Running stock with bore

[J2PUISANT]

I was riding and blew my rings because I thought the red oil indicator light was for low tranny oil as oppose to low 2 stroke oil. That beside the point. Now I need to change my piston and rings, BUT as I thought about it I figure I would do a little modification. I want to do some boring. I don’t feel I have to buy a new jug. A local machine shop is going to bore it. I have a stock header and a slip on FMF, stock reeds, and carb set up. Can I run the bored motor on the other stock parts?

 

[Wifesblaster]

Boring the motor will add ZERO power. The purpose for boring is to clean up the cylinder walls. Do not bore any more than you need to, your only taking life away from you cylinder. If you want to do some mods look into a pipe. Sense you already have an FMF silencer I would look for an FMF fatty pipe. You can usually pick them up used on ebay for 100 bucks. Just remember that you have to rejet when you put a pipe on it.

 

[Blaaster]

Not to sound on the down side, but if you have been zipping along without any oil in the tank, enough to wear out the rings, I would seriously be checking the bottom for evidence of lack of lubrication.

Revolving and reciprocating parts do not take kindly working at high temperatures without oil.

 

[J2PUISANT]

So why do i see blasters with 240 kits and 260 kits. whats their purpose?

 

[Trinityblaster]

Boring increases cylinder size so you can run a bigger piston and receive more power.

 

[Larry's Shee]

They have a larger inside diameter sleeve cast in because they are aftermarket cylinders. Stock bore for Blaster is 66mm, 240 big bore is 72mm. You "freshen up" your stock cylinder by boreing it .25mm each time, with the max Weisco piston being 68.25. As you can see lots of difference in size, plus the 240 cylinders have a better port design. Tripple exhaust, built in Boysen ports, etc.

 

[Larry's Shee]

Even if you bored to 68mm (half way to 72mm) you wouldn't even have a 220, it's a function of algebraic value of Pi, 3.1416.

You only bore enough to have a straight, round cylinder. The power increase comes from having a fresh engine

 

[J2PUISANT]

Ah ha. You’re a genius. Thank you. The motor is not seized. It still turns. If it turns out to be the rings only must I change the piston as well or can I just replace the rings? Or at this point should I just get the 240? If I get the 240 can I still run stock pipe and carb? I’m very fresh to the motor stuff. Please bear with me.

 

[joeak47]

Its a shame that happened,but....
topping off the oil tank is such a simple thing to do.
You can get a 240 kit,but PORTING is where the power really is,regardless what cylinder your running. To make it all work,you'll need a good pipe. I:I

 

[J2PUISANT]

PORTING!!! Good idea. I think I will take it to the machine shop and have them hone/bore the jug and have them port and polish. Does the piston need to be changed?

 

[joeak47]

PORTING!!! Good idea. I think I will take it to the machine shop and have them hone/bore the jug and have them port and polish. Does the piston need to be changed?

Does your "machine shop" know how to properly port two stroke engines? Be careful.

 

[boomadge]

No offence but if I where you I would send out the cylinder with the head to a reputable
builder who does port work. Have them check cylinder wear, they will give you the correct information on what needs to be done. While its there they will be able to
port it and get the head setup.

Dont be a ginnie pig for someone who isnt specialized in blaster porting.

 

[Blaaster]

If you are very, very, very lucky, you may be able to get away with just a set of rings.

In my experience any motor that has worn out rings due to lack of lubrication will have also worn the bore.

Have the jug measured to see wether it is within specs.

Just because the motor turns over is does not mean that the bearings are in good condition, running without oil can marr them.

Seals can also be damaged by running dry.

Why not drive the safe road and have the bearings checked rather have them come back to bite you after the top end rebuild.