To bore or not to bore

[Indymike]

73 115 V4.<br /><br />When going through a motor what are your opinions on boring cylinders still in spec. Trying to make his this thing real fresh. If one or two are out of spec do you do all or just the ones out of spec. Maybe this is a no brainer to the 2 stroker gurus but I'm struggling a bit with it. <br /><br />Thanks,<br />Mike

 

[R.Johnson]

Re: To bore or not to bore

As long as the engine is apart, to be on the safe side, I would have it overbored just enough to clean up. If going with Wiseco piston's, that would be .020. That would give you the fresh start you are after. Replacing any other worn part's of course.

 

[WillyBWright]

Re: To bore or not to bore

I know it adds a lot to the expense of an overhaul, but that thing is over 30 years old. Anything short isn't going to be good enough.

 

[Solittle]

Re: To bore or not to bore

According to OMC you can punch out only the cylinders that actually need it. Though I would follow Willy's advice I don't think that the parts know if they are 3 or 30 years old so long as they are within specifications.

 

[CFronzek]

Re: To bore or not to bore

Two-strokes are very sensative to piston and ring fit. This is because you don't want combustion gasses bypassing the piston/ring and diluting the incoming charge in the crankcase.<br />If you want performence, good straight cylinder walls and properly fit pistons are in order.

 

[Indymike]

Re: To bore or not to bore

Block is getting machined now. +.020 on all four.<br /><br />Thanks guys

 

[Dhadley]

Re: To bore or not to bore

Good for you! Just make sure you order 1973 pistons. Thats a one-of-a-kind year for the V4 crossflow.<br /><br />Just out of curosity -- whats the shop using for the finished bore size?

 

[Indymike]

Re: To bore or not to bore

Pistons are covered wiseco 3174P2.<br /><br />3.520 for bore size.

 

[Dhadley]

Re: To bore or not to bore

Correct part number. The finished bore size should be 3.5205" to 3.521". Youll have a great motor.<br /><br />Good luck!