A
First ride of the year. 05 M7, new pistons last year.
Notices when we started if for the first time this year it tried to back fire a couple times. I was thinking reeds. But it fired up and ran fine, tank was completely empty, I filled it with 91oct unleaded. I also filled two other sleds from the same pump on the same day.
On this day, the sled again started fine, little backfire again, nothing big. Started and was fine, the kid rode it for about 5 miles, and it died. We had lots of snow so the coolent temp was good. So I tour it down today and it looks like something caught the PTO side intake port, chipped the top of the piston, and it bounce around in the head, and worked it's way over the MAG side and damaged that piston also. The Mag cylinder is good, PTO is junk, head is in tough shape and pistons are shot of course.
I pulled the reed cages thinking I lost a peddle or maybe even the screws in the cage and it went through. Nope they look like new.
I would at first glance say detonation, but this sled is bone stock and running 91 grade fuel. Sled is using oil, oiler is set correctly.
My thought is this. Last ride of the year last year or starting this season, the ring caught the intake port. So starting this year this blow by on the ring was causing the backfire.
Anyway I am looking for parts if anyone has cylinders or a head laying around, going back together with stock cat pistons, wrist pins and bearings.
Thanks Thunder
Notices when we started if for the first time this year it tried to back fire a couple times. I was thinking reeds. But it fired up and ran fine, tank was completely empty, I filled it with 91oct unleaded. I also filled two other sleds from the same pump on the same day.
On this day, the sled again started fine, little backfire again, nothing big. Started and was fine, the kid rode it for about 5 miles, and it died. We had lots of snow so the coolent temp was good. So I tour it down today and it looks like something caught the PTO side intake port, chipped the top of the piston, and it bounce around in the head, and worked it's way over the MAG side and damaged that piston also. The Mag cylinder is good, PTO is junk, head is in tough shape and pistons are shot of course.
I pulled the reed cages thinking I lost a peddle or maybe even the screws in the cage and it went through. Nope they look like new.
I would at first glance say detonation, but this sled is bone stock and running 91 grade fuel. Sled is using oil, oiler is set correctly.
My thought is this. Last ride of the year last year or starting this season, the ring caught the intake port. So starting this year this blow by on the ring was causing the backfire.
Anyway I am looking for parts if anyone has cylinders or a head laying around, going back together with stock cat pistons, wrist pins and bearings.
Thanks Thunder