normal compression test on new 750 kit w/ cam???

[urbandork]

so ive been having some white smoke issues with the recent 750 kit that i put in. at first i thought it might be due to the valve guides since that was the only thing that wasnt changed.

BUT

i did a compression test and both cylinders are reading around 110 lbs/sq. in. is this normal? Im pretty sure the cam has more duration right? which cuts down on compression. what should the compression reading be for a new 750 kit with a cam.

also the white blue smoke use to go away after warm up but now it doesnt... could this mean that the new rings and cylinders are causing the smoke??? I know i installed the gaps in the rings 60 degrees apart from one and other.

 

[xsjohn]

How many miles on it..............what does the blue smoke cylinder's plug look like as compared to the other...............which side is the blue cylinder.......

I have never had it happen to me but some have had head gasket leakes in between the cylinders from the tunnel on the stock bikes sometimes...?......have your retorqued the head....I go to 35 with antisieze........?

xsjohn

 

[urbandork]

only has 50 miles on the new cyl and rings

white/blue smoke cyl is the left hand side and the plug looks like its been in contact with oil (wet)when i pulled it out for the first compression test.. after warming up the motor the plug looked dry

i only torqued to 30 lbs and i did retorque after..

i already ordered new gaskets and thinking about taking the motor back apart to take a look at the cylinders and head and gaskets.

looked in through the exhaust ports and no sign of oil from the valve stems... on the intake side however one side looks dry while the left side (smoking side) does look different... kinda wet but its hard to tell.. I double check the valve stem seals and they look fine and are on the guide.

maybe a piston ring didnt seat???

any ideas before i tear into her again?

 

[xsjohn]

Is there any waranty on this before I continue..........

 

[Sundie]

Almost certainly rings if you can't see gooieness on the back of the valve from the intakes.

Maybe you put a ring in upside down? There are few enough miles on it that you should be able to pull it apart, check all the rings, hone the cylinder, and put it back together fine.

 

[urbandork]

sigh .... no waranty unless mikes xs carries one as its their 750 kit im bought.

nope im am 110% positive that i put the rings right side up.... double checked.

blllaaaah ... the lady is becoming a pain in my @$$ lol .... pulling the motor tmw

any more info or support is welcomed.

adfjalfjadklgvnlnasvio im at work and frustrated lol.

 

[Sundie]

i imagine you'll find something interesting that you'll smack yourself for as you're taking it apart. cheer up!

 

[xsjohn]

You said 50 miles.......gee that's nothing........and the left runs way cooler than the right and takes at least 10 miles to warm up to operating temp (and in the cooler spring it may have never got there) so it may have never got to operating temp or near it.........now if it were mine and I was satisified that I put it together correct I would throw a level teaspoon of baking soda in the left down the spark plug hole and turn it over a few times with the plugs out .......start it and let it idol till it quieted down (valves held slightly open by the soda momentarly) and take it out and run it........but that's me........

xsjohn

 

[Sundie]

Ou, i missed the "only 50 miles" thing.

Dude, run that for 450 more, THEN see where you are. While i wouldn't be surprised if the rings seated in 50, i wouldn't expect it, if you get what i'm saying.

 

[malloym]

beat the piss out of it to set those rings.

 

[xsjohn]

Having a perspective on all of this kind of thing sure has payed off for me after 45 years of doing this..........only 77 thou in this one after being lazy and removing the pistons from the bore once by mistake when they didn't need it...fixed that as above without problems....( lifting the cylinders without pulling the pins with a hangover cost me a bit)....and even when knowing it was set up originally and correctly with smoothed outside edges of the rings and divited pistons for some extra oil........lazy cost me a bit of soda...........and heat will kill all of these XS's long before their real longivity can be achieved unless that situation is understood and corrected........for sure ..............unless luck is on your side...........

xsjohn

 

[urbandork]

hummm perhaps i will try out the baking soda trick cus ive heard xsjohn talk about that over on the old forum...

 

[xsjohn]

Well it won't hurt it if all that is wrong is that the rings are being stubborn to seat .......some running with off and on throttle afterwords...........then run it a while and see what you have.....every time your remove the rings from the bore you have a fresh break in..........and associated wear........

xsjohn