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Jetting and set up help!!


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Soooooo I have been riding the bandito for a while now. I knew it was running rich and it hits a wall at 6-7000rpm. 

Just replaced all fuel lines and tidied a few things up and though it was time for a dyno run.

It was extremely rich!! (Forgot to take pic of page) but was a huge rich spike...... Couldn't do a full run as wouldn't rev out. Just hit a wall.

Main jets are 125. 3psi base fuel pressure

Pitot is 8mm i/d in line with air flow and pipe from pitot is 7mm id to carbs and f.p.r

What would I need to alter to get this richness smoothed out. 

Jet size smaller??

Restrictor in the pitot tube to restrict pressure?

Less base fuel pressure? 

See video attached for dyno run.

 

 

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I've found the pitot tube design has a large effect on the size of jets you run . I originally ran 115 mains on my bandit then altered the size of the boost pipe and it then wouldn't rev past 5k with that jetting . I would try lower base fuel pressure and drop mains and needle slightly . Really you need to invest in a AFR meter like an innovate lm2 , that way you can connect it all up and take the bike for a run and check which way the fueling is going . If its really rich or lean its not going to run but slightly lean and you are going to end up melting something . Sounds like the clutch was slipping on the dyno ?

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2 hours ago, Gixer1460 said:

Agreed - a blow thro only needs slightly bigger MJ's than for NA. And very surprised if std miki's are holding 3 psi fuel pressure - most leak / pass fuel anything approaching 2psi LOL!

And the the fuckin back end of the bike strapped on the dyno - that was plain dangerous!

My first statement to the guy was shouldn't the back end be strapped down....... 

I have ordered some 110 jets and 115 to try. Along with a turn to close valve for in line with the pitot to give it some adjustability if that's the problem.

Dobt think Clutch was slipping as it running lock up. The back end was spinning tho as wasn't tied down.....

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9 hours ago, colinworth79 said:

the units have data logging . My LM1 has 45 min you can then plug in the computer and see .

Ha Ha Ha - perfect for reliving the moment when your engine melted in the comfort of an old arm chair with a mug o' tea!

A dyno is definitely the place for WOT tuning turbo's IMO! 

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3 hours ago, Gixer1460 said:

Ha Ha Ha - perfect for reliving the moment when your engine melted in the comfort of an old arm chair with a mug o' tea!

A dyno is definitely the place for WOT tuning turbo's IMO! 

yeah I agree only if the rear wheel can grip the dyno drum and is strapped down properly. Still think a wide band is useful for checking .

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All my tuning is on the race track with a data logger, and an AFR meter in front of me. I start rich and work it back to best power/speed. If I see lean get off the gas and correct it before going back on the track. I can get three track days for the cost of one dyno session, and have a lot of fun on the track even when tuning. With a dyno you are a spectator and hoping that the operator has enough knowledge to not lunch your engine while he learns what to do, and lets face it every dyno operator is learning what your engine needs. I do professional failure analysis on engines for a living, and most of them have failed during or shortly after a dyno session.

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Thanks for the input guys. Back on the dyno tomorrow with some smaller mains and a few options.

Will be starting easy and see what's happening and alter to suit.

@wombat258How do you get a few track days for the price of a dyno run? I usually do the jet changes etc myself and just pay for dyno time so works out pretty reasonable.

Hoping to get it sorted tomorrow :-)

Video will follow

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Typical dyno sessions "down under" start at $300. Track days near here are $110 per day, and I get at least 5 x 15 minute sessions. Last time at the track I could pull up on track, adjust the EBC, and get back into it. And when I was finished I went onto the track and went flat out for a few sessions. Doing another track day next week to bed in the new brake discs *wink*

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