I have a 98 zrt 600 that I have just gotten out for the winter. Last year the sled ran fine. The sled idles fine at 2000 rpm but when I give it throttle it starts to bog out and will occasionally backfire. I have loaded 3 plugs already. I have also noticed that there seems to be more smoke coming out of the exhaust then last year. The one bad thing that I do have is gas from last year. There is probably a gallon or so but I am about to fill it up with some new premium. The only thing I can think of is the gas. If this doesnt cure then what else to look for? Last year I went thru and cleaned the carbs and resynched them; also adjusted chokes.

I guess I have other issues to deal with also. After writing this post I went outside to check up on the sled (i was letting it idle) and my temp light was on and my coolant was boiling like crazy in my tank.

Backfiring means a fouled plug, or a clynder that is not getting spark, or not all the time rather.

Sounds like the thermosat is not opening up and allowing the coolant to flow through the rest of the system.

I would also bet that the old fuel is causing it to run rough. Was the fuel drained from the carbs before it was put up for the summer? That could also be a reason it is running rough. Cleaning the gunk out of the carbs along with some fresh fuel will improve the way it's running.

I will have to look into getting a new t-stat. I just poured 4 gallons or so of new premium fuel and will have to go from there.

all oil injected cats have check valves in the oil lines.these over time can stay open somewhat to the point where during hot summer months and exacerbated by synthetic oil (read thin oil ) you can end up with a lot of it that need`s to burned off from inside your case = fouled plugs .the rest of it i cant help you with M

I should also note that I am using the BR9ES plugs. I forgot about the other plugs (cant remember the number... something YA), I will have to try those.

Originally posted by jruppert@Dec 7 2004, 12:16 AM
I should also note that I am using the BR9ES plugs.* I forgot about the other plugs (cant remember the number... something YA), I will have to try those.
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BR9EYA, I say you just need to rip it once or twice and blow it out good! I have seen this more than once.

Originally posted by fast426@Dec 7 2004, 02:56 PM
BR9EYA, I say you just need to rip it once or twice and blow it out good!* I have seen this more than once.
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If you have gunk in the carbs, will it clean itself after a couple hard runs and fresh gas? My sled seemd to idle at 3000 rpm after it has warmed up....1999 ZRT 800

Originally posted by jpbedard@Dec 7 2004, 11:03 PM
If you have gunk in the carbs, will it clean itself after a couple hard runs and fresh gas?* My sled seemd to idle at 3000 rpm after it has warmed up....1999 ZRT 800
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that is the idle enrichment screw .fatten it up a little and your idle will come right back down.and if you have gunk in the carbs you better clean them .you know what happens when a piece of "gunk" plugs a main jet during a full pull ? $$$$$$$ come flying out of your wallet

Originally posted by jruppert@Dec 6 2004, 03:56 PM
I guess I have other issues to deal with also.* After writing this post I went outside to check up on the sled (i was letting it idle) and my temp light was on and my coolant was boiling like crazy in my tank.
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let a LC sled idle too long and that can happen

Id have to agree,,, pull and clean the carbs real good,,, you probably should have gotten rid of the old fuel before adding the new,,, your octane on that old fuel is getting pretty low by now,,, I pull out the extra and add it to the wifes car,,, add new fresh fuel to the sleds every winter.

as for fouling,,, heavy oil on the plugs??? you may want to check your oil pump adjustment,,,,

Originally posted by jpbedard@Dec 7 2004, 06:03 PM

If you have gunk in the carbs, will it clean itself after a couple hard runs and fresh gas?* My sled seemd to idle at 3000 rpm after it has warmed up....1999 ZRT 800
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Do not count on gunked up carbs cleaning themselves up. One hard run with dirty carbs can cost you a piston and cylinder, but you'll find out which carb was dirty.

The symtoms you describe can also be caused by the infamous Cat throttle safety switch. Bypass the throttle safety switch at the connector at the base of the handlebars and see if it makes a difference. The fix for that problem is about a buck for new plastic washers for the throttle pivot pin.

Sounds like I need to pull them then.. I started it up today and my 3 br9es plugs loaded up pretty quick. at this point i pulled them and replaced with br9eya and they loaded within 10 seconds then wouldnt even idle. :(

What I dont understand is how this sled ran good during the summer. I periodically started it and even ran it across the lawn a couple times and it never hesitated or caused any fouling.

