From Vegas. Working on a 1975 CB500t (twin)

[marylandpkwy]

Hello everyone. I'm trying to set up a CB500t as a cafe racer. Has clubman bars and I'm putting K&N air filters on it as soon as they arrive (so, I had to remove the strange airbox system). Eventually I'm looking to get a fiberglass cafe seat, re-paint the tank and seat, remove the rear fender and put smaller front fenders on it. Then, I'd like to actually make some performance enhancements like different brakes, sprocket, carburetors, electronic ignition, etc. This site seems incredibly helpful, so I'm looking forward to getting and, hopefully, sharing some knowledge. Please let me know if anyone has any advice. Especially, where I can get the best cafe seat.

 

[RichPugh]

I'm putting K&N air filters on it as soon as they arrive (so, I had to remove the strange airbox system). Please let me know if anyone has any advice.

Welcome to the forum FYI, changing the air filter setup on the twins isnt as easy as it is on the "fours"... Youre most likely going to have to re-jet the carbs to suit the free flowing filter. The carbs on those bikes are great once tuned with proper jetting for the intake and exhaust... The stock airbox and stock filter is fairly restrictive but works well with the current jetting. When going to a free flowing K&N filter set up (not just a replacement K&N filter in the stock airbox), youre gonna run lean and you'll probably end up taping the filters to restrict any benefit from additional airflow just to keep the bike running well. Search the forums... tons of info. Good luck! p.s., Post Pics! We all love pics!

 

[marylandpkwy]

Rich, thanks for the advice. I figured I'd have to re-jet the dang thing when I put the K&N's on. Funny thing, its running really rich right now for some reason I haven't yet discovered. So, I'm thinking the new air filters will probably help until I get the carbs squared away with. Haha.

As for the jetting, I assume the bike has a #38 slow jet and a #145 main jet because thats what all of the replacement kits come with and thats what I was told by a really helpful motorcycle shop guy. K&N, the idiots, suggest a 25% increase in jet size which can't really be possible because all of the jets I've heard of only go up to #160. So, I guess I'm going to go with the #150 and, trying to take good advice, move up in #5 increments from there.

Also, K&N's web site says that the inside flange diameter necessary for the CB500t is 40mm, so thats what I bought. They didn't fit because the actual outside diameter of my carburetor was 50mm. I had to pay a 20% restocking fee. I'm pretty sure I have stock carburetors (although there's always the possibility they're not), so anybody who's working on this bike should keep that in mind. Get the caliper out- don't trust the web site.

 

[Blake]

I'm about to rejet and ditch my airbox. Any advice before I dig in? What size pods do I need? You mention 50mm. Where did you get your jets?

 

[Blake]

I'm about to rejet and ditch my airbox. Any advice before I dig in? What size pods do I need? You mention 50mm. Where did you get your jets?

Also, I have a 75 cb500t