Bike Carb Manifold

[m0rg]

I'm looking for a bit of advice in regards to fitting bike carbs to my project car, my main issue is that there is not a huge amount of space on the intake side as it is obstructed by the airbox and brake master cylinder although i could get the carbs to fit this would not leave allot of room for an air filter

i was wondering if its possible to orient the carbs the other way facing the front

(excuse the mspaint skills)


this would give me more room to fit a decent air filter , is this an option at all or is it not going to work
i did spend a while googling but couldn't find any examples .

Image of the bay , airbox removed


Many thanks
Matt

[ssray]

Would the carbs be at the same angle as they are fitted on the bike? The distance between the carbs and the inlet valve may be a bit too long, could cause fuel drop out issues when cold

[m0rg]

Yes they would be angled the same as on the bike but facing forwards instead of to the rear .

What would you suggest to be a max recommended length for a standard intake.

I would think it would be relatively easy to keep the run tight , to avoid excess length but how far is too far

[stevieturbo]

Length of intake runners will depend where you want the power to be. Longer tend to favour lower rpms, shorter much higher.

[m0rg]

It's going to be used as a road car so it's not going to spend a mutch time at a high rpm , so low down power wouldn't be a problem .

The car originally was a 0.8l and the new engine is a 1.2 16v so whatever I do it should be better power wise.

Again it's a project car so can always rethink things later if it's not working

[gazza285]

Could you relocate the air box to the spare wheel well?

Would different carbs work better? Bandit carbs are nearly horizontal, while some Honda ones are much nearer to vertical.

Edited by gazza285 on Tuesday 23 March 21:22

[m0rg]

Sorry its the heater airbox not inlet , yes may be worth looking at different carbs i will have a look at bandit carbs though they seem to go for a premium

Thanks everyone for the reply's

[gazza285]

You could always put an engine in the boot, wasn’t there one kicking about with an RS Turbo engine in the back?

[m0rg]

Yea that is an option , though i would rather keep it so that i can put it back to stock . only 21 750L 's left on the road at the moment so the model is starting to become rare

[anonymous-user]

m0rg said:

I'm looking for a bit of advice in regards to fitting bike carbs to my project car

my advice is: DON'T

lol, sorry!


Bike carbs on cars are not a great idea. The jetting if often miles out, they don't like lateral g (bikes lean remember), cold starting and driveability is terrible, and the amount of effort and cost to fit them properly is much better spent on a basic injection system that will provide a much better control over fuelling over a much wider operating range.

A long nearly 180deg swan neck style wet manifold is going to be terrible at low rpm and when cold, and will be terrible for flow at high rpm too, so no real win their.

[chrisr29]

What about bike throttle bodies? Plenty of bikes had fuel injection. Currently fitting a couple of Triumph ones to my old Mini. They’re nice and compact and cost peanuts. I paid something like £40 for a whole set and they cleaned up like new.

[m0rg]

could do that i assume you would need an ecu to control fuelling , and is it possible to run without a fly by wire throttle as i don't really want to mess with he peddle box

[chrisr29]

Yes you need an ecu. No you don’t need drive by wire. I’m using Speeduino. Look on the DIY EFI website. It’s very cheap but does the job.