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Doing some more research, the hole is most likely a lean condition caused by one of water in gas, frozen injector, clogged injector, or air boot leak. I will troubleshoot all of these including new premium gas + preservative juice that I run.
 

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Discussion Starter #962
Good for you for using the off season for sled work. Not sure why I stopped by?

Yes, by all means use allen type screws to replace the phillips. I do it all the time. But, use button heads, not socket caps. With the button heads clearance wont be an issue. Most likely someone used the wrong driver on those phillips. For future reference, a bit of direct heat will free those more easily, I use a butane torch in there. As for the flywheel, clean up the shaft and slide it back on. Once torqued to spec it will be fine. They always come off hard, thats why you use a puller.

Glad to see you answered(somewhat) your burn down question. A "holed" piston isnt caused from lack of oil nor overheat, and a picture of that piston could be worth a thousand words.

Since your in this deep, change out the crank seals. Cheap and easy, and could have been an issue with sucking air. At least you will know they are good come snow time.

Carefull with running pre-mix along with the injector system, you can actually lean it out again. Too much oil wont let the fuel cool things.
 

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Pictures

Roger that on the button heads. I've been going through the Fastenal catalogue, I plan to get an assortment, since I've been finding that fasteners have a way of wanting to either strip or disappear or what have you. Thankfully I deciphered the Yamaha part number code and found a chart in the service manual with sizes and pitches.

Crank and jug went out for check and bearing/seal change. Bearings were rough. Somewhat odd for a sled with 1400 k, but I don't imagine ingesting liquid piston was very helpful. While I have the time, I might just pull apart its sister sled that I got at the same time, to make sure everything is on the up and up.

Roger that on the risk of mix + pump. I will think through the priming step carefully.

Here are the pics I have of the offender.
 

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86 ET340TR. Same carb as Phazer, mostly anyway. Cleaning up carb since it didn't start how I'm used to. No plugs found, but black debris which is likely old plug. Manual shows plug on choke tube only. Will pull carb again to replace plug. Question, will there just be the one plug required on the center tube? I want to get this right.
 

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I think I got it. So, in the conventional “airbox side towards you” sense, the left tube is the pilot jet, the middle is the starter jet, and the right is a blank tube that is cross connected to the starter jet tube. All signs pointed to the middle tube being the one requiring the rubber plug. I inserted it so that its recess abuts the center tower where the main jet sits. The middle tube now will accept fuel from the hole on its side as well as the blank tube cross connection. Note in the photo that there was a fragment of the old plug in that hole.

It started perfectly, much better than before. It seemed to want to become too rich and flood previously. It now idled fine, ran up fine, and had no real hesitation. Can’t wait to get out on it.

There was a bit of scum in the carb, but nothing I have dissolves that scum. I rubbed the worst of it off and cleaned it as best I could.

The plug placement matches the concept of the schematic in the service manual, but does NOT match the orientation suggested in the schematic drawing.

I did not plug the pilot jet tube, since it appeared that it would not be able to get any fuel if plugged.

Stamping on carb says 80E 01 on one side and 5 5 3 on the other.
 

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Edit: it needed the one on the right as well. It seemed to want to flood without it. Stains on the bottom of the bowl gave it away.
 

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Discussion Starter #968
I am thinking you have an underlying blockage hiding in plain sight. I have been there, believe me.

Somewhere in that carb something aint right and no fault of your own. Sometimes all it takes is a beer or three and some thought.

Cant remember if it made a post or was something in a pm, but I have experienced just about everything on those b-38's and led someone on the right track.
Stick with me or contact me directly and we can walk through.
 

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Gotcha! I was reading as which orientation was correct. Thanks for the clarity.
Yes I had it apart one more time over the summer for a deep soak cleaning (hard to find the good old halocarbon solvents, so Yamaha dip it was) to get out some of the scum that was in it. While doing so, I noticed an impression in the scum on the bottom of the bowl that was almost certainly created by two plugs. Since I had purchased four plugs, I put one in the second spot. It has been a one or two pull start every time since. Love that popcorn idling sound!
 

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How low of compression is too low? I'm working on an 80 ET 300. Tested at 110 today. Runs ok, but trying to figure when I need to rebuild.
 

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Discussion Starter #973
Tough call there. On the bubble depending on test equipment accuracy along with procedure. I wouldnt be overly concerned with 110, but under 120 makes me question whats inside. Look at the pistons for any indications through both intake and exhaust. You may also consider a warm test for comparison.

The fact it runs ok is the kicker. Does it start easily as well?
 

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Yes it starts and runs ok. I plan on a full rebuild anyway, it's just a matter of when. For now I will wait until next year.
 

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Hi Yamaha dad I have a quick question for a 1994 vmax 600 are they reliable have you ever owned a vma x600 and did you like it and do you ever race it thanks oh and did they have piston issues
 

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Next question. I have an 85 Excel III that is making a weird buzz sound. I've never come across it before. Any ideas?

Here are two short videos.


 

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Discussion Starter #977
Sounds like something stuck or sticking in the primary clutch. Something to rule out as the last time I heard that sound thats where it was.

Starter motor stuck, oiler housing being dry, or tach drive can be checked as well.
 

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Checked oil pump, all good. Unless it’s something internal, this points me to the starter. I kinda hope it’s nothing internal. It runs fine.
 

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I’ve got a 94 vmax and the seat is pretty ripped, so I am debating just getting a new seat cover for it, but I was wondering if there is a taller seat that I could swap in relatively easily because I prefer not riding so low as it is and having a custom built seat is just too much to spend on a sled of this value. If anyone has any ideas, that would be great! Thanks
 

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1997 Vmax 600 XTC leaking gas

Hello, thanks for allowing me to post.

I have a 1997 Vmax 600. A couple of weeks ago I added around 5 gallons of gas to the gas tank. A couple of days later I went out to my barn to do some work and noticed a strong gas smell. I looked all around and found there was gas underneath the Vmax. So my question is, where could this be coming from? Since this has a fuel pump, and the sled had not been run, could it be I have a cracked fuel tank? This is the first time I put this much fuel in this sled.

Any suggestions would be appreciated.

Thanks :thumbsup:
 
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