Wolverine jetting help

[Jakeonawolv]

Hi folks, here’s an odd one for ya:
01 wolverine, stock except for a high comp piston (I forget the ratio, I bought the quad from a buddy as-is) and a slip on exhaust. Anyway, after the rebuild it runs really rich with the stock 141.3 main jet in it. Before the rebuild, the stock jet size ran fantastic. After though, it’s so rich under throttle that it barely runs, and won’t get to full throttle.

I did put in one size up pilot (45?) to help it start a little better, and that reallly helped the cold start and idle (it used to die constantly at idle, and be really hard to start cold). I also replaced the diaphragm, thinking that might be it... After many hours of fiddling, I’ve found i can get a 132.5 main to work pretty well (just a HAIR rich), no stumbles.Needle on 3rd clip (middle)

something feels off to me about that though. It just isn’t right having to run such a small main!!

I live at 4700’ and regularly ride to 8,000 or so (eastern Idaho), so I expected to go down a couple jet sizes, but not almost 10 points...

help!!! Any other ideas?

 

[tomcat]

Maybe drop the throttle valve needle all the way down to lean it out.

 

[Jakeonawolv]

Well like I said I’ve got it working pretty well on the 132.5 main, no stumbles or flat spots, and it winds all the way through the RPM’s, plug comes back white on top with a dark line down deep on the porcelain.
I’ve moved the needle to 2nd and 4th positions and it runs worse on either of those. What else could be wrong that would make it so my jet needs to be so small?

 

[tomcat]

Well. if you're spark plug is that color, you're no longer running rich. Sounds like like its close to where it needs to be. Oh, is your air filter setup good? Air filter setup also has a lot of effect on the way it runs too.

 

[Jakeonawolv]

That’s what I was thinking. Yeah, air filter is good. There stock one was on it and pretty clean when I first found the right jet size. Nothing really changed after I put a Uni filter with yamalube filter oil on it. The slip on exhaust I have has melted a hole in the side of the Airbox too so I figure it’s being fed a little more air.
Idk, it just feels really weird to me to have to run 4 jet sizes lower.. I could see one or two for the elevation, but 4?? And after a bunch of years at this elevation with stock jets?
Could the valves or timing have something to do with that? What else could I check?

 

[tomcat]

No, you're not off on timing. if timing was off, you would have different symptoms, like hard starting or a miss or popping. Try patching the hole in the air box, you're getting extra air through there. Once you do that, try it out. Oh, you might have to adjust the mixture screw to bring back a good mixture. First, patch the hole then try it. Then do the mixture screw at idle. Hope this helps.

 

[Jakeonawolv]

Wouldn’t the hole in the Airbox make it lean though? I’m struggling because it’s too rich, and I have to jet down for it... that’s what’s confusing to me

 

[tomcat]

Yep, that's why i said you would have to adjust carb after patching hole in your air box. With Uni filter you're already getting extra air. You are way above sea level than i'm in here in ms. You're way up there in the air (altitude). I think when you changed the piston, that's when you needed to rejet and you did. Sounds like it is pretty close to where it needs to be. like I said earlier. So what is the bore size of the piston? Did you just hone out the cylinder for the rebuild or did you bore it for s bigger piston?

 

[Jakeonawolv]

Ahhh yeah I see. I bought it from a buddy, and he wasn’t super clear, knowing his style I’m pretty sure he just threw a new piston in it. I know he did it to help solve oil consumption issues. I’m not sure whether he honed it much, but I know he didn’t bore it at all.
So same bore, but I think he used the 10.25:1 compression piston. Maybe 10.5?

Idk, it doesn’t burn oil anymore and it was 1600$ with a snow plow, so the tuning I’ve had to do still feels like a steal haha

 

[tomcat]

Hi, just went back through and read your original post, here's what i would do if it were mine. I would patch the air filter box hole first then put the original jet back in and drop the the throttle valve needle to the very bottom. put the clip on the very first groove at the top of the needle. Then see how it runs. i've seen this before and by dropping the needle to the bottom it will lean it out, if it runs like crap after that, it means that the needle and spray nozzle not the jet is worn out. Sounds like that is whats wrong with it. Hope i'm not confusing you. Finally by going to smaller jet you are compensating for the wear on the needle and spray nozzle.