I'm having the exact same problem with mine (98 EXT 600 Triple) now. Fouling up plugs after approx 15 min ride. Ran fine all summer, and yep, I ran her on the lawn too. Idles like crap, but like you I took her out of the garage with old gas. I haven't had a chance to drain it but thats my next project. If you figure out a solution to this problem, other than a gas problem, please post it.

Sounds like the pilot jet is plugged, if so the main may have restriction, what happens is the cyclinder dies at idle from lack of fuel and when you advance the thro and gets fuel causing backfiring. Is it fuel fouling the plugs or oil fouling. The 98 ZRT/EXT triples mix the oil at the fuel pump not in the manifolds and leaving it all summer with fuel can leave a gummy mess.
Any restriction in the main jet can cause a burn down, there is only about .0015 difference between a 350 and a 360 main jet as an example.

When I pulled the plugs they were full of oil and were wet so I assume this is an oil foul. I havent had a chance to pull anything apart because its been cold and I dont have a garage. I do know that last year when I went thru the carbs I found one of my choke cables had slipped off the hook prong at the plastic lever. Maybe this is where I am at now. Either way, if I clean the chokes and get it to run I may ride it to my dads house and take it apart in his garage. 'fingers crossed'

when you get it there, check to make sure your oil pump is adjusted properly,,,, I readjusted mine as I was fouling plugs like crazy and that was the ticket,,,, didnt foul 1 plug last year on that machine

I adjusted the oil pump according to the arctic cat shop manual. should i do it differently. i dont remember exactly how i did it except that i had to synch the carbs and then adjust the oil pump to where the lines matched up. isnt this correct or is there a better way?

thats the same way I do mine,,,, not saying its perfect, but it has always worked for me

My guess at this point would be stuck choke(s). Chokes are staying open and flooding out the motor, fouling the plugs, making lots of smoke, etc.

never thought of sticking chokes,,, if one is sticking, your fuel economy should be down quite a bit also,,,,

I had a chance to look at the chokes today and they seem to have been off by quite a bit. I am not sure how you guys adjust them but what I did was take a pencil, slide it down in the hole and mark a line where it meets the top of the carb. Then take the cable and adjust it according to that mark. They were off by 3 dime thicknesses. I dont know if this is an accurate way but if you guess have a better way please share. Anyway, I started it up and it ran good for about 15 seconds after that it stalled and wouldnt start. So I was looking around and I think I found my problem. My freaken fuel line from the valve to the tank is full of ice! :bash: So now I defenitely need to take it do my dads and put it in the garage with a heater. This would explain why it ran good in the summer! :dazed:

I also noticed my gas cap is all frozen and ice underneath. I'm wondering if it has a crack in it and allowing water to get inside. Anyone ever seen this happen before?

I normally put some deicer in every other tank,,, good insurance,,,, I did have my 900 suck ice into the airbox and then into the carbs,,, that was fun getting it home, but once home, I was able to thaw it all out. frozen fuel in your line,and behind your gas cap,,, time to replace the cap,,, it is evidently letting way to much in,,,,,

Do you think I will need to pull the tank and drain it? I have a Cat repair manual but havent had a chance to look for it. I assume it shows how to do this. Do I need to pull the seat for this procedure?

Also, do you think the way I adjusted the chokes is ideal. Lengthening them out to the length of the hole was the only way I thought.

bump..

add a little deicer, then siphon it out with a kerosene pump into a jug,,, then put it right in your car or truck,,,then put new in your sled and your set. Your car will still run fine with that gas,,, you sled motor is a little more finicky (sp)

My dad and I removed all the water and ended up getting almost a whole 2 liter of water. This is crazy! The only thing I can think of is someone is playing a dirty trick on me. I've had a cover on the sled all summer and the only time I had the cover off was when it was sitting by the road with a 'for sale' sign.

Originally posted by snofrog@Dec 6 2004, 11:28 PM
all oil injected cats have check valves in the oil lines.these over time can stay open somewhat to the point where during hot summer months and exacerbated by synthetic oil (read thin oil ) you can end up with a lot of it that need`s to burned off from inside your case = fouled plugs .the rest of it i cant help you with M
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I agree... oil check valves could be problematic... stuck open... their 20 bucks each...is it always the same plug fouling up?

If it smokes like crazy and then goes away, then you let it sit for a while, restart and and it smokes heavy again, then oil check valve (or both) could be defective...