KR-1S.co.uk Forum

martin wrote:stan stevens told me all about the jetting when i had my 300cc conversion, he reckons standard pilot jet, needle in the second clip position from the top [standard second from bottom] and standard 135mains and [and maybe one size smaller main jet as there is a possability of the bike running rich at the top end] i am running mine all standard jetting with the 99e needle on the second clip from the top, i like you have had all sorts of problems getting the bike running right, i found that i needed to spend time getting the carbs right, they have to be spot bollock on. also found new coil and new stator made a big difference

Martin,

I read somewhere you have some holes in your airbox. Did you try these taped up at all? Were these in there specifically for the 300 kit or is that how you got the bike? Have you got any details if you still have this lid fitted?

Cheers

Andrew

Naa..Not the Airbox..
it would have to have
great big Holes..
Its all pointing to the Engine..
Because ...
You say the last owner rebuilt it..
he may have...but then a monkey can
peel banana's..
Get my drift..
The reason is its not pulling clean
its hesitant...
Like Your Elsie...Just before the 6thou..rev
it pulls clean into the power band..
well the krs does the same principle
with its power valves...
Its defo something with the barrells..
Thats where it is..whether the
kips is broken or not returning..
You have checked the motor
when you switch the ignition on
the power valves rotate then after 5 seconds return..
its not unusual if the battery is disconnected
when the motor is half way through its motion to mis align
..just check ...and make sure...the valves are free..
not any spinning..
apart from that...The Big Barrells..
give us shout iam about for a chat..
G

yeah , tried the holes taped up with no difference [the holes were in the airbox lid when i bought the bike] think waki is right , but me, i would,nt rule out carb sync or electrics

Bit more playing today. With lid, airfilter, 135's and needle on lowest position this gives some improvements particularly midrange but won't pull clean up top starts "shunting".

Put the 120's back with the air filter lid and needle in it's lowest position and low and midrange seems normal, it will rev but doesn't pull up top like it should.

I think it maybe needs mains between 120 and 135 with the needle in it's lowest / 2nd lowest position. Looks like I'll be calling Allens tomorrow .

Could the Swarbrick cans encourage it to run rich?

if its 'shunting' its probably because its running rich - having the clips
in the bottom positions will ony make it worse

before you order any bits i would run the 135's with the clips in the
top position (drops the needles and weakens mixture) - hopefully that
will cure the problem

standard clip position makes bike run horrible mid range - previous owner
probably fitted smaller mains to try and cure rich running, when it was
only the clip position which needed changing

simple enough to try

Garry wrote:if its 'shunting' its probably because its running rich - having the clips
in the bottom positions will ony make it worse

before you order any bits i would run the 135's with the clips in the
top position (drops the needles and weakens mixture) - hopefully that
will cure the problem

standard clip position makes bike run horrible mid range - previous owner
probably fitted smaller mains to try and cure rich running, when it was
only the clip position which needed changing

simple enough to try

Hi Garry,

Thanks for that. What you have suggested is actually what I meant. clip in the top notch, needle as low as it will go. That's what I tried and it "shunted" with 135's.

I might also try switching the ignition on so the PV's open and then disconnect them so they are set open. They currently do cycle when stationary they open at 8k but I am not 100% convinced the are opening when running at high speed. This way at least I can be sure to eliminate the PV's from the equation.

Be interesting to see what it's like at low speed LOL..

Bertie_Mollie wrote:
I might also try switching the ignition on so the PV's open and then disconnect them so they are set open. They currently do cycle when stationary they open at 8k but I am not 100% convinced the are opening when running at high speed. This way at least I can be sure to eliminate the PV's from the equation.

Be interesting to see what it's like at low speed LOL..

Took exhausts off and checked powervalves are actually opening when they should. Cycled valves to open and disconnected them. Tried running in the mains range with 135's and exacty the same as with the KIPS connected. At least I can now categorically eliminate the PV's. This setup also "shunts" but if I turn the fuel tap on (whilst on reserve i.e. no fuel) is will start to pull for a few seconds at higher engine speeds.

I am starting to feel more confident some smaller mains will sort it.

