Yamaha 2-Stroke Cylinder Resizing

It's Yamaha time @ Costa Mesa R&D Automotive Machine. Watch John hone a single cylinder Yamaha 2-stroke barrel to size for a new piston. www.engine-machining.com (949) 631-6376

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Autos & Vehicles

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• yamaha
• honda
• kawasaki
• suzuki
• kma
• honing
• sunnen
• cv161
• engine
• rebuilding
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[MultiUnanimous]

When boring a 2 stroke engine , do you usually have to change out the main jett aswell? Ever since the rebuild my bike runs like crap boggs and backfires allot , can't even get it out of 2nd gear because of lack of power , and its a yz 125 so this is not good for me lol,Any suggestions would be appreciated , btw i have bessed with my ratio of oil and gas mixture it was at 32:1 so i tried leaning it up little by little didnt help , have even adjusted my carb needle with no success.

[fiatnutz]

@MultiUnanimous - Since I personally don't run two-strokes, I can't tell you, but boring the cylinder out .010" shouldn't require a jetting change, I would think.

[xtrebelx]

I got a question if you do bore it like lets say from 49mm to 50mm is there away I can find a piston for it or would you provide one if i paid for it and for it to fit a kx80 engine.

[fiatnutz]

@xtrebelx - You get the piston.

[MyanmesKenny19]

when you hone the cylinder like that, do you need to apply a new coating to the cylinder walls???

[fiatnutz]

@MyanmesKenny19 - Depends if the cylinder is chrome or Nikasil plated. 

[MultiUnanimous]

@MrLloyd0071 It is fixed now thankyou:))). I actually was running it lean had it6 at 50:1 gas/oil ratio but it was the ignition coil being loose was the reason why it was missing into about 1/4 to full throttle almost like the timing was off xD yeah but its all fixed now i got her running back at 32:1 thank you though :)

[MrLloyd0071]

@MultiUnanimous try running it for a little bit,.then turn it off immediately(don't let idle if you can help it) and check the spark plug. The backfire makes it sound like you're running lean. May be an air leak somewhere. If it's lean, the plug SHOULD be whitish. not brown. If you rebuilt it after the bore job, double check the carb fitting and everything. it happens

[Cmcbmx1]

that is a yamaha rt100

[quading22]

is that a 1982 yamaha mx 80?

[spl3ndr]

Nice video, I was wondering how that worked.

I brought my honda nsr75 cilinder in for resizing. Standard diameter is 48mm and the next standard size offered by honda is 0.25mm larger.

Costs around 40€ here.