OK, just got back from the dealer with the new jets, have a few questions before I begin. First off, I might have gone a little TOO far down, as I believe Minehunter had a 142 stock, then dropped to a 138-is that correct? I have a 150 main stock, and just got a 140 to replace it with. The main jet works between half, and full throttle, right? So, just to refresh my memory, to check spark for the main jet, run full throttle, then hit the kill switch while still on the gas, not letting off the gas till the engine dies entirely-this will give proper coloring for the main jet right? Now, do you actually have to be running full out, or could you leave it in neutral with the park brake on, doing the same thing but not actually moving? Not sure if you need the extra "load" of actually moving or not???

My dealer also mentioned that I should check the needle, maybe drop it down to lean it out a bit. Now, to my understanding, this works just backwards to what you would think-to lean it out, you need to drop the needle, which means RAISING the clip a notch-and lower it to make it more rich, is that correct? He said to move it one clip at first, just to see what it does. Now, I was kind of thinking that if I find the 140 main is TOO lean, could I then move the needle position up a click to maybe make it a little more rich? Or, is the needle position only important in the low range, up to about half throttle? It seems I remember something about the pilot jet and the needle being most crucial around low to half throttle, then the main kicking in from half to full throttle-is this correct?

Also, the great majority of my riding is from 3,000' and up in elevation. The problem is, my home is around 680' according to the GPS, so I won't be able to do any testing at all with the new jet down here-right? I should wait till I get up to the ranch before taking any plug readings?

Next, while messing around with it, I just realized I have about a full half-inch of play in my throttle cable-meaning when I press the gas, the button moves about 1/2" before any fuel gets to the engine to increase rpm's. Should I back that down to the 1/8"-1/4" range-I seem to remember somebody mentioning this not too long ago-maybe in the Polaris forum???

Then, while messing around with things, I pulled the muffler plug to blow out the carbon build up. Man, was it built up! On my machine, the plug was about half-filled itself with a rock solid build-up. I chiseled it out down to the base of the plug itself, then used a screwdriver to remove a large chunk over the hole in the muffler itself. Once this was removed, a bunch of dust fell out. I had the front end elevated about 8" or so, then gave it steady throttle up to about full throttle or so, held it there for probably 30 seconds or so. It didn't blow much at all out up to about half throttle, then as it approached full throttle, huge clouds of black dust came blowing out, in varying intervals. A cloud would blow out, then it would run clean, then another cloud, etc. I held the gas on long enough that no more black coulds came out, it was all clean air. However, once it was all clean air, it sounded as if there was an exhaust leak somewhere, with a popping sound. Is this what it should sound like after blowing it out? I'm letting them both cool off as I write this, so I don't yet know what it sounds like with the plug back in yet.

My dad's machine had a lot more build-up than mine did. My guess for this is even though his has a lot less miles than mine, he has never really had the rpm's up high enough to blow it out while riding-does that make sense? And, with that much heavy build up, would that have any further indication that I should definately lean the machine out a bit?

Anyway, if you're still reading this, sorry for the extra-long list of questions. I want to make sure I do everything right the first time, so I don't have to go back and do it over again, yet also want to make sure I don't jeopardize anything with the machine at the same time.

Thank you for any and all comments, suggestions, etc., I greatly appreciate it! Hopefully on Monday I'll be able to let you know how it performed, and what kind of mileage gains I ended up with-if any.

Mike

-oh, also asked again about the air filter. Seems we misunderstood each other last time-he said yes, definately oil the blue foam filter! So, I got a can of the AC filter cleaning fluid and a bottle of the AC filter oil, as well as a brand new filter to change out between cleanings. I'll be running this new filter with the new jet-FYI

 

Go to my site and click on Service. I have a chart from Dyno that portrays the jets and where they affect throttle.

Moving the needle clip up will move the needle down making it leaner.

Yes you can check jetting while in neutral. The engine is moving just as it would when you are riding it. The only difference there would be airflow into the air intake. Not sure how much of a variable that is. If the carb is professionally jetted they measure the air fuel mixture with a machine (like DynoJet sells) while the quad is on the machine...not moving around.

With your elevation problems jetting will be more dificult. If you ride up there mostly....do your jetting there.

Take that slack out! That is a problem that Hondas have from the factory. I'm not sure how your cat goes but I have instructions for a Honda on my site. Remember whenever you take the carb off you will be changing the slack down at the carb....so always readjust it when you install the carb.

You should clean the muffler every month or so depending on the riding you do. A dirty muffler will make you run rich. Mine recently was so packed with mud my quad would not even idle.

 

Cowboy, mine came with a 142 and I went to a 140. I left the clip right where it was. Boise has a base elevation of 2750 feet and it's up in any direction out of town. I haven't had any problems with it running lean at all.

Cleaning out that muffler will help also. That will lean it down a little too.

Don't know what else to say other than " good Luck". Let me know how it works out for you.

