Hey OlManMoses, saw your response on another thread about spinning the tires on dry grass at mid range RPM's. My stock 360 will not do that at all! Even now with the rebuilt engine and running stronger than ever.

When you settle on a jet set up and get it just like you want it I sure would like to hear the final word. I may or may not do the same mods as I do have the extended warantee and am not sure just what the effect on coverage would be. Next time I am at my dealers I'll ask the lady that takes care of their warrantee claims.

What is the elevation where you are doing this testing? Most of the areas I use the Prairie in are between 1500 and 4000 Ft.

I havent seen where anyone has experimented with different heat ranges on the spark plugs. Have you tried this? Could be a little hotter plug may clean up the mid range for you. I know we used to change heat ranges on the drag cars depending on the ambiant conditions, fuel setup and other things. I have been told you can avoid rejetting for altitude by going to a different plug as long as the altitude change is not too drastic. Higher altitude, hotter plug to ignite the richer fuel charge. Maybe you could give yourself a whole new frustration level by getting into this. [img]i/expressions/face-icon-small-smile.gif[/img] [img]i/expressions/face-icon-small-happy.gif[/img]

 

Funny you mention frustration--Maybe you can give me some insight???
All my testing is done on my 1000ft paved driveway that ends in the last 200' on a pretty steep uphill. Totally stock at the top of the hill my speed would decline to 28 mph. After all my mods, this is where I am at tonight: With airbox cover removed, flywheel shim installed, twin air filter, no needle shim, and 170 main jet bike broke up from about a quarter throttle to wide open.
With all the above and the 165 main installed, midrange was awesome(best ever) but broke up at wide open and top speed at top of my hill was only about 27 mph,
With all of the above and 162 main installed, mid range was lessened and still broke up at full throttle with about 28 mph at top of my hill.
Installed 160 main and midrange got a little worse but breaking up at full throttle improved a little as did mph at top of hill, about 29 mph
I dont have the 157 main so I installed 155 main (stock) and mid range was about normal (weak) but top speed at top of my driveway improved to 30mph.
At one point when I still had my dial a jet installed i put in a 150 main jet and top speed was 32 mph at top of driveway. I am going to reinstall 150 main and go back to shimming my jets to try to get that awesome midrange back.
My question is??? I hate leaning this thing out so much---but if my best WOT performance and top speed on a hard pull are best with the smaller jet--could it be running this good with the 150 jet and be to lean??? or will I be near optimum performance?? I did notice last time I had the 150 main in my cooling fan seemed to run a lot.
Looking for some advice!
Maybe instead of buying the larger jets, I shoulda got smaller ones and given the dial a jet another chance.

 

The factory settings on the carb are doing that to you.

You should probably stick to dynojet mains, since they tend to run leaner at high flow. That way, you can lean you top speed out and still have enough gas for the midrange. Or, at least you can get closer.

Another thing, there is a jet called the "air jet". Just about all carbs have them. It only affects full throttle at higher rpm. If you drill your out with a set of jet drills a little, it may lean you top speed down a little and still leave you with gas for the midrange.

I used to have to do that on the aftermarket carbs that I installed on various cars. I found the air jet on my 650 carbs, but I never removed it. It is extremely small and looks like it just pushes into place. Look on buykawasaki for it.

I have a spare one if you are worried about ruining yours. I was going to remove mine, but that was when all us 650 owners were learning why our top speed was so flat (timing).

 

Trying to digest your info Nyroc, and it sounds like if i locate and drill my air jet, it will allow more air into the mix at full throttle high rpm, where i am loading up with the 165 main jet, but not affect my awesome midrange ??? Sounds like a plan---Am I incorrect then, in assuming, that with a smaller jet (say the 155 stock main jet) that I can shim my needle and get the mid range that I am experiencing with the larger 165???

Dazed and Confused (Zeppelin, mid 70's I think)

 

Hey NYROC---Hope your reading this---I pulled up my carb at buykaw.com and cannot find any reference to an air jet?? where would I look for this on the carb at??--There is a second main jet though, right next to the main that I had asked Uinthas about and he said manual refers to it as the starting jet---It is a dupe to the mainn jet (size and thread) but maybe this has something to do with the choke and cold starts???? It is jet size #90

What your saying about leaning out full throttle while keeping midrange rich is certainly my dilemna--I do remember last time I had 150 main in and thick plastic shim in needle, bike was awesome both on top speed and mid range, but was giving me problems on acceleration from a standstill and low end putsying around.

Appreciate your input

 

Frustration is diesel fuel with water added; tune up kit with defective points; spare fan belt thats 2" short; too many combinations of jets, shims and spark plugs; this list could go on forever. [img]i/expressions/face-icon-small-smile.gif[/img]

Sounds like nyroc may have an answer for your top end problem. Hope it works out. Your fan running more when using the smaller jet may or may not indicate a very lean burn. What did the plug look like when you had the small jet in? Maybe a colder plug would help in that situation.

PKUA

 

Hey tencubed
plug was burning lean with 150 in, but not white---I am going to reinstall the 150 main tonight and play with the needles---I am also going to look for the insert that nyroc is referring to--he said if i ruin mine he has another??? wish I knew what he was referring too, but I may have a better understanding of it after i take it apart tonight---if you get a chance, go to buykawasaki.com and download the info on the 360 carb, picture and parts list---it is a pretty mixed up carb---hope someone can explain the #90 main jet and what it does??? maybe thats the key???

Stay tuned

 

I can't see it on the 360 carb.

On the 650 carb it is called JET-AIR,LEAK part number 16035-1055

I am not sure if your carb doesn't have one or if it is built into the carb or if it is there and not listed as removeable.

Good luck.

 

Just got back from the local motocross races, early night, poured down the whole time and they just ran 1 moto---I think maybe I can take some of them 400 yamahas, doesnt look like their goin to fast in the mud!!! LOL

Question for NYROC (or anyone else thats wants to take a try at it) You obviously took a look at the 360 carb at buyakaw.com--you had to then see the #90 main jet located right next to the #150 main??? Could this be like the air screw vs fuel screw dilemna on certain carbs??? you know, adjustment screw in front of carb controls airflow, if its behind carb it adjusts fuel flow???

Maybe the second jet is a reverse airjet and sucks more fuel at WOT ??? This would be way to cool---then I could bump my main back to 165 for awesome midrange, and bump the other main from a #90 down to a #80!!! I know this is a pipe dream because then it would be way to easy to dial in the carb, AND AINT NOTHIN EASY!!

 

My shop manual shows a Main Jet, Air Bleed Pipe, Starter Jet and Pilot Jet. If you are holding the carb body, with bowl removed, with the jets facing you and the heater at the bottom, toward you, then the main is the one at the top (you know this but I want to get it laid out right), the air bleed pipe appears to be just to your right of the main jet, the starter jet is the one nearest you and the pilot jet is below and left of the main jet. Is that reasonably clear? Hope so. Don't know if this will help any but I see no other referances to an air bleed of any kind.

There are several referances to being sure the fuel level is correct. In the trouble shooting section it specifies this can cause a loss of power at high RPM's. Apparently you need a special tool to adjust this level correctly.

I see the carb has a vacuum piston, they mention this needs to move smoothly or be replaced.

If you need to drill out a small jet a good place to get this done is at a Natural or LP Gas appliance repair shop. We always keep a full set of letter and number drills on hand.