Kz650 b3 no compression on 2 and 3

Wookie58 wrote:

I'm not sure of the relevance regarding timing given that a compression test is purely mechanical and carried out with all the spark plugs removed ? 

I suspect after such a long lay-up (and with the plugs being oiled) the the rings are stuck. Perhaps a good soaking with WD40 or similar overnight (don't forget to spin it over with the plugs out to clear the excess) may release the rings and recover the compression loss.

It's not intended to be relevant to timing Wookie.  So far no proper compression test has been done.  That should be the first step in diagnosing the problem.

To faceplateman...have you checked to ensure your cams are in their correct location and not reversed?  Just thinking out loud on this one.  I don't know if that would cause your problem but it's a check that you could do before pulling the head off.

hardrockminer wrote:

Wookie58 wrote:

I'm not sure of the relevance regarding timing given that a compression test is purely mechanical and carried out with all the spark plugs removed ? 

I suspect after such a long lay-up (and with the plugs being oiled) the the rings are stuck. Perhaps a good soaking with WD40 or similar overnight (don't forget to spin it over with the plugs out to clear the excess) may release the rings and recover the compression loss.

It's not intended to be relevant to timing Wookie.  So far no proper compression test has been done.  That should be the first step in diagnosing the problem.


 

Agreed 

Yes i will check that the cam shafts are in the right position. And this weekend i will go and get a proper compression tester and a leak down tester because i think that would help too. 

faceplateman wrote:

Yes i will check that the cam shafts are in the right position. And this weekend i will go and get a proper compression tester and a leak down tester because i think that would help too. 

A sensible investment, they don't have to be expensive (you don't need professional quality equipment for things you will only use maybe once a year or less)
As an "aside" sticking your thumb in the hole is not the best idea for the same reason you shouldn't put an air line blower against your skin - with in excess of a 100psi of cylinder pressure (potentionally) you run the risk of introducing air bubbles to your blood stream which will ruin your day 

Ok so i just tested the compression test here are the results.
Test done with engine cold, all spark plugs removed and the throttle wide open.
#1=90psi
#2=0psi
#3=0psi
#4=110psi
Idk if thats good for a cold reading.
i also looked at the exhaust valve clearance on 2 and 3. 2 was at .45mm and 3 was at .17mm

You could do a “leak” test to see where 2 &3 have lost all pressure but  guess with 0 readings it’s time to get the spanner’s out (did you try soaking overnight to release the rings?)

Yup!  Time to take the head off and have a look.  The clearance on #2 is much more than spec.  Not sure what impact that would have.

Yes i tried soaking everything overnight. It did not work.

Even 1 & 4 is way low. 650 motors should have a hot compression of 160 - 180 psi which cold would be 140 plus.
For 2 & 3 to have 0 you must have a valve hanging open or worse. 2 & 3 always wear faster and run hotter due to lack of cooling air. A super lean mixture for a long time will put holes in pistons 2 & 3 first. Are the exhaust header pipes on 2 & 3 very blue compared to 1 & 4?
If it were me I'd strip down the complete top end and check EVERYTHING, your past hoping a soak/adjustment quick fix. 

Yes im past that. My plan now is to remove the head and rebuild it completely. 

I should note that the tester i used was a 25 dollar Pittsburgh tester i got from harbor freight. The hose attachment didnt even work so i used the straight tube with the rubber cone on the end. Even then i had to push pretty hard to keep a seal on the gauge. 

Due to the large valve clearance and zero compression, i bet you will find some bent valve stems  on #2 and #3