impact of valve clearance being too low

[skids]

Did you check your timing marks at TDC after you reinstalled the tensioner?

[skids]

I think I had 0.23 inches of travel on the tensioner after replacing a cam chain with an Enuma(?) chain. What is that, like about 5.8mm? The thickness of the gasket comes into play for that.

[dansmith65]

I would not take the head off until the motor has been run a few hundred miles. The rings are still stuck from long period of non-use. Those numbers will come up after some use, they always do. JMHO

Just to make sure we're on the same page; the last time it ran was Nov 25th and the "before" compression test was done on Oct 5th. I have heard of rings being stuck, but I thought that was from years of sitting. Given that's it's only sat for 3 months, do you still think rings could be stuck already?

[DiverRay]

Pour a little bit of motor oil in each plug hole. Let it set for a bit then try again. Put rags over the open plug holes so the oil doesn't fly all over the shop.
You can also use a little ATF instead of the oil. It's much better at cleaning oxidation.

[bikerphil]

I bought an 80 special last summer and have only ridden it home and started to work on it so far. It's got 34,800 km's (21,600 miles) on it and I don't really know it's history

I was reading your first post in this thread and figured the engine wasn't run enough to free stuck rings. I would do as Diver Ray suggests and pour MMO down the cylinders and let it sit for a while.

[dansmith65]

Did you check your timing marks at TDC after you reinstalled the tensioner?

Yes, I did and it's a little off... In reviewing these photos to post, it almost looks like I'm off by a tooth; would you agree?

Crank aligned with the "T" mark for these photos:

Alignment before cam removal:


Alignment after cam removal:


Thanks for the reminder of oil/ATF/MMO down the cylinder; I'll try that after correcting the timing.

[skids]

If it was spot-on prior (hard for me to tell) and you ended up as shown, I would say there is a chance that it may have slipped a tooth on the right hand sprocket. I have had my marks not spot on and it was the best I could get it. Just saying. I even tried to check TCD with piston maximum...

[DiverRay]

Top looks correct, bottom looks off!
I would say skids has it, one tooth off on the intake cam.
If you have the bike on the center stand so it's upright and not leaning, easy fix. Line the "C" mark up, pull the tensioner, and starting at the rear of the intake cam slip the chain one tooth. You would start at the back lower part of the gear, and use needle nose pliers to try and start the one link, turning just the intake can SLIGHTLY as you work the chain up the one link. Once done, tighten the cam chain again then turn it over by hand two revolutions before checking the marks. They should be dead on again.

[skids]

Top looks correct, bottom looks off!
I would say skids has it, one tooth off on the intake cam.
If you have the bike on the center stand so it's upright and not leaning, easy fix. Line the "C" mark up, pull the tensioner, and starting at the rear of the intake cam slip the chain one tooth. You would start at the back lower part of the gear, and use needle nose pliers to try and start the one link, turning just the intake can SLIGHTLY as you work the chain up the one link. Once done, tighten the cam chain again then turn it over by hand two revolutions before checking the marks. They should be dead on again.

Absolutely on the center stand! I am wondering about the slack being on the exhaust side when the tensioner is pulled. Do you think that an assistant could push a bit on the tensioner slipper through the hole with a flat tipped screwdriver while the crank is rotated slightly counterclockwise? Just enough to get some slack to work with on the intake sprocket and prevent slipping the crank sprocket?

Once the chain is pulled over the sprocket one tooth, push again with the screwdriver in the hole while the crank is repositioned clockwise (slightly) to move the slack to the exhaust side so that the tensioner can be reinstalled. I would think that the C mark should be checked carefully to ensure the chain doesn't slip on the crank sprocket. If it doesn't work, disassembly is required...

I can not say this will work, but it is just an idea. Anyone care to chime in?

[MaximPhil]

Hi Dan,
While removing the carbs will be better than wide open throttle try it with the Spark plugs installed......or the air escapes out the hole
The MMO will do it good too. After sorting the cam chain out as described by Ray.

Phil

[dansmith65]

Quick update for now, will post more tomorrow... Got the timing corrected, compression improved but still low, drop of oil improved compression more, too many drops had it upto 200+ psi... Oops!

[DiverRay]

Not really an Oops, just what is expected. Once you start riding it, just ride hard for a bit and try again. you'll be pleased with the difference.
Oh, as a hint, 50/50 ATF and Acetone does a VERY good job of freeing up rust. Seafoam or Berryman's B12 will cut carbon and old gas buildup, but is VERY HARD on paint and rubber..

[dansmith65]

Now for the details...

