looks like cookie missed on the link, that wasn't me...
what i was talking about was maybe someone's improving the intake first would make more sense. the port on my 70 is nicely shaped (ellipsical/rectangular) and very clean, but the primitive round-pipe intake has to be a bottle-neck.
my thinking was along the lines of better utilizing the fuel the stock carb already provides. i agree that an expansion chamber would surely help, but i also think the intake flow (on my "howell" 70) could be much improved with a better-matched flange/shape.
What does the port map on these engines look like? If the carb is indeed 17mm at the venturi then it should be plenty adequate with the stock muffler and stock cylinder porting. You don't really want your engine to be over carbureted. I really need to get a used motor just to pull apart and check out.
What type of speeds are you getting with the 80cc cylinder and 17mm carb?
worked it out getting custom rectangle flanged made up then getting a pocket rocket bike expansion chamber muffler that i need to do a cut and reweld that will be the exhuast side of things should get some decent power & torque around mid range rpm .
For the carby going to use stainless steel manifold and put washer on the mixture screw to make it sit lower and also drill out slighly larger the carby not the jets but actual carby.
I am working on (too many things at once) adapting the intake and carb. from my 69 Honda 70 to my 80cc...
There's also enough material on the intake pipe that I should be able to match the ports.
We'll see how it goes. The hard part will be the aluminum welding, I'll probably farm that out...
rif, i've had pretty good luck in the past with car-manifolds using any ole piece of aluminum i had and sorta 'low-heat brazing' it. too much heat gets messy, but with practice you can get a fairly decent flow.
I'll give it a whirl. The intake on the ol' honda 'snout foward' engines curves to a 90, but in the wrong direction, I wanna make mine go out to the side rather than upright.
This should not be too difficult, and, like i said, there's plenty of material on these to play with, so with a little cutting, milling, and brazing, we should have somnething that uses a carb I'm really partial to, and should be pretty closely "matched" to the engine. I can jet appropriately if needed. This will also allow me to utilize a better, or at least snazzier, air cleaner.
Again, thanks for the tip on the low heat brazing.
Rif, it is entirely possible the weld aluminium with an oxy-acetylene torch(or oxy-hydrogen), but you need the correct flux. Some skilled race car builders prefer this metod of welding for tank fabrication over heliac welding.
I've read that. I may give it a go, it's not like I don't have a few of these intakes to mess about with from various parts bikes I've scrounged up...
BTW- are you going to the annual old bike swap this year?
I'm trying to get the local folks together for this and possible a motoredbikes.com moto cruise after...
I'd really like to, but it depends on cash on hand( it cost about $50 from Whidbey to Seattle roundtrip for ferry fare and fuel unless I came by motorbike,(then it would be hard to haul junk home unless I used a bike trailer)), and any schedule conflicts. Do you know the date yet? Last time I checked the website the 2006 info was still up.