jlc84cam350

okay baught this sled last year road it for 3-4 rides, i have always had the trouble of not having it run always on all 3, just by the way it soundsand feels i can telll, even though this is my first sledd... On a cold start no way it would run on all 3, after 5 minutes of warm up, i would take off and after about a minute all 3 cylinders would comme on, it kinda backfired 4-5 times when i was giving it slowly and would catch on all 3, for as long as you would keep the rpm's over 4000 it would be good but if you went under and ran it a few minutes going on in a slow trail etc it would fall back on 2 cylinders.

What could be causing this?
I fired it up for the first time this season last week and did a bit of maintnence on the suspension etc, ichecked out the engine, i do know this on one cylinder (oposite side of pullstart) this cylinder has less spark then the other 2, its actually very hard to see the spark, compression is 125 on all cylinders cold without throttle, and have tried new spark plugs with no change on spark strength.

I definetly need this fixed ford the new season!

Any help would be apreciated thanks

Kemo

I'm always a fan to start with the basics: Is it getting sufficient fuel?

If it is an electrical issue, try swapping around coils, as you may have a faulty coil.

Do you have a multimeter? You should pull some measurements regarding the primary and secondary coil resistance values. My 600 twin's primary is supposed to be .2 ohms +/-20% at room temperature, secondary is supposed to be at 4.9k +/-20% at room temperature. Also, you may want to test the spark plug cap for resistance. As stated before mine in particular is at 5k ohm, i would imagine yours would be relatively close to that too.

Yamadad might have a service manual to share resources with you regarding what YOUR specs should be. food for thought!

jlc84cam350

okay i am going to try cleaning carbs today, my first attempt ona snowmobile i have torn carbs on 4wheelers before but nothing with multi-carbs, im a bit afraid of getting them all out of wack but hopefully i wont lol, i will try an firgure out how to syncronise them on the web also, at least i will know thats the fuel part is good, i still doubt its the fuell all 3 sparks are a nice brown color exept for the one with weak spark wich is slightly darker wich makes sence since its probably not burning all fue hence the poping at low rpm's and when coldl.

I am not sure what you mean by primary/secondary coil

Kemo

There are good "how to's" regarding carb rebuilds in the How To section.

Regarding the coil,this is an example. As your coils MAY be different, just use this as a reference, not for specifications.

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jlc84cam350

Okay i took off all 3 carbs and started cleanng them, they were actually very clean, the previous owner said that maintenance had been done not too long before i baught, they all seem well syncronized also... BUT i did find something strange and am guessing this might not be helping my problems,

2 of the carbs have 143.5 jets I think they are the main jets, and one of them has a 145, the adjustable screw 2 of the carbs with 143.5 where at 1 /1/2 turns out while the other was at almost 2. What do you guys think???? I am guessing all 3 carbs should be set up the same right?

I should also mention that i have a aftermarket can on this machine.

yamadad4

staggered jetting is common on the triples. it allows more fuel to whichever cylinder may need the additional. your correct that the fuel screws should have been a little closer.

aftermarket can wouldnt make that much difference.

i would suggest replacing the plug cap on the questionable cylinder or at the least removing the existing one and clipping about 1/4" off the wire and reinstalling it. you may be pleasantly surprised with the outcome of a $5 investment.

jlc84cam350

i double checked my compression today, i hadent checked it since last year, the cylinder i was saying that didnt run well, only has 100psi, the other 2 are still at 125. Is this my problem?

jlc84cam350

i also found the the TORS sensor i think its called? was not plugged

yamadad4

i wouldnt be overly concerned about comp numbers until you get it to fire. too many variables in the equation.

reread my last post as i was adding info about the time you were posting.

jlc84cam350

i got fire on all 3 cylinders now, one of the plug had bend clip and wasnt making good contact, i have good fire on all 3 right now but it still is not running on this cylinder, when i take off the spark plug after i have run it a few minutes, a puff of smoke comme out the spark plug hole for a few seconds, spark plug is completely black and wet (the one with bad compression)

yamadad4

couple things to consider based on the information given.

one would be carbs, the other would be the cap or the wire.

based on your earlier description where it appeared the cylinder would fire over a certain rpm would lead me to the carbs, keying on that side in particular, especially the pilot circuit and the air jet. even though you mentioned the carbs appeared clean, it doesnt take much to replug these jets. seen it happen over and over, especially with crap fuel. over 4000 r's your overriding the pilot curcuit and relying on the main jets and the needles.

if you had a dead cylinder, it would be dead regardless of rpms. if yours is lighting sporadically, its the carb or the plug cap/wire. not saying that cylinder isnt dead, your description leads me elsewhere. hard to tell, your there and i am not.

if it was me, i would pull the carbs and double check them. thats free. once you dive into the engine, you will be buying parts like gaskets and such. easier(and cheaper) to rule out
a few items before diving in.

now if something in the cylinder caused the ground electrode on the spark plug to close the gap on itself, that would be a different story. assuming i read your last post correctly.

jlc84cam350

sorry what i meant on the other message was not the spark plug that had a bad clip, what i meant was the rubber plug that goes on the spark plug lol my bad.

