6 replies to this topic

[998dave]

Hello Guys,
Anyone ever tried fitting motorbike carbs to a mini, was thinking I got a pair of 28mm Mikuni Slide carbs of a Yamaha RD250LC. Now I know thats relatively small, however, the bike revs to 10,000rpm and is a 2 stroke, so despite being a quarter of the capacity the pair should be okay to supply the car, maybe... Like this:

250cc x 10,(000) x 2 = 5000 (units)
1000cc x 5,(000) x 1 = 5000 (units)

Now that works fine, except the new engine in my car is a 1275, however the same choke size carbs are fitted to the Yamaha RD350LC too, (I have one of these as well so checked).

Now why do this? 1 it's different, 2 I think the choke size is about the same as the port size in the cylinder head (wheres my vernier), and as the carbs are fully floating I could run straight inlet pipes between the carbs and the head, then fit two seperate K&N's or run ramair from above the bonnet, yes? no?

Just asking and whittering now, what does everyone think? I might measure up to make a manifold anyway, I'm a bit bored today!

Dave


Also Cross Sectional Area.

HIF44 = 44*44*Pi = 6082.1

Mikuni 26 = 26*26*Pi = 2123.7

For twins = 4247.4 which is considerably smaller, but these have no butterfly, maybe a bigger carb is available... humph!

[Bungle]

i have seen bike carbs on 8 port heads but not 5 port

i dont know if there is a reason for this give it a try

[Dan]

Hey my response completely vanished!

I seem to remember reading something about Mikuni's on a Mini before. I think whoever did it was fairly happy with the result. I'll see if I can dig up the article. One question, do they have a choke control?

I wouldn't bother with ram air induction, it doesn't actually work until you are doing a couple of hundred miles an hour in a reciprocating piston engine. And a big air filter sticking out of your bonnet will ALWAYS make you look like you should be in a Nova .

[998dave]

Hey my response completely vanished!

I seem to remember reading something about Mikuni's on a Mini before. I think whoever did it was fairly happy with the result. I'll see if I can dig up the article. One question, do they have a choke control?

I wouldn't bother with ram air induction, it doesn't actually work until you are doing a couple of hundred miles an hour in a reciprocating piston engine. And a big air filter sticking out of your bonnet will ALWAYS make you look like you should be in a Nova .

They each have a cable go in the top of the barrel that pulls the slide up, it's sprung to return. The slide means that the full CSA of the 'throat' is clear of obstruction. well except for the teeny tiny needle.

They also have a choke, although it is currently a little knob that you just reach down and grab i'm sure this could be made to work remotely, just need a cable. Then there is a carb balance pipe and a fuel balance pipe, both of which are fully adjustable in length, they being a piece of metal pipe, and a piece of fuel pipe respectively.

Dave )

[minislapper]

It has been done. Some of the grassing lads have done it successfully.

[Ethro]

yeh mikuni carbs are nice, you could get some dell'otro 34mm from an aprilia RS125 as these are considarably cheaper and i think the PHSB ones are the same as mikuni. Also RS250 has 38mm dell'ortos but ehy are as rare as poo from a rocking horse.

Thinking about it, RD250 has same engine as rs250? Maybe a TZR 250 carb set would be better then RD ones as they are commonly raced so i would of thought easier to source...

[998dave]

yeh mikuni carbs are nice, you could get some dell'otro 34mm from an aprilia RS125 as these are considarably cheaper and i think the PHSB ones are the same as mikuni. Also RS250 has 38mm dell'ortos but ehy are as rare as poo from a rocking horse.

Thinking about it, RD250 has same engine as rs250? Maybe a TZR 250 carb set would be better then RD ones as they are commonly raced so i would of thought easier to source...

I can source them easily, got a set of nice clean Mikuni SV26 something's in the garage, they came of my 250 engine but didnt go on the 350, different jetting and drillings!

The rs125 carb is a single, the bonus of the 250's is the bike is a parallel twin with about the same distance between the two inlet ports as on the 5-port mini head! see?

Dave