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Old 11th March 2005, 09:15   #1
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Thumbs up Diff between weber dcoes and 4 bike carbs?

Hi guys,
been quite a while but had my head stuck inside the bonnet of my ezen all this while . just fixed a pair of almost brand new weber 40 dcoes (type 151...newer, with the infamous air bleed screws! ) , and the engine is a revelation!! omigod i loved webers before but now... all this while, my contessa carb couldnt keep up with the engine's demands, but now the engine cant keep up with the webers! goes low on manifold vacuum even with quarter throttle.. albeit low rpm's. right now i can putter around behind a bullock cart (2nd gear, no throttle, engine purring) then u step out and nail the throttle, the intake noise of the webers are louder than my side pipe exhaust! and off she blasts away! man i'm in love! but that apart, i started wondering, i know you bangalore guys have experimented with superbike carbs...any comparison guys? cause they have variable venturies right? any feedback plz? iceman? i know a place where i can get a set of CBR 1100 carbs for just 8000 bucks! i almost bought them , but since the webers just destroyed my bank account... feedback on the carb comparo would be helpful guys , thanks and cheers!

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Old 11th March 2005, 09:39   #2
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well the best guy for these details would be psycho. also i would prefer the 4 carbs only for strip as street is practically impossible with 4 carbs. but the twin webers will do good for both.
in case you dont need the cbr carbs let me know, i know someone who is very much interested.
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Old 11th March 2005, 09:46   #3
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hey stage3 i am coming to coimbatore tomorrow morning. where are you located?
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Old 11th March 2005, 10:31   #4
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Guess you are right iceman, the webers are really good even for puttering around town, they do a great job of taming the 300 cam too. one thing that always put me off variable venturies from bikes were, they are tuned according to the vacuum for the particular bike right? and if we stick them on a different engine with diff vacuum characteristics, they fail the purpose right? do correct me if i'm wrong. and the cbr carbs, sorry i forgot to mention bro, they are still sitting on the shelves in bangkok where i saw them. (well if they land here they would cost twice as much eh ) harrie, i am just on my way to chennai bro, i'll post here when i'm back in cbe.

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Old 11th March 2005, 12:29   #5
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Quote:
Originally Posted by Stage3Monster
but now the engine cant keep up with the webers! goes low on manifold vacuum even with quarter throttle.. albeit low rpm's.
Hey Stage3... looks like you are enjoying the newfound pleasures of CFM mania...

Just be careful to check how lean your engine is running on full revs and also limit your revs when you drive as the DCOE's tend to help over revving a lot more. Hope you have also fitted filters to the DCOE's if not please do so immediately till you get the filters in place suggest that you get some children's synthetic socks and place them over the openings else you may damage your engine especially your valve seating due to the dust getting in. The best filters would be the sock type filters as they do not tend to take up too much space.


Quote:
Originally Posted by Stage3Monster
one thing that always put me off variable venturies from bikes were, they are tuned according to the vacuum for the particular bike right? and if we stick them on a different engine with diff vacuum characteristics, they fail the purpose right?
Each carb is tuned for the given vehicle that it is designed for excepting the generic aftermarket models from webber, dellorto etc.

I have personally always had a liking for single body carbs for car's and tend to tinker around with the stock CFM ratings, jets and venturies on them, it is a lot easier to manage than 4 individual carbs as no 2 carbs have the same flow characteristics and they tend to be quite a handful to tune.

And another thing how badly is your car putting you back on milage with the cams and the carbs
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Old 11th March 2005, 13:51   #6
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Hi Psycho , thanks for the feedback bro. well i know of the horrors of not having filtered air before so i started her the first time with filters tinkering with bikes before was an advantage as i knew the shogun's filters would be great for the webers, so i have them on. although i have to do something to have them run well in the rain. the mileage...ahh that was a revelation as i knew the type 151's were not as bad as the older type webers. someone had compared the new vs old type webers akin to the Subaru wrx (old vs new) -- old-max on power, temperamental power band, new- more refined read more mileage, so just to get figures , i did puttter around town with occasional bursts of aggression and i got 7.42 !! this was for around 17 lts driven on weekdays in max traffic and man i'm pleased no end! i'm not doing WOT now as i need to check the mixtutre at WOT. will do that shortly and post. also i'm having a very slight bog in transition to the main venturies, suspect the pump jet, as the webers were idle for too long,maybe the pump piston is stuck, so i'm just running the whole package in. will gt more detaiils soon..
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Old 11th March 2005, 16:00   #7
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Quote:
Originally Posted by Stage3Monster
also i'm having a very slight bog in transition to the main venturies, suspect the pump jet, as the webers were idle for too long,maybe the pump piston is stuck, so i'm just running the whole package in. will gt more detaiils soon..
Suggestions:

1) If you are using the standard fuel pump add another in series.
2) Typically there is a jerk when you move from the idle jets to the main jets, just service your carbs it should be fine. (BTW have you rejetted the whole set or are you using it as you got it.)
3) please do note your vaccum timing advance will no longer work hence you will have to advance your ignition manually to the desired setting.
4) Hope that you have upgraded your brakes...
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Old 12th March 2005, 07:07   #8
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hi, well i knew i'll have trouble finding a jet kit, so i made sure all the jets were in the ballpark for this engine when i bought the carbs. the primaries are 45F9 and mains are 115F11 ( would have preferred 40F9 and 120F11 though. i'm slightly running richer low down cause of 45s.
i'm aware there's no vac advance , so i'm running 22deg initial (so total advance at 4000 is a massive 36deg! . i'm surprised as i'm still using only 91RON (ioc premium, i dont get speed 93 here) but still no pinking at all ??!! anyway good so far. guys anyone know where i can source 40 primaries? ( not avbl in coimbatore though). and Psycho dude, whats the mileage ur gettin on ur weber equipped esteem? and give me details on the timing ur running to plz.

Last edited by Stage3Monster : 12th March 2005 at 07:08.
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