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Discussion Starter · #1 ·
I just picked up a 98 FormulaIII 600 with 2200 miles on it. I ran it at the guys house, it ran great and had tons of power. When I got home I decided to take it out on the lake and blow it out. I got mabye a mile into it and it just started bogging really bad as if it were only running on 1 cylinder. I limped it home and it died in the driveway. I pulled the plugs to find not only did it have BR7ES plugs in it but the middle plug was extremely dry and grayish while the other 2 were full of carbon and extremely wet. Should I be worried here or will it be fine with the proper plugs in it.
Thanks
John
 

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I just picked up a 98 FormulaIII 600 with 2200 miles on it. I ran it at the guys house, it ran great and had tons of power. When I got home I decided to take it out on the lake and blow it out. I got mabye a mile into it and it just started bogging really bad as if it were only running on 1 cylinder. I limped it home and it died in the driveway. I pulled the plugs to find not only did it have BR7ES plugs in it but the middle plug was extremely dry and grayish while the other 2 were full of carbon and extremely wet. Should I be worried here or will it be fine with the proper plugs in it.
Thanks
John[/b]
I would do a compression test , sounds like you might of burned up the middle cyclinder. Those sleds were knowen for crank bearing going out too. Did the pervious owner have the update done?
Middle cylinder was running lean from your discription of the plugs. Pull the plugs and roll the center cyl up to top of the stroke and look down in it to see if theres a hole in the pistion, any type of melting on the plug tip or metal pcs ?.Could be a clogged carb to making it run lean , check for air leaks(boots).As for the plugs even if they where the wrong ones but were firing I would be worried about the colors of them , the white/gray one over the black ones. the lighter the color the hotter(lean cond) , black not so bad at least your getting lube to the cylinder.

It stinks after buying a used sled and it goes south as soon as you ride it , you never know :bash:

mutt
 

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Discussion Starter · #3 ·
thanks for the info, I checked and the piston is fine. I put new plugs in it and let it Idle and revved it and it seems fine, I will take it back out later to see. I called the guy I bought it from and just asked him when he changed the plugs last (didnt metion my problem for fear of a lie) and he said he hasnt run the sled in 3 winters so he never changed the plugs. I dont know if this means anything or not.
Thanks again
John
 

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Hopefully I'm not telling you this too late but if the sled sat for 3 years, you need to take your carbs apart and give them a thorough cleaning. Besides old gas in there possibly, there could be varnish build up from old bad gas that'll clog your jets and passages in the carbs. That could result in a lean burn down as Snowmutt described.

Jeff
 

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I would clean your carbs, drain the old gas & put new gas in it. Check your carb boots for holes or cracks. If it runs good after that then do another run & recheck your plugs. :D
 

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FYI concerning Canadian refined gas and US RFG (Re Formulated Gas). Because these fuels are Oxygenated blend containing alcohols and MMT, they cannot be kept in supplies of less than 5 gallons for longer than 30 days. Research has found that certain microbial growth will prevail (the same green bacteria that blocks Mains & pilot jets). Stabilizers help but will not put oxygen back in these reformulated fuel after they have depleted. I have used catalyst tabs with good success as the metallurgical properties of said tabs create a very low voltage in the fuel reservoir hence killing bacteria.

Enjoy !!!
 

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Discussion Starter · #7 ·
I went throught the carbs and drained the fuel and then headed out to the lake. Within 1 minute the problem was back. This time it was the third cylinder that was lean, so I changed that plug and it ran like crazy for the hour I was out there. The only thing that was different from changing the plugs at home versus changing at the lake was I did not let it idle and warm up, could the idle be causing this?
Thanks to all
John
 

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I went throught the carbs and drained the fuel and then headed out to the lake. Within 1 minute the problem was back. This time it was the third cylinder that was lean, so I changed that plug and it ran like crazy for the hour I was out there. The only thing that was different from changing the plugs at home versus changing at the lake was I did not let it idle and warm up, could the idle be causing this?
Thanks to all
John[/b]
Sounds like carbs are dirty,check your floats,I bought my sled from a guy in boston mass he told me there was nothing wrong with with mxz i ran it at his house ran fine then when i got home i drove it for 3 hours and it blew, took sled to skidoo and they told me that he packed barrings with grease, honed cylinder reringed it, droped the pto side main jet to 300 to keep it runing long enough for me to test ride, had to rebuild the hole engine, the guy told me he was a man of his words, the biggest lier east of the mississippi. 1200.00 mistake and 500.00in gas, do a compression test, sounds like your carbs. Crash dummy
 

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Discussion Starter · #9 ·
Well I went out today choked it, jumped right on and headed to the lake. While riding turned the choke off and it ripped the whole time. So my question again is, could the idle be to low and fouling the plugs or are there bigger issues. Also I failed to mention that the temp has been -5 to 5 degrees, would this have anything to do with it.
Thanks
John
 

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It almost sounds like you are not letting your sled warm up. Most of the time it won't idle worth a crap when it is cold. I will give it a little gas untill it will idle on its own (2-3min). I like to let it run for about 5min when it has sat for a while. What is your rpms at idle when your engine is warm?
 

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Discussion Starter · #11 ·
When I let it warm up is when I have all the problems, by just hopping on and going it runs great.
It idles at about 1500rpm's.
Thanks
John
 

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Discussion Starter · #12 ·
On a different note, what would be the best track for this sled. I ride mostly groomed trails and lakes, very rarely anything to deep.
Thanks
John
 
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