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[deucedog]

Friend wants to know:

Front Cylinder: 160
Rear Cylinder: 150

Dealer says this is this to spec and normal.  True?

Thanks, Dog

[Chief]

Friend wants to know:

Front Cylinder: 160
Rear Cylinder: 150

Dealer says this is this to spec and normal.  True?

Thanks, Dog

Yes, that is just about right. The numbers seem low because the Automatic Compression Releases (ACRs) are open while cranking. If the ACRs are disabled, the compression will be much higher, over 200.

[d o g o l s]

yes thats right just disable the acr and you get more
 
 

[deucedog]

Thanks, I passed the information along, much appreciated...

[Unbalanced]

These numbers are correct.   150-170 with ACR enabled   /  200-230 without ACR.

[sadunbar]

Harry,

I am going to do my own repair and rebuild - and supply my own parts.  (leaking rear head gasket) (ala Hoist - I intend to do this right - and only once).

I checked compression prior to starting the teardown - and had 140 front and rear - a bit lower then I had expected.  I was looking for closer to 150 - 160...  BTW - my crank runout was .0012.

Scott

[Unbalanced]

Scott,

I wouldnt think that 140 was out of the question, but I will throw one piece of caution out there.   With the heat issues I had, I had to replace the rings on the rear cylinder and because of that happening I would suggest to you if your going to do it right that you do a leak down test to ensure your not going to have to go back in there and do this again.

-harry

[sadunbar]

Scott,

I wouldnt think that 140 was out of the question, but I will throw one piece of caution out there.   With the heat issues I had, I had to replace the rings on the rear cylinder and because of that happening I would suggest to you if your going to do it right that you do a leak down test to ensure your not going to have to go back in there and do this again.

-harry

Harry,

  My plan is to replace the cylinders (with aftermarket), pistons, rework the heads, replace the entire valve train, ect.

  Ala Hoist - no need to do this twice.

  The plan of replacing a gasket multiple times (as in the MOCO plan) without addressing a root cause is a bit senseless.  In the end I will have a more reliable, better performing motor.

Scott

[skreminegul07]

Harry,

I am going to do my own repair and rebuild - and supply my own parts.  (leaking rear head gasket) (ala Hoist - I intend to do this right - and only once).

I checked compression prior to starting the teardown - and had 140 front and rear - a bit lower then I had expected.  I was looking for closer to 150 - 160...  BTW - my crank runout was .0012.

Scott

One more thousand and you get a new motor.  Maybe the dealer could help you there.

[Unbalanced]

Scott,

Piece of mind is definitely a whole lot better than the road I have been down thus far with this engine and its issues.    I agree whole heartedly with your approach on fixing the current issues that the Moco has yet to really address.   I am giving Wes's solution one try before following in your footsteps.   I only have about 600 miles on the bike since trying his gasket idea / approach.   If this attempt at fixing the head leaks fail for me I will most likely be looking at one of 2 choices either going up to the 113" where this has not been shown as an issue or to a new motor like the 120/131.

If it is not to much trouble, when you tear it down let us know how scored your cylinders/piston skirts are and in what shape the rings were in if you would.  Mine looked pretty bad, so Wes had a new set of rings made with what he called a thicker scavenging ring.   So far everything is running great.  My fingers are crossed it is fixed although I am not overly optomistic.

[djkak]

Harry,....BTW - my crank runout was .0012.

Scott

One more thousand and you get a new motor.  Maybe the dealer could help you there.

Doublecheck the decimal point; Scott's posted runout is one tenth of the maximum allowable.

djkak

[Hoist!]

Doublecheck the decimal point; Scott's posted runout is one tenth of the maximum allowable.

djkak

Absolutely! It's the best I've seen in a 110"! Lucky dude Scott! good luck with your new top end!

This is gonna be fun. Another Hot Rod Top End build, right before our very eyes!

Too bad it needs this, but you'll be real happy with the way it runs when you're done. I'm glad I broke everything you can so far, so ya'll can see what you have to do to keep them from breaking. I hope some of that helps you guys out!

Hoist!