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They are off a 1982 suzuki gs750. They are super responsive from idle and it is very hard to not spin the wheels when taking off I am having trouble with them at full throttle where it is blowing huge amounts of fuel out the front of the carbs and i think it is from the fuel pump supplying to much pressure and the lack of an airbox supplying enough vacuum across the front of the carbs. I still have the standard 750cc jets in there but bigger ones are on there way. Any bike nuts out there with tuning tips?
More Suzuki parts going to the big Suzuki Heaven in the sky!
Absolutely none, but I imagine the sound would be awesome. I was looking seriously at doing this to a 4age that I had sitting there for my corolla. but then I went and got my missus pregnant so it all got sold.
mate i did this a long time ago on a mazda 1300 you will need to put bigger jets and change (file a flat side to all the neddles in the main jet) the reason being more fuel delivery
the fuel spitting out is caused by air pusles coming back from the cam timming at high rpm
yes went like sh!t of a shovel but get som air cleaners on or you will get a defect for not having enough polution gear on i did thats why i sold them for triple what i spent setting them up for
i think 4 dirt bike carbyies would be more suited to off road work.
A carby is just a form of a fuel delivery and these are super simple ones which were fitted in many different configurations on bikes of the era. Being off a bike they will handle any angle as bikes see very g-forces and angles compared to car carbies.
mate i did this a long time ago on a mazda 1300 you will need to put bigger jets and change (file a flat side to all the neddles in the main jet) the reason being more fuel delivery
the fuel spitting out is caused by air pusles coming back from the cam timming at high rpm
I haven't heard about filing a flat side on the main jet but sounds like a good idea if I can't get enough fuel out the new jets I'm getting. So the fuel spitting problem Is that normal in the operation of the CV carby? Mines pretty acute as my fuel pressure is too high so I think thats making it spray droplets and flood out not just spraying a mist. I have a midrange cam in mine too so it has more duration and much different timing to the standard cam which might make it worse?
More Suzuki parts going to the big Suzuki Heaven in the sky!
fuel presure on a bike is gravity i had a surge tankset up ou mine to gravity feed the carbs with return line to let exces / all pressure bleed back to tank the needle is what you need to mod not the jets as they were cheaper back then and i was a tight arse aswell
and yes your cam will have an effect on the fuel comming out
A problem i struck years ago was that the carbies i was using didn't have accelerator pumps ( apparently not required for bikes ) so there was some flat spotting and stumbles. In the end gave up and went to Webber DCOE's..... ah sidedraft Webbers - brings back memories.
Glad to hear yours works so well.
( usual disclaimers )
It seemed like a much better idea when I started it than it does now.
MightyMouse wrote:A problem i struck years ago was that the carbies i was using didn't have accelerator pumps ( apparently not required for bikes ) so there was some flat spotting and stumbles. In the end gave up and went to Webber DCOE's..... ah sidedraft Webbers - brings back memories.
Glad to hear yours works so well.
You had the webber DCOE's on a zook! I would have thought they'd be way to big! I still haven't looked at the fueling problem with my setup yet because work has been getting in the way! I haven't tested these enough to find any problems without having an accelerater pump as they seem very very responsive of the line especially when compared to the stock aisin carby. I need to fab up a water bottle and hang it up off the bonnet and see how that goes gravity feeding the carbs to see if they run properly otherwise they may need new needle and seats. I'll keep yas posted!
More Suzuki parts going to the big Suzuki Heaven in the sky!
It was definitely the fuel pressure that is flooding it. It still pretty much dies when it gets up around 3000rpm and starts dropping revs dramatically and almost stalling unless i get off the throttle and let it go back on the idle circuit. I was thinking that maybe the diaphrams had a leak but i pulled one out and it was fine so it must be the fuel leaning out severely. I'm still waiting for the new jets to arrive to see if that fixes them The joy of living well away from a major city
Also going to start work on the new airbox to suit them. I'm going to be using a panel filter from an early 80s 300zx as they are fairly compact and have a brand new original one that been sitting in the shed for about 10years. Shouldn't be to hard to fab up a box to suit it and attach the intake pipes for the carbs to it.
More Suzuki parts going to the big Suzuki Heaven in the sky!
mine also had a flat spot around 3000rpm that is why we filed the flat spots on to the needles to try and get more fuel in it helped alot almost perfect but sold before we could finish the tune up propley good luck
I am having trouble with them at full throttle where it is blowing huge amounts of fuel out the front of the carbs and i think it is from the fuel pump supplying to much pressure and the lack of an airbox supplying enough vacuum across the front of the carbs. I still have the standard 750cc jets in there but bigger ones are on there way. Any bike nuts out there with tuning tips?
The joy of living well away from a major city