1981 ATC 200 with ("85" 200x cam and Wiseco 10.25:1 Piston 65MM) STUMPED...

[Snyderman]

Installed a new piston, rings and cam in a 1981 ATC 200 I am restoring. (Didn't want to hi-jack McQuade's post but similar issue)

Checked/measured all the ring end gap clearances, cylinder bore , piston , camshaft journals, cam bushing clearances and camshaft lobes/wear, and installed new timing chain. All measurements were spot on, and within tolerances.

Did not touch the valves as they looked to be in good shape. Got it all together and I can barely pull the recoil starter...?

So... I am wondering:

1. Could it have this much compression with the 200X cam and 10.25:1 piston.( Standard bore 65MM)

2. Could I have installed the cam 180 degrees off.

3. The decompression lever doesn't seem to be helping any, could this be because the cam is not installed correctly.

4. Could the cam chain be too tight, I did not adjust it after install.

5. Should I be adjusting my valve clearance to "85" 200X specs.

6. Most importantly... I am not an expert in motor rebuilds, my favorite color is bacon, and I failed Algebra in high school so... Please be kind!

Note: I did not try starting the bike as of yet, wanted to double check the cam before I put it back on the frame. Not certain if this is "normal" but I could not spin the flywheel by hand..? (no plug installed)

Heading to the garage this morning once the temperature gets over 20 degrees Fahrenheit...

[flynfish]

Installed a new piston, rings and cam in a 1981 ATC 200 I am restoring. (Didn't want to hi-jack McQuade's post but similar issue)

Checked/measured all the ring end gap clearances, cylinder bore , piston , camshaft journals, cam bushing clearances and camshaft lobes/wear, and installed new timing chain. All measurements were spot on, and within tolerances.

Did not touch the valves as they looked to be in good shape. Got it all together and I can barely pull the recoil starter...?

So... I am wondering:

1. Could it have this much compression with the 200X cam and 10.25:1 piston.( Standard bore 65MM)

2. Could I have installed the cam 180 degrees off.

3. The decompression lever doesn't seem to be helping any, could this be because the cam is not installed correctly.

4. Most importantly... I am not an expert in motor rebuilds, my favorite color is bacon, and I failed Algebra in high school so... Please be kind!

Note: I did not try starting the bike as of yet, wanted to double check the cam before I put it back on the frame. Not certain if this is "normal" but I could not spin the flywheel by hand..? (no plug installed)

Heading to the garage this morning once the temperature gets over 20 degrees Fahrenheit...

If you installed the cam with the lobes pointing down its in there right.

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[Snyderman]

Yeah... I cant remember if the lobes were down... Rookie move...

[flynfish]

Ha-ha i be done it alot myself only to find it once I'm real pissed

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[yaegerb]

Either your valves are too tight or your cam is 180 out.

[Snyderman]

Either your valves are too tight or your cam is 180 out.

I loosened the valve adjusting nut(s) before I installed the cam, then I set valve clearances at .005, I am gonna check the cam again soon as it warms up a bit... Thank you!

[Mackus84]

I agree with the other guys. Its easy to pull the cam back out and check everything. Follow the manual exactly, or theres a good write up on her for it. Pretty simple to do. Once you know WHAT to do. I was able to use the instructions on this site for setting the timing and it walks you through thoroughly. First time i had ever did it and fired first kick on my 200x. Cam Lobes down, the little pin on the cam will be somewhere around 11 oclock. Let us know

[Snyderman]

I agree with the other guys. Its easy to pull the cam back out and check everything. Follow the manual exactly, or theres a good write up on her for it. Pretty simple to do. Once you know WHAT to do. I was able to use the instructions on this site for setting the timing and it walks you through thoroughly. First time i had ever did it and fired first kick on my 200x. Cam Lobes down, the little pin on the cam will be somewhere around 11 oclock. Let us know

The cam was exactly at 11:00 when its was installed. I had the manual on the workbench through the entire install... Heading out now to try and make some magic happen. Thanks!

[Snyderman]

UPDATE: Took out the 200X cam and installed the original cam and it fired on first pull...Still lots of compression though...

Still seems like timing is off and it just isn't running smooth...?

[Mackus84]

Ok, cam/valve timing looks good. How about the ignition timing/ pulse generator. Got all that timed right? Also, maybe wanting more fuel with the higher compression piston?

[Snyderman]

Ok, cam/valve timing looks good. How about the ignition timing/ pulse generator. Got all that timed right? Also, maybe wanting more fuel with the higher compression piston?

Ok so... I advanced the timing a bit on the pulsar coil and got is starting now on first pull and idling pretty smooth with the exception of a slight vibration I'm feeling through the handlebars and a slight noise coming from the motor? Wondering if maybe my crank bearings are bad.

[Snyderman]

UPDATE#2

Further inspection revealed the Wiseco piston direction was wrong. I heard a slight ticking/subtle knocking and thought it could have been crank bearings. I had the arrow on piston top facing towards intake which should face exhaust valve.

-2nd Einstein find was a scored cam bushing on the 200X cam that was causing the bushing to seize up on the journal about 3/4 of a rotation. Not sure how I missed this one... Anyway... Contacted the seller on Flea-bay and he sending me out a replacement that he guaranteed will be within tolerance and perfect working order.

Took the whole motor apart last night and didn't see any other issues or damage... Hopefully have it together this weekend with no more gremlins in the mix.

Thanks to all who contributed their help on this one!