Well, I'm going to try my hand at rejetting my '93 SP. Since I have never done this before, I thought I'd ask for advise from anyone on this forum. Could someone please type out fairly comprehensive instructions on how to go about doing this? Also, I'm looking for any jet sizing advise I can get. The bike has a Daytona filter, Tyga pipes, HRC derestrictor. I haven't installed the pipes yet and I'm pretty sure the jetting is stock at the moment. In the mornings the temps may be 65-70 deg. F and by the afternoon they're up around an average of 90 deg. F with HIGH humidity.

Thanks for any help you can provide.
Don

check out NSR-WORLD Jetting for detailed instructions on jetting.

thanks,
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Charles Gallant

DO NOT RIDE THE BIKE ON STANDARD JETTING ONCE THE PIPES ARE ON!

You will seize, and no doubt sh*t yourself. Ask me how I know. I was that impatient idiot who just couldn't wait for the jet kit.

Have you enlarged the airbox intakes to comliment the exhausts? The box will not flow as much air as the pipes are capable of in standard form.

I've got the HRC jet kit, and found that even after blocking the PJ's the lowest jet - 180 - was still a bit too big. Once I'd modded the airbox and ditched the filter it was better, but I took it off the track before i ever got it setup correctly. I'd suggest with a free flowing filter, Tyga pipes and the airbox modded, you'd be looking at about 160's. I'd personally still start at 190's to be on the safe side.
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Dave,

I am thinking your warning is a little more then it needs to be. I ran my bike on stock jets with TYGA pipes for over a year, and didn't have an issue. Of course that was with a stock intake system. Once I started modifying the intake system, then I had to rejet the bike.

thanks,
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Charles Gallant

To anyone with the HRC jet kit, what is the range of MJ that you get? Is 150 one of them?

There were two HRC kits for the MC21, an "unleaded" kit and a "race fuel" kit.

If you are successful in finding an unleaded kit, I believe the MJ sizes range from 160 to 195, but these kits aren't easy to find. The more common (i.e. readily available) Jha kits are designed for 105 octane "premixed" fuel and range from 180 to 210.

Individual main jets can be ordered from ANY Honda main dealer for a couple of Dollars each. The formula for the MJ part numbers is on the Carburetion page of the 250 Tuning section.

Andy.
NSR-WORLD.COM

i got my unleaded kit from tyga

cgallant wrote:Dave,

I am thinking your warning is a little more then it needs to be. I ran my bike on stock jets with TYGA pipes for over a year, and didn't have an issue. Of course that was with a stock intake system. Once I started modifying the intake system, then I had to rejet the bike.

thanks,

Well maybe I'm just unlucky then. I had done no other mods at all, and had ridden the bike for a couple of months without mishap before the conversion. I fitted the pipes and took off up the road like a scalded monkey. Then at 105mph the back wheel stopped going round whilst I leant intoa corner. Fark knows how but I grabbed the clutch and hung on through the monster tank slapper.

Won't do that again, and felt I ought to warn others of what is likely to happen...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

I would personally NEVER make any modification without checking the jetting after.

When I bought my Ethos chambers, they even supplied a set of (staggered) main jets suitable for the upgrade.

Andy.
NSR-WORLD.COM