machining 6m6 cases for 701 sleeve clearance

[jetski9010]

I am trying to get a set of 6m6 650 cases bored from my local machine shop to accept 61x cylinders. He said he could do it but would be a lot easier if someone had some specs from the two pins in the case to the center of the bore. I am not sure 100% what info he needs but I am hoping maybe one of you machine shop guys out there knows what he is talking about and have any info for me.

 

[Midlake Crisis]

When I got my ski a previous owner had put the 62T cylinder on 6m6 cases by machining the outside of the bottom of the sleeves. I don't know if that is a better way or not, just throwing it out there.

 

[jetski9010]

thats what I am trying to get done. The guy is talking about having to map for his machine to bore my cases. I am not sure what reference points and measurements he needs but maybe someone knows. He said there is a way he can use the bottom of the cylinders to set up a map to bore the cases but that would take some time so if I could find someone witht the info he needs it would cut down on the price.

 

[Midlake Crisis]

on my deal they just shaved down the OD of the sleeve skirts to match the cases, left the cases untouched.

 

[#ZERO]

Just have the machine shop use a co-ax indicator to find the bore centerline in the cases.

Also it might be cheaper just to purchase a set of 61x cases.

 

[jetski9010]

I was going to just get 61x cases but I already went through all the work of expoxy and porting these cases and they are a good matched set with the bottom so I wanted to just keep these ones.
I will ask the machine shop about the co-ax indicator. Thanks

 

[Crab]

good x cases are less than 50 bucks.........

 

[jetski9010]

then i need 61x reeds, 61x manifold, and porting work again.

 

[SUPERTUNE]

Just tell him to just use the bridgeport mill and a boring head, just touch off around the bore and bore .020 bigger than the sleeve O.D. and go to the bottom. Or if you ever going to go to a big bore cylinder, go ahead and bore it out to 3.655 and you can use any of the big bore sleeves that can use up to 86mm piston.

 

[kevbo]

At one time I cut them on a drill press with a rotary file. Just mark the edge and go slow.

 

[Matt_E]

on my deal they just shaved down the OD of the sleeve skirts to match the cases, left the cases untouched.

Doing that limits the overbores left on the cylinder.

 

[jetski9010]

He is saying he cant use the co-ax indicator because of where I ported the cases he is saying is messing up his measurements. I didnt even port where the sleeve goes I just textured the whole area. Anyways I guess he is just going to use the bottom of the cylinders to map his machine and then I told he to bore them to 3.655. Thanks for the info supertune

 

[#ZERO]

You should have taken the cases to a machine shop that familiar with jet-ski work because they'll end up charging you more than what you can get a good clean set of 61X cases, intake and reeds would cost. Also the stock 61x cases & reeds will perform better than a ported 6M6 set IMO.

 

[jetski9010]

Yea I should have just sent it out to someone but I was thinking it would not be that hard to do and I thought with shipping cases to someone the cost would come out to be more.