A friend of mine just bought a '99 670 Summit X. On the second ride out, he crashed it and shortly after it burned down on the mag side. We discovered that the carb on that side was falling off and sucking air past the boot so it makes sense that it would burn down on that cylinder. We replaced the piston and cylinder but could not find an inexpensive H.O. head so we used a non-H.O. head. Now the sled will NOT run past 6500 rpm. It runs fine up to that point then starts stumbling and sputtering. We did find that it was missing one exhaust valve spring and replaced both of them. We also replaced the spark plug boots that got broken in the crash. We checked the jetting and it's at factory spec for the elevation and such and it seems to be getting adequate but not too much fuel. If it was a Polaris or Cat I would say it's a coil or CDI problem but I don't know a whole lot about Doo's as far as their characteristics and the DPM. Anyone have any ideas?
Need Help From You Knowledgable Doo Guys Please!
- Thread starter HIGHMARK
- Start date
Are all the lines for the dpm hooked up? Are any of the fittings on the dpm cracked or broken? I broke one taking of my air box and never noticed it. Went for a ride and sled would idle fine but would not rev up properly. Lifted the hood and did some more checking and noticed the line sitting there with the fitting broke off inside.
Not sure if it is the issue for you but something to look at
Jared
Not sure if it is the issue for you but something to look at
Jared
S
snowcross338
Active member
One guess of mine would be you changed compression by not useing an ho head and didn't rejet for this.
This may seem too obvious, but does the exhaust pipe have any cracks in it? My '01 800 started crapping out really bad at WOT, would pull 7500-8000 for a couple seconds, then drop off, missing badly. Idled perfect. Checked all the basics, changed plugs, checked wires etc. Every time I checked something and tried it again, it got worse. Finally the crack devoloped into a full blown seperation and it got louder then normal (I have a stinger on it 
), and I looked carefully and found it split wide open on the bottom side of the pipe.
Just something to check.
), and I looked carefully and found it split wide open on the bottom side of the pipe. Just something to check.
ttt
I think the 670 and 670x or h.o pistons are different. (different shaped domes) I would check squish. I think the head design is different as well.
I had a friend that put a non h.o head on his 670. I measured the squish and we came up with .026 squish. He wouldn't listen to me about the squish. (way to tight)
He made it 11 miles from the trailer when he finally did a wide open pull and boom.......
when you put the head on did you compare the head design? The stock h.o. or x engine head has a deep middle hole (lack of better words) around the spark plug. I know the 583 had a head design like the old 440's....
jon
I had a friend that put a non h.o head on his 670. I measured the squish and we came up with .026 squish. He wouldn't listen to me about the squish. (way to tight)
He made it 11 miles from the trailer when he finally did a wide open pull and boom.......
when you put the head on did you compare the head design? The stock h.o. or x engine head has a deep middle hole (lack of better words) around the spark plug. I know the 583 had a head design like the old 440's....
jon
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