Board logo

Carbs motorbike or webers
Autosri - 18/1/12 at 12:31 AM

Which are better for day to day use and why would you chose one over the other

Thanks

[Edited on 18/1/12 by Autosri]


john_p_b - 18/1/12 at 07:33 AM

webbers if you have money to burn, bike carbs if you don't mind tinkering a bit.


atspeed racing - 18/1/12 at 08:12 AM

Both will give the same amount of fuel return if calibrated correcty and you make the Weber choke size small like the bike carbs. 100 BHP will need a given amount of fuel, so it doesnt make any differance if you have 10 carbs or one, without getting to exacting...please!!!!
Webers will give more power if you keep the choke size up at the expence of MPG.
Where the bike carbs score over the Weber/Dellorto is in its smoothness, it softens the engine performance at low RPM making a light kit car a pleasure to drive on the road.
So, for road use go for bike carbs, for race or track day use, Webers or Dellort's every time.


whitestu - 18/1/12 at 08:21 AM

I've had Alfas with twin webbers and have Mikunis on my Zetec Indy. Both worked equally well day to day and didn't need any more or less fiddling with.

The main difference is that the bike carbs cost about £50 to buy and install. Webebrs would have been way more.

Stu


Autosri - 18/1/12 at 08:44 AM

ThE car already has twin 40 webers on from the previous builder but someone at work made me think

Im in the process of wiring up the megajolt on the pinto and I spoke to a guy at work who said once that's finished get rid of the webers and get some r1 carbs on there but I couldn't work out why

I thought dcoe style were the best with bike carbs just behind that's what confused me


Norfolkluegojnr - 18/1/12 at 08:47 AM

My zetec is on weber 45's, and Luego Snrs is on fireblade carbs.

Both have a similar output, but to get the best out of either you really need a tuner / rolling road session.

If I was going to do it again, i'd use which ever was cheaper - I had Webers on my last engine so it was the obvious choice.

Webers have a reputation of 'falling out of tune' which in my experience is total balls. Once they've been set up, leave them alone and they'll do a grand job.



[Edited on 18/1/12 by Norfolkluegojnr]


Autosri - 18/1/12 at 09:00 AM

So you wouldn't even coincider rebuilding to whole system to the other type


Norfolkluegojnr - 18/1/12 at 09:06 AM

Well, if it was me i'd start with what i've got, then change if it doesn't work the way I want it too.

Twin 40's will power a Pinto fine unless you are planning on hardcore tuning. They can be a bit more difficult to set up though.


Autosri - 18/1/12 at 09:13 AM

No hardcore modding at most it will get a cam and a port cleanup and I'm just getting used to tweaking the webers now lol


Norfolkluegojnr - 18/1/12 at 09:18 AM

I'd start with them, see how you go.

You'd be able to sell them for a few hundred to cover the cost of BC's if you change your mind later, but if you know how to fiddle with them, its gotta be worth a try!


kipper - 18/1/12 at 10:22 AM

Changing from webbers to zx9 carbs has been the single most best thing I have done to my car.
Bogg bross manifold fitted straight on and the carbs were already dynojetted. When tested for emisions etc it was spot on with no other fettling.
With the webbers I was for ever trying to get them to run clean and starting was a hit and miss affair
(1720 crossflow vulcan engine).
Go for it.
Regards Denis.


Nickp - 18/1/12 at 10:58 AM

quote:
Originally posted by kipper
With the webbers I was for ever trying to get them to run clean and starting was a hit and miss affair
(1720 crossflow vulcan engine).
Go for it.
Regards Denis.


Maybe there was an issue with your Webers? If I had a good set of working Webers then I wouldn't be going to the trouble of fitting bike carbs. Bike throttle bodies and mapped fuel injection maybe, but bike carbs wouldn't be worth the effort in my opinion


Norfolkluegojnr - 18/1/12 at 11:07 AM

quote:
Originally posted by Nickp
quote:
Originally posted by kipper
With the webbers I was for ever trying to get them to run clean and starting was a hit and miss affair
(1720 crossflow vulcan engine).
Go for it.
Regards Denis.


