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I’m not sure what those are, but the cam chain tensioner should be on the back of the cylinder head, not in front
 

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I’m not sure what those are, but the cam chain tensioner should be on the back of the cylinder head, not in front
I was under the impression that these DOHC engines have adjustment front and rear as per the attached link.
Although I haven't actually owned one.


OP What doe's your manual say regarding cam chain adjustment?
 

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I was under the impression that these DOHC engines have adjustment front and rear as per the attached link.
Although I haven't actually owned one.


OP What doe's your manual say regarding cam chain adjustment?
Interesting. A little more complicated than it needs to be.
 

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Looking at the parts diagram, it appears that there are 2 chains.... thus 2 tensioners. Seems a bit much...
Font Line Auto part Fashion accessory Drawing
 

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Discussion Starter · #25 ·
Oof there is a lot of excess silicone sealant oozing out of that motor.
That coupled with the snapped bolts doesn't make me feel all warm and fuzzy inside.

The head should be perfectly salvageable.

Personally i would pull the head and send it off to someone who knows what they are doing to unfuck the snapped tensioner and give it a refresh.
Then a fresh tensioner and chain.

Still though i would want to get those all important compression readings first!
I’m not sure what those are, but the cam chain tensioner should be on the back of the cylinder head, not in front
On the 1980 there are 2 spots for adjustment 2 bolts on the carb side and one on the front.
I was under the impression that these DOHC engines have adjustment front and rear as per the attached link.
Although I haven't actually owned one.


OP What doe's your manual say regarding cam chain adjustment?
Here is what the Clymer manual says. Cam tensioner adjustment
 

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At the very least pull the valve cover off, the previous owner already did. & he didn't sell it because that operation was 100% successful. Would not be surprised if he didn't even pull the engine out of the frame to do it. You will see more from there and know if you need to go deeper. and deeper and deeper
 

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Discussion Starter · #27 ·
At the very least pull the valve cover off, the previous owner already did. & he didn't sell it because that operation was 100% successful. Would not be surprised if he didn't even pull the engine out of the frame to do it. You will see more from there and know if you need to go deeper. and deeper and deeper
I did have the cover off to look and check the condition of everything, nothing seemed out of the ordinary. I'll be checking valve clearances tonight or tomorrow. The compression guage I was able to get a hold of didn't fit my engine (guage threads too big), so I haven't done that yet. Also couldn't get a timing light yet so that also needs to be done.
 

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No surprise on the compression gauge, automobile tools don't work so good on motorcycles. When you set the valve clearances have a micrometer handy, that is the best way to get a feel for the right clearance on your valve adjusters, which too bad for you will likely be bucket and shims I would imagine.

You didn't pick the easiest first bike to work on, they were far from designed for ease of service.
 

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Discussion Starter · #29 ·
No surprise on the compression gauge, automobile tools don't work so good on motorcycles. When you set the valve clearances have a micrometer handy, that is the best way to get a feel for the right clearance on your valve adjusters, which too bad for you will likely be bucket and shims I would imagine.

You didn't pick the easiest first bike to work on, they were far from designed for ease of service.
I didnt think to open the case, as I figured there would be some sort of adapters in it, oh well.. I do have a set of feeler gauges because thats what the manual says to use. A micrometer would be handy to double check the shim sizes though.

I'm starting to figure that out. I would imagine once its running correctly and all of the routine maintenance is kept up on, they seem to last a while.
 

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Discussion Starter · #30 ·
Update:

Timing adjustments have been made per the manual.

For the compression tests:
#1: 115
#2: 110
#3: 120
#4: 120
Compression seems consistent but low. Would that be a vacuum leak?
 

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Those compression readings whilst not brilliant aren't the worst.
It will run ok-ish with those and it shouldn't make any difference to the sounds coming from the motor.

A little tip squirt some oil into each cylinder and carry out the compression test again.
If the readings go up its piston rings not sealing.
If they remain the same its valves not sealing.

Low compression is always the valves or rings not sealing. A vacuum leak won't give low compression.

Personally with those readings i would do a top end rebuild.

+0.5 overbore
+0.5 pistons and rings
Head rebuild - checking the valve guides for play, new valve stem oil seals and lapping in the valves.
New cam chain and tensioner

Not hugely expensive if you do everything yourself apart from the specialist machining bits (overbore and valve guides if needed)

How far out are the valve clearances?

