BannedCR500Riders.com

I have a cr500 supermoto. Cr250 ignition, pwk 39.5 carb, rad valve, milled head, fmf fatty. Was very satisfied with my stock cylinder for low end torque but it lacked up top. The exhaust bridge cracked so i bought another cylinder. Looks like it was ported. Exhaust port widened and slightly heightened. It lacked on low end. Going to get another cylinder to start fresh or get the old one sleeved. Was thinking 196 degrees on the exhaust without widening it. leave the transfers alone, as for the intake and boost ports what would the best thing to do be? I want to retain much of the stock low and and give it more midrange and topend push. Any advise would be great, thanks.

hang on, if the crack in the bridge is the issue, cut it out!
i have an 86 enigne inmy 88 bike, bridge was cracked, port was stock width, i cut it out and it works great, lots more rpm uptop.

Thought i could have it welded so i grinded into the crack with a dremel it's pretty deep now. I'm not sure i could salvage it.

Wow, how many hours do you have on that? Have you ever damaged a ring? I like it. What did you use to completely remove the bridge?

people remove bridges all the time, I haven't heard of any failures.
The only reason some people can't is if the exhaust has been ported and is wider than stock.

Alright that's the plan. Any advice on porting for the street though?

it needs torque, keep it as narrow as possible, dome the top of the port so the ring wont snag

What about the boosts and intake?

searcher415 wrote:What about the boosts and intake?

open them boost ports like your prom date

searcher415 wrote:Wow, how many hours do you have on that? Have you ever damaged a ring? I like it. What did you use to completely remove the bridge?

lots of hours on mine

pretty sure blow down time will be fugged up with 196 exhaust and stock transfers. never tried that combination but it dont sound right.

Having some trouble doing the port mapping and i want to get the bike back together before it snows lol. Came across a guy who claimed he tuned cr500 motards occasionally on another forum. His specs were raise the exhaust 4 mm and the transfers 1mm. Does that sound ball park?

I would like to do the math myself but i am having trouble finding time to do the port mapping accurately now that schools started. Does anyone know the stock port areas? Also what tools do you usually use to raise the transfers?

4mm is a lot, I think that comes out to over 200*
I raised my exhaust like 3mm and it was good for the dunes, but that was about it. The bike was wicked fast.

leave it where it is, just cut the bridge out

dannygraves wrote:4mm is a lot, I think that comes out to over 200*
I raised my exhaust like 3mm and it was good for the dunes, but that was about it. The bike was wicked fast.

Did you touch the transfers at all?

i think he did a lot with them, heres a link with a bit of info heres the thread

http://www.bannedcr500riders.com/board/ ... php?t=9239

heres a part of it