Motorcycle carbs on a Metro?

[JackMcCornack]

I'm interested in putting bike carbs (horizontal draft) on a three cylinder 996cc Metro/Sprint/Etc three cylinder engine. Anybody got ideas for me? Or even better, experience?

It's going in a Lotus Seven look-alike, it'll be a gasoline version of my Kubota diesel car (MAX), working title MAXine. Any clues will be appreciated.

[Ryland]

well, your metro engine is going to be turning alot slower, so carbs from a smaller engine should work, but then you are going to need new jets to make up for the change in air velocity, I don't have a copy of any intake and exhaust books in front of me any more but there are definent formulas to make this work, another option would be to get multi throttle bodies, there are a number of motorcycles that have fuel injection like that.

[Coyote X]

A few people on teamswift have done the motorcycle carb conversion. It is pretty much only good for racing and top end power. If you are interested searching around on that site will give you some ideas on what is involved in doing it.

I don't think it would be easy to do but maybe drilling out the injector ports in the head and just adding 3 throttle bodies from a bike would work out good. With a setup like that you also would need to run a Megasquirt computer and a huge amount of custom tuning work. If you are really wanting to push the power and rpm limits on a 3 cyl engine it is probably a good setup to use. For economy it won't get you much if anything.

[JackMcCornack]

It's a Metro engine, but it's not in a Metro. The carbs are an interim proof-of-concept step, the objective of side draft in this application is to reduce frontal area...I know this is a bit over the top, but it's a very small car and I believe it will help overall vehicle efficiency even though it won't help engine efficiency. Team Swift has lots of info on bike carbs on the DOHC 1300cc bangers, and yes they do seem to get more power, but for me it's a space issue rather than a muscle issue.

I was hoping somebody had done it allready, and could tell me that Hodaka Ace 90 carbs are just the ticket, or a set of Amals from a 1932 Henway or something...

[Tygen1]

I believe the Hodaka Ace was a two stroke, if so the carbs will not tune correctly because the slides are shaped differently than four stroke slides. I wouldn't touch Amals when Keihen carbs from many four cylinder hondas are in abundance. I would try to get a set of mechanical (not vacuum) carbs off an early '70's Honda CB-750. There is a good aftermarket for them, you can get the adapter boots with them, they will not be too big, and they will be very easy to tune. I'd favor an undersize carb because it will help your low end responce, giving a better vacuum signal over the venturi so it will be easy to tune. Also, if you use those Honda carbs, you can use the throttle cables right off of it to make sinc'ing a cinch.
Just my two cents...