Kawasaki kx65 expansion chamber on a 2 stroke?

Discussion in 'Performance Mods' started by mcassMB6, Jun 30, 2008.

  1. mcassMB6

    mcassMB6 Member

    My kid brother just welded on an expansion chamber from a kawasaki kx65 dirtbike and it seems to be fantastic!

    Is this a reasonable modification? The pipe fits well with the profile of his bike and his legs are in the clear in terms of burns.

    Does anyone know if this is a compatible mod for a PowerKing 2 stroke?

  2. A chamber is a very compatible mod for a two stroke. I am running a pocketbike chamber myself and love it......

    I am now rejetting a mikuni carb off a 1970's 80cc Yamaha dirtbike. I have it mounted and running and am in the process of tuning it to the motor and chamber.....

    Attached Files:

  3. BSA

    BSA Guest

    In general expansion chambers are designed fairly specifically for the engine they were used on. That said with a fair bit of mucking about you could make it work. Try looking in the wild in streets section to see other expansion chamber systems.

    Last edited by a moderator: Jul 1, 2008
  4. fastboy9

    fastboy9 Member

    each expansion chamber is tuned perfectly for the size of the engine it was designed for, most pocket bike expansion chambers are designed for 47 or 49cc engines. So these pipes would be best on the 48cc Happy time engines. The "80cc" engines are actually 67cc, and the KX65 engine is obviously 65cc, so the pipe is nearly perfect! Have you got any pictures? I bet it sounds a bit better too! If I was you I would drill a few little holes into your air filter to make the engine breath a bit better with that pipe.

  5. fastboy9

    fastboy9 Member

    Did the Mikuni carb just go straight on? did you have to do any modifications to the intake manifold?

    I'm going to move this thread into the wild in the streets forum, expansion chambers are more of a performance option.

    Look forward to seeing some pics though!

  6. The mikuni did go strait on, I did wrap the intake with a piece of gasket material. There are 2 different mikuni carbs in the 18mm a clamp on like the stock HT carb is, and which is what I have, and a "spigot" mount where the manifold is rubber and the carb slides into it and is held in place by a hose clamp. I dont know yet what I am going to do for a filter because I am limited for room. I had to order a smaller pilot jet (slow speed jet) because it was way to big .45mm I soldered it closed and drilled it the smallest I could which was .35mm, but still too large for the HT. I ordered a 15, 20, and 25 and also a 70, 75, and 85 main jet, I am running a drilled 80mm main now.. I'll post pics and jetting sizes when complete......
  7. Simon_A

    Simon_A Member

    Id like to know in the end, what jet size you have, as I am going to start an equivalent mod on my bike, also what air filter is that on your carby?

    The Mikuni looks a lot like my dell'orto.
  8. The filter on there now is the stock kit air filter just painted red. I have to figure something on the mikuni as there is not much clearance, prob gonna go with a "sock" type air filter..