KR-1S.co.uk Forum

Found you all again at last!! Hope you can help me out again.
I'm having trouble getting my KR-1S running right. Flat out and in the power band it runs fine, but at part throttle / low revs (<7000rpm) it splutters and misfires as if it is running way too rich. Maybe this is normal, I know that there is no power available at low revs and I would expect it to oil up a little around town, but I would not expect it to misfire so much. When I then try to accelerate it takes a little while to clear itself until it hits the powerband. It is not smoking excessively, but the plugs are oiling. Can I adjust the carbs at all to try and make it pick up smoother?

I have changed the plugs and battery which didn't make a lot of difference. I'm hoping it is not the crank seals. How can you tell if these are leaking?

Colin

My KR-1S does this as well although it is probably knackered.

Having said that I recall that Cliff reckoned it was a common issue.

When I was following Cliff's bike the other week you could see a bit of smoke when he opened the throttle after riding through a village presumably at lowish revs although with my KR-1S clattering away underneath me it was hard to tell.

Also, after breathing burnt 2 stroke fumes for an hour or so I was probably about to pass out anyway

John

I'm not too sure how everyone else checks but mine was sort of the same. Started smoking a lot though when round town. Mine was bad enough to notice that I had no gearbox oil left and as it is not leaking it must be the crank seals.

I assume you could still check and make sure your gearbox oil is staying constant then you would know if it was the crank seals.

I have managed to find that SEP at kegworth will do a crank rebuild for £55 although you will need to strip everything and just supply the crank and case but very cheap I thought

Maybe I am asking too much of it!! It's just that I don't remember my last two stroke (an AR125 20 years ago) being such a pain to ride at low speeds.

As for the gearbox oil, it appears to be holding its level. I've only recently changed it and about a litre came out which is a good sign. Is this the first sign of crank seal failure then, losing gearbox oil?

Sacko, the price you have been quoted seems too good to be true. What parts does that include, or is it labour only?

Colin

They generally run like shit between 5k-6.5k, it is a flat spot on these machine's. You could try running a hotter plug, BR9ES as fitted to the KR1 as standard, this will help prevent fouling, but dont hold the bike flat out for any length of time as this could cause hot spot's on the top of the piston crown. (Either that or just live with it like i do .)

John, i'm glad you enjoyed the fragrance of my 2T , you can lead next time so you can get your own back .

i run my KR & KR1s with the needle clip in the top position (drops the
needle and leans the mixture)

this has all but the got rid of the problem - pulls smooth all
the way once its warm

are you just winding open the throttle in 5th or top at 40-50ish mph?
if so then its never gonna pick up cleanly and it will blow smoke when you finally get into the power.
we all know about the huge flat spot in the middle of the rev range and it could be that your just stuck in that area.
if the seals go you'll see a lot more smoke than normal.
try setting the carbs and oil pump and see how it goes from there

What do you call running like shit?

Round town they four stroke and are a pain - once you are moving then it should be ok.

sure the KIPS-valves are closed at low revs ??

Thanks for all your posts.

I'll try adjusting the needles as Garry has suggested as I think it might be that it's running very rich on part throttle.

I am assuming that the KIPS valves are operating OK. They open and close when the ignition is turned on and are closed at tickover, what happens from there is anyones guess. If I raise the revs at standstill will they open at 8K?

I expect that it won't pull smoothly right through the rev range, but at the moment it seems to be oiling up everytime I'm not flat out and then takes a little while to clear again. Even when I slow for a corner or I'm stopped at traffic lights for only a couple of minutes it's spluttering and misfiring as I pull away until it's been thrashed through the powerband - the best bit of riding a two stroke anyway

Like I say I'll try adjusting the needles and take it from there.

Colin

mako wrote: If I raise the revs at standstill will they open at 8K?

yes

sacko wrote:I have managed to find that SEP at kegworth will do a crank rebuild for £55 although you will need to strip everything and just supply the crank and case but very cheap I thought

Is that Kegworth in Notts? If so I'll pop my spare crank round to them and get it done over the winter.

Yes - had 4 cranks built there a year or two back.

£55 sounds cheap for a full rebuild, rods, bearings and seals - that cost me £165 each.

thats where i live!
are you sure thats not just for labour?
when i was thinking about getting one done they quoted me
to strip/examine even before any other work
i know they have a good reputation

It was just for Labour yes they are doing a full engine rebuild for me and labour is about 200 so expect about a 400 bill