Big bore questions

[Waternut]

Since I'm waiting on my hull, I've had lots of time to think about various scenarios... My latest thought is one big bore cylinders. From what I've read, the 61x cylinder would make a better BB cylinder for freestyle than the 760 cylinders but obviously the cylinder itself (not the sleeve) would need to be bored prior to installing the BB sleeves.

My question is, when you bore the cylinder, is it as simple as just taking the cylinder to a machine shop, boring the cylinder, and dropping the sleeve in or is this really something that needs to be left to the professional engine builders so that all the intake and exhaust ports are sized properly for the larger bore?

 

[MADMAT]

Korn did it with his bro....so anyone that knows how to sleeve (heat and cold...) could do it....but then proper porting...

I wouldn't do it myself.

 

[Big Kahuna]

any machinest could do the swap. Problem is getting the porting matched and ported to the correct spec's. You have a good builder not 2 hours from you that can do all this for you.

 

[Waternut]

Yeah I'm basically just weighing motor options (cost vs performance) while I twiddle my thumbs. The brainstorming usually dies down a lot when I have something to work on and ride.

 

[Patrick Star]

I'm in the process of debating of what my options are on a set of 62t cases. I can I just run 64x cylinders? I'm more than likely running the 701 61x top end, but want to learn more about this 760 ordeal. Here are my conclusions so far:

I figure I would have to swap out the CDI box as well, don't want to loose my MSD CDI.

As far as the stator and flywheel are concerned I could run a matched 61x or 62t set up? I searched for a while and found some different answers, I don't think I would have to machine the 62t cases but not for sure.

What are the differances between 62t cases and 64x cases as far as the reed blocks and intakes go, I believe they are pretty much the same but also not sure.

 

[BombThreat]

I'm in the process of debating of what my options are on a set of 62t cases. can I just run 64x cylinders? Yes but you need to bore the cases to clear the larger 760 sleeves. I'm more than likely running the 701 61x top end, but want to learn more about this 760 ordeal. Here are my conclusions so far:

I figure I would have to swap out the CDI box as well, don't want to loose my MSD CDI. I want to say you can but I'm not 100% sure b.c ive heard the stocker has reduced timing on the rear cylinder..

As far as the stator and flywheel are concerned I could run a matched 61x or 62t set up? I searched for a while and found some different answers, I don't think I would have to machine the 62t cases but not for sure. Dont have to machine anything, but you gotta run either 61x stator/flywheel or 62t stator/flywheel. They dont swap together.

What are the differances between 62t cases and 64x cases as far as the reed blocks and intakes go, I believe they are pretty much the same but also not sure. 62T's have metal reeds where as 760's have fiber reeds. Also the 62T came with dual 38's and the 760 came with dual 44's. The 760 intake is very desirable b/c it has a seprate plate to get the carbs off quickly. As does the 62T but they are 38mm carbs, which have a different bolt pattern then the 44, 46, 48's

 

[Patrick Star]

I'm thinking I 'll just stick to a 61x 701 topend. Maybe big bore sleeves, but we'll see. I had a misplaced sentence up above as far as machining for the stators, it was refering to the cases, lol. I have read the 97+ 62T cases don't have the lip that must be bored in order to accept the 760 sleeves. How much metal is left to bore on the big bore sleeves, or are they pretty much maxed out to start with? Also, I have read stories about BB sleeves leaving the 61x cylinder prone to cracking. I'm looking for diplaccement, but also a reliable platform, I'll stick to a 701 before I build a time bomb.

 

[BombThreat]

BB arent time bomb's. They only are if you try and bore out a stock 701 (81mm) to 84mm then the sleeves gets real thin.