Powervalve problem?

[andydunne]

I got the new valves today, much better



I will probably get a mechanic to fit them as I am unsure which way to position them. The mechanic in mention, is the top Kawasaki mechanic in Ireland and is only 10mins from my place, so it would be foolish not to bring the bike to him and have her running sweet

[1989kawasaki]

those look so sweet. those wont be available for too much longer unfortunately
so sit and gawk at them while they are new 
they discontinued the valves for my 89 kx250 years and years ago..

but i am interested to hear the improvements you will gain from those.

[andydunne]

Ha im going to sleep with them tonight
I noticed the 88 kx125 valves are different to the 89 and they are discountinued, so im lucky they are still available.
I cant bloody wait

[andydunne]

A little bit of an update, I got a new Clymer manual so I found out how to replace the powervalves and the collars above them myself. Couldnt believe the size and detail of the manual, it made the job simple. So I put everything back together,all timed up , everything clean, new base,head,pv,exhaust gaskets, fresh fuel, air filter etc.
Cylinder was in good condition no marks etc.
With that I tried to fire the bike, wont fire at all with a kick so I got my bro to push me and kick it into gear, the bike then attempts to fire but makes a bogging sound for 2/3 secs and then dies. Before it always was difficult to get her going after lying up for a while but usually 1 or 2 kicks when used regularly.
The plug is wet when i check it.
I am getting a spark, although the plug isnt new but it looks fine. I have both br8eg and br9eg plugs, not sure if there correct?
Havnt touched any of the jets or slider on the carb, same as before.
Maybe the compression isnt great, I was thinking this before I started any work. So I will test the cylinder for compression, it would be a good start right?
About 300-400 feet above sea level
4-5 degrees celcius, if they help!
Any tips would be good, not the most detailed sorry

[andydunne]

I have tested the compression in the topend and it is making 90psi. This is without warming the engine beforehand as I cant start the bike atm which probably isnt ideal.
What is this figure like?
Is it time for a new piston and rings?

[Foxx4Beaver]

yeah,it's more than ready.anything under 150psi,and it's starting to get on the weak side....just my opinion.

Foxx

[sandblaster]

I have tested the compression in the topend and it is making 90psi. This is without warming the engine beforehand as I cant start the bike atm which probably isnt ideal.
What is this figure like?
Is it time for a new piston and rings?

Did you hold the throttle wide open when testing the compression?
If you don't it will cut your PSI reading drastically.

[andydunne]

yeah,it's more than ready.anything under 150psi,and it's starting to get on the weak side....just my opinion.

Foxx

Thanks for that mate, it is pretty low alright. It always was hard to start when not riden for a few weeks but fine when out riding. Low compression would make it harder to start right, as my mate reckons it should start even if it has only 10psi, but i doubt that

[andydunne]

I have tested the compression in the topend and it is making 90psi. This is without warming the engine beforehand as I cant start the bike atm which probably isnt ideal.
What is this figure like?
Is it time for a new piston and rings?

Did you hold the throttle wide open when testing the compression?
If you don't it will cut your PSI reading drastically.

No I didnt touch the throttle when testing it, I will test it again today to make sure I did it right!

[weymouth399]

It will not start well under 80ish psi. As said earlier WFO throttle position, kick it 8-10 times, read gauge, for proper comp test. If under 125psi new top end time, and probably more.

If you want you can pour a "LITTLE" 2 stroke or any oil in the cyl, then slowly kick thru the stroke a few times (spark plug out) reinstall plug then try to start it it will smoke more but it should boost compression enough to start easier.

Also if you don't start your bike for a few weeks it is alot easier to start if you lay her on her side. That will drain the carb bowl, and then start with fresh fuel in the carb bowl. It will also flood her a little and help start her when she's cold.

Bob W

[andydunne]

It will not start well under 80ish psi. As said earlier WFO throttle position, kick it 8-10 times, read gauge, for proper comp test. If under 125psi new top end time, and probably more.

If you want you can pour a "LITTLE" 2 stroke or any oil in the cyl, then slowly kick thru the stroke a few times (spark plug out) reinstall plug then try to start it it will smoke more but it should boost compression enough to start easier.

Also if you don't start your bike for a few weeks it is alot easier to start if you lay her on her side. That will drain the carb bowl, and then start with fresh fuel in the carb bowl. It will also flood her a little and help start her when she's cold.

Bob W

Thanks mate, I did all that but still nothing happening. With the throttle open I am still only getting 90psi so I think its time for a new piston and rings! I will measure the cylinder for size and wear.
Any opinions on piston choice, I can get a Mitaka piston for 50 euro or so, but would I be better off spending a little more for a Wossner, Wiseco piston. Are the Mitaka cheap for a good reason?

[andydunne]

Said id throw up a few pics seeing as I am bored and cant ride..
Clymer manual i got a few weeks back, by god does this make life easy, never would have touched the piston etc only for this


Here is my piston removed, no real damage afaik, just a few small nicks at the edges. Im waiting on tools(calipers,gauges etc) to arrive to check the cylinder size, ring gap and other tolerances according to the manual so when I order a new piston its correct! Does this piston look stock?


I am going for a Wossner piston kit probably, they are pretty good right?

[bige]

beware of wiseco piston kit, i bought a wiseco and the rings  end gap is way to big .069" should be at .014", the part numbers are correct so some how the manufacturing is wrong because i measured my old ring and its at .014" i even ordered another ring and it measures the same .069"  im not the only one who has had this issue. i called wiseco and they are of no help said they would send me correct rings but its been three days now and no show, will have to call again. all i can do is look at my bike and wish i was riding. if id known this i would of just ordered oem piston.

[andydunne]

Cheers dude, I dont think ill be touching a wiseco piston, they dont have a good name here anyway.
I might just price a stock piston versus the wossner I was going to buy, stock seem to have the least amount of complaints

[andydunne]

I did a few checks today with the manual at hand,
Piston ring end gap is 1.04mm(0.04") which is beyond service limit.
Piston ring groove width is around 1.06mm(0.04") which is beyond service limit.
Piston to cylinder clearance is roughly 0.05mm(0.0020'') which is good thankfully.

So now, I need to measure the piston and cylinder for size to be sure they are stock, so I order the correct size new piston. Is a vernier calipers an adequate tool for measuring these??