1994 Vmax 500 belt dust in the airbox and carbs..

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brmurph

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Austin, TX
New to working on snowmobiles and not sure how belt dust gets into the airbox, is it a common problem? The carbs were just cleaned less then 100 miles ago. The top of the airbox is clean but the bottom has oil and belt dust all over as well as the carbs. Could this be as simple as the rubber boots between the carb and the airbox being loose? This is a new sled to me and is also going through a lot of oil (putting a new oil pump in to fix this), maybe the problems are related.

Thanks in advance.
 
brmurph said:
New to working on snowmobiles and not sure how belt dust gets into the airbox, is it a common problem? The carbs were just cleaned less then 100 miles ago. The top of the airbox is clean but the bottom has oil and belt dust all over as well as the carbs. Could this be as simple as the rubber boots between the carb and the airbox being loose? This is a new sled to me and is also going through a lot of oil (putting a new oil pump in to fix this), maybe the problems are related.

Thanks in advance.
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Pretty common and even worse with a aftermarket belt. How many miles since you cleaned it out?
 
I have only put 100 miles on this sled since I bought it last year (mostly because the carbs kept pushing gas through the overflow, now I know why:-(. The carbs were cleaned before I bought it and again before I rode it, had to take the carbs off 3 times because of the needle and seat plugging (gas out the overflow tubes). I just tore into it again last week and found all the belt dust (haven't taking it out yet this year).

How does it get in and is there a fix? I have a new yamaha belt that I can put on (and will), will that most likely fix it or is there still an issue. The only thing I can think of is maybe the clamps did not get tightened last year the last time we but the carbs back on.

Thanks.
 
brmurph said:
I have only put 100 miles on this sled since I bought it last year (mostly because the carbs kept pushing gas through the overflow, now I know why:-(. The carbs were cleaned before I bought it and again before I rode it, had to take the carbs off 3 times because of the needle and seat plugging (gas out the overflow tubes). I just tore into it again last week and found all the belt dust (haven't taking it out yet this year).

How does it get in and is there a fix? I have a new yamaha belt that I can put on (and will), will that most likely fix it or is there still an issue. The only thing I can think of is maybe the clamps did not get tightened last year the last time we but the carbs back on.

Thanks.
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Inlet needles are not going to stick from belt dust... the belt dust should never get into the float bowls. Clamps and boots on AirBox bad?
 
Clutch’s must be out of alignment. Isn’t this your 2nd round w/ belt dust issues.
Use non-adhesive silicone when fitting the boot on the carb/slush box. I’ll get pictures of my 96s slush box & hood portion that drops over the box tomorrow. I supplemented them w/ weather stripping so nothing except fresh,cold outside air get to the carbs.
 
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Well to be honest I am not sure what is going on, I assume it is belt dust. The clutch's could be out of alignment, also it sat a long time before I bought it so the belt could be very old. That being said I don't see that much belt dust around the clutch's or the clutch cover/shield. Here are some pics if that helps (see next post for pics).

I haven't posted about clutch dust before but I did post last year about the carbs plugging up. I was about to put in the new needle, seats, etc that was suggested in that thread when I found all the crap in the air box. would love to see any pics you may have..

Thanks again.
 
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Looks like your inlet foam in the hood, located under the gauge pod and on top of hood, right in front of the handlebars. At this age they are often dry and will crumble. The airflow into the engine will pull it apart, or whatever is left of it in the cavity where it sits. You'll want to pull out whatever foam is left and thoroughly clean out that whole area, maybe even remove the windshield and gauge pod to get better access. If you already re-cleaned the airbox, make sure nothing has fallen in it and put a rag over the opening before trying to remove the foam, that stuff gets everywhere when it is falling apart.

If you have some extra cash burning a hole in your pocket, Yamaha will be happy to take a bunch of it for a new inlet foam. Otherwise you can use gutter foam or anything similar from one of the home improvement stores and just trim it to fit. You want a very course foam (use what's left as an example), not the tighter cell stuff like on the top of the airbox or sound deadener foam glued inside the body panels.
 
srx700c said:
Looks like your inlet foam in the hood, located under the gauge pod and on top of hood, right in front of the handlebars. At this age they are often dry and will crumble. The airflow into the engine will pull it apart, or whatever is left of it in the cavity where it sits. You'll want to pull out whatever foam is left and thoroughly clean out that whole area, maybe even remove the windshield and gauge pod to get better access. If you already re-cleaned the airbox, make sure nothing has fallen in it and put a rag over the opening before trying to remove the foam, that stuff gets everywhere when it is falling apart.

If you have some extra cash burning a hole in your pocket, Yamaha will be happy to take a bunch of it for a new inlet foam. Otherwise you can use gutter foam or anything similar from one of the home improvement stores and just trim it to fit. You want a very course foam (use what's left as an example), not the tighter cell stuff like on the top of the airbox or sound deadener foam glued inside the body panels.
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That's exactly what I thought it was up until I found so much of it in the intake as all my intake foam is missing. Apparently there are two pieces per the parts diagram but only one is still available (which I did buy) . That being said you could be right, maybe I need to remove the windshield and check for pockets of the foam. As it is it just appears to be missing but I suppose there could be pockets of it in places I can't see.
 
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brmurph said:
Wow. Did you find the source of the problem? Is it filter material or Belt dust? Did you get the problem fixed?

Thanks!
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Yes it was belt dust. The guy I bought it from was a liar and told me he cleaned the carbs so I did not touch them and it ran not all that bad just was drinking gas like crazy. I cleaned them replaced the needles and seats and adjusted the floats that was the most important part they were off and its been running mint ever since. still a tad rich because I put both the plastic shims under the needle clip. I was told after that one goes on the top and one on the bottom. That was just the way it was when I took it apart.
 
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