Vmax 700 intermittently dies

P

Phase

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Dec 9, 2013
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Ohio
Hey folks I have a 98 vmax 700 deluxe. At the end of last year I had the sled taken to a shop for a complete maintenance check up as the sled was new to me last year. Carbs were cleaned an synced. The sled starts up with 1-2 pulls. The issue I'm having is that it will die when at constant throttle position. I took it out for the first time this year a couple of days ago. Started it up an let it warm up for about 5-10 min. Rode it around in a small field for about 15 min. And everything was fine. Went to a bigger field and was running 3/4 to full throttle up an down the field after 15 min or so, the engine died at full throttle. Started it up and no probs for a little while. Then running about 20 mph the engine died again. Started it back up took off and it did the same thing while going at a constant 20 mph. This time, the pull cord seemed stuck, like the engine seized. Lifted the hood and manually turned the engine at the pulley to free it. I was afraid to start it up so I towed it back to the barn.

Engine is free. Compression is good. Plugs are pale/ gray and all three are consistent. By looking at the plugs,it does not appear to have overheated, no chalky white. Starts an runs perfect but I'm nervous to run it to much until I figure out what is going on. I'm going to premix my tank of gas in case it's not getting oil. It is smoking like it normally does, but it has me baffled. Anyone with any thoughts on what would cause this? Not getting enough fuel? Side note... Not sure if this matters or not, but the battery was dead, so I was pull starting it, however after running it, the battery did not charge at all to use the electric start.

Any advise would be appreciated. Thanks.
 
spark plugs 1.jpg

I'll have to work on getting the picture of the plugs attached. I wondered about it running lean, so i'm going to pre mix the tank before I run it anymore.
It did seem to run a little hotter (By feeling the radiators) than I remember it last year. My temp light never came on, but who knows. Thursday i'm going to lift up the front of the snowmobile and make sure the coolant system is properly bled. I'm also going to replace the fuel lines, as i'm not sure when it was done last. I've had issues with bad gas lines on other vehicles that have caused intermittent issues.
-I had some time to look into the wiring today. I traced all of the wires and I did find a pinched wire, but the insulation was not cut or anything. I didn't have my tester with me to check any of the wires. I'll have to dive into it more on Thursday when I have more time.
The carbs were cleaned before I put it up last year. Didn't do it prior to riding this year (my fault) I will do that Thursday.
Thanks for your help, i'll let you know what I find out.spark plugs 1.jpg
 
I understand that the primary purpose of oil is for lubrication. I was just thinking that it would run hotter with no oil due to metal against metal. On thurs I will pull the exhaust and see what I find. If I can't see anything, I might go ahead an pull the cylinder head to physically get a look at the pistons.
Since the battery is shot, I've been pulling for my compression test, which I understand is not as accurate. If I can't see anything in the exhaust, I'll get a new battery and redo the compression test before pulling the head.
 
Pulling for the compression test is perfectly fine. You just want to do all 3 cyls the same way so you can see if there's any major differences. What are the compression test numbers and how are you doing them?
 
Well I stopped an got a battery for the vmax this morning and redid my compression test. It was 130, 115, 130. Bummer. Took the exhaust off and I could see scoring on the piston. The two outside pistons were damp/ oily on the exhaust ports the middle one was dry. Took the head off an same thing with those. It's hard to see in the pictures, but there is a definite change in color. The Cylinder wall has some definite scoring as well. Sucks but glad I didn't keep trying to run it. It doesn't took like any of the piston broke off, at least on the top side. Looks like I can just replace the center, but would you guys recommend doing them all? Thanks for all your help!image.jpgimage.jpgimage.jpg
 
I would pull your carbs again and clean them good make sure you don't have a float stuck or a cloged jet bent needle messed up choke so on and so forth. Does it have fresh gas in it? I know it sounds dumb but bad gas leads to bad things, I made it a habbit of cleaning my carbs end of season and then again at start of season cause its better to be safe then sorry. As far as the cylinder goes I would do all of them cause you have it apart anyways but that is just me.
 
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