Air filter won't stay on.

[MissionMtnMax]

Finally got a chance to get sled out yesterday that I bought a week ago. It's a '99 MM 700 and did well on my 40 mile jaunt.

The only issue is I have three individual air filters at the carbs. The middle one is right against the steering shaft and after a couple miles of riding it always falls off. It's been "formed" to fit there but I can tell it has been an issue with previous owner as the hose clamp is worn out on that filter - can't tighten it down anymore. So I switched hose clamps and got it good and tight on the middle carb, but 10-15 miles later it was off again. Any suggestions on how to handle this?

 

[RXMax]

Put the stock airbox on with the airbox mod and don't look back. Your sled will probably run better than it does now IMO.

 

[MissionMtnMax]

An update on the sled. I did get an airbox and boots off of ebay that arrived late Friday - had a poker run already planned for Sat. morning, so didn't have time to change it out. I had fixed the middle K&N filter so it would stay on and it did for the entire 40 mile poker run.

But about 20 miles into the run, the sled started running very sluggishly. Could tell it was getting way too much fuel or not enough air. I checked altitude when it started doing this - was 5100 ft. - the weekend before I was running at 4600-5000' with no problem, but I stopped a lot more. So I wondered if the lack of cool air thru the pods was causing the issue and I limped on in to the warming hut. It idled fine, it started right up each time, but it was just bogging down bad - all I could do was just run it around 5000 rpm and putt-putt along. Pulled a plug - it was a bit oily.

So got to warming hut and shut it down for an hour or so. It was basically 10-15 miles downhill back to the truck - I was curious whether there may have been a jetting issue for the elevation and that it may improve as I started going down hill. So we took off - and it ran fine the entire way - didn't need to drop in elevation. The other thing I noticed was the terrible gas mileage - I used over a 1/2 tank for this 40 mile trip while my wife's MXZ 670 didn't even use a quarter tank.

So I concluded the issue was less around jetting and more around the K&N pods and sucking warm air. Sunday, I pulled the pods off and installed the
air box. I didn't pull sled off trailer, but fired it up. What I noticed right away was that instead of clutch trying to engage around 4200 rpm as it always had done, it was pulling on the tie down straps right at 3000-3200 rpms. So I'm hoping to find time this week to run up to where I made the first run with it and just run it like I did at poker run and see if it will bog down at all. We have another poker run of same distance this upcoming Sat. and I'd like to see if this airbox makes a big difference - it sounds like it should?

 

[RXMax]

I am fairly certain you were experiencing the dreaded yamaha carb icing problem.. There are jets in the mouth of the carbs that become iced up due to snow dust,etc getting into the carbs and freezing when riding. When you stops the underhood heat melts the ice and the sled starts to run fine again until it freezes up. This also causes very poor fuel milage when they are iced up. Turn your water on to your carbs and it will fix this problem.

 

[MissionMtnMax]

Interesting - this icing problem - that kind of makes sense to this slow mind. However, it is a '99 MM, and conditions that day were groomed trails - not snowing and about 30-33 degrees the entire trip. I wasn't getting snow or anything else under the hood. When you say "turn the water on", is that some kind of petcock I'd be looking for? I see one petcock on top of carbs on the clutch side, but I'm pretty sure that's the fuel shut off - I didn't look that close, but it came to mind when you mention it. Thanks.

 

[RXMax]

If you were riding with a group of sleds just the fine snow dust can cause this. yes the petcock for turning on the carb heaters is above the carbs. Its normally connected to the airbox on the clutch side.

 

[Lt Rascal]

Interesting - this icing problem - that kind of makes sense to this slow mind. However, it is a '99 MM, and conditions that day were groomed trails - not snowing and about 30-33 degrees the entire trip. I wasn't getting snow or anything else under the hood. When you say "turn the water on", is that some kind of petcock I'd be looking for? I see one petcock on top of carbs on the clutch side, but I'm pretty sure that's the fuel shut off - I didn't look that close, but it came to mind when you mention it. Thanks.

That petcock is normally mounted to the airbox. That should be the carb heater. Fallow the lines, One side should go to the cylinder head the other to the carbs. On the other end of the carbs it will go up under the motor to the water pump cover under the exhaust in the front right side of the motor.

Your motor will run much better with fresh cool air rather then hot air from under the hood.

 

[MissionMtnMax]

Thanks to both of you for responding - the airbox I got supposedly came off a '99 MM 700 - I do not have or do not see how a petcock/switch was attached to it at all. However, I'll check the petcock I do see above the carbs on the clutch side. I know it was fully open or closed - just not sure which.

What I need to see is a pic looking down at a stock engine for that year....I'll have to look for one.

Thanks again.

 

[Lt Rascal]

Here are some pics of a '99 I have in the garage. You can see the petcock attaches to the bottom half of the airbox. One hose to the head, one hose to the carbs. Yamaha added the carb heater in '98 so if the bottom half does not have the tab for this to attach then the bottom half at least is a '97 airbox

 

[MissionMtnMax]

Thanks for pics - I do have that tab - wondered what it was for. I noticed something else different - your spark plug wires - they look like that run up to top half of air box?

 

[theultrarider]

30-35* is prime conditions for icing a carb. Believe it or not, they ice up far worse at that temp than at -30. That said, keep it turned off for best performance unless you have an icing problem. That is usually like one ride a year for us. Had a Skidoo ice up bad about 3 weeks ago. Turned his carb heaters on and problem went away within 5 minutes. Oh ya, it was about 30* out that day

 

[suva]

Thanks for pics - I do have that tab - wondered what it was for. I noticed something else different - your spark plug wires - they look like that run up to top half of air box?

The coils mount to the air box too.

 

[Lt Rascal]

Thanks for pics - I do have that tab - wondered what it was for. I noticed something else different - your spark plug wires - they look like that run up to top half of air box?

Yes the coils mount to the air box. I have been asked to help work on a couple M-max's with the air box removed. I put stock boxes in all of them. On most of those cases they had mounted the coils to one of the bolts for the carb boot that holds the reeds in.

 

[MissionMtnMax]

Yes, the carb heat petcock was mounted on a carb rail with zip ties. I mounted it back on the tabs on airbox. The petcock was and is open...so either it's getting nothing thru the lines or i'm back to simply seeing if installing the air box (meaning cold air into carbs vs. warm with k&n pods) will have an impact on what I originally talked about when it bogged down last weekend on poker run.

 

[Lt Rascal]

It looks like you got the coils on. I took a couple pics if they help. The CDI also can attach to the airbox. Notice the routing for the throttle cable.

 

[MissionMtnMax]

Thanks for pics - I'll have to see if I can work on remounting coils and CDI back where they belong.

Looking forward to see if I have "bogging down" problems this Saturday as I did last Sat.