Boring 701 to 760

[jetster98]

im looking at punching out my rn 701 to a 760, should i send it out and get it bored or should i look for a 760 cyl. and why?

 

[Wolf Child]

get a hemi

 

[#ZERO]

If you bore your 61x cylinder all the way up to 84mm you won't have any room left for an overbore because the sleeves will be too thin.

The 760 cylinder is good up to around 85mm before the sleeves start getting thin and the exhaust port timing is 2mm higher, which is not as desirable for freestyle engines.

The ultimate setup would be to have your 61x cylinder machined for big bore sleeves which are good up to 86.5mm depending on which head you're using.

 

[wave faster]

what size can you bore 62t cylinders out to?

 

[blari]

ttt

 

[BombThreat]

The ultimate setup would be to have your 61x cylinder machined for big bore sleeves which are good up to 86.5mm depending on which head you're using.

This is what im having Jetworks do right now, if you plan this route give them a call he's very reasonable and always willing to help and give advice.

 

[Freakrider]

im looking at punching out my rn 701 to a 760, should i send it out and get it bored or should i look for a 760 cyl. and why?

I would bore your 701 to 83mm and widen exhaust ports some... then you have 1mm of bore left for the future and u will have plenty of power and money...:biggthumpup:

 

[jetster98]

so port out the just the exhaust to match the mainfold from the b-pipe and bore it to 83mm would be a better bet for a good power gain? would i need to run an aftermarket/ milled head or would it run out good with my stock head?

 

[MADMAT]

A milled head and a lightened stock flywheel are excellent!!

 

[Andrew1289]

Quick question. So boring to 83mm you can run the stock head, however with if you bore to 84 mm you need to modify the dome or buy a 760 head correct?
thanks in advance

 

[#ZERO]

Just buy an aftermarket girdled head then you won't have to worry about the base of your cylinder cracking as you increase the compression and you can change dome diameters.

 

[Andrew1289]

Yea, I understand the logic of getting a girdle head. Protects from cracking cylinder and you can use different domes so it will work with many setups. But I'm just looking to get together a CHEAP engine for now. Will a stock 701 head work with an 84mm bore?

 

[Mouthfulloflake]

the thing is, its not really a cheap mod if it costs you a cylinder.

a girdled head is an investment, that wont really depreciate in value.

to answer your question though, I think it will likely seal off, but the dome size will be too small and likely give an odd compression and and squish scenario.

 

[Big Kahuna]

Yea, I understand the logic of getting a girdle head. Protects from cracking cylinder and you can use different domes so it will work with many setups. But I'm just looking to get together a CHEAP engine for now. Will a stock 701 head work with an 84mm bore?

No, stock head will only go up to 83mm. you can have your head machined for 84mm

 

[Andrew1289]

Thats what I thought. Thanks