Kawasaki KR1S has running problem

andre993 · L Plate Warrior Joined: 30 Jun 2011 Karma :

I am the owner of a 1990 Kawa KR1S. From the outside it is a wonderful machine like new, specially painted in full in Red Bull colors. However, I encountered a problem with the engine. When it has warmed up at full throttle the RPMs suddenly drop, then rise again, drop, rise, drop, rise. Anybody a clue what is happening here? My shop thinks it is the ignition unit, but as it cannot be ordered anymore, I have a serious problem here. Can anybody possibly be of some help? Any idea where I can get such a unit? Sad

tatters · Exxon Valdez Joined: 04 Jan 2004 Karma :

I would check the ignition coils first, both are located at the front under the tank from memory, the CDI is very unlikey to have failed.
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Past:NRG50,AF1125(x2),NSR125RR,ZZR250,CX500,VFR400,KR1S,ZZR600(x2),CB400N,YZF1000(x2),KH125,Z200,FX400R,CBR954RR(x2)GPZ500S,GT550,VFR750F(x2),RD350N,XR650R,CBR600F,CB250,KDX250,YZF750R,CRM250,400EXC,KLR650,TTR600RE,DR350S,R100GSPD,RGV250,VMAX1200,DL650,KZ750 Present:G650XC,C12,CRF450X,1190ADV

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

I dont think it'll have any sort of advance curve on the ignition (although the KR1s was feindishly complex for a 2-stroke so it might do). As such, the CDI should pretty much spark when it receives a pulse from the rotor just like any other 2-stroke CDI.

In my experience, a CDI either works or does not work.

"Searching" at idle could indicate an air leak around the inlet manifold, crank seals or base gasket. How does it run under load and at higher revs?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

tatters · Exxon Valdez Joined: 04 Jan 2004 Karma :

The only problem l had with my one apart from it sezing twice and blowing a crank, was the linkages for the KIPS power valve system on top of the twin cylinder head vibrating loose which would casue one set of power valves to close when the other was open at full throttle which made the engine stutter quite badly.
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Past:NRG50,AF1125(x2),NSR125RR,ZZR250,CX500,VFR400,KR1S,ZZR600(x2),CB400N,YZF1000(x2),KH125,Z200,FX400R,CBR954RR(x2)GPZ500S,GT550,VFR750F(x2),RD350N,XR650R,CBR600F,CB250,KDX250,YZF750R,CRM250,400EXC,KLR650,TTR600RE,DR350S,R100GSPD,RGV250,VMAX1200,DL650,KZ750 Present:G650XC,C12,CRF450X,1190ADV

Frost · World Chat Champion Joined: 26 May 2004 Karma :

Does the problem only occur at full throttle? If so i'd be thinking fuel stavation either from something blocked or badly set up in the carb, blocked tank breather or the like. Try running it with the tank cap off. Try cleaning and balancing the carbs. Check both KIPS valves are free to move and open when revved.
Checking the colour of the plugs after a plug chop always helps. So clean the plug, warm it up go for a ride and when it starts acting up hit the kill switch and pull over and inspect the plug.

Fortuna · World Chat Champion Joined: 29 Oct 2004 Karma :

Pickup coil, check it with a multi meter.