KR-1S.co.uk Forum

In manual it says regarding needle jet position = 4th notch ? Is that 4th notch from taper end or from top of needle?

Also manual says - main jet = 135. air jet = 60. pilot = 38. needle jet = N68A. cutaway = 3.5. and 1.5 turns out for slow running.
Are the above all OK settings for a standard engine with squish set at .8mm?

Yes should be fine Ronnie, although I believed standard main was 137.5 on the 1S, possibly 135 on the 1, or maybe I'm thinking of the pilot jet plus 100

each engine is different, specialy with strokers. good starting point but I'd never presume it's ok but make sure.

and 1.5 turns out is too lean, I Always start with 3/4 out.

russell wrote:In manual it says regarding needle jet position = 4th notch ? Is that 4th notch from taper end or from top of needle?

Also manual says - main jet = 135. air jet = 60. pilot = 38. needle jet = N68A. cutaway = 3.5. and 1.5 turns out for slow running.
Are the above all OK settings for a standard engine with squish set at .8mm?

The needle clip should be in the 4th notch from the top, although I have found that setting rather too rich. I presently have my needle clips in the 2nd notch from the top, which has improved response a lot. My bike is standard KR-1 with KR-1S pipes, 0.8mm squish clearance (with combustion chambers milled out to restore standard compression ratio) and oil pump removed (fuel & 3% oil mixed in fuel tank). As it is a road bike, I spend a lot of time "pottering around" and relatively little time at high engine speeds. I tried the clips in the top notch, but that setting was definitely too lean. I have a CHT & EGT gauge for each cylinder, so I can keep an eye on running conditions, as well as what I can feel when riding. I'd definitely err on the richer side for high-speed use though!

Also, I have 35 pilot jets installed at the moment, due to perceived richness at idle. The difficulty in making adjustments to the idle circuit with the engine running (viewtopic.php?f=19&t=12616) has led me to experiment - I may end up going back to the standard 38 pilots.
Although the factory recommendation for the air screw setting is 1.5 turns out, experience has shown me that several factors may require a different setting. I just go through the usual procedure to find out what setting seems best for a particular engine. The usual range of adjustment for air screws is from 0.5 to 3 turns out. Therefore, having the screws set at 1.5 turns out (i.e. midway between zero and 3) is perhaps theoretically ideal (but not essential), provided that the pilot jet size allows it.
If you contemplate a lot of high-speed travelling, it may be wise to have the idle circuit purposely set rich, to try and keep the engine cool when shutting the throttle at high engine speeds - no doubt someone with more experience in this area could advise.

Regards,
James

Thanks for all your helpful replies, will soon know in next Saturday s practice sessions.
Ronnie