3/4 to full throttle goes FLAT

[Alberta_KDX]

Just recently bought a 99 KD220 that was used pretty good. I think everything is stock except the bars. There is a huge flat spot from 3/4 to full throttle and i was wondering is anyone had any suggestions. Thanks

 

[cr25096er]

if it cuts out completely no matter what id think its a pluged up main. but if it just revs liek mad but not much power then its probly lean. If the engine dosnt rev out as well then its probly too rich.

 

[Mac]

From what I've read the 220 does fall flat at high revs because it was created to be a stump puller. Hopefully someone with a stock 220 can verify this.

There are some things you can do to make it rev better like jetting, rev pipe(kg-30) and a carb bore. This will make your 220 rev!

 

[John Harris]

Based on my experiences, I would say it is far too rich on the main jet. Do a plug reading. Described many times on this site.

 

[MUDMAX]

FMF rev pipe (kg30), air box mod. Not too expensive.Mine is juuuuust perfect like that !!!

 

[Canadian Dave]

Welcome Alberta_KDX

The stock KDX220 typically has a flat spot from about 80% throttle on where it makes more noise but not much more power. This has to do mainly with the pipe Kawasaki uses and can be easily fixed with an after market pipe.

Other problems can cause the bike to run flat on top too though. Do you know if the top end has been serviced i.e. a fresh piston etc and by whom? A couple problems jump to mind if it has. One, its a good idea to switch to a Wiseco piston when it comes time to do your top end as the stock piston may crack if the engine has been modified of run hard. Two, most factory shop manuals wrongly identify the left and right sub port valves so if the top end has been rebuilt and the manual followed exactly the power valves could be reversed. Three, the actuator shaft for the KIPS valve needs to be properly supported when the nut on top is removed. If it was not properly supported when/if the top end was serviced it may have snapped off and the KIPS valves are no longer working.

If you need more details just ask.

I may be able to help you with a pipe if you're looking for one.

David

 

[The Axman]

Check out the Kips valves. They could be completely "gubbered" up. Not knowing the history of the bike maybe someone put her back together incorrectly. Double check your main jet. If you change your main jet and the condition remains the same, I think you probably will find the problem rests with your Kips valves. My brothers 220 had this problem. We messed with the jetting but the condition never improved. Finally we tried the extremes, we put in a 150 main and rode the bike. We then installed a 142 main. Absolutely no difference........That night I tore the top end apart to double check the Kips what I found was that while putting in a new piston the valves had lost there allignment and we didn't notice. AAAHHHH the pleasures of home mechanics...... Ax

 

[Alberta_KDX]

thanks guys, you have some good ideas, i was planning to put a different pipe on when money permited, and new reeds. The compression is 125psi so i was hopping to leave that but i will definetly check the kips valve and the jetting. Thanks

 

[procircuit21]

How can you tell if the power valve is bad? On the right side of the engine there is that little cover that covers up a rod coming out of the engine with a round thing on the end and another piece that goes into the engine case. That moves just fine on mine, so is it ok?

 

[canyncarvr]

To verify the KIPS valves are working as they should, remove the pipe and while looking into the exhaust port, manually activate the KIPS. You should see the two drums (subports) rotating in sync and the main valve raising in concert.

On 'H' model bikes, you can easily manually activate the KIPS using the nut under the slotted cover that is on the LH side of the bike.

If you want to check if the centrifigal advancer is doing its job, you can observe the KIPS main shaft (under said cover) rotating and going back to proper rest postion while the engine is running (pipe either back on or not taken off in the first place).

If you have trouble seeing the shaft turn if you put a tie-wrap, piece of tape or maybe even white-out on the nut.

You kinda have to do both. If you can manually move 'stuff' that doesn't mean the activation mech is working ok. If you observe the activation process working properly, that doesn't mean one of the subport drives isn't stripped, or the drums have been installed improperly (due to mech error or because the manual is incorrect).

It's a good idea to check its operation from time to time anyway...notwithstanding the classic 220 flat spot.