Exhausts

[250 drummie]

Is it worth changing the KR1 pipes to the KR1S pipes? Is there any power to be gained. Also are the carbs the same and if not is it worth changing them. I noticed there was holes in the lid of my airbox that had been taped over. It looked to me like someone drilled the lid and when there was no benefit taped them back over.

[ScottaKR]

Yeah, the KR1S pipes are worth about 3hp over stock KR1 pipes (I'm pretty sure someone here tested this on a dyno once) and look a heck of a lot nicer to boot. There's very little difference in the carbs appart from the needles (and maybe slight change in jetting), but that all comes down to fine-tuning, which would be best done on a dyno if your after the best results. You could use the KR1S spec needles and jets in your carb which may give you a slight improvement in mid-range drive, but it's unlikely youd feel it . The airbox is commonly believed to be a bit of restriction on the KR. There's many different theories on how to improve it, but the most widely agreed upon is to increase the volume of it. There's room under the battery holder if you want to do this without going to the extreme of relocateing the battery or encloseing the carbs.
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KR250 Tandem Twin (Naked)
KR1 Red/White
KR1S Track Bike (has been put on hold for now)
ZXR750 H1 (Winter project)

[250 drummie]

I am trying the wreckers for some S pipes at the moment. How do you know what to do with the airbox? Does someone have some pics or measurements.

[john-b]

if it helps the slides are a 35 cutaway on a kr1 and 40 on a 1s as i remember and the needles are slightly different a 68x as opposed to 99x on a 1s, all the jetting is the same.
A kr1s runs leaner but to be honest i doubt you will notice any difference, i would just change the pipes not that you notice 3 hp in the real world but they look nicer
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always remember someone else will buy all the parts you got by mistake so carry on until your an expert.

[TwoStroke Institute]

I have a pair of S pipes I want to get rid of
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crochet & croquet

[250 drummie]

pm sent