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Bike carbs on car engines... Which will work/fit? (noob alert)
paul the 6th - 5/3/09 at 11:32 AM

So I've got my 92 sierra donor with 1.8 cvh & type 9 box. I've had a search around for carb info but questions people have asked in the past are very carb specific etc.

I'm just trying to find out which bike carbs will suit a cvh and if it's as simple as finding a set which will fit with an adapted manifold, or is itmore specific than that? What are the pro's & cons of using carbs from a 1000cc as opposed with a set from a 750cc motor? Are there any different characteristics across different carbs I.e. R1 carbs against gsxr carbs? All advice on jets, sizes, fitting etc is greatly appreciated


r1_pete - 5/3/09 at 11:35 AM

On a 1.8 cvh I'd go for something 36 - 38 mm, I have 38mm CVK's off a ZXR750 Kawasaki on my 1.8 zetec, after lots of fiddling its running really well, I'm confident it will do its maiden 100 mile trip to Boggs rolling road without problems.

Big carbs - good for top end, but poor torque at low speeds.
Smaller carbs - More torque and drivability, less top end.

[Edited on 5/3/09 by r1_pete]


Mr Whippy - 5/3/09 at 11:40 AM

Tbh I'd still just fit a Webber, they only cost about £130 new and the dual choke ones are hardly restrictive considering they were fitted to 3ltr engines. Just can't be ar$ed with the hassle of setting up bike carbs when I could just buy a carb I'd know would run perfectly out the box


Paul TigerB6 - 5/3/09 at 11:47 AM

i've got a set of 36.5mm bore Mikuni's going onto a 2L Pinto - from a GSXR600. As above, you dont need to go too big on the carb bore size at all so a set off a 600 - 750cc bike should be more than adequate


paul the 6th - 5/3/09 at 11:51 AM

I've thought about webers but from what I've heard they're quite old technology and very thirsty? Bike carbs strike me as being more efficient and quite technologically advanced seeing how modern sportsbikes have been pushing the boundaries of what's possible for around 15 years...

By "setting up" to run well on a car engine, are referring to the air/fuel mix, or are there other aspects which I've yet to learn about?


Mr Whippy - 5/3/09 at 12:08 PM

quote:
Originally posted by paul the 6th
I've thought about webers but from what I've heard they're quite old technology and very thirsty? Bike carbs strike me as being more efficient and quite technologically advanced seeing how modern sportsbikes have been pushing the boundaries of what's possible for around 15 years...

By "setting up" to run well on a car engine, are referring to the air/fuel mix, or are there other aspects which I've yet to learn about?


na I'm talking about a single WEBER 32/36 DGV 5A downdraft and if jetted right will be fine on fuel, may be old fashioned but they work

linky


paul the 6th - 5/3/09 at 12:28 PM

Cheers whippy, will have a gander at that in a sec


Paul TigerB6 - 5/3/09 at 12:44 PM

Give me a set of bike carbs or twin webers over a single downdraught anyday. I'd rather have the extra power and cant stand filters sticking up out of the bonnet.

Plenty of people upgrade from a single downdraught to twin sidedraught / bike carbs so there should be plenty available if you go that way (and plenty of direct comparrisons from same people)


paul the 6th - 5/3/09 at 01:14 PM

so is it a case of "fashioning" a new manifold to make them fit where the inlet manifold was? Or if using weber's/proper car carburettors, do they bolt onto the original inlet manifold in the first place? Still trying to get my head around all of this since I know bugger all about engines

Still, it's the main reason why I want to build a roadster... to learn something new.


Paul TigerB6 - 5/3/09 at 01:21 PM

if using twin sidedraughts then you can buy a manifold off the shelf from the likes of Burton Power etc. For the bike carbs, then Bogg Brothers etc or make your own if you can - dont think you will find one off the shelf for a CVH unlike you would for a Pinto.

Boggs can recon a set (or supply a set even) of bike carbs / manifold pretty much ready jetted. Fine tweeking will still need a rolling road - but thats the same for any setup. Bike carbs are simpler than twin sidedraughts to set up so should work out cheaper at the rolling road.


Slater - 5/3/09 at 03:10 PM

Here is a handy article on the subject.


I cannot attach it for some reason. u2u me your e-mail and I will send it.

[Edited on 5/3/09 by Slater]


westf27 - 5/3/09 at 05:31 PM

Surrey Dave on here is your man, got just that setup and hes a nice bloke


RichardK - 5/3/09 at 05:53 PM

Rufforth Sat, any bike over 600cc on carbs and don't pay more than £15!

I can help with the inlet manifold when you get round to it.

Cheers

Rich

These are Hornet ones that I used

or these

Anyway, get off here and get in that bloody garage! See ya tomorrow m8

[Edited on 5/3/09 by RichardK]