I cleanedboth the pilots and main jets inside all 3 carbs but i guess i could do it again.

As for if it catches at 4000 rpm i could not say right now but it did last year after it was well warmed up with a few minutes of riding, i have not taken it out in the trails we don't have any snow yet.

But i do know no matter what right now at idle or any speed running with the the rear suspension jacked, that cylinder will not fire up, i took off the rubber plug and no change in sound, if i put this plug on another cylinder say center cylinder it will run that cylinder, thats why i no longer think my problem is electrical, its either a fuel problem or compression problem (in my opinnion)

sorry if my descriptions arent great i am doing the best i can!

jlc84cam350

i just had a wacky idea... i don't know if i could do this but would it be possible that i could try and switch carbs with another cylinder? that way if its still the same cylinder not working i will now definetly now that my problem is not the carb...

yamadad4

do not unrack those carbs! not worth the effort.

re-think your cleaning efforts. even though the pilot jet was deemed clean, could there be a blockage in its associated passages?

in other words, if you were to spray either some aerosol spray or compressed air into the portion where the pilot jet sits, does it exit? it should exit out the airbox side of the carb through the air jet or if the fuel screw is out, it will exit there as well. this is true with all the circuits in the carb. if it goes in, it must come out somewhere. you may even consider confirming operation and sealing of the choke plunger on that carb. just because the jets are clean doesnt mean the circuit is clean.

i would go to the extent of removing the reed cage once the carbs are off and take a look at the piston. you can also inspect the exhaust side as well after removing the manifold and pipe. a wash light may even get you a view of the top of the piston. this only after confirming carbs are clean.

jlc84cam350

i recleaned all jets and passages everything checks out, i can easily see day light threw the holes where the jets are when i place a light inside, and yess the carb cleaner exits very well. As for the choke i checked the mecanism it works well and removed the top cover the plunger works great, i don't know about checking the seal tho... the plunger is the brass (goldenish) piece that slideds right?

If i remove the manifold will i have to replace the gasket, i can't see much threw the reed valve hole.

jlc84cam350

forgot to mention that their is a bit of what i think is gasoline in the botom of the crank case from what i can see from the reed valve hole, is this bad???

yamadad4

most times the intake gaskets will be reusable. be careful when removing and you should be good to go. same on the exhaust side, however you can always add some high temp sealant on the exhaust gaskets.

i would be surprised if you could see fuel pooling in the cylinder looking through the reeds. more than likely collecting fuel in the reed cage.

you had spray cleaner exiting both the air jet and the fuel screw?

jlc84cam350

yess its the small adjustable screw i too it out cleaned it and also sprayed carb cleaner down the hole where it treads, did the same with the pilot jet, as stated i can see light threw the hole and the carb cleaner flows right threw the other side

I took the reed valve off and it looks fine, no chips or broken bits. i had already too the reed off when i mentioned i could see gas in the bottom of the crank case i just didnt think of using the word intake port lol sorry

yamadad4

you lost me in that somewhere so lets back up a little.

on the airbox side of the carbs at about the 6:30 or 7:00 o'clock position there is a small brass jet. this is the air jet. its not adjustable and usually a pain to remove, so dont fight it. with the fuel screw installed(the one under the carb thats adjustable), spray or air through the pilot circuit should exit this jet and vise versa.

now back to the fuel screws. have you accounted for the washer and the o ring on these? should be screw, spring, washer then the o ring from out to in. missing the o ring can create your problem as can any of the other related parts.

lets check the obvious first and work from there. in theory, if the cylinder was dead, it wouldnt have any measurable compression, let alone 100 lbs. although i have seen some stuck rings offer false readings.

jlc84cam350

okay i checked it out and found that air jet you were talking about, had no clue that was a jet, anyway the carb cleaner did flow very well from pilot circuit to that jet and it actually was easy to get that air jet out wasnt seased or nothing...

Also i took back the adjuster screw off and all parts were their except the order was screw/washer/spring/oring and not screw/spring/washer/oring.

Should i put it back together correct order and try her out?