Bob

 

Thanks guys, I was kind of worried about the elevation thing here-680 or so at the house here, but yes, all of my riding is done at 2,500 minimum, mostly around 3,500-7,000. I think what I'll do is put my jet in tomorrow, get a "feel" for what to do exactly, that way when I get up to the ranch I can do the testing properly at elevation. That way I'll already know what to expect and it should go much faster the second time around with Dad's 'Cat.

TexMud-
Yeah, Boner emailed me the link to your site a couple days ago-Nice Job by the way! It is an awesome sight, TONS of great information. Now that I think about it, I think that's where I started thinking about my throttle adjustment. Thanks for the comments there-guess I screwed up already! I adjusted it earlier today after blowing out the muffler. Guess I'll just loosen it back to where it was before I mess with the carb tomorrow morning. It was really easy to do-just slip that rubber booty thing back down the cable, that exposes the two lock bolts-whatever you call them. Yeah, you have to back the one on the left off-which pulls the slack out-then screw the jam nut back on tight against it. They are both plastic though, so you've got to be careful not to overtighten them and strip it out. Anyway, I pulled all the slack out earlier, so now the instant you touch the throttle, it moves immediately-no slack at all, and tighter as well.

I tried looking at your dyno chart that you had scanned in, but I couldn't make it out very well-pretty small. I think I may have had my computer adjusted though to the smaller scale as I was working on a project at the 1024x768 scale, when normally it should be on 800x600. I'll check it again now and see if it gets any better. Thanks too for the tip on blowing the muffler out every month-I'm rather ashamed to say that they're over a year old now, and this is the first time I've done it.[img]i/expressions/face-icon-small-blush.gif[/img]

Anyway, Thanks Again guys, greatly appreciated!

Mike

 

Howdy Cowboy! Gonna start messin with your jetting huh? You and Texmud are right about the needle clip... drop it to lean (raise clip)and raise it for richer(lower clip). I do disagree about running it at a stand still to read the plug though. The plug needs to be read after a wide open throttle run (under load) You never want to rev your motor that way when not riding under load. And doing it while holding the brake will be hard on your clutch and belt. Make sure to use a fresh plug too to get an accurate reading.
Being that you are riding at higher altitudes you do have a little room for improvement. Hopefully this will help you. The charts I have and have used successfully for my own stuff say this..............And remember THESE ARE APPROXIMATIONS (not gospel) for stock applications. What you should do is jet it for the "middle ground" of your riding altitude, So here is what I can tell you. For every 1000 ft you go above your factory setting (Usually 0 to 1500 ft above sea level) you need to reduce jet size by 2 percent. Remember, this is a percentage of the factory jet size. So by my calculations if you are riding at 5000 ft. that is 3500 ft over the factory setting. So a reduction of 5 or 6 percent would seem safe. So if the factory jet was a 150... minus 6 percent of that (which would be around 8 or 9) that should give a proper jet size of 142 The 140 you have should be ok for you especially since you dont do a lot of wide open riding. Then you can fine tune it with your needle clip. I usually start in the middle position and work up or down from there. Also if you err on the safe side (rich) it will run better at the lower altitudes. Another thing to keep in mind is if you do a lot of cold weather riding you dont want to lean it out as much. The colder it is the more fuel it will need! It may take a few times to get it just right but its worth the effort. These are general starting points but with time and patience in your tuning you will get optimum performance.
Good luck !! Trailboss450

 

Cowboy go with trailboss, he's right on jetting & needles but if it was me I'd go 145 main, 10 pts 150-140 seems like a big jump to me. Also for plug check try to find a long gentle uphill & run it a couple or three times them chop throttle & do plug check. Main jet primarily controls 3/4-full throttle while needle & needle jet contol 1/4-3/4 throttle.

 

Hey Sxr6 this "chop throttle" you refer to is the procedure that Cowboy said?


<< So, just to refresh my memory, to check spark for the main jet, run full throttle, then hit the kill switch while still on the gas, not letting off the gas till the engine dies entirely-this will give proper coloring for the main jet right? >>


Thanks

 

Yes, but you must do it under full load.

 

TEXmud's website sounds interesting. Can some one post or PM the link to me?

Thanks!

Ethernut

 

Cowboy, good to see you are still around!! I was begenning to wonder [img]i/expressions/face-icon-small-wink.gif[/img]

I think that for the most part the jetting advice you got was as good as any. Just keep in mind that any plug testing you do above idle, should be done with at least some load on the engine, and the farther open the throttle, the more load there should be.
About all I have left to add involves cleaning the carbon out of the muffler. Since you had so much, and it took quite a bit of throttle to break it loose, get a soft-face hammer, and bang on the body of the muffler with it, and blast the carbon out again. Tap on it while cold before you start up, and occasionally while running, for as long as it jars loose more carbon. What seems to work best is to hit it as hard as you can without denting the pipe.(sharp blows with a light hammer are preferred over heavy banging with a sledge)