Maybe there was an issue with your Webers? If I had a good set of working Webers then I wouldn't be going to the trouble of fitting bike carbs. Bike throttle bodies and mapped fuel injection maybe, but bike carbs wouldn't be worth the effort in my opinion



I'd agree with this. Guess its always best to go with what you know best initially.


kipper - 18/1/12 at 06:35 PM

Wana buy the webbers?
They were new when fitted to the car , car had done about 6000 miles when I changed them.
Complete with crossflow manifold.
£350 + postage.
Regards Denis.


Xtreme Kermit - 18/1/12 at 10:30 PM

I have a theory about webers going out of tune.

Each of mine seems to stay in tune (until the MOT man meddles) but the balance between front and back does go out.

My theory is that my problem is caused or exacerbated by each carb flexing against the other this flex I believe is caused by the lack of an airfilter backplate bracing the two together. (mine has filter socks)

I reckon if I had a proper filter across the carbs, they would be more stable.


Oddified - 19/1/12 at 09:19 AM

quote:
Originally posted by Xtreme Kermit
I have a theory about webers going out of tune.

Each of mine seems to stay in tune (until the MOT man meddles) but the balance between front and back does go out.

My theory is that my problem is caused or exacerbated by each carb flexing against the other this flex I believe is caused by the lack of an airfilter backplate bracing the two together. (mine has filter socks)

I reckon if I had a proper filter across the carbs, they would be more stable.


Absolutely agreed, i had the same issue and when i fitted a pipercross 600 back plate/filter, they never needed fiddling with again

Ian


atspeed racing - 19/1/12 at 09:41 AM

Webers and Dellorto's should be braced from under the carb with a stay down to the block to support the carbs. No one bothers much with it though. There is a stud under the carb for this. But the above posters are correct if the carbs are set up correctly, not fiddled with they will never "go out of tune".
Normally its other items on the car such as the bloody owner that causes the problem.


Paul Turner - 19/1/12 at 09:50 AM

Webers and Dellotos should never be braced to the block, they need to be able to move slightly, thats why you use misab plates and thackery washers to mount them. If you mount them solidly or allow engine vibration to affect them the fuel in the float chambers will likely foam up and you will get missfires or worse.

If you already have 40's there is no advantage fitting bike carbs, get the 40's set up properly and enjoy years of happy motoring, they will only need an occasional balance, suitable balancing devices are not expensive to buy.


atspeed racing - 19/1/12 at 09:52 AM

you rubber mount the brace as well!!!


Paul Turner - 19/1/12 at 10:02 AM

That makes more sense but I have never seen it or even heard of it before in over 30's years of using Webers.


Autosri - 19/1/12 at 10:32 AM

Would making a brace that joins them together be benificial even if the brace doesn't attach to the engine


Xtreme Kermit - 19/1/12 at 12:24 PM

I was planning on using a px 600 airbox to brace them if it'll fit under the bonnet...


Paul Turner - 19/1/12 at 12:38 PM

In the 30 odd years since I started using Webers I have neither braced them to the engine or had a backplate to join them together, always used K & N type filters. Yes they go off balance over a year or so but I bought a balancing thingy years ago and it only takes 5 minutes to whip the filter covers off, balance and replace. Some of the change is accounted for by the balance screw eating into the bar that is part of the interlinking throttle mechanism. Other than the butterflys and floats there are no moving parts to wear.

Using Jenveys now but still check balance occasionally, to be honest its never needed adjusting which is down to both the interlinking bar and screw not wearing (better metal?) and the bodies being solid mounted on the manifold.


atspeed racing - 19/1/12 at 12:43 PM

quote:
Originally posted by Paul Turner
That makes more sense but I have never seen it or even heard of it before in over 30's years of using Webers.


I havnt either.