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Timing Info needed on 90cc Knock Off Engines

1066 Views 4 Replies 3 Participants Last post by  five0addict

I have a 90cc engine with the long cylinder and electric starter. The flywheel does not have the T and F marks like the old hondas so I am a bit lost. Instead there are these lines and dashes. So, because I was hasty in ripping off the top to put on a 106cc kit, I neglected to see what the correct timing point is.

There is a series of lines with little 0's on the top of them, a blank space, and then a series of dashes on the flywheel. Where am I supposed to line up the O mark?

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Before you put the head on, put the piston on TDC and look to see which mark corresponds to TDC.

TDC is Top Dead Center.
Addl Info

Well, it is all bolted back together and is running but I just don't think that it is all there.

I tried to use the spark plug hole to reference TDC, but I just can't get the know how it lags there for just a second. That can be the difference of being a tooth off on the timing in either direction. I just don't want to pull it back apart to do this...someone must have one of these laying around??? I just have this sneaking feeling that I have the engine slightly retarded...If I move it the other way, do you think there is a chance that I will bend the exhaust valve up?

I am running a ported and polished E22 Head hd springs, a 52mm domed piston and 49.5 crank, takegawa coil and rev box, a 24mm Mikuni TM jetted 15/160, a Classic Honda Pipe and a special modified camshaft with a 6.7mm lift and nice duration setup for midrange power from WebCams in California with a 2 degrees advance. All this is in a modified 1972 CL70 frame with a 17" front and 14" rear running a 15/31 sprocket combination. I expect to hit 75-80 mph on this with a crusing speed of 55.
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Do you know of anyone who has a bore scope so you could look into the combustion chamber through the spark plug hole?

That may be the easiest route.

My guess is you'll put down somewhere in the neighborhood of 10-11hp with that motor. I have a 108 with 11 HP and I can barely hit 70mph full bore with a 26mm carb. With your motor setup, I'm afraid you won't have enough HP to push the bike past 65-70mph full open.

You have an interesting project, and I would request you keep us posted on your speed goals.

On a 12" tire bike, with a tad under 20 hp, I've seen people go close to 85mph with a full race motor. With 15 HP on tap, people get around 70mph, and with an 11-12HP motor, the most I've seen is right around 70.

Cool project...
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take off the two silver screws with a flathead.

theres one on top, and one on the side. the one on top is to look through, the one on the side goes to a bolt that is turned with a socket, and extension to the outside.

tdc is 2nd from right to left.

if this doesnt make sence respond and ill get pictures.


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