99 mtn max back firing no power

M

max 700 99

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Joined
Jan 1, 2012
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5
Age
46
Location
montana
I rebuilt my 99 mtn max 700 with bender pipes. I had it together this summer and ran it around the field. It ran fine I can't remember if it popped this summer. Now it does . I cleaned the carbs. All three jets. I run a modified intake system too carbs. I am wondering if the reeds are bad. I have moved the clip from the bottom to the top. No difference in how it runs. It runs great at idle. It has new plugs. It bogs and will back fire in exhuast. air screw is 1 7/8 backed out from seated. I am running 145 mains in all three carbs. pilots are 45. I am baffled. The carbs are clean. I run this sled around 3000 t0 7000ft mountian riding. I fergot to put the oil cable on when I rebuilt it the first time and siezed the motor. So it is back together. could the crank seals be leaking and if i could put a video with audio up on here to help out let me know how to do it or I can put it on my youtube.
 
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I had an artic cat 580 that acted real similar. It was left outside and to be blunt it was for freinds,friends of friends, neighbors kids to ride so it wasnt really all that well taken care of. It would fire up, run with no power back fire a couple times and die. After a few days of beatting my head against the wall I relized the can had gotten water in it and wasnt letiing exhaust flow. After pulling can and setting it by the wood stove over night it fired right up and ran as good as you could expect a cat too! If your not finding a leak with starting fluid look at exhaust and make sure it has somewhere to go.
 
What was done on the rebuild? Could something have not gone back together properly? Bad gas? When were the carbs cleaned last. I know you said they were clean, but was that this summer during the rebuild? If they sit for any length of time, the carbs can get gummed up very easily depending on where you filled up last. I just did the carbs on a buddies MM700. Every jet and orifice was jammed full of crap. It was fogged and he used stabil. They were cleaned mid season last year previously. They can gum up in a matter of a couple months depending on storage area and humidity.
 
Could it be a TORS problem? Mine backfired when it was acting up. Just bypass it to rule it out.
 
I cleaned carbs last week. I disconnected the tors and plugged it back into itself. Yes checked muffler had them dam mice do that before. Exhuast is coming out of all three mufflers. I will do a video tomorrow and test for crank seal leaking. Not sure if reeds are bad.
 
taylzee said:
What was done on the rebuild? Could something have not gone back together properly? Bad gas? When were the carbs cleaned last. I know you said they were clean, but was that this summer during the rebuild? If they sit for any length of time, the carbs can get gummed up very easily depending on where you filled up last. I just did the carbs on a buddies MM700. Every jet and orifice was jammed full of crap. It was fogged and he used stabil. They were cleaned mid season last year previously. They can gum up in a matter of a couple months depending on storage area and humidity.[/QUOTe


Put new pistons and jugs plus cleaned the magnetic pick up on the stator. It was rusty.
Click to expand...
 
Not something silly like pistons in backwards???I have seen it done before.
Did you check compression before and after initial rebuild burn?
 
video is done but you can't hear it when it back fires. Around 4 to 5000rpms. Bogs and has no power. go to dustin800xrsdoo to see video but you cant hear it pop. There will be two videos just loading the last one. It pops even with choke on. These are 97 jugs on a 99 mtn max. Don't think that should change much. The guy I bought them from said they would work. More old jugs got scatched bad and need nickel plating.
 
I had a '99 SX 600 that would pop and backfire because the reeds were worn out. As soon as I changed them the problem went away. I can't say this is your problem but from my experiance reeds can cause the issues you are having.
 
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