KR-1S.co.uk Forum

Used to large twin cylinder 4 strokes so this is first stroker since 1983!

Did about 131 miles as a shakedown ride today. Now there is a flat spot big time in the 4,000 to 7,000rpm area.
I tried checking/watching the KIPS while riding (yeah, not easy) and they seem to be fully open (as opposed to flapping and half thinking about it) at 8,500 ish.
Above 9 it flies but having to stay in 4th just to run was not fun on a dual carrigeway.
I first thought it was just choked up from lots of idling (finding that earthing problem I had) but it just didn't 'clear'.
What controls the KIPS opening point by the way?
Any pointers you experienced stroker lot?
Cheers in advance.

Itt won't have much power low down below 7K you will be looking at about 20bhp. you should be keeping it above 8k or she'll choke up.

KIPS is controlled by the CDI unit and opens around 8-9k. Only way to adjust it is to buy a programable ignition system.

Thanks, but it really is 'starving' below that 7,000 rpm mark. Sort of jerking slightly and won't pull through to the 8 grand plus. They aren't like that as std for sure!!!
In fact open the throttle (slightly or full or anywhere in between etc) and it will just go slower and slower. Every now and then it shows a spot of "well this is how I should be".
The bike sat for at least two years and although started up by its previous owner to keep the seals 'wet' it has done very little (about three miles). Maybe the jets are laquered yellow with old fuel (hopefully only laquered not Knackered!!). Haven't stripped the carbs yet so?
I have a spare (std) CDI so may change it just to try it?
Have an oil leak from the gearbox so sprocket or linklage seal to change (or both knowing my luck )

I had identical prob's !!!!!! replaced the coil,,,, & ,,,, dropped the needles.
One or both did the trick ? . Did both at once so not sure Alan.

Alanw.

Wow. How did dropping the needles cure the gearbox leak on yours?
Gosh, this white jacket has very long sleeves but is rather tight!!!!!

I have a spare set-up (bike!!!) so will give these items a try, but one at a time. A mate said he smelt a lot of petrol fumes when following on his BMW1150 so maybe too rich mid point though it felt too lean to me???
I noticed slight fuel misting/staining on the cans where the carb overflow (?) pipes exit so maybe float heights wrong/sticking blah blah.
Thanks for all the comments/suggestions. Appreciated.
By the way, you have a PM.

strip the carbs and check the jets, pilots in particular as the smaller drilling gets blocked easily. its possible to clean/enblock them easy enough if your careful but for precice operation replace em. been so small it only takes a tiny amount in size to affect the flow through the jet. also, try new plugs assuming you havent already. check the kips is operating/setup correctly. on the ypvs its possible to join the cables up the wrong way round which makes riding a pig until you realise. i guess it proves that powervalve systems do work for those older boys that think they were a gimmick!! also decoke the pipes. the amount of shit in 20 yr old stroker pipes that have been pootled round on (ie not wot thraped like a race bike) is suprising. it will be obvious that pipe area is reduced as a result hence the strangled performance. people use caustic soda but this is messy. if you have oxy acetylene equipment this works very effectively and less messy but just as dangerous. welding gloves/goggles will reduce the risk of evil burns inflicted by glowing hot metal. carbs are easy to work on and just swap electric parts bit by bit to eliminate the problem if carbs are blockage free (bet there blocked) with known working boxes etc, first thing id do though is fit new plugs/ngk race ht caps. hth, good luck matt

Does it run any better if you give it a tiny bit of choke?
As mgtkr1 suggests this points to iffy pilot jets, a good clean up cured mine.

Good luck,

Mike

Yep sounds like your pilot jets are bloked up. You can get new one's from Allens performance.

Right guys.
Betcha can't guess what I'll be doing tomorrow then............ OK, so you can?

Thanks for the suggestions. =D>

a standard KR has a weak spot at about 6.500 rev's, just before openning the KIPS (which is at +/-7.000-7.500 I believe) nothing much to do about it, but it should run OK from 4.000 up (don't expect too much, but should run ok to be just faster than ordinary traffic).

Food shopping and a route march, sorry walk around the local lake with the other half (!) just got in the way of doing anything about it yet!!
I am sure my KIPS open a bit late and that the bike is not right as weak spot or not it should at least be able to travel through to the next stage and not go backwards!!!

I would clean the carbs out, check the pilot and mains and replace if blocked, check fuel lines and tank filter, (on end of fuel tap) and if required think about cleaning and sealing the tank.

The only real way to get rid of that flat spot is to get a programmable ignition and PV controller, and adjust the pv opening point to get a dead smoth curve, ie run it with the powervalves locked open and print out the power curve and do the same with them closed. Lay the two charts on top of each other and the point in the rev band where the two curves pass over each over is the point where you want your valves to open. This will be different for every engine/tune etc.

You can improve it by playing with the needles etc,if you don't want to go to the expense of the above.

Thanks Elf.
I am sure a good clean will get it back to acceptable for what is just my new weekend toy. All thanks to a mate who races a TZR getting me hooked back onto strokers.

The tank has been completely sorted, cleaned etc as there was an unknown piece of alloy sitting in the tank that required me to remove all things from the tank (ie filter, fuel cap etc so as to get some way to get it out). Magnet didn't work so knew then it must be alloy!!!! What fun...................................... not! That tank has been flushed, shaken, turned around and around at all angles so is clean and rust free.

Like that overlay idea and programmable ECU and can see just how that'd work.
Must save some money though to sort my Caterham 7 cars front end too (and keep the h***a VTR FireStorm in petrol).