Even if you don't have shims to make adjustments you can and should check to see if they are in tolerance as this could be the source of your noise, although i have already stated its 99 percent going to be the cam tensioner.
 

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First of all, you should make sure the valve clearances are in spec before doing a compression test. Secondly always do a compression test warm, and with the carbs held wide open. I’ll bet those numbers would be much better on a warm engine. If they do not improve then the oil trick Miniman described will tell you if it’s rings or valves.
 
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Discussion Starter · #33 ·
Those compression readings whilst not brilliant aren't the worst.
It will run ok-ish with those and it shouldn't make any difference to the sounds coming from the motor.

A little tip squirt some oil into each cylinder and carry out the compression test again.
If the readings go up its piston rings not sealing.
If they remain the same its valves not sealing.

Low compression is always the valves or rings not sealing. A vacuum leak won't give low compression.

Personally with those readings i would do a top end rebuild.

+0.5 overbore
+0.5 pistons and rings
Head rebuild - checking the valve guides for play, new valve stem oil seals and lapping in the valves.
New cam chain and tensioner

Not hugely expensive if you do everything yourself apart from the specialist machining bits (overbore and valve guides if needed)

How far out are the valve clearances?

Even if you don't have shims to make adjustments you can and should check to see if they are in tolerance as this could be the source of your noise, although i have already stated its 99 percent going to be the cam tensioner.
Valve clearances will be checked this week (hopefully tomorrow.)

But as of right now, I agree that it needs a top end rebuild. Especially since i need to get in there anyway for the cam tensioner.
 

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Discussion Starter · #34 ·
First of all, you should make sure the valve clearances are in spec before doing a compression test. Secondly always do a compression test warm, and with the carbs held wide open. I’ll bet those numbers would be much better on a warm engine. If they do not improve then the oil trick Miniman described will tell you if it’s rings or valves.
I guess I must have read over the part in manual to have it warm, whoops. I guess I'll retest tomorrow on a warm engine.
 

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I didnt think to open the case, as I figured there would be some sort of adapters in it, oh well.. I do have a set of feeler gauges because thats what the manual says to use. A micrometer would be handy to double check the shim sizes though.

I'm starting to figure that out. I would imagine once its running correctly and all of the routine maintenance is kept up on, they seem to last a while.
No sir, the micrometer is for the feeler gauges, to confirm their thinness and to train your hand to know what the feelers should feel like between the bucket and cam.
Or if they had screw adjusters, to know how much tension to put on them when you lock down the lock nut.
 

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Discussion Starter · #36 · (Edited)
Update 2:
Warmed up the engine and retested the compression. Better numbers as 8ball suggested.
#1:155
#2:160
#3:165
#4:160
Table of my valve clearances: (didn't realize that I didn't have a metric feeler gauge, so i did the conversions.)
Rectangle Line Font Parallel Pattern
 

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Not sure I understand your table. What are the clearance specs listed in your manual?
 

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So your range is .06 to .13 mm. I always set clearances on the high side because they close up over time, not get bigger. Looks like most of your measurements are in the .09mm range. I’d leave those alone, but record ALL the shim sizes so you know what they are in the future and you can figure out what size shim you’d need to make adjustments next time BEFORE removing the cams.
Most replacement shims come in .05mm increments and the size is in mm. (The originals may be in smaller increments) Example: a 185 shim is 1.85 mm thick. So if a valve has a clearance of say .06mm and the shim size on that valve is 195, a 190 shim would increase your clearance by .05mm. In this case your new clearance would be around .11 mm. Which would be a good clearance to shoot for.
 

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Discussion Starter · #40 ·
So your range is .06 to .13 mm. I always set clearances on the high side because they close up over time, not get bigger. Looks like most of your measurements are in the .09mm range. I’d leave those alone, but record ALL the shim sizes so you know what they are in the future and you can figure out what size shim you’d need to make adjustments next time BEFORE removing the cams.
Most replacement shims come in .05mm increments and the size is in mm. (The originals may be in smaller increments) Example: a 185 shim is 1.85 mm thick. So if a valve has a clearance of say .06mm and the shim size on that valve is 195, a 190 shim would increase your clearance by .05mm. In this case your new clearance would be around .11 mm. Which would be a good clearance to shoot for.
Just to be clear, I would want to get the clearance to .11mm and not .08mm? You'd want it bigger because over time, the gap closes?

Awesome advice, thanks!
 
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