matching cases to ported cylinder

[seanmx57]

Hi people. I was reading thru some posts that danny made a while back. I noticed he matched his cases when was grinding the jug.

I have a eric gore standard, not superhero port job. The cases are split and getting ready to go together. My application is MX. I don't own any tools other than carbide burrs and die grinders. I have been considering getting a dremel set up but have not had a real need. More importantly I don't know squat about doing the work.

Does anyone know how doing this will affect power delivery and jetting?

I'm assuming I'd do it with the cylinder dowels in? They are out at the moment do to the nikasil work that was done recently.

Getting accuracy on matching at the case/cylinder junction on the dowel side would be easy, but what about the other case?

I've been running an atomic 22 exhaust flange. I still have the stock one and it's in new condition. I'm thinking I should hog out a flange to match the jug as well. Which one would work better. I bought about 20 extra orings for the 22 when I bought it. I seems to be a waste of time so far. It leaks and there is no wear on the pipe of flange. I'm not sure if with the STR crank it will seal better or not. she was vibin pretty heavy. I'm pretty sure RTV will be the best but it is definalely more of a pain.

[Roostius_Maximus]

I always check to make sure the gasket or jug is not making a flange or lip into the crankcase, but havent seen it be a big problem, never had to cut a gasket yet, and the jug matching is by the rear transfer port where it can be opened a bit, but it wont change jetting and power is going to be likely un-noticeable.

I used the same flange o-ring spec as that aluminum one i seen advertised here, but made the whole piece out of steel, theres an o-ring in the base of the socket in the fatty, 3 on the tube of the flange instead of 2, and one at the base of the flange = tight as a ducks ass
Its larger id than stock and my jug is also ported larger all arround the exhaust port

[dannygraves]

it might have been my thread where you read that. I matched mine only because I had some pretty radical porting work, opened up the transfers and redirected the lower boost ports, so I reshaped things to flow better. in your case, as roostius mentioned, I would just make sure there isn't any lip and be done with it.
for an MX applictaion you want to change as little as possible. messing with porting on a cr500 quickly turns it into an uncontrolable beast that cannot be ridden on the trails or track anymore, like my gen-1. its a dunes only bike because the last time I hit the trails on it I had to go to the hospital and replace a lot of gear

[seanmx57]

maybe I should stuff a squirrel in the airbox. I don't really need more power but I like the idea. At times more RPM would be nice. I'm putting a spare 01 CR250 ignition on for the hell of it. Maybe that will produce RPM.

[Roostius_Maximus]

i know that my '86 engine turns so dammn high with a stock '88 500 ignition i dont think it needs the 250 treatment, but in my af the engine feels alot smoother and i can ride it all the way up top too with the '88 250 ignition