98 formula z stator testing

[plumcrazycuda5]

Hello, I have a 1998 formula z 670, i keep fouling plugs and have checked or replaced, coil, plug wires and boots, carbs are clean and set to factory specs, all factory jetting and needles, just put in new exhaust valves as old ones had stripped threads for some reason. I would like to check my stator, does anyone have specs and instructions on checking it? I would really appreciate it. Thanks. It seems like im getting weak spark at low rpm and its intermittent, i can go through 3 plugs within 20kms then all of a sudden go for 100kms and not burn one.

 

[Barker]

I think, that the H.A.C. opperates by applying vaccum to the float bowls to lean out the mixture as the temp or altitude goes up. If it fails, it fails to full rich. 98 Summit X 670 uses the first generation DPM and it definately fails rich. That could be your issue. If your only issue is at idle, you can simply lean out the idle mixture by backing out the pilot air screw a 1/4 turn at a time. If a full turn doesn't solve the problem you probably need a different sized pilot jet.
Does this sled have a primer or "choke"? A "choke" on a Mikuni carb is not really a choke. It's really a starter system that allows fuel to flow freely into the crankcase. When a Mikuni "choke" gets out of adjustment or stuck it will allow fuel to flow too freely and foul plugs at idle. How long have you had this sled? Has the problem just happened up suddenly? Haven't really heard of a sator fouling plugs to often.

 

[Barker]

Download Factory Service Manuals - 1998 SkiDoo Snowmobiles
this might be well worth it of $13 or what ever they are

 

[plumcrazycuda5]

Thanks for the input, my sled just has a primer and i have had the sled for 4 years now and have been chasing this problem since i bought it. I bought it with a blown motor and had the motor rebuilt and previous owner didnt mention anything about fouling plugs. My sled doesnt have Dpm or anything like that. They just seem to foul at low rpms, if i stop and let it idle for a couple minutes then take off it will foul a plug. 90 percent of the time it is clutch side plug. I brought it home and am going to put new pilot jets, main jets and needles in and see if that makes any difference. Sled doesnt idle very good either, my idle screws are just about all the way in and when cold it idles around 2500 but after 30 seconds or so it slowly dies down and would stall if i let it. Thanks for the input.

 

[plumcrazycuda5]

I should also mention that it just rolled over to 10000kms so i think its possible that the main jets and needles maybe wore and letting fuel by when it shoudnt be? Is it possible for the jets to wash out a bit? I was going to back my mixture screws off a 1/4 turn but never did. Thanks for the info and i will keep this updated. It's a frustrating problem.

 

[Barker]

Deffenatly sounds like its running rich at idle! I'm assumeing your plugs are black and maybe wet when you pull them out! The should be looking tan in color. Try backing that pilot air screw see what happens keep checking the plugs if they start turning white your to much on the lean side, see what jets you have in there they ussaly come from factory a little on the fat side. Let us know!

 

[plumcrazycuda5]

Yep, they are black and wet when i pull them, it has factory jets, i went through them quite a few times! Lol was just a little nervous to lean out my mixture screws but i will turn them out 1/4 turn and check them. Thank you

 

[plumcrazycuda5]

Sorry for all the questions but does anyone know if these sleds use a exhaust doughnut off the y pipe? Mine didnt have one and i can't get it to seal but i think its too tight to put a doughnut in.

 

[Barker]

Looks like they just use a antisieze dosent show a doughnut!

 

[Barker]

I think the stock jets are supose to be mag side 290 pto side 310 pilot jet 60. Is this what you got for sure? also do you have a automatic oiler? This could be the problem too? If not set up right you say the engine was a rebuild some people get in there minds that you need more oil on a new engine as increasing the rate or putting oil in the first tank of fuel or two. This is not a good idea it changed your fuel mixture.

 

[plumcrazycuda5]

Thank you very much, i believe that is what my main jets are but not sure about the pilots, i havnt pulled the carbs since last year and i just remember finding the factory jet sizes and they matched. I will be pulling my carbs in the next few days here if i get a chance. Yes it's oil injected and i checked that over too, its set right, i think that was one of the first things i checked. I did mix my first tank after the rebuild but have 1200kms since it was rebuilt. Im going to pick up new main jets and needles and new pilot jets, hopefully that will solve it. Thanks again for the input!

 

[Barker]

Did you get it working good? What did ya find?

 

[plumcrazycuda5]

Hello, i pulled carbs apart again to make sure they were clean, put them back together, i dropped my needles one notch(raised the clip) and backed out my mixture screws another half a turn but im not sure how many turns out they are supposed to be? Ive found anywhere from 1 turn to 2.5 turns out. Right now they are out 2 turns, my idle screws are all the way in and it idles at 1500rpm, but i let it idle for about 10 minutes and it didnt foul a plug and rpm stayed at 1500. I think i might go 2.5 turns out on mixture screws and see if it idles smoother and higher. I cant get to the screws with the carbs on. I havnt had a chance to drive it yet but when i do i will keep checking the plugs. Im nervous about leaning it out too much.

 

[plumcrazycuda5]

Also i changed the rotary valve when i got the motor back from getting rebuilt and im 99% sure i put it on exactly how the old one was. If it was a notch off could that cause these problems?

 

[plumcrazycuda5]

I almost forgot! I pulled out my exhaust valves to clean them and the threads on the end of both valves were stripped right off? I put new valves in and thought that was my problem but i took it out once after and went through 3 plugs in about 15kms then didnt foul another one for the rest of the ride which was another 30kms but i drove it hard. I havnt drove it since i changed the mixture screws and dropped my needles though.

 

[plumcrazycuda5]

Sorry for all the posts, i have #20 pilot jets and you said i should have #60. I just realized that, i dont know why i am running rich at low rpms then. This sled is starting to really frustrate me! Lol but other then this its an awesome sled so i would like to get it running right.

 

[plumcrazycuda5]

I just found that my oil pump is not returning all the way back, stays open about 1/8 of an inch. Can i just put a weak spring on it?

 

[plumcrazycuda5]

Well pulled carbs again and put the right pilot jets in. It had 20's and supposed to have 60's so now it seems to be flooding really bad so im trying to find some new jet needles and needle jets. Im pretty sure they are wore out as the sled has 10000kms. My needles are 7EDY1-3 and are discontinued so i will have to do some calling around and hopefully someone still has some in stock.

 

[plumcrazycuda5]

Another update: Winners cirle in ontario special orders the needles that are now discontinued. I have 2 needles and 2 needle jets on the way. I know they shoudnt cause any idle problems but the one needle even looks smaller then the other and might be bent a bit so i'll give it a shot.

 

[Barker]

Ya let us know if that works, did you find why the oil pump wasn't returning? Cable adjustment? Spring should bring it back,
ps sorry for the late post!