Carb tuning for a Race can

[cc123]

Has anyone ever had to do this before?

I've ordered a Viper race can and have been told that I may have to play with the carb settings to get the bike running right. My old Ninja needed no adjustment but thats a few people told me that Viper cans make the bike run crap unless the carbs are set up...

Any thoughts?
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[G]

'Needs no adjustment' doesn't always mean that it wouldn't benifit from some adjustment - it's advisable to get it done anyway when changing, as it's probably out for the original can, never mind the new one you're puitting on.

[Kickstart]

Hi

Likely to need some playing with, and unless everything is close it will be just about impossible to do it yourself.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[cc123]

So whats the chances of the bike running right from the min I put the can on?

As I said, my last can ran fine on the standard carb settings....
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[G]

It will probably run 'ok', but some parts of the rev range may be worse than before etc.

How much you will notice is another manner, still worth doing - if nothing else you may save some money you spent on fuel economy etc.

[Kickstart]

[cc123]

I'll run that past my mate, hes the one thats ordered the can for me so he can set the bugger up, also getting him to do my pads and service the front brakes.

Does it just depend on the make of can? My old MIVV was designed to run on the standard fuel settings but was absolutely biblical noise wise and the bike ran great after it getting fitted.

OH, and how will I know if the bike IS running lean?
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[Kickstart]

Hi

Opinion of those selling race cans is that if it does work with the standard jetting then it is luck.

Mivv normally make complete replacement exhausts (think they are also an original supplier to some of the European factories).

You won't know it is running lean. Slightly down on power, and not likely to be a problem except under certain conditions (high load up hill, hot day, high altitude, for example). Some bikes are prone to holing pistons (old GPZ550 for example) and on these it would certainly help them on their way.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[EuropeanNC30R...]

Wouldn't high altitude cause the bike to run richer and compensate for the leaness caused by the can?

[Kickstart]

Hi

Possibly would, but the same reduced pressure is working on other bits of the carbs. CV carb works by using the difference in pressure between the air going through the carb and general air pressure to live the slide / needle. Possible that you might have a higher pressure drop in far thinner air. Mind you the same applies to the air pressure in the float bowl To be honest do not know enough to be certain either way.

Maybe I should have said extremes of pressure and temperature.

By the way, an exhaust might well not cause a lean problem, or may well cause it to be lean at some revs and rich at others. For a very rough example the Bandit has a full Akrapovic system and was jetted for running without the road baffle. Stick the road baffle in and it gets a flat spot around 3000rpm, which is worse when cold (and pretty awful when the engine is cold and it is a cold day). Currenty fixed by lifting the needles half a notch to richen the mixture.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[cc123]

Thanks for the help, I'll try running the can for a few days to see if I notice a difference. The idea was eventually get a Dynojey kit and K&N, then set the bike up on the dyno bt was going so wait a few months vefore splashing the cash.
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[the grim reaper]

I always gas test a bike after putting a new exhaust on it. If you use a decent gas tester then you can check the CO2 content across the rev range. I know a lot of exhaust manufacturers like to claim that the exhaust 'requires no rejetting' but there will always be some change in the running of the bike, unless it has a lamda sensor.

A free flowing exhaust will always run differently to the original can. Re-jetting and shifting/changing carb needles will almost always give a better performance.

Cheers

Grim
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[EuropeanNC30R...]