250 mi. on odometer: Im getting 15 MPG. riding slow rough trails all in high
range. Cat is getting hard to start. getting ready to foul plug?
Has anyone had to rejet? If so what changes, Pilot? Needle? Main Jet?
Air filter? Sparkplug? Any advise? THANKS

 

I went from a 145 main to a 142 and it worked well.If you do not do alot of cold winter riding you could go to a 140 main.

 

It all depends on altitude. Dropping to a 140 could cause too lean of a condition, burning your piston depending on where you ride. I've heard before that AC jet's there machines from the factory based on where the dealer is located. This would make a lot of sense as my 'Cat came with a 150 stock jet, and my dealer is around the 350' elevation level. That is the right jet for that altitude, but I ride around 3,000'+ elevation, and it is just too rich. I think Minehunter came with a 145 stock, which would make sense, as he is a lot higher altitude over in Idaho than I am here in the desert of Washington.

First off, do a plug test for your main jet-this will be what you'll need to change if anything is wrong. Do a wide open full throttle run on your 'Cat for a fair distance. Then, while you have the throttle pegged out, trip the "kill switch" with your left hand, while still keeping full throttle. Do not let off the throttle till the machine has died. Come to a stop, when it's cool enough to touch, pull your plug and see what it looks like. If it's black, yes, you're definatley rich, which is probably the case. Drop a couple jet sizes and do the same identical test with a brand new plug. The jet's cost around $3.00 from your dealer, so go pick up a couple and try them out, see what works best. My dealer gave me 3 different jets to try, then let me return the ones I didn't want-yours may do the same. Find a jet that gives you a nice brown or tan color for the altitude you ride the most. Your main jet works on roughly 3/4 to full throttle, and replacing it will give you slightly better gas mileage.

As far as the spark plug goes, my 'Cat came stock with a NGK CR6E. I replaced it with a NGK CR8E, which is a cooler plug, and gave better performance results. You might try the same. Do your new test with the brand new plug, and whatever jet you stick with, use a brand new plug, you'll be fine.

As far as the air filter goes, you probably don't need a new one-just make sure it is good and clean, and oiled well.

I'm not sure what machine you're running, but judging from your name, I'll assume it's the 500 Auto. If this is the case, and you're running "slow rough trails" like you mentioned, drop it into low range for the really rough and up hill stuff. Sure you can do it in high range, but it will be much easier on the machine in low range.

Best of luck,

Mike

 

Cowboy, when you went with the lower jet, did you get any performance improvement. If so, what types of improvements did you get?

I think the elevation here is probably around 1000 feet. Would that little bit of elevation require a different jet?

How often do you change plugs under normal conditions?


Thanks for your help.
Dan

 

Rule of thumb is 1 jet size for every 3000 ft.
When I start my engine cold I can immediately shut the choke off and ride.
This indicates the pilot jet is too large.

 

Yeah, it seems to run smoother, idle a little better, and seems a little "peppier" maybe, if that is a good word choice. I thought the main only worked from 3/4-full throttle, so I don't understand that idling better bit, but it does act different-for the better-across the entire range. I think it's running better because it is not being "force fed" fuel anymore with the 150 stock jet-that was way too rich. I'm running a 145 now, that seems to be just about right. I also got quite a bit better fuel mileage out of it as well.

As for what AC5a mentioned-when you start mine up with the choke, it has to run for a little bit with choke on, then you can remove it. I'd say maybe 30 seconds or so??? Does that sound about right? Just curious-you mentioned yours starts with the choke, then immediately you can shut it off, indicating a too large of pilot jet. How long should it idle with choke on-just as a proper indication?

-sorry, forgot to add-manual states to change spark plug every 4,000 miles, or 18 months. I've changed mine a couple times-once because I sunk the 'Cat in a river, getting water in EVERYWHERE, then also changed it with the plug test and jet changes. I pulled the plug on my Dad's 'Cat, replaced it with a CR8E when Boner first mentioned that little trick to me over a year ago. I'd have to say I had maybe 200 miles max on his 'Cat at that time, and haven't touched it yet. For the 18 month bit, we've had our machines since March of '00. Mine is basically brand new since the jet change, I don't think I'll mess with his till I swap mine-unless I find he NEEDS it done.

Oh, about your 1,000 feet bit-again, I'd do a good plug test just to make sure. If it comes out black, yeah, you'll need to re-jet. I'm a little confused though, because of AC5a's comment-I don't doubt him in the least bit, I'm sure he's right, but I went from a 150, down to a 140, found it to be too lean, went to a 142, and while I was riding at a lower altitude than usuall, I felt it was too lean for that area. I think it will work fine where I'm normally at however. Instead, I put the 145 in just to be on the "safe" side for that lower spot, just haven't removed it yet. According to the "rule of thumb", if each jet is roughly 3,000 feet, then I would take that to mean that the stock 150 would be good up to 3,000 feet, then the 148 jet would be good from 3,000-6,000, the 145 good from 6,000-9,000 and so on down the line to the 140, which is the smallest jet made for our 'Cats. Like I said though, I'm running the 145 around the 3,000 foot range on the low side, working up to around 6,500 and 7,000 feet occassionally. Maybe there's some "overlap" in there???

Thanks, Hope that helps,

Mike

 

Thanks for the info everyone. We ride at 1000 to 3000 ft. usually.
My sons Warrior needs 3 minutes or more to warm up before it can be ridden without the choke, after warmup it runs fine. Every other quad or motorcycle
I have had since 1952 required a warmup period of 2 to 5 min. Street bikes
take the longest due to lean jetting thanks to the (EPA). Never had anything
before that required no warmup. Maybe mine was jetted wrong from the factory?
I havent checked it so I dont know what size jets it has. Thanks again

 

Again, Good luck getting that straitened out. It's not hard by any means, just takes a little time to figure out which one works best for you, and the different plug readings. Like I said, from your dealer, the main jet should be around $3.00. I THINK the pilot was around $5-6 or somewhere around there, and the needle was the most expensive, around $10-12. I don't remember for sure on the pilot and needle, but I think they're close. But, I DID pay $3.00 for the main.

Happy Trails,

Mike