?

Yes, I have checked for flatness. And I sanded the Cylinder, Cylinder Head & Piston so they all should be flat & smooth now. I'll try making my own gasket, and attempt turning the head 180*. I say attempt because my bike frame is a little tight on space.

the smaller sprocket keeps the engine from reaching the needed rpm to produce the maximum horse power

When you say Smaller Sprocket, are you talking about the Rear Sprocket, or that little 9T/10T Sprocket that is Part of the engine itself. I don't count myself as stupid, but I like clarifying when there are multiple bits & pieces that have the same name.

never forget to check case bolts and suchlike for seepage tho

By that do you mean to simply say to make sure everything is tight? I remember trying to take the Crankcase apart at one time, but for some reason I could not get it apart even though I was watching a youtube video on how to do it. And I am confidant that I put everything back in the correct place.

 

[Greg58]

I was referring the 36 to the 44 on the rear, depending on the weight of the rider the 36 may be too tall of a gear. Remember the more teeth on the rear the lower the gear, more teeth on the front the higher the gear.

 

[Greg58]

One good way to check for a good seal is to spray the head gasket with paint on both sides and torque the head down, then removed it and look for spots on the head or cylinder that doesn't have paint or the paint is very thin. We used to spray metal head gaskets to help them seal before permatorque gasket were available for auto engines.

 

[Lloyde]

OK since the last comment, I made some new seals (upper & lower cylinder), tried turning the Cylinder Head 180* (could not do it because of the frame), Somehow I have lost one of the bolts that go in the Gear Case Cover (could not find it, so I made a replacement using a longish bolt a couple washers and a lock nut), i'm about to try it out and i'll get back to Y'all weather or not it is working.

 

[Lloyde]

OH MY GOD! DX I decided it would be a good idea to check on the Spark Wire Loop Set - Magneto, because I had heard that there is sometimes a problem with its wiring. And Guess What!!! the 12V Generator that I had installed last year was literally, . . . . well I'll just attach some Pictures. The First picture is a stock photo from Gasbike.net, The Second picture is after I took everything out of the Magnet Electric Cover, it ain't pretty.

 

[Lloyde]

BUT! The Good News is after I removed the broken 12V Generator, I put the cover back on and tested her out. AND SHE IS ALIVE AGAIN!!!