9000 ft plus jetting and clutching for stock king cat

800/900 cat twin carb jetting ?

If that where your are and not stock with a pipe, egt's are ok if you are in the ball park,

1. critical on these motors that you have some good clean piston wash in front of the intake ports, that won't lie to you. This motor carb combo from cat has forever tooooo lean mid range jetting, don't ever let a pilgrim trail ride this at 21mph on flat ground, that usualy the end of things........too lean there.

2. last of the good old easy to look at piston wash suzuki motors, egts are good to tune side to side after you have good pistons wash, look good when lit in the dark, don't believe then unless you know that tune by heart.

3. the closer you get to ideal piston wash, the better this old motor will run.

4. piston wash on an efi sled has nothing to do with what you're looking for.

Stock these sleds were often in the mid 300's maybe 350 etc. I can't remember, what I do know is when running at full song stock moror with more open air box you need to be in the 420 range to get piston wash.


then you need to look for richer needles

make sure it idles and starts without a lot of choke, otherwise go up in pilot jet, wondering idle on these is partly poor carb design, but make sure its not too lean down there and stock most were. All mikuni carbs flow gas from every jet ALL THE TIME, keep that in mind when tuning. Every jet change of any jet affects all areas of the jetting all the time. The issue is if you can tell that? So the 800/900 too lean mid range is improved by bigger pilot jets, keeping the low mid gas screw flowing as much as the engine can handle.

Don't confuse the "what sounds fat stumble" as toooo rich a condition. That sound and stumble just indicates you have a jet to jet differential in rich and lean. So you fatten up the bottom and it idles nice and pulls on the bottom but stumbles going into the mid range, that often indicates your mid range is tooooo lean, not your bottom being too fat.............? look at your piston wash, still not good, still narrow? yes too lean mid.

BETTER FAT AND TOO MUCH WASH, and work your way backwards !!
Why? Well... way lean is no heat / no hp, dry scratchy punchless motor. As you creep up in jetting and approach good fuel air ratio's, whoa .......no all of a sudden you see improvement and you make power / LOTS OF HEAT. so you just went up in jet size and burned it down ???? Yes one of the mysteries of melting pistons.

Anyway, the art of correctly rejetting a carbed motor is slowly creekping out of the sport with the EFI....thank you engineers. When carbs are referred to as " ORGANIZED LEAKS " keep that in mind, you gotta leak a little here and leak a little there.

Yeah its a little quiet at the office this morning.

clutch

similar cat;

yellw white cat primary spring
60 gram weights
green secondary spring in ( between 2nd and 3rd hole.....a mod you have to make )
54/48 or 53/50 helix
153 challenger track
21/43 gearing
pretty durn stripped down sled so about like your king

I have ridden with this sled here in West mont 4000 ft and we've ridden all over the state of Id and Wy in the spring and top of the world in Cook, one notch tighter on the sec spring and worked great.........42-440 main jets.

I run 320/330 at 9,000. Egt's are at 1200 W/O and 1250 Mid. stock needles in the middle. I have power jets on it and if I open them at all the egt's drop and power drops off. I have no explanation as to why castleman can run 420's at this elevation and it works for him. My jetting is by cat's charts right on the airbox top.

Hey Digger............ I haven't had any of the later Kings with carbs around to jet, stock air box, stock King ??? Just watch your piston wash. No piston wash, no crank. Later Kings could have later bigger needle jets, we had to punch out the original 800 twin carb Needle jets and run the bigger race shop ones that Polaris had avaialble ? When those 900's came out with the low 300's jetting chards I remember thinking .........WOW.

Running EGTs ? check in with your gauge prob mfg about what temp you should run low and mid throttle? . depending upon probe placement, etc 1000 degreess or less in the mid on the sleds I have owned. EGT numbers show temp at proble, not temp on top of piston, shown probe temp can be hot due to gas burning at the probe not in the engine or show low when raw gas hitting the probe leaves the combustion chamber lean. Probes always good info, now what to do with that information.....ah just a reminder of what we all know......be careful and have fun.

I guess it's best to put neeles for a 900zr in the kings and it helps with the mid-range. My wash looks good and have over 4000 miles on the old girl. I just replaced the pistons because I got an air lock in the cooling system and got it hot. The top of the air box have all the jetting charts and they are all very safe. You can't rely on just egt's too rich and too lean will both read cold. Guys running twins will run the low 400's for jets.

I run 360's with opened up airbox and ethanol fuel at 3-6000 ft. and 20+ deg. temps. I would think 330's sound about right for that altitude? Just make sure outside temps are not too cold. Mike

I am running 330/340 at that elevation in mine. Runs great !

The midrange seizure problems is more timing than lean jetting. Especially if running a timing key. The Cat ignition box advances the timing too far at partial throttle settings, a timing key makes it worse, on-the-edge jetting makes it even worse.

dont hold yer throttle steady in mid range,vary it on and off no more than 10 seconds in one spot,and the midrange leaning should not hurt...the king was set up from the factory for higher elevations,guys would run them stock at lower elevations and cook them..

1Mike900 said:

I run 360's with opened up airbox and ethanol fuel at 3-6000 ft. and 20+ deg. temps. I would think 330's sound about right for that altitude? Just make sure outside temps are not too cold. Mike

Click to expand...

Is that with the stock pipe Mike? Mine is running really good these days with 350's. But I am installing an SLP single right now, might go 370/380 or 380/390.

That is with the stock pipe, Actually 350 in PTO and 360 in Mag. If you go to the SLP it is much fatter, I was down at Waldron's and they had set-up sheets for the modded Kings they did. It said 380/390 on one, and 390/400 on another. This is with the same SLP pipe I don't know what the difference between the two were? But there was a guy there that said he never wished he modded a King EFI! He said stock ran great and all the mods cost money and now a new engine! Had some miles and it burned down in the mid range, Had to ride it out and toasted the bottom end. Don't make too many mods at once, See how it runs with one at a time.
Good luck Mike