Blaster Engine rebuild help.

[Chanler]

Hey guys, newish to the blaster world. Have a blaster i bought to steal some parts off of (fmf fatty, extended swing arm, rear brakes, bars) The engine needs to be rebuilt. Piston skirt broke off and is somewhere in the bottom end. engine spins most of the way over so its not locked up, just stuck.
Was just going to swap my stock parts back onto the frame and let it go, until i seen the OEM cylinder and head. my engine has unknown parts as i bought it that way, probably will need a rebuild soon aswell.

Thought about rebuilding the spare engine with the OEM parts seeing as its not leaking oil like mine.
So to start since im going to have to split the cases anyway to remove the broken skirt, and inspect the internals, looking for suggestions on gasket and seal kits, and mods to do while the engine is apart.

The cylinder and head both look to be in good condition, could use a hone and already has some porting.
It has been bored before. Currently at 66.40 diameter with a 66.25 unknown piston.
planned to hone the cylinder and reuse, is a +.25mm piston the correct size for that bore?

 

[Larry's Shee]

The worn bore and piston is why it broke the skirt. It was probably already out of spec when that piston was installed. Unless a machinist measure it and says it’s not out of round or tapered, it needs to be bored. Nobody likes a sloppy hole . I’ve used lots of Vito’s seals and gaskets with good results. Cometic and Vesra are good also.
DO NOT BUY CHEAP Chy-NA PARTS !!
Which means most cheap parts on Egay or Amazon.
Quality doesn’t cost, it pays.
Buy once, cry once.
Where are you located?

 

[Larry's Shee]

Here is where I get all my machine work done. Worked with Mike for 20+ years.He was doing a special with free return shipping, don’t know about now.
https://www.lakesmotorsports.biz/cylinder-boring-services/yamaha-yfs200-blaster/
The other recommended shop is back logged a couple months and is not actually taking on work because of it , actually read it on Fakebook yesterday
http://www.kenoconnorracing.com/

 

[Chanler]

The worn bore and piston is why it broke the skirt. It was probably already out of spec when that piston was installed. Unless a machinist measure it and says it’s not out of round or tapered, it needs to be bored. Nobody likes a sloppy hole . I’ve used lots of Vito’s seals and gaskets with good results. Cometic and Vesra are good also.
DO NOT BUY CHEAP Chy-NA PARTS !!
Which means most cheap parts on Egay or Amazon.
Quality doesn’t cost, it pays.
Buy once, cry once.
Where are you located?

So i actually measure the cylinder with a bore gauge today, was only using calipers before, turns out its +50 over and slightly tapered(.003 max difference) i believe, cant remember if it was up and down variation or out of round.
Most likely going to have it bored,

 

[Larry's Shee]

Be aware that you MUST have the new piston in hand so it can be fitted correctly. I sent banshee cylinders to Lakes and they came back marked A & B, just enough difference between the piston sizes.

No matter where you take your cylinder make sure they are familiar with chamfering the port openings.
It may sound weird but wash the cylinder well after bore/hone to remove all debris. I actually use soap and water, immediately dry and oil it

 

[CycleTech]

I do that service here and do them ALL the time. Your cylinder is out of spec. Give me a shout. You can find me in Facebook at CycleTech Performance and also my website cycletechperformance.com
I have a fast turnaround (At the moment lol) so get in touch soon because the shop gets crazy at times.