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Discussion Starter · #1 ·
For those that don't know, i have BMP heads, pipe mode, fuel reducer @41 psi wot, and d and d y-pipe. I had to take the exhaust off today and for the heck of it i looked down the y-pipe to inspect the pistons. I wish i hadn't. The mag piston was scuffed, the top feels like it was sand-blasted, and the back of the cylinder i can see a couple of spots that looks like i had a piece of something that cut a groove. The pto piston is perfect, as is the cylinder. So what the heck happened? I did a compression check to see if i have enough life to run the remainder of the season. I have 135 mag, 145 pto. Not as bad as i thought it would be. My guess is something happened to the fuel delivery on the bad side at some point. My first thought was too lean with the restrictor, but i would figure both sides would be buggered up it that was the case.

A little background, my very first run of the year with the mods, i was running around my apartment building up north, and made about 5 laps around, and it started bogging and would hardly run, wot, idle, everything. I pulled plugs, one was wet, the other normal. Couldn't figure it out. I would restart, and it would idle normal. Hit the gas a little and start to die. The plugs that were in it were brand new. Changed them, and it seemed to run normal. Ran around the house a couple more times, seemed normal. Got ready to go down the trail, and it started to bog again, then cleared up, and haven't had an issue since.

Before that, my first start of the season, i couldn't get the sled to run for a crap, was super rich and wouldn't rev. I ended up finding that i still had the blue shop towels in the intakes plugging them off, i had forgot about it and tried numerous times to rev the motor on the stand before hand trying to figure it out.

So with that being said, i'm not sure what happened, maybe i got a piece of crud in one of the injectors? What would effect just one side, and not the other? I had planned on pulling the cylinders off and getting them ported and honed during the summer, guess i don't have a choice now. Plan on running it the rest of the season, hopefully she makes it. What are your thoughts on this guys...............???
 

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I wouldn't run it if I was you. You caught it just in time, maybe you can save the cyl. If it goes down when you are running it the rest of the motor can go with it, crank etc, $$$$$$$. Right now is your cheapest fix. Sounds like it was leaned out or a cold seize, end result ring stuck or broke. Again now is the time to fix. 41 psi for fuel isn't alot with the y-pipe and mods on, should be closer to 44. What fuel are you running? hope it is in the 90's, 87 isn't safe with those mods. good luck !
 

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I am running a d&d light pipe and y-pipe,4 bullseyes,bmp headmod and bmp fuel reducer at 41-42 psi at wot,no problems yet at 600+ miles this year on 03 f7
 

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I've seen lots running 87 with those mods. Long hard pull (WOT) stop and pull your plugs, the inside is white not brown. 87 isn't safe with fuel reducers and those mods. They haul A$$ but on the edge. Good to hear your running 93.
 

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Discussion Starter · #8 ·
Well, i ran it today, and blew it up today. I think the ring broke on that side. Great. Guess it didn't really surprise me much. So now i'm down to my Jag for the remainder of the season. I guess i'm scared to put the money into it and fix it and have this problem again. I don't know what made that cylinder go down. I did take the 320 jet out of my restrictor before the ride today. And i noticed that my fuel pressure according to the BMP guage was pretty much the same. About 44 at idle, and 41-42 at WOT. So i don't know if that is the problem? Is it common for one side to go down on these and the other side is perfect? Same gas? What are the chances that i have a bad injector on that side. Is that known to happen. Maybe i should send in my computer for analysis? What should i do?
 

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Discussion Starter · #10 ·
How do you say my mods blew it up, i pulled the jet out with the same psi afterwards??
When i do fix it, what would be different for next time then?
 

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You took the jet out and the pressure stayed the same, what does that tell you ?
If your sled is crisp and on the edge or close to it and you add heads, pipe, f/r and y-pipe, yes the motor will go booooooooom.
Now if you have a dog, really slow fat boggy sled(talking motor not clutching) then add f/r and pipes to clean it up, make it crisp. My guess is you had a really good working 7 and you found the lean spot by adding what you did. Probably the y-pipe was the last thing you did and finished it off, the motor that is. Hope it didn't go down hard and punch the rod through the cases.
 

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Discussion Starter · #12 ·
so what should i do when i fix it to keep this from happening again. Get BMP's regulator and turn up the psi, or a boondocker? I just don't want it to happen again. I'll even run it rich till broken in, then take it to a dyno if i have to.
 

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Discussion Starter · #13 ·
<div class='quotetop'>QUOTE (Smokin @ Feb 14 2007, 08:20 AM) <{POST_SNAPBACK}></div>
You took the jet out and the pressure stayed the same, what does that tell you ?
If your sled is crisp and on the edge or close to it and you add heads, pipe, f/r and y-pipe, yes the motor will go booooooooom.
Now if you have a dog, really slow fat boggy sled(talking motor not clutching) then add f/r and pipes to clean it up, make it crisp. My guess is you had a really good working 7 and you found the lean spot by adding what you did. Probably the y-pipe was the last thing you did and finished it off, the motor that is. Hope it didn't go down hard and punch the rod through the cases.[/b]
I don't know the extent of the damage, but it was running fine, then i was at about 1/2 throttle and it sounded like my drive belt was starting to go, so i let off and pulled over and let it die. Locked up from that point. I think the ring or rings let go.
 

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You will have to see what is left of your motor, the head could be done. Jug, piston, rings, pins etc for sure, maybe rod, crank who knows til' you take it apart. And yes with all of those mods the best thing to do is dyno, $$$ most don't, expensive and who can you really trust. Anyway as i said check what's left of your motor and go from there. Go back to stock if you don't want the headaches, sounds like you had a good one to start with.
 

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<div class='quotetop'>QUOTE (Fircat_Freak @ Feb 14 2007, 10:28 AM) <{POST_SNAPBACK}></div>
so what should i do when i fix it to keep this from happening again. Get BMP's regulator and turn up the psi, or a boondocker? I just don't want it to happen again. I'll even run it rich till broken in, then take it to a dyno if i have to.[/b]
Keep the dam thing stock!! :stop_nono: If it ran 2 lean before the only way 2 prevent is 2 get a boondocker. Id say just leave it and get ur clutching spot on. Stock engine with spot0on clutching could even be faster than a mod engine with stock jetting. :thumbsup:
 

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Discussion Starter · #16 ·
it's too late to go back stock now, exhaust is modified and heads are sold. So i'm going to have to figure this out and make it work. Just got off the phone with BMP and the guy i talked to doesn't think it's due to being lean. I just would like to know why i hear some guys talking on here about being 47 psi at idle when i'm at 43-44 at idle. Why am i lower, do i have a problem, or is it the nature of the beast. Also, i'd still like to know why only one side went down. I'd think with water in fuel, too lean, would effect both sides?
 

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HELLO ! read my post your sled is 44 psi because you have a good one, crisp and lean in stock form. You didn't fix it when you seen it so don't worry about stock parts, you are going to be buying lots of them when you tear it down and see the damage.
 

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Discussion Starter · #18 ·
So then what's the answer if i leave the parts on i have now and rebuild it. How to make it safe and reliable with the above mentioned installed parts..........
 

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Discussion Starter · #20 ·
Yeah, but how's a guy to know what the settings should be for a super safe sled without dragging it to the dyno being that my current fuel pump output seems to be leaner than most? I would maybe think that putting in the regulator and cranking it to 47 psi may be the way to go. ??????
 
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