What makes a 660 a 660

[cummins17]

Lets say i wanted to do my own 660, whats all done to the motor? a good friend of mine owns a machine shop and he could do the boring and porting for me, hes done all his sleds with really good results but i want a 660.

 

[Jonce]

When I got mine from Carls, it was basically 700 pistons/rings/cylinders/exhaust valves for the base kit. I also went with the SLP pipe, HPS can, VForce 3 reeds, and bored carbs.

http://www.carlscycle.com/custompage.asp?pg=performance04

 

[bigfoot]

Carl's doesn't but you should clearance the upper case half for the bigger 700 piston. You also need to cut the squish band in the head wider for the bigger diameter 700 piston.

 

[cummins17]

Carl's doesn't but you should clearance the upper case half for the bigger 700 piston. You also need to cut the squish band in the head wider for the bigger diameter 700 piston.

thats what i was also wondering about has the upper case half, so all i would really have to do is bore the cylinder to a 700, port to a 700 and modify the exhaust valves & cyl. head. would i have to do anything to the CDI box?

 

[bigfoot]

The cdi box is fine, you don't have to do anything to it. I don't know about porting to a 700, I think the port timing on a 600 is a little more aggressive.

 

[Mandic]

660s have their own porting. The 600 and 700 cylinders are different, so you can't base anything more than bore size off of the 700.

I went back and forth about this a few months ago on another site. I am a BIG TIME DIYer, and I was really kicking around building my own 660. In the end, by the time I bought all new parts, paid to have my cylinders bored, ported, recoated, and paid to have the valves cut (what local machine shop is really going to know how to do that?), it ended up to cost about the same as a kit. So it sort of makes sense to just buy the kit where you know you are getting all the right parts right away, and setup guidelines as far as clutching and jetting.

 

[svensdream]

after the cylinders are reniked a piston and cylinder can get set on so that the port timing can be surveyed and then you can adjust port height from there with porting. with the cylinders done and installed then you can cut the head for piston diameter and then put it on and check the squish and do an install and figure out the compression ratio and then adjust the squish band width and the chambering.

On a side note there is more to porting that port height. port shape, port timing, port size, septum angle, port "hook", septum "hook", and blow down time all are part of a good port job.

 

[Chern_889]

Carl's doesn't but you should clearance the upper case half for the bigger 700 piston. You also need to cut the squish band in the head wider for the bigger diameter 700 piston.

This is a must! Im riding JONCE's old 660 mod mentioned above, and when i pulled the top end last week to replace the pistons, i found out that the cyclinders slid forward, and the bottom half-inch of the pistons where "scrubbing" on the case, the bottom skirt was basically a knife edge.

So long story short we ended up clearancing the case ourselves, didnt take much to touch them up with a die grinder.

And yes Jonce im loving the sled still, nothing like embarrasing my buddies rev 800s!