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Re: [turbobike] CV carb springs

Tim Drew (timdrew@cix.co.uk)
Tue, 4 May 1999 10:07 +0100 (BST)


 I'm not suggesting this is necessarily the way to go, but for information 
a friend of mine (Mark) had a similar problem setting up his GSX-R11 T2 
turbo system. What he did was plug the air corrector jets and adjust the 
main jet sizes accordingly. He tells me he is still using the stock slide 

--Word of caution--
Mark has done a number of things on his system that don't sound at all 
right to me. For example he has taken the control pipe for the fuel 
pressure regulator to the vacuum side of the carburettors, and put his
ignition retard switch in the plenum (Arse about face by my reckoning). In 
saying all that he tells me the bike is running well, but I'll reserve 
judgment until I've taken it out for the promised test ride later this 


Tim Drew

> All,
>     Took my CBR600 turbo for it's first ride this weekend.  It's
> suffering from 2 carb related probs.  I have a baaad lean spot around
> 6-8000 rpm, off the guage on my 02 sensor.  If I can get it to cough
> through that (scary) it pulls hard and runs OK, but I get a wicked
> backfire between shifts (chase vehicle reported 3 foot exhaust flames
> before I buzzed out of sight).
>     I've been moving my stock needles richer each time and am getting
> some improvement in running, but am always full lean at 7-8000.  It
> makes 6-7 lbs of boost here and 10lbs above 8000.  Originally, the
> slides were opening too fast and flooding the motor at about 3000, so we
> plugged 1 of 2 holes in the slides at the suggestion of the mechanic
> where we were dynoing.  I think this is my backfire problem, they are
> slow to open and therefore slow to close.  So I will be removing the
> plug and going to stiffer springs like y'all suggested.
>     Where do I get stiffer springs, and how is the stiffness rated????
> I'm planning to shim them tonight to see if I can get rid of the
> backfire at least.
>     Feedback?  I'm thinking I need a different taper needle to fix the
> lean spot, but how are the tapers measured?  I made a see through cover
> on my airbox, so I know approximately where the slides are at this rpm
> under no load.
> thanks,
>     Dave.