VMAX SX 700 Backfire and White Smoke

bluemonster1 said:
clean the pilots and all carb passages.Check float levels also.Sounds like you don't have the belt on when you rev the motor.I can hear the primary just slamming shut..you'll end up damaging the primary or create cracks in the sheaves if you let it slam shut like that. Also check the float fuel pins if they are sticking.There are also 3 small screens where fuel comes thru,remove them and see if they are being restricted.
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Where exactly are those 3 screens located?


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In the first video it defintely had plugged up pilot jets. In the second video it sounds good and its running on all 3 cylinders, so you did a good job of cleaning them. The fuel screws should be set at 1.5 turns out from lightly seated, set all 3 the same.

Is the exhaust still getting cherry red? The smoke is normal gonna smoke alot until its run and up to operating temp, youll never get there in the garage, so take it out and ride it, if its not making the exhaust cherry red.
 
shaggyzr2 said:
I don't think the 97's had the screens. I've worked on a few 97's and none of them had the screens.
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I could be wrong, but the parts catalog show the same needle-valve assy part number for a few model years that I looked at. I think the screens on the older models were just removed by people over the years. My 97 700MM has them ans so does my 98 700sx. If the exhaust is not getting "cherry red" anymore ride it, and see how it runs. By the sounds of the second video I think you have the carbs clean.
 
I hear what sounds like the spring rattling on the exhaust can. Just like mine. It also sounds like mine do. Which I think it sounds like it is running pretty good. Mine smoke pretty good. I have 2 in a 20x24 garage with the door open it looks like cheech and chongs van with the smoke rolling out. When they are warming up. When you get some snow I say do some plug chops and see what the spark plugs look like. If you are sure all passage ways, jets are clean, floats are not sticking in the carbs. One of the main reasons we turn the fuel screws out a little more is due to the idle hang these have. (common issue) So instead of the 1 1/2 turns out some including me go 1 3/4 turns out. To help with that. Hopefully you paid attention to what jets where in what carbs because one of the main jets is different size. Just a fyi. I hope you put in fresh fuel. Also in getting them ready I like to spray a little starter fluid around the seals and carb boots. If the rpms increase then you have a leak.

owner manual some good info. http://www.yamahamotorsports.com/assets/service/manuals/1998/lit-12628-01-93_756.pdf

carb cleaning http://www.totallyamaha.com/snowmob...Carb Cleaning/Carb cleaning 101 with pics.htm

reading plugs http://www.totallyamaha.com/snowmob...g a Sled/Jetting a sled and reading plugs.htm

I have made this mistake when I have had the cards and air box off. The oil cable pulls apart under that rubber boot. Make sure its together right. The throttle will feel a little funny if its not.

Also when your showing the clutch side in the video something does not sound right in the primary. could just be my speakers. I might take that cover off and just check it for loose parts.
 
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mrviper700 said:
In the first video it defintely had plugged up pilot jets. In the second video it sounds good and its running on all 3 cylinders, so you did a good job of cleaning them. The fuel screws should be set at 1.5 turns out from lightly seated, set all 3 the same.

Is the exhaust still getting cherry red? The smoke is normal gonna smoke alot until its run and up to operating temp, youll never get there in the garage, so take it out and ride it, if its not making the exhaust cherry red.
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Thanks. It deffinetley needed it! And I don't know if it's still getting red. We don't have any snow yet so I can't really test it yet. But it sounds healthier!


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mes882 said:
I hear what sounds like the spring rattling on the exhaust can. Just like mine. It also sounds like mine do. Which I think it sounds like it is running pretty good. Mine smoke pretty good. I have 2 in a 20x24 garage with the door open it looks like cheech and chongs van with the smoke rolling out. When they are warming up. When you get some snow I say do some plug chops and see what the spark plugs look like. If you are sure all passage ways, jets are clean, floats are not sticking in the carbs. One of the main reasons we turn the fuel screws out a little more is due to the idle hang these have. (common issue) So instead of the 1 1/2 turns out some including me go 1 3/4 turns out. To help with that. Hopefully you paid attention to what jets where in what carbs because one of the main jets is different size. Just a fyi. I hope you put in fresh fuel. Also in getting them ready I like to spray a little starter fluid around the seals and carb boots. If the rpms increase then you have a leak.

owner manual some good info. http://www.yamahamotorsports.com/assets/service/manuals/1998/lit-12628-01-93_756.pdf

carb cleaning http://www.totallyamaha.com/snowmob...Carb Cleaning/Carb cleaning 101 with pics.htm

reading plugs http://www.totallyamaha.com/snowmob...g a Sled/Jetting a sled and reading plugs.htm

I have made this mistake when I have had the cards and air box off. The oil cable pulls apart under that rubber boot. Make sure its together right. The throttle will feel a little funny if its not.

