Ducky
Back in the game!
- Location
- Charlotte, NC
Well I can give up two lap dances for some new crank seals...may just have to hit up amateur night instead
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Amateur night is always far more amusing!
This melt down just might have me stumped..
- Thread starter Roseand
- Start date
Amateur night is always far more amusing!
Mark44
Katie's Boss
- Location
- 100% one place
10 pages for a scratched up piston..................... WOW
Ducky
Back in the game!
- Location
- Charlotte, NC
He's young and trying to learn as much as possible. I dont blame him for that.
Big Kahuna
Administrator
- Location
- Tuscaloosa, AL
No, Its 10 pages of a well discussed topic about a scratched piston.
- Location
- Saskatoon,SK
And how to convince a full bottom end disassembly over a scuffed piston! There is no broken piston or sleeve skirt, what makes all these guys think there may be metal in the bearings, where might this metal have come from?
- Location
- Red Bluff CA
Yes. I agree. The top end got smoked. The bottom end gets doused with so much lube it will almost never be damaged from a lean condition. The top end will always blow well before the bottom even begins to take damage.
It never hurts to tear things down tho. I wouldn't have in this particular situation because to me. It looks like someone had their ski a little too lean and was running it a little too hard. That is all. I'm not a master 2 stroke tech tho. I also have never had an engine fail from any fort of fuel or air leak issue.
It never hurts to tear things down tho. I wouldn't have in this particular situation because to me. It looks like someone had their ski a little too lean and was running it a little too hard. That is all. I'm not a master 2 stroke tech tho. I also have never had an engine fail from any fort of fuel or air leak issue.
- Location
- Saskatoon,SK
If he thinks it's leaking then the disassembly is justified, do another leakdown if he wants, but the op doesn't think it leaking. New piston and a hone and he could be riding this weekend.
- Location
- freedom,usa
.005 aprox. ??? Is that a new piston you used to check, or a used one? If used.. how far was the skirt colapsed? If any.
- as far as anyone in quiestion as to airleak/full teardown. Its the ONLY way to verify . As a note.. i have seen a motor that had "normal"wear on pistons... but tore down b/c it had freereved from an air leak (crack int.mani) wish i had pics of all the bearing "dust" that was inside. Everything seemed fine b4 teardown, but would have neen a much bigger problem if had not inspected.
Everyone has a choice. Do correctly or pay the price next time.
- as far as anyone in quiestion as to airleak/full teardown. Its the ONLY way to verify . As a note.. i have seen a motor that had "normal"wear on pistons... but tore down b/c it had freereved from an air leak (crack int.mani) wish i had pics of all the bearing "dust" that was inside. Everything seemed fine b4 teardown, but would have neen a much bigger problem if had not inspected.
Everyone has a choice. Do correctly or pay the price next time.
- Location
- Saskatoon,SK
.005" is bare minimum on a ported cylinder IMO, when I building 800cc race motors they need. 0055" minimum.
Quinc
Buy a Superjet
- Location
- California
Are you talking about squish or ring gap?
I was using a telescoping gauge and micrometer and then a digital calipers to double check. I honestly was just making sure it was over 3-4 thousands and it most definitely isn't a tight fit in the bore. As my porter said, my porting is very mild and he's positive it isn't piston to wall clearance that caused the issue. I'm pretty sure my pistons with stock porting at 7000 rpm WOT last season in 75+ degree water temp and 90 air temp with stock porting were expanded more than my pistons in my ported cylinders that were running 1/2-3/4 throttle in 65 degree water and 60-70 degree air temp.
if that doesnt tell you it was a lean squeak, nothing will. rebuild, rejet, braap on.
- Location
- Annapolis, MD
LOL calls for a Tshirt. " leaned out 701. 10 pages on X."
Thanks for the compliment! I'd gladly take a new t-shirt to promote the x and the great info it creates about mechanical failures!!! It was your choice to read the thread man. If you bothered to read it in detail, alot of people were considering it too tight of a clearance rather than a lean siezure. Also, plenty of reputable people took the time to post some awesome information on this subject and things that tons of people would over look. Honestly, this thread has enough great info that it could be a sticky. It's probably the most detailed thread on here about seizures like this. As others have said, if you know me, I think through things very analytically and like to know everything about a situation, especially before I spend money on things. Sometimes the most surprising things cause mechanical failures, so it's good to check over everything. Thanks everyone for the great insight! I highly appreciate it and will probably come back to this thread in the future and brush up on the good advice.
Ducky
Back in the game!
- Location
- Charlotte, NC
- Location
- freedom,usa
Just a note: as far as "race min.0055"" or any ski... i have used UNder .003" on 701 that turns 7800rpm, 58+on radar
Ur piston grew ...through whatever p/c clearance it had, and stuck.
I would adress making sure you control heat ...correctly
Just my op
Ur piston grew ...through whatever p/c clearance it had, and stuck.
I would adress making sure you control heat ...correctly
Just my op
I'm running dual cooling too. Part of a lean siezure is due to expansion... With less lubrication means more heat(more expansion), and that also will cause the amount of oil between the cylinder and piston to decrease. Plus, 45:1 or 50:1 is fine in ideal situations but 40:1 or a higher oil content ratio could have maybe prolonged the amount of time before this happened. The heat created was enough for the ring to be welded flush to the piston. It could have happened even if I had .008 clearance if it was running lean and hot enough.