KR-1S.co.uk Forum

Bit oif an odd one this. My KR-1S c2 road bike runs fine normally - bit smokey when cold starting then clears and all ok. No gearbox oil loss, oil pump and carbs set spot on, compression fine, no plug fouling etc

If take the bike up to max revs in one go there is no noticeable smoke in the mirrors. The problem is when you feather the throttle around 7.5 thou for 10 or 15 seconds, mid corner for example, then bang it open. This results in a cloud of two stoke smoke in the mirrors!! This then clears and no more smoke to be seen either at low or high revs until you do the same again.

I'm wondering if I'm getting oil buildup in the power valves or resonators? maybe its not even a problem but simply a case of not giving it enough consistent high revs to keep the valves open and so keep the resonators free from build up. I havn't had the resonator covers off since buying the bike.

I don't tend to ride everwhere at high revs and may go for 10 miles or so before having a mad moment and using the KIPS!!

Any constructive thoughts? other than thrash it more

arround 7.500, your KIPS should already be open, so can't see it beinh connected to them.

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nothing abnormal - I would say, while the resonators become tar-like inside, the oil is collecting in the belly of the exhaust pipes and the silencers

it is embarrassing and humourous barnstorming down the road with great plumes of smoke emitting but its just the nature of a two stroke and the approximation of an oil metering device based on throttle opening and not fuel flow

on the track you wont see smoke because the oil is consumed/combusted with no chance of collection.

as you say, theres less and less opportunity to run these motors where they are happiest on the road but the more you can keep purged out, the healthier you piston will be.

the type/brand and viscosity (thinness) of your oil will have an effect - also check your metering pump is aligned and not overdosing/overly generous at low throttle

Thanks for the advice guys. Glad to have it confirmed that it's probably what I was thinking and not time for an engine rebuild.

I use Motul 2T Ester 710 so I would't think oil type would be a problem. It even claims to be 'anti smoke formula' - just noticed that and I've been using it for years.

I'll bung some premix in and check the pump ouput as a final check.

Thanks again

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dont bother measuring the pump - just confirm the adjustment on the fully open position on the (pump) cable/marks

KR-1R wrote:.
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dont bother measuring the pump - just confirm the adjustment on the fully open position on the (pump) cable/marks

I agree - but only to a certain degree.

just check that oil comes out, don't bother how much thow. Once the plastic oil-pump gear went bust on mine so it stopped working. best to check to be sure it's ok

Pump marks all line up ok and the pump works as it should. I've done over 1000 miles this summer so no pump problems.

I think it's probably smoking like KR-1R says due to build up in the chambers - that makes total sense.

Split the exhausts down this summer for a respray and there was nothing too thick in them. Maybe should have bunged some caustic in the expansions to give them a good clean out but didn't bother. It may have helped reduce a bit of smoke but not to worry as I said it doesn't cloud out the back too often.

Quite like it really so long as it ain't anything major