Nickel Posted May 11, 2019 Author Posted May 11, 2019 My suggestion is that the small float bowl is not the real problem. I think the problem is the small diameter of the float bowl valve, that restricts the flow to fill the bowl in a efficient way and time. 2 Quote
Gixer1460 Posted May 11, 2019 Posted May 11, 2019 Clive - Sean never really cured the fuel starvation situation with that bike nor the Spondon Kat. It didn't help using the same pumps for the NOS systems. PW was using so much fuel pressure, fuel would drip from the carb mouth at idle and flood entirely after a few seconds - lots of rpm just about kept it running. For 'mere mortals' with less extreme installations, the bigger bowl may be of a benefit with or without a pump. I agree on the S&S though - Huge float bowls - shame their fuel metering is so bad! Quote
Duckndive Posted May 11, 2019 Posted May 11, 2019 1 hour ago, Gixer1460 said: Clive - Sean never really cured the fuel starvation situation with that bike nor the Spondon Kat. It didn't help using the same pumps for the NOS systems. PW was using so much fuel pressure, fuel would drip from the carb mouth at idle and flood entirely after a few seconds - lots of rpm just about kept it running. For 'mere mortals' with less extreme installations, the bigger bowl may be of a benefit with or without a pump. I agree on the S&S though - Huge float bowls - shame their fuel metering is so bad! TBH ian I know but did not want to "Misquote Private Pike" I remember woody having the dripping carb on the Kat.....the S&S is not that bad but needs patience to set up accel pump hit position is the key....and needs to be different for road & strip......I think with the HSR you need to run the 45 or 48 as the 42 is a little wheezy IMO.....even on a street bike..... I had a cheap fuel reg and pump on mime for the strip and 2 psi was the limit before I got the dribbles so to speak.... Augy Harrison used to use boost pressure to feed the fuel by pressurising the tank.....KISS as they say Quote
Leblowski Posted May 11, 2019 Posted May 11, 2019 (edited) 17 hours ago, Duckndive said: My 1216 Draw Thru runs Gravity Feed to an S&S "Tractor Carb" 245BHP and 9.5 1/4 Quarters no starvation "but the carb has huge float bowl" My Old 1198 EFE Draw thru with T3 and HSR 42 ran gravity feed and was fine on the road as long as tank was above 1/2 full.....I added a pump and reg set at 2 PSI that I could switch on when I did RWYBs and it was fine 9.8 1/4s..... I was going to try a regulated line from plenum to pressurise tank under boost but never got round to it.... BigCC posted on face ache on a similar thread " Float bowl spacer is not a solution . Fuel flow v pressure is" And Added This was making 400+hp on the track with a HSR48 & Big CC carb mods I spoke to Sean years a go bout this problem, he told me they did a shot if nitrous at a certain point cause of starvation to prevent destroying the engine iff i recall correct. What clive said they just couldn’t fill the floatbowl. He also tried to fill it under pressure with a boostsignal regulator and pump but that didn’t work it just pissed out of the carb. The only way to fill it up is with a fuelpump that’s it. What also helps is using a straight fuelentry into the carb instead of the 90 degrees, and bigger seat and floatneedle. There are boundaries using a hsr a bigger floatbowl doesn’t work either said sean. Edited May 11, 2019 by Leblowski 1 Quote
Nickel Posted May 27, 2019 Author Posted May 27, 2019 Last week I installed a fuel-pump from an CBR600, that is pressure regulated. Had not much time to test it, but after a short roll-out it seems to be much better. No starvation at full throttle anymore and by the way no leaking carb in combination with the pump. Quote
Gixer1460 Posted May 27, 2019 Posted May 27, 2019 I'm intrigued to know which pump you've used as the carb'd CBR's used a std low pressure interrupter pump that isn't regulated and the injected models used a regulated high pressure 3 bar pump. I suspect the former as they stop once bowl is full and start again once level drops? Quote
Nickel Posted May 27, 2019 Author Posted May 27, 2019 Yes you are right, it's one of the interrupter pumps. Sorry for inconvenience Quote
Gixer1460 Posted May 27, 2019 Posted May 27, 2019 4 hours ago, Nickel said: Yes you are right, it's one of the interrupter pumps. Sorry for inconvenience No inconvenience - just clarifying for those that may not appreciate the difference. Quote
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