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75 Tl 125 (122cc) Cam To Crank Timing


biffsgasgas
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The internet is a great thing but I just couldn't find out how to time my tl 125 k2.

I had a worn gear bushing and a bad one way for the kick starter. With a set of new gaskets from bike bandit i have dug into the internals and gone though the gear box. I am all sorted out now but decided to give the ole beast a new set of cam and crank gears along with a timing chain. I felt it deserved the attention. I am at the point where i want to get this thing timed. I discovered that the crank gear is a pressed on with NO key way???? Ok well i might for go the crank gear because mine seems to be in good condition with nice square teeth. I have the new one but if it is not broke dont fix it. The cam gear had three teeth that were worn so that has to go and i have the new chain. I have a circle mark on the cam gear and i can find top dead center with the flywheel and my dial indicator. I am wondering where i can time the cam to? I think i see a mark on the head but i have also heard that you need to just line up all marks straight up. When i got home tonight i was going to just pull the cam adjuster caps off to look at the lobe but i want to be a little more scientific than that. Any help would be greatly appreciated. I am an experienced engine builder but for some reason this one is not intuitive to me. Thanks in advance.

--Biff

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Hi Biff. It just goes straight up. You might see a little notch like thing on the part that the cam cover goes on.

The flywheel will have a mark on it to line up with the case. Get it on TDC and take a look. 0 on the top of the cam sprocket. Pay attention to the way the chain tensioner works, it's counter intuitive.

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with the TL125's, it is _possible_ to get the timing 180 degrees out

1. Get the flywheel on the "T" mark, making sure you hold the camchain up so it binds with the teeth when you rotate the flywheel

2. Set the camshaft so that the cam lobes are pointing up, ie they are in contact with the rocker arms (you should loosen the valve clearance adjusters to take off the strain)

3. take the mark from the camshaft sproken (an "o" normally and align it with the mark on the cylinfer head)

run it over by hand. The Clymer manual for this bike (and the other Honda singles) goes through this pretty well

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Excellent. Thanks guys.

I did clean out the oil slinger. I had metal in the filter screen from the bushing that had failed on the output shaft. This was the gear on the shaft that mates up wiht the kick starter gear. It seems as if the gasket failed in the case halfs and instead of draining down into this bushing it was bypassing. I got a bushing from a donor cr80 that i was junking and I am proper through the whole case with new gaskets and every thing.

Yesterday i loosened up the rocker arms and also spun the cam by it self to do a non evasive inspection of the cam gear bushing. It seems to be ok. I am giong to keep this thing stock for this summer. This winter i am sending the jug and head to B&J to have him put in the 150 kit and have him go through the head bushings. I wont compete on it untill thats done.

The guy who owned this used it as a trail bike. The exhaust was rusty but it does not even look as if the thing had been on its side. The oil had tons of fuel in it so i am chalking up the failure to lack of maintance. I have replaced all of the case bolts with 8mm's to get rid of those silly phillips heads.

The cr 80 shift lever mounts right up too and its a flip back type so i ditched the oem shifter for the more trials friendly version.

I see what you mean about counter intuitive. It seems if you back it out it should tighten but thats not the case. I discovered that upon tear down.

I should have this at mid ohio as a pit bike. Look for the only repsol colored tl125.

--Biff

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