No compression in #2 Cylinder

After tearing into the motor again today I found a few problems which might be the reason for my low compression problems. I am to blame as I installed the rings on backwards... Let me explain what I mean..


I had the top and second ring backwards. On the OEM rings only the second ring is marked "N" the top ring is not. This would be the first mistake I made.



Secondly I broke a bolt in the head on the number one camshaft section. I had over torqued the bolt. I then tried to use a bolt extractor and completely messed the head up trying to remove the broken bolt. I then had taken the head to the machine shop and was told by the shop owner because I had drilled into the aluminum slightly he couldn't fix it. He advised I take it to a head shop. I'm looking at buying another head unless someone also had this problem and can share the solution. Lastly I need another cylinder piston head as I broke the head by also over torquing the bolt.



Boy this is a bad day for me and the KZ.. You live and learn... Valves are ok.. I know 85 PSI is low for compression.. I guess having them installed backwards was probably one of the contributing factors.. I will also look at the pistons and see if they are worn and need replacement..

Been there, never use bolt extractors, if you break them off your done, compression is a funny thing, been dealing with this myself, I had left all the spark plugs in, with carbs off and was getting around 100, took plugs out, got 120,cranking speed, battery power,compression guage, all affects it,
rings on a newly rebuilt motor may have not seated good also, and valve adjustment is also critical, the most important thing is your learning, and that sick feeling you get in your stomach when you screwed something up, will go away when you get that thing fired up. So read, learn and dont give up, man always has power over machine, it gets frustrating, but is very rewarding.

Were you assembling the engine using a torque wrench and the published torque specs, or just doing it by "feel?" Ed

Your 0 Compression on one hole, what have you found to explain that? Looking at your cam timing pictures it looks correct. Having the rings on wrong will be responsible for some loss, but 0 is another problem. Since the broken cam cap bolt, take the head to a machine shop that knows bike heads. Let them do a valve job to it, as they also repair the hole for the bolt. You must have valve issues.

nightmare on KZ-STREET.....poor guy....

monroeraustin wrote: ...You live and learn....

Such things as doing a leak-down test before tear-down usually contributes to a better diagnosis after tear-down.

In the case at hand, a leak-down test would likely have indicated exactly which valve in #2 cylinder was failing to seal when supposedly fully closed. Or whether compression was being lost past the piston/rings into the crankcase.

Good Fortune!

You might want to call Paul Gast (Fast by Gast). He could probably salvage the head. Might be cheaper than buying a new one.

sflaz1 wrote: You might want to call Paul Gast (Fast by Gast). He could probably salvage the head. Might be cheaper than buying a new one.

I am definatly intrested in saving some cash.. Been looking on Ebay at heads and found a few below $60 bucks.. not including shipping.. so If he can do it cheaper than that Its worth a try.. How do I get in contact with him?

Here is a link to his website

www.fastbygast.com/

monroeraustin wrote:

sflaz1 wrote: You might want to call Paul Gast (Fast by Gast). He could probably salvage the head. Might be cheaper than buying a new one.

I am definatly intrested in saving some cash.. Been looking on Ebay at heads and found a few below $60 bucks.. not including shipping.. so If he can do it cheaper than that Its worth a try.. How do I get in contact with him?

Good luck with that...most heads on ebay can be junk or are in need of work...So $60 get head and put it on and go ....not likley??? more like hella no.

4TheKZ1000 wrote:

monroeraustin wrote:

sflaz1 wrote: You might want to call Paul Gast (Fast by Gast). He could probably salvage the head. Might be cheaper than buying a new one.

I am defiantly interested in saving some cash.. Been looking on Ebay at heads and found a few below $60 bucks.. not including shipping.. so If he can do it cheaper than that Its worth a try.. How do I get in contact with him?

Good luck with that...most heads on ebay can be junk or are in need of work...So $60 get head and put it on and go ....not likley??? more like hella no.

Were talking about a 30 year old part. I don't know of a part 30 years old you can buy in excellent condition. So its understood it may need reconditioning.
I understand the risks of buying used products especially 30 year old motorcycle parts. I just broke a bolt on my existing head and now I am seeking a replacement. I am still trying to see if its fixable so to salvage it. Otherwise I will be buying a used head and having it evaluated by a certified machine shop. I am rebuilding this KZ750 so I expect it to last after this investment..

Be aware that if you by another head, to get the matching bearing caps. They are machined to the head. Watch out for the guys selling heads without bearing caps.
Your head looks repairable.