You know my dilemna---Too rich at wot and perfect at mid range with big jet, or good at top end and lean at mid range.with small jet

Two Questions:
1-What exactly does shimming the needle do, and what does it effect?

2- If I did some precise measurements on the needle spring, say maybe with a postal scale and measured ounces at say 2" compression, 1" compression, whatever---could I buy a couple of these springs and trim them according to spring pressure at a given distance to allow my needle to open faster?? thus increasing fuel quicker to richen the mid range??

 

Holy MOSES... hey, did you check out my thread "dialing in the "little" Prairie" ??? I can understand your frustration with the speed ( or lack there of ), on the 360... this last weekend, while I was working on the 300, in the condition it's in now, it will easily run up to 45 mph, well within 1/8 mile ( on out gravel drive way ), it would likely pull wheelies, if I tried, even with a big guy like me on it... the quad is internally stock, has the stock air filter, & completely stock exhaust... & is full time 4 X 4 ( at least until the Warn 424 kit goes in )... IMO, unless the compression ratio is hugely different ( lower ), on the 360, then perhaps you need to take a look at the 300's Primary & secondary clutches... the stock spring, in the 300 ( seems ) equal to the very aggressive Dalton Orange / Blue... I currently have my most radical spring from my 750's assortment in it, for the mud race, & while clutch engagement in it is abrupt, it is probably not beyond getting used to, & if I can get to 45 mph in the 1/8 mile, I would suspect that top speed is likely around 50 mph... not to shabby with a 265 lb rider... the 300's primary is more like a typical Comet clutch, with 3 cam weights, rather than 4 like the 360 / 650 / 700's... the weights must be much heavier, to make use of such a heavy spring, in stock form... by the way, removing the steel stock wheels & ( IMO, too big a rear tire ), that were on for winter plowing use, & installing the stock big Prairie, aluminum wheels & Dunlops ( the normal summer tires for the last few years ), adds 5 mph to the top end of the "little" 300 ), so I'm sure that tire / wheel weight will be critical to the 360 as well... also on the big Prairies, unhooking the KBEC, adds 2 more mph to the top end... IMO, this accessory, is costing the Prairie engine 2-3 horsepower... have you tried unhooking yours ???

 

Hey Newbweatle--I did read your thread yesterday and was impressed. I am thinking though that the 360P is probably a bit heavier than your 300?? I will also definitely replace my stock wheels as soon as I can burn the rubber off the stock tires. I still dont fully understand the clutch setup yet, but I also think that with some tinkering it can be lightened and improved.

But right now I am on a carb high (sniffing too much gas everytime I pull the float bowl) I had some awesome midrange with the big jets, and I want that back. Even if I half to buy a new carb. It was pretty cool nailing it and spinning the tires for a change.

Do you have any comment on the needles??? Sure sounds like a good plan on paper---I will be ordering a couple of the needle springs and do some experimenting. What did you think of the so-called starting jet I replaced??? I was on bike last night and it is still running normal and starting normal with that big jet in there.

 

Oleman, I believe that needles usually have the most effect from 1/8 to 1/4 throttle (on most machines).

However, the direction you are going with the spring and the plunger is probably a good one to go. That spring is reponsible for keeping the slide at the right distance to creating a venturi effect (low pressure that sucks gas uphill from float bowl).

Somehow, at higher RPMs and full throttle, you have too much venturi effect. I would hope that you carb had a circuit to prevent over richening at high rpm like the 650 does, but I couldn't see it.

It almost seems to me that you carb is too small for the flow you suck through it? Maybe replace the carb, maybe see if there is an air correction circuit in it (to lean it down at high rpm).

Maybe if you richesn the needle you can run that leaner main like you want, I dunno. Try it.

I do know that if my 650 was doing what you describe, I could fix it very quickly with that air correction jet.

 

Thanx for the input--Is there someone you might suggest I call to get a schematic of this carb?? Better yet, would you suggest a replacement carb?? Do you think SUDCO would be the folks to talk to about a replacement carb?? What specifics do I need to know before replacing the carb?? Back in the late 80's I bought a honda 500 xl dirt and street bike---the honda dealer was very helpful back then and hooked me up with a carb for a two stroke---had a manual choke lever amd really opened that bike up with an added XR exhaust pipe.
I gotta say it again, everything aside, this bike has alot more power than what it is showing--I think I would be temporarily satisfied to get this midrange up to par.

buy the way, i called sudco yesterday and they said they had no additional info on this carb---suggested i talk to Mr. Dunlap at 4 stroke tech---is this Mickey Dunlap???

 

Before I bought my P-360 I owned a 01' P-300 2wd.. Top speed I obtained was 36mph. Now I have seen other people post that the 300 is faster then the 360, in my experience that certainly was not the case, infact the reason I got rid of it is I bought a set of 589's for it & the damn thing would barely go up a moderate hill. After I broke in my 360 & hit full throttle for the 1st time I actually thought I was hell bent for the races, the power seemed impressive compared to that 300. Maybe I had a weak motor for some reason but I did buy in brand new, & did no mods other then a K&N & those 589's after about 1 year of owning it.

 

UINTHAS... ours is an '01 as well, 4 X 4... perhaps it's your altitude ??? we are only at 800 - 900 ft here in MN ... I thought the 330 Polaris's we rented in Colorado, were really bad, ( they didn't have the power, to get out of each others way )... although I understand, that they were jetted for over 10,000 ft...

I rode the 300 the 1st year, that we got quads, & it is a full sized quad, probably as heavy, if not heavier than the 360... I just had to go out & buy that shiney new 650, as soon as one hit the showroom floor... anyway, our 300 had the power to easily keep up with my buddys 600 Grizzly, that he had at the time ( after 3 Yamaha's, he admitted defeat, after seeing what the 650 Prairie was capable of )... 45 + mph, was probably the top speed, the 1st year I rode it, & adding the take off aluminum wheels & lighter, smaller Dunlops, off my 650, only helped... adding this Polaris Brown spring, has it as lively as it has ever been, & its several years old now...

 

Altitude, possibly but not that farr off, I know I loose some power because of altitude 4700-11,000 ft when riding, but it's like the P-360's I see allot of post indicating the 360 can only do 45mph tops, though that is close to the case for me, I can generally do 48mph on a flat road & can hit 50mph on a slight downgrade, other's dont seem to be able to do the same, dont know why, infact you'd think at my elevation I'd be worse then most. I have re-jeted for the altitude however.. I'd like to do some more experimenting with the clutche's, I have replaced my stock clutch weights & purchased the lighter ones from Kawi (dont know the specific weight off hand) I think I rev just a bit higher now but I think that is about it, sure seams like the motor is capable of more, & very well might be in the clutches. I know I can obtain the higher top end with the stock clutch apposed to the black I currently use.

 

Hey Uinthas---You figure out the clutches, and I will keep trying on the carbs---I know with the right setup, I will be able to beat the Honda 450 that smoked me, or i will get seriously hurt trying LOL

 

and by the way, I never did disconnect my KEBC--I really appreciate it going down some of the steep hills we have around here--although it does clunk and clank on a steep one in 4 wheel drive---refresh me, what do i do to disconnect--i am willing to give it a try.