What do you think of this cyl./piston??

[Summit8]

Did you find out the cause of the "intermitant"oil supply?

If oil pump is working, it has to be running with motor, maybe that inline check valve or filter before the pump??

 

[bonecracker]

Did you find out the cause of the "intermitant"oil supply?

If oil pump is working, it has to be running with motor, maybe that inline check valve or filter before the pump??

No, not yet. Hopefully I'll get to it this week. I'm going to have lots of time while my jug gets re niked. I'll post here when I do.

 

[mark4]

also, look at ring gap position in proportion to scoring... Ive ran double ring pistons in my 700s with no major gains in performance of reliabilty except for the cost of pistons and rebuilds. ring gaps are one of the most common spots for failure since the hottest spot in the combustion chamber is at the ring tips and it gives two points insted of one for failure.. when the most common failures occur at the 4 corners and you are putting your 2nd most common point of failure (piston ring gaps) near these area it just seems ironic to add another ring and add even one more failure point... just my 2 cents. cracks at the bottom of piston skirts usually mean piston slap try to find 2 good spots on pistons to measure and a few good spots on cylinder to measure. a loose cylinder can cause wider ring gaps, more leak by and in turn more heat at the tips of rings. just remember you can get 150 lbs of compression with 1 ring and 150 lbs of compression with 2 rings but you are increasing your wear rate when you are running 2 rings... where is the performance gain in using 2 rings if you are not increasing the total compression of the engine?

you can't measure running compression ecspecially at wide open, your only testing static compression which will be similiar with same comp ratio and oiled pistons.

 

[mark4]

What, no thoughts on this ??? motor doesn't have many hrs on it.

Faulty renic job? Crank going out again??

Not trying to bash BJ work, just want some opinions, wondering if I'm missing something.

poor pistons and clearance not set proper.
theres oil in the pic in cases.

 

[mark4]

Just my opinion but I believe it's lack of oil. Just had it happen to me. 2 pistons before I realized that the oiler was working intermittant. The pistons will stick with close tolerance within 1 km of when it stops receiving oil. Everybody who looked at the pistons said cold seize. Too much "seize" on the intake compared to the exhaust, exactly like my new ashtrays.

what type of motor do you have?

 

[bonecracker]

what type of motor do you have?

800 HO bored to 827 with pro-x pistons. The clearance was tight but I know the oiler is what caused the issue on my motor. Tight tolerance caused the piston to grab as soon as the oil mixture got thin.
May not be summit8's issue but it looks exactly the same as my issue. There was oil in/on everything and all signs pointed to cold seize.
Just my 2 cents cdn.

 

[Tdubbs]

I had an 840 go down the exact same way at the beginning of this year the cylinder showed 4 corner, turns out it was the thermostat it would intermittently stick wide open...it just so happens that it stuck wide open while riding two feet of powder this time and she squeaked....its all back together now and 2000 miles later and $2000 runs better than ever (rebuilt the crank and bottom end at same time, because the motor had over 7000 miles on it)...

 

[Summit8]

Topend headed back to Minnesnowta, my season done before it even got to halfway, so much for Cooke in April.

Wish I had my stock jugs and Wisecos back,dangnabit!!

 

[bonecracker]

I said I'd post what my oiler problem was. I don't mean to hijack the thread but here is what the issue was that caused my problems. Hope it don't happen to you.