 

[Jakeonawolv]

Interesting!! I’ve not heard of that! Can the nozzle be replaced? Or is it fixed in the carb? Obviously I can get a needle, that’s easy enough.

 

[Jakeonawolv]

I snagged a needle and a nozzle (they’re cheap, it’s a 20 year old quad... what the heck) - I’ll put those in when they show up and see if that does anything to help.

 

[tomcat]

That'll work, should be able to go back to stock main jet. Wow that old, yep that needle has slid up & down a bunch of times. Since you will have a new needle, try setting it in the middle with the stock jet, then go from there. I used to work as a mechanic back in the early 90's at our local Honda dealer. I know a few tricks here and there. Lol Hope this helps you out. Good Luck!

 

[Jakeonawolv]

Thanks!! Yeah I’ll give er a go and let ya know either way!

 

[Jakeonawolv]

I did finally get the emulsion tube (needle jet) in, along with a new needle. The jet itself is actually stainless I think, or at least nickel plated, so it hadnt worn too bad. It was worn though. After replacing them both, I still have to run the 132.5 main. though it does run noticeably cleaner with this jet. After all this, I figure this must be what the engine wants, since it’s running good now with this jet size.
Thanks a ton for your help in trying different things!

 

[Jakeonawolv]

Actually, I went and rode it more this afternoon to plow snow, and after it got hot it started showing signs of being too rich again. Plug chop yielded about 1/2 the porcelain white, 1/2 black. I’m still getting a dang sputter under WOT, albeit much less severe than before. The fact that it sputters more when it’s fully warm also tells me it’s too rich (right?!)
Should I step down to the 130?! That seems crazy!! From a stock 141.3 to a 130?! What else could it be?! This thing is driving me nuts.
I’m also using mikuni branded jets, so they should be correctly sized

 

[tomcat]

Hey, Stay with the same jet, just move your clip up one notch on the needle so the needle will go further into the carb and lean it out. Also on the sputtering at WOT, check and made sure that the rubber intake boot is tight and in good shape, like no holes or cracks. Yea, i know that these 4-wheelers can be a pain. Just because I'm an old motorcycle-atv mechanic, i have had plenty of head scratchers working on these things. i've seen some weird stuff with these engines. Lol. I've have had a few 4-wheelers with bad spark plug caps cause sputtering as well as the sparkplugs wire leaking fire where you couldn't see it. Don't lose faith. You'll get it.

 

[Jakeonawolv]

I’ll give that a try, I think I’ve tried it before though and if I remember right it makes it a little boggy in the mid range. Worth a shot though haha. I might also try throwing the original slide back in just for grins (though I’m pretty sure the diaphragm on that one is shot, even if I can’t find )

I’d have a hard time believing it’s the plug wire/cap - this one is in really good shape still... I’ll probably snag some new plugs (again) anyway just to check though.

thanks for all your help!

 

[tomcat]

Oh, the plug wire leaking and spark plug cap was just to be examples of weird stuff I've seen, not for you to try. Your problem is in the carbueration. Is the carb really clean ?

 

[Jakeonawolv]

Oh! Lol, gotcha. Yeah carb is pretty dang clean. I’ve blown out as many of the bits as I can with carb cleaner and got good flow through. I was thinking about spraying some down the vent tube maybe to clean that out, and through some of the other orifices as I can find them. The pilot is a new 45 that I’ve put in there, so it’s clean. I’ve drained the tank through the petcock on “on” and “reserve” and both have good flow. I cleaned the screen over the needle once, it was fine. The float has been set and checked at like 12.5mm or so, which is within range. I’ve had the side cover on the carb off looking at the little pumper diaphragm, which I’m told is for deceleration enrichment only...

I’m at a loss!! I’ll hopefully get totoying with the needle this week. I’m also going to try running it without theseat, and without the filter, and maybe without the air box lid to see if that makes any difference.
Maybe there’s a bees nest up the exhaust?!