Also when your showing the clutch side in the video something does not sound right in the primary. could just be my speakers. I might take that cover off and just check it for loose parts.
Click to expand...

Thanks a lot!! I'm not exactly sure what the primary is. This is my first sled ever and the first sled I have worked on! I'll have to look for a how to thread on that. Thanks for your help!


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Another quick thing, when I had the carbs apart. The fuel/air screw on the bottom of the middle carb was bent a little. The needle end was bent a little and the other one on the end, the o ring on the needle was really rough looking. Should I replace with new needles, seals, and washers?


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97 700 sx's didn't have the screens but 98's did. part#1J7-14994-00-00 NET,FILTER. The 94-96 vmax's had them too but for some reason they didn't put them on the 97's.
 
Don't feel bad when I started working on sleds it was take it apart and figure it out. I learned a lot on my kids 1st sled it was a nightmare bought it for the right price but ended putting a lot more money in it. That was about 6 years ago and I am still learning.

Go to the tech section and do some reading in there. Full of great information. I would just read the stuff on keeping it pretty much stock and maintenance stuff. The primary is the clutch that spins when the motor is running. On the left side when your sitting on the sled. The other clutch is called the secondary. Just sound like something is rattling in there to me could just be the way the sound is or the speaker in the video. I believe these Yamaha clutch are known to last. Give them a good cleaning once a year with soapy water.

On the fuel screws I would at least replace the o rings if they looked bad.
 
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You guys have no idea how much these few posts yas sent helped me... I can build you a 1100 hp diesel street truck, but you hand me a carburetor, I'm gunna look at you like you have 4 heads.. Haha. I catch on quick tho. I mean I'm basically a professional now! (Just kidding)
So thanks a lot for all your help! It is much appreciated!


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Straightsixmafia said:
Another quick thing, when I had the carbs apart. The fuel/air screw on the bottom of the middle carb was bent a little. The needle end was bent a little and the other one on the end, the o ring on the needle was really rough looking. Should I replace with new needles, seals, and washers?


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Yes, definitely replace them. Most likely bent from some one over tightening them, just lightly seated when turning them in. Raise the rear of the sled, put a belt on and run the track a little, see if the pipe gets red.
 
Straightsixmafia said:
Thanks a lot!! I'm not exactly sure what the primary is. This is my first sled ever and the first sled I have worked on! I'll have to look for a how to thread on that. Thanks for your help!


Primary = Primary clutch, which is clutch on the motor. Secondary = secondary clutch, other end of the belt. If you haven't yet I would check for air leaks, with motor running you can spray carb clean/starting fluid around the carb boots and around the clutch end of the motor. If its sucking air some where it shouldn't be this will cause a lean condition.
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Straightsixmafia said:
Thanks a lot!! I'm not exactly sure what the primary is. This is my first sled ever and the first sled I have worked on! I'll have to look for a how to thread on that. Thanks for your help!


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Click to expand...

I think I found my problem for that noise. Check this video out once. I'll upload it right after this comment.


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check the primary for loose or broken parts,also for worn bushings in the rollers and sheaves.Check the weights for wear and also the springs in both clutch's.
 
Okay guys! My fueling issue completely resolved!!! I bought new fuel/air screws because of the 1 bent one and out new washers and o rings on them. While I had them out I out all my pilots and stuff in my ultra sonic cleaner. Threw it back together. She sounds beautiful and just a hint of smoke while it cold!!
Now...... We got a little snow today as I finished the sled up. So I took her out for a loop around my house. It sounded like someone was stomping the hell out of my hood! So this is prolly what you hear when I had my sled running while troubleshooting it. Anyone have a good thread with pictures on how to pull my primary off and what all I should check? I do not know the names of the parts in there so bare with me!


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