Board logo

N/A Cosworth on bike carbs
Craigorypeck - 22/8/10 at 12:50 PM

Hi All. nasping a YB cossie and the twin 45 route is expensive, £400 + at least. Anyone had good results on bike carbing one of these? Tried a search but it bringing up nothing.
Would 38mm chokes be ok? Have SRAD 600 carbs got 38s??
Thanks

omega0684 - 22/8/10 at 02:03 PM

i would say that if you are going to be shelling out for a cossie then you should be doing the job right! Get some 45 Jenveys on it if your going down the N/A route!

SPYDER - 22/8/10 at 04:13 PM

Hi there.
I would be looking at Blackbird 42mm carbs to ensure better potential from your cossie.
Or as an alternative, look at these....


48mm carbs LINKY

Geoff.

[Edited on 22/8/10 by SPYDER]

skibikejohn - 22/8/10 at 05:51 PM

On my Yb I am using Dellorto 45s and find them a joy to tune (but I like fiddling). I would be wary of the Solex carbs unless you are sure you can readily get jets etc.

RAYLEE29 - 22/8/10 at 05:56 PM

Hi, theres a lot more to it than just bolting on some carbs youll need a rebore and pistons first then a set of cams then a suitable induction system and new exhaust and a new ignition system
its actually cheaper to keep the turbo
youd be better off selling it and getting a duratec if you havent got lots to spend
Ray

2cv - 22/8/10 at 06:06 PM

quote: youd be better off selling it and getting a duratec if you havent got lots to spend Ray

Good advice, I'd second that.

Craigorypeck - 22/8/10 at 06:34 PM

I have the engine pistoned to 12:1 comp, megajolt from my current pinto will be transplanted over, cams are non turbo fast road newmans.

The engine was pretty cheap but didn't have turbo, injectors, ecu I also would need a swirl pot and uprated pump and intercooler.

I sold the turbo pistons, in and out manifold so when I sell the pinto I'll not to far above breaking even!!! Unless I go for a massive port job of course..
I have the usual case of budgetitis.. so jenvey are out.

Heard that bike carbs are a really good alt to trad sides??? Boggs said anything over a 40 choke isn't advisable. I have DHLA 40s on my pinto now and They are better than DCOEs.
Just fancied something a bit different, I like to fiddle too!

This is my everyday drive lol! Capri BTW

Craigorypeck - 22/8/10 at 06:53 PM

Also whats this dynotuned craic all about??
I'm not after race car performance, just something I can drive knowing I built it and its capabilities when I plant it.. I heard LB was thee place when it comes to bike carbs on 4 pots.

[Edited on 22/8/10 by Craigorypeck]

RAYLEE29 - 23/8/10 at 07:24 PM

well in that case the best way to size the carbs is to think of a realistic power output that you can expect to acheive then get a set of carbs from a bike with simillar output
so gsxr 600 carbs would be a little small for your set up perhaps some r1 carbs or tb's and a mega squirt
Ray
oh my gsxr carbs and manifold cost me less than £50 but i did make my own manifold

Craigorypeck - 23/8/10 at 10:46 PM

Cheers, so 750cc carbs would be more suitable?

Craigorypeck - 8/9/10 at 09:15 PM

So after a bit of hunting I have a set of ZX9Rs.
What exactly do I need to do to get these working well on my 16v?
They come with new 180mm main jets (and original size jets too). what needs to happen with the needle?
I'm in the process of trying to sort a manifold so what angle should they be fitted at? I know boggs would do all this but I cant afford and appreciate any info you have to get me running well so when I get to the rollers I'm 90% there!
Ta

FASTdan - 8/9/10 at 09:23 PM

25-30 degrees seems to work well for ZX9's

Craigorypeck - 8/9/10 at 10:29 PM

Thankyou Dan

Nash - 8/9/10 at 10:57 PM

I have a related question on this thread. The rumour mill suggests going from 600cc to 1000cc T/B's does not necassarily equate to improved performance as you lose velocity through the body due to its bigger size. I can see the logic as long as the 600 is sized to the inlet and capacity of the bore?

Is this fiction or does anyone actually know?

.....Neil

atspeed racing - 9/9/10 at 07:09 AM

For a road vehicle it is sometimes better to carb a little on the small size, this will give you a much better drive. This is why a 2.0 pinto drives well on a small choke 40 dcoe. You do sacrifice top end power going down this route.
But.....with a CD type carb such as the bike carb, it is not so important to get the choke size so accurate as you have a constant variable choke.
Always go a little smaller for a road car if you have a choise as it will drive much better.

[Edited on 9/9/10 by atspeed racing]

Craigorypeck - 9/9/10 at 10:34 AM

Will 40mm chokes be ok as an all rounder on a 16v with fast road cams?

atspeed racing - 9/9/10 at 12:05 PM

quote:
Originally posted by Craigorypeck
Will 40mm chokes be ok as an all rounder on a 16v with fast road cams?


All depends on the engine spec and what you hope to get out of it.
If you want a nice easy car to drive with good fuel consumption that will pull from very low RPM on wide open throttle then put small chokes in, say about 34mm. You will suffer at the top end with chokes this small, but would be a nice car to drive around in, if its power you are after then go for 38/40mm chokes.
Sometimes people are suprised how much power you can get from a small carb! Remember it is not always about the big number for a road car.

Craigorypeck - 9/9/10 at 09:42 PM

I'll give these a go and i can always go smaller as they are cheap anyways. Thanks