Ruined big bore kit I think

[joeweir1]

I think I may have ruined my new bore kit!!I bought a bigger jet and Installed it when putting the new cyl kit in.Only went up one size on the jet which it appears was a mistake.Took the scoot for a drive and and then died.Thought at first I could of had soemthing witht he fuel line came losse or soemthing electrical.After sitting a few minutes got it started and got it home.Was not sure what was wrong.Moved the needle clip down to botttom to richen it up and then took another ride.It went further this time before shutting off again.Was able to nurse it home for 1/4 mile.Pulled the muffler and saw scoring on the psiton.Pulled the new cylinder off and found the cylinder wall scored near the exhaust port.Made me sick.I may just have to try a quick hone and live with it if it will run.Not sure.Talked to a a scooter shop and said it may stil run?

[Bear45-70]

Lots of time extra oil in the gas will keep this from happening. Once a piston is scored in usually means the rings are stuck and until you pull the jug, you don't know. If the rings are stuck you need a new piston and rings and at least an acid job to remove the aluminum from the cylinder and then a hone job. It is irresponsible for the shop to tell you it will run that way. It might run, but not right.

[maddog]

So what size bore? what size carb+ gear ratio, only then can i dog you out then educate you

[joeweir1]

Stock carb with #85 jet.Stock air box.Stock gears, not sure what the ratio is?The rings are not stuck.I thought I had done enough research on this site but I guess not.These 2 strokes are alot more touchy than a 4 stroke and I guess I am not the first person to do this.The thing is how can you deternine the jet size unless you ride the thing.Experience is everthing !!I may just hone my OEM cyl. and put that back on?

[Clivester]

Did you do any porting on the new jug? If its too much the ring could have been catching in the exhaust port.

[Wheelman-111]

Greetings:

JoeWeir1 axt:

The thing is how can you deternine the jet size unless you ride the thing.Experience is everthing !!I may just hone my OEM cyl. and put that back on?

Ah, excellent question! My suggestions:

1. Buy and install a CHT gauge.
2. If it starts but barely runs, put in a smaller jet
3. If it starts and immediately runs well, install a larger jet right away.
4. Keep it well on the fat side of jetting until break-in is completed.
5. Take small steps in jetting down, and keep an eye on that CHT.

A soft seize or two won't hurt anything as long as compression remains good. Sometimes it's best not to look.

[odinxxix]

was anything done with the airbox? mine ran like crap til i opened the air box. which brings me to this question. would removing the lid and finding say a rubber strap to hold in the stock filter make it work like a free flow? after my break in im running i believe to be 88 jet and the stock oil pump with 90:1 premix. 5...1/2" holes drilled into the top of stock air box lid.

[mopar4u]

I think I may have ruined my new bore kit!!I bought a bigger jet and Installed it when putting the new cyl kit in.Only went up one size on the jet which it appears was a mistake.

I thought going to a bigger jet is making the mixture richer? I keep hearing that after installing the bbk you need either to put holes in the stock airbox or put on a free flow pod filter. Not doing this will cause poor running issues.

Post pictures of the piston and cylinder that your calling damage.

[joeweir1]

thanks for all the input.So should I be running premix in every tank of gas?I was told to add maybe a 1/4 ounce of oil to my first tank.Also, would you say a 90 jet would be large enough?I was told after the fact to go 2 sizes over the original which was a #80.I thought the #85 would have been enough.