The chain was surprisingly easy to move by one tooth on the exhaust cam. I hate to admit it, but I failed many times when working on it over the weekend, but I think I gained some experience in the process. Mostly, I kept making silly mistakes and had to re-do stuff. I was sure to slowly turn the crank by hand, to not cause any damage, though. So, to move the chain by one tooth, I did this:

1. bike was already level, from checking fuel level in carb bowls before tear-down
2. turn crank to the "C" mark
3. remove CCT
4. turn crank counter-clockwise, towards the "T", stopping as soon as I felt resistance.
5. using fingers only, pull up on the chain at the back of the intake cam sprocket, move it one tooth.
6. re-install CCT
7. slowly rotate crank to check alignment again. Found that both cranks were off by the same amount this time. (turns out the crank skipped a tooth because I didn't put tension on the chain through the CCT hole, as skids suggested I should, but to be fair I did this work before his post)
8. I cant remember clearly, but I think I turned crank past the "C" mark a bit (guessing how much one tooth would be)
9. remove CCT, again
10. turn crank counter-clockwise, to the "C", making sure the cams didn't move as I did this.
11. put my finger in the CCT hole to get the chain to grab/engage the crank sprocket
12. re-install CCT
13. rotate crank/re-check alignment; it was all good this time!

I had just gotten a new Hex Bit Set in the mail yesterday and they made the job go so much quicker. Getting the valve cover off and removing/installing the CCT was a breeze when paired with a little 12v impact driver; so much better than a hex key!

While I was at it, I measured the remaining travel on my CCT to be 2.2mm. I thought that was way too little considering how much travel is available until skids said he only had 5.8mm with a new chain. Considering the bike has only done 22,000 miles, do you think I'd be good for another 5k, at least? If so, I won't bother changing it now.

Compression after correcting timing:

1. 143
2. 115
3. 110
4. 132

A few squirts of oil in #2 brought compression over 200 (stopped cranking at that point). I thought that meant I put too much oil in... hence the ooops. A few drops of oil in #3 brought it up to 132. Since the oil improved compression, I'm assuming that the lower compression is NOT due to leakage at valves, so I'm back to thinking I don't have to take the head off. Does that sound correct?

I only had enough ATF on-hand to put a few dribbles in each cylinder, so I also added a little oil and a little kerosene. I haven't been able to find MMO locally and I haven't gotten around to ordering it online yet, either. I'm hoping that will loosen things up, as I work on other parts of the bike. Now that all that fluid is there, I can't get a reliable compression test; #2 is still over 200psi. I'm assuming I'll have to either let it sit for a while so the fluid drains into the engine, suck it out, or start it and burn it out before I can do a proper compression test again.

[DiverRay]

I only had enough ATF on-hand to put a few dribbles in each cylinder, so I also added a little oil and a little kerosene. I haven't been able to find MMO locally and I haven't gotten around to ordering it online yet, either.

You should be OK. I would still put a little Seafoam or Berrymans B12 into each hole to help free up the rings.

Now that all that fluid is there, I can't get a reliable compression test; #2 is still over 200psi. I'm assuming I'll have to either let it sit for a while so the fluid drains into the engine, suck it out, or start it and burn it out before I can do a proper compression test again.

DO NOT worry about the test! Wait until you have at least 100 miles on the bike before trying it again. Sync carbs, ride about 100 miles, test, and re-sync carbs. As it's been sitting, old gas, bits of carbon, etc. causes problems with the rings.

While I was at it, I measured the remaining travel on my CCT to be 2.2mm. I thought that was way too little considering how much travel is available until skids said he only had 5.8mm with a new chain. Considering the bike has only done 22,000 miles, do you think I'd be good for another 5k, at least? If so, I won't bother changing it now.

The chains usually go for 100K miles, so I would not worry about it for a while. I WOULD try and change out the CTT for the ACTT from a newer bike. That is the best thing you can do for these, as stock WILL loosen up on hard de-acceleration. That has caused problems to owners in the past, and is an easy fix.

[dansmith65]

The chains usually go for 100K miles, so I would not worry about it for a while.

That's great to hear! I thought I read 30-35k somewhere recently, but that might have been a different bike with a different chain for all I know; I did a lot of reading on cam chains recently!

If I need something stronger than what I put in the cylinders, I'll keep Seafoam and Berrymans B12 in mind. For now, I'm switching to other parts of the bike, so I'm ok leaving what's in there sit for a while.

I have read about the ACCT mod, but was planning to put it off for now; I've got to draw the line somewhere, or I'll be broke before I get to ride it! In the meantime, I'll try and avoid hard deceleration, I guess

Thanks again for all the advice; it's been helpful.