'71 leaky head gasket teardown reveals bigger problems

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I bought this '71 remotely, sight unseen a few years ago. Supposedly it had an original 4000 miles, after speaking to the original owner on the original '71 Texas title who said engine never been apart! Ha.

After its second club ride last weekend, we noticed a lot of smoke out the right hand exhaust when heavily on the throttle, and a leaky head gasket.

Here is what we found upon taking the head off.
Anyone notice anything amiss? :eek:


'71 leaky head gasket teardown reveals bigger problems
 
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Is there written + 0.20 on the right piston? 4000 miles, never been opened? Mmmh??
What are these blobs behind the left cylinder on the gasket surface?
 
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Are the pistons in backward? Seems to me I remember another thread here in the past where someone had discovered this.
 
Are the pistons in backward? Seems to me I remember another thread here in the past where someone had discovered this.

Not backward but fitted in the wrong cylinders! :)

'71 leaky head gasket teardown reveals bigger problems
 
Yes, that funny depression just toward center of the valve pocket looks like it isn't standard.
 
Correct!

I don't doubt the 4000 miles as original, but it has definitely been opened up before. For one, it had copper head gasket. Bore was like new. Pistons are standard size. I don't believe this engine was ever run before I bought it. Timing was way too far out.

What pistons are these with the thick wire circlips? They look too new to be factory stock. Wire circlips are tight but I don't like them.

Can they be replaced with the JC recommended eyelet circlips?
https://www.mcmaster.com/91580A175



'71 leaky head gasket teardown reveals bigger problems
 
What pistons are these with the thick wire circlips? They look too new to be factory stock. Wire circlips are tight but I don't like them.

Can they be replaced with the JC recommended eyelet circlips?

If the circlip grooves are machined for wire circlips (which I assume they are) then you must use wire circlips.
 
Thanks Les, I seem to remember hearing some bad things about the tang wire circlips, but I will re-use them if they are still tight on re-install. Chris
 
Yes, the indentations are from the intake valves banging the pistons. You can see the wear marks on the valves also.
Will tear apart the head this week to check straightness of the valves which will probably need replacement. Head had previous work done on it also. Has bronze guides.


'71 leaky head gasket teardown reveals bigger problems
 
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Just buy new wire circlips. I wouldn't ever trust reusing them. They are cheap compared to the damage they can do.

The picture makes it look like the intake valve hit the top of the right piston. How are the valve guides ?

Greg
 
Years ago when i raced a Yamaha TZ350 engined sidecar outfit As a matter of course we cut the tang off on the gudgeon pin wire circlips as the pin used to wear into the tang and allow it to break off. Causing considerable engine damage, it was a two stroke remember! You had to grind a little extraction notch in the piston to allow the removal of the circlip when the tang was removed.
Later, the manufacturers (suzuki for one) fitted pistons with this notch and tangless circlip.
 
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Pistons say JCC underneath so i am guessing they are old JCC with the wire clips. Will check pushrods, valves, guides and seats this week.
 
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I pulled the head off a spare Ranger motor last year and found a similar situation. Good thing I planned on rebuilding before trying to use it! Commando pistons fitted, but in the wrong holes! I'm surprised it didn't bend a valve.
 
I seem to remember hearing some bad things about the tang wire circlips, but I will re-use them if they are still tight on re-install.

I certainly wouldn't re-use them. You can use the wire circlips without tangs.


Pistons say JCC underneath so i am guessing they are old JCC with the wire clips.

It might be worth taking a close look at the circlip grooves just to be certain.
 
I think you need to use at least one-tang clips in order to have an easy way get them out. These pistons don’t have a relief machined in the side to facilitate getting the non-tang wire clips out.
 
Surely who ever done the work would have made sure they had the right piston for where the valves are for the valve pockets, he must have forgotten to put his eyes on (glasses), I be pulling that motor down to make sure anything else hasn't been done wrong with it, must have been a reason why pistons had been removed in the first place, there are so many dishonest people around who lie about things when selling bikes or car for that matter, in the long run pulling that motor completely down might be cheaper than having something else go wrong with it.

Ashley
 
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