Bike Carbs ..nightmare!

[Guest MrT]

Hi

 

just been on rolling road with brand new GBS carbs- Honda CBR 600 , fine on rolling road but when driving at cruise they lean off and the car is sputtering .

The car under acceleration, and low revs fine, the needles have been lifted and the jets up from 1.38 to 1.48, no difference.

The conclusion now - when you look at the angle the carbs sit on the bike engine - they had one in is not far of vertical and the float bowls level when you look at the GBS they totally differnet.

 

After 7 hours the conclusion is the angle this carb sits at is not correct on the GBS manifold Russ from Torque tune - opposite GBS is going to have a chat with them tomorrow

 

Any one had any similar issues?

 

I think at this rate I will drop the DGAS back on

 

Paul

[Guest woolly]

yes they must sit at the same angle as when on the bike. else the float levels can never be correct. my GBS manifold is correct for the Kawasaki zx6r carbs.

 

woolly

[Guest SEgan]

My bike carbs did this when first fitted, after much fiddling over the last year I have found two jet size/ needle combinations that work.

 

With the air correctors left open : 1.8 mains needles at their lowest setting

(ran like this or over a year but in search of better mid-range I now run the setting below)

 

With the air correctors sealed up : 1.4 mains needles at their mid point. (now the preferred setting!)

 

Mine is not the GBS manifold, I didn't think angle was that important with bike carbs but I made mine so that the carbs bowls sit level.

 

 

With 1.48 mains I suspect you are running with sealed air correctors, are they fully sealed up?

 

Current Engine Spec Info. SRAD 750 carbs DIY manifold FR1 CAM 2ltr Pinto 10.5:1

 

Good luck

 

Sean

[speedtripledan]

You need 900cc fireblade carbs the manifold i got from gbs with these aforementioned carbs and the angle is spot on.. i thought the gbs manifold was for these carbs and no other did gbs sell you the whole set up?

If so i,d be straight back to them.

 

Russ as you know set mine up with no issues at all, you can pop round and have a look if you want to see how different my carbs are to your 600 ones.

 

38 dgas i'd rather poke my eyes out with cold blunt sticks than go back to that setup my bike carb set up is better in every way.

 

Dan

[Guest MrT]

Hi

 

yes the carbs were from GBS including the air filter/manifold -£400 - I thought new would be better- I will pass onto Russ the info above but he is going to see GBS for me re the angle - but ALL the newer GBS cars are using the new carbs and when I asked they said they had no probelms -

 

Paul

[Guest scrabster]

hi,same as dan,russ set my 900cc blade carbs with no probs.russ was going to speak to richard about doing something with him about setups with this car engine and bikecarb combo,looks like he is going to do it now.i had 2 sets of carbs from gbs,could not get them right so gbs swapped them with the demo car,touch wood all is ok at the mo.

jess.

[Guest nick-c]

Hi all

Although we have had success now with the bike carbs/manifold set up from GBS I will say it is in no way as simple as we were led to believe. When trying to get any sort of history on the carbs even what sort of bike they came of they were vague to say the least. Also the were suppose to be reconditioned but it was quite clear that apart from the jet being drilled out they had not been touched. Although it is a massive performance increase I do wonder whether with the cost of the rolling road time required to get them right (nearly as much as the set of carbs)is justified.

 

We identified our carbs eventually as Fireblade CBR 900

 

Nick

[Guest MrT]

hi Nick

 

the guy who did the rolling road also does bikes and he knew what they wher off and he did have a bike there with the same carbs on.

He is 50yds away from GBS and I am hoping that he goes to see them. I am hoping that he will convince them to make a new manifold as the angle to the vertical is drastically different so the floats will not opperate the same.

Looking at his 2 workshops his builds and modifications he does know what he is talking about and has good logic but at the moment I am £750 light and a car that you cant crusie in at 50+mph.

I just wonder what I do next?

 

Paul

[miikae]

Hi Paul, i would suggest that you either get GBS to modify the manifold or you get a friend to mod it for you to start with and then see how the carbs perform, if it was me i would do it myself as then it would be as i wanted it, whether it worked or not in the end, as it has cost you far too much already in my opinion.

 

I was thinking of taking the 4 carbs of my old Kwaker but dont think i'll bother now, even thought of going old skool and fitting 4 Mono block Amals or even 4 -1 1/8" SU's but its all room for thought as i will just stay with my DCOE 40s as they are doing a good job at the moe.

 

Mike

[Guest craig030774]

i got cbs manifold used cbr 600 carbs off ebay and drilled mains out to 1.75mm and used standard mech fuel pump runs a dream

[Guest enginetorque]

i got cbs manifold used cbr 600 carbs off ebay and drilled mains out to 1.75mm and used standard mech fuel pump runs a dream

 

 

Pinto - 205 block - standard cam - distributor - GBS manifold - Fireblade carbs - after spending a lazy half hour with a screwdriver, the carbs are 'balanced' (ish) and the car is better in every way than it was with the twin choke Weber - more economical - heaps faster (revs like a *bleep* now) and very tractable still - idles at 700 RPM all day with no hiccups!

 

It is a bit lean right down low but when warm it's ok - get the odd spit back and a crackle on the overrun but really it's all win win.

 

Oh - you DO need a choke - GBS say no need but if it's cold, your poor starter motor will be whirling like a spin drier!

[Guest MrT]

hi

 

Cracked it !!!!!!!!!!

I went through the logic of what is differnet with the GBS cars and mine plus the fact when on the rolling road fueling was spot on. Main difference is the GBS carbs stick through the side of the bonnet mine are enclosed in a series 3

Had a chat with Richard at GBS and they had a similar issue to me on rolling road ie but bonnet off ok bonnet on not ok

 

Just had 30 mile drive with bonnet off - absolutly perfect ! will pull easy, drives smooth all revs all speeds!

Now need to look at how to get air in without a bonnet bodge

 

 

 

Paul

[speedtripledan]

My bonnet covers the carbs but has shark gill vents right next to the carbs to provide cold air, i did that at the time as its well known cold air is better.. maybe thats why mine has worked so well from the off..

Glad its sorted.

Dan

[Andi]

I use the vents too

http://www.kitpartsdirect.com/page12.htm

The one on the carb side I have reversed for a bit more "air in"

 

Andi

[Guest MrT]

hi Andi

 

I was searching for these and could find any ! thanks

 

I will get couple of these I think down the side of the bonnet and see what happens, if this is not enough I could put air intake on the side under the swept wing and duct to the bottom of the carb.

 

thanks for th info

 

thanks Paul