On the phone to allens Monday.

or may be a fuel tap rebuild kit, dont think you need a smaller main jet, you have already tried diff needle clip positions, are you sure the float heights are ok and shut off valves working, or as i found with my bike, did every thing and then found the stator was,nt right, they fail underload first [higher revs

The 135 jetting is just about spot on for a KR1S road bike. The needle comes into play in mid range but comes slowly less important until at full throttle your on main jet only.
I'm guessinjg that the only reason the engine isn't dead is that its not at full throttle for long on the 120's???, The standard race kit went from 130 to 140 jets, So either you have a very special engine or something else is badly wrong .

If its running rich then I would guess at carbs. Leave fuel tap on prime and check for fuel leaking, slowly, from the overflow pipes (it might take anything from a few mins to a few hours for enough fuel to leak that you'll notice it).

I do not think its the main jet and the only thing in the carbs that I can think off that'll make it run rich are very badly worn needles/jets.

Can you get a run on a dyno, to check the fueling?

like Elf says : check your needles/needle-tubes for wair. but then again : worn needles might not have an effect at full throttle.

if the bikes starts pulling when the carbs are nol longer getting fuel, can mean 2 things :

* too rich jetting

* float level is too high, which makes it easier for the vacuum to suck up fuel and so making the mixture more rich.

but this is certainly good news as now you can almost be certain that mecanicly/electricaly everything is OK


setting up a carb is normaly done in the following order :

1/ main jet-full throttle

2/ only after you have that one correct, you start playing with the needles to make the bike run nice on +/- half throttle, and make sure the bike picks up smoothly whan openning the throttle

3/ after that is ok, adjust air-mixture and idler to make the engine run nice at idling speed, and make the engine pick up nicly when slightly openning the throttle.


so stay off hte needles (if they are ok ) until you have a good main jet

Yep Jan is right , which makes it hard to figure ou,t why your bike is jetted so lean, Might be the carbs flooding with fuel. or worn needles . IIRC even with the small main jets you were having probs? One guess is that you have a decent working fuel tap but worn float valves which are allowing the carbs to flood under heavy use. Try the tap on prime and check for fuel leaks from the carbs.

I hat 2 check everythin

Have you tried a new HT coil and leads?

Hi Guys,

Thanks for the comments,

I have tried 2 sets of carbs now on this bike with 135's and they both ran the same. I suppose I could have been really unlucky but I guess probably not.

Also one of the first thinks I did try was a replacement coil and plugs, This made no difference.

Just to clear up the situation with the main jets It came with 120's which didn't pull so I tried 135's which didn't fix it. From memory I am pretty sure it revs better on 120's now than it did when I got it. It doesn't splutter now like it does on the 135's with 120's but it doesn't feel right so I am thinking is lean with 120's? I am not familiar enough with KR1's sensitivity to main jets to know if I am likely to find a suitable main above 120 and below 135 that would sort my symptoms.

I have previously adjusted the float height and don't think this is the problem but I will check again. I'll also check her for float valve leaks.

I think my nearest dyno is Tyre Torque in Birmingham. When I spoke to him on the phone about my LC before he wasn't that keen on 2 strokes and didn't hane suitable jets but would set it up do if if I bought some along. I suppose it could be useful to get the fuelling checked at the least.

Still in the meantime I can probably do some more double, double checks LOL.

Cheers

Andrew

only thing I can say is try out other main's. going from 120's to 135's isn't the way to go. try 125's max first (or anything close but not bigger). work your way up (or down) in small steps, not in giant leaps

check the colour off the spark plug when trying different mains to give you an indication.

JanBros wrote:only thing I can say is try out other main's. going from 120's to 135's isn't the way to go. try 125's max first (or anything close but not bigger). work your way up (or down) in small steps, not in giant leaps

check the colour off the spark plug when trying different mains to give you an indication.

Thanks Jan,

Will do. I'll speak to Allens tomorrow and order some. I don't know what steps they go in but I was thinking 125's and 130's.

Just been doing some looking round on the RD forum and I think Tyre Torque might now be Calsport in Tysley Birmingham.

Cheers

Andrew