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Discussion Starter #941
My gut feelings say dig deeper into the engine. Make the venture go and make an off season project out of the vmax.
 

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My gut feelings say dig deeper into the engine. Make the venture go and make an off season project out of the vmax.
Yep, that's the plan. Kind of looking forward to digging into the Vmax, since I'm a car guy, working on sleds is new for me- love learning new stuff! I'm sure I'll be asking plenty of noob questions!
 

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Same chaincase, should apply. Never seen that nor done it. On the flip side, the fact you played with the adjuster and the issue went away would make me want to open up the chaincase and make sure all is good. If you do open it, I think the chain deflection is somewhere around 10mm on the straight side of the chain's 1/3 upper portion. I will confirm if needed.
I didn't pull the cover, but upon inspection after removing the rubber plug it looked pretty dry in there. I used my electric scavenge pump to try and suck up the remaining oil in the chain case, but it came up dry!! In any case we put new gear oil in it and followed the "secondary clutch deflection measurement method" I mentioned above. All is good since that point, let alone having the piece of mind that there's oil in my chain case !!

My only other dilemma at this point is the dang pilot screws. On both of my sleds they'll back out every time you ride them. I put a small rubber o-ring on each screw / spring and that didn't help either. I guess I'll have to see if replacement springs are available.
 

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Discussion Starter #944
I have never had that problem unless they were too far out. Dont think I ever set them much more than 1 3/4 turns out and I know if your running them more than that, yes, they will loosen.

If the springs are fatigued from perhaps being over compressed, replace them. You could try stretching them a bit and turning them over, but I dont know if they will retain a memory. Choke plunger springs wont, so you may be in luck.

Where did all your chain case oil go? In all my years, I dont think I ever ran across a dry one without evidence of leaking. Hmmm.
 

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Hey there, I have read countless posts with your input trying to figure out the issue I am having with my phazer - 1990 phazer 2 with e start. I cannot get this thing to do over 40mph or ~5500rpm. It just sits there like it is governed at that speed. I might add that the lights dim quite drastically when the rpms drop and it does not seem to be making full power right off the start either - kind of a bog, brap, flat powerband. Sled has a psi single pipe and I have cleaned the carbs multiple times thoroughly jetted 110 pilot 150 main for the pipe and fresh rubber plugs in the proper holes.

Reeds are good, compression is good in both holes, I just tried swapping choke cables from another parts sled I have and nothing changed. Mag side plug is nice and cardboard brown, pto side gets wet. I also tried adjusting choke cables but could use a guide there (what is spec for cable length out of adjuster?). Air screws are 1.5 turns out. I tested spark by grounding to the head and each has good blue spark. Belt deflection is in spec almost flush with secondary. I am by no means a clutching expert though. I honestly don't know what to try at this point...I might add that is runs all the way to 100+mph on the stand...my issues are under load.

Could it be the stator, cdi, coil? I have another parts sled I can swap things from but really have no idea what to try and what is causing this. I appreciate the help.

Peter
 

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Discussion Starter #946
This may take a few angles to rule some things out.

Firstly, it almost sounds like the pto cylinder is not firing at lower rpms and along the rest of the way. Funny part on this is at higher rpms the engine can seem like it running proper, but only being masked by the noise. Hence the 100 mph on the lift. Fact that plug is wet means it aint lighting. Lets rule out the choke cables by simply loosening the adjuster nuts all the way and confirming the cables arent sticking. Look at the 2-1 connector as well. You have e-start so dont worry about your arm, but be sure the battery is good.

Is the tors connected or bypassed? Do the choke cables and report back.
 

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okay here's the update. I just adjusted and checked the chokes....backed out the adjusters, cables aren't sticking etc. Bypassed tors and took it out on the lake and still have the same issue. I did make a few more observations.

Sled idles very nice and makes good power from 10-40mph where it then just stays (~5000 rpm might peak to 5500 but steadies around 5000). Sharp turns etc it wont get a nice power hit until around 10mph (can't spin the track in a power turn which it should be able to). Pulled plugs as soon as I got it back in garage - mag side is nice cardboard and plug was hot, pto side plug was barely warm and i could touch even the metal portion with bare skin. Slightly wet again as well. Oh and there is definitely some splooge or unburnt oil/fuel etc starting to blow out where the Y pipe meets the single exhaust.

What's next?
 

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Discussion Starter #948
Couple of things come to mind. First is a weak, leaking, or pin hole in the diaphragm on the fuel pump. Next is a plugged or kinked vent line off the tank, and lastly is the overflow vent on the pto carb is plugged or partially obstructed.

Back to the ill firing pto side, its lacking/starving fuel. Usually a bad vent will affect both carbs, but dont rule it out. With a bad pump diaphragm, it can be restricted to one carb or the other, or both. If the overflow circuit is constricted, its carb specific, and will create a vapor lock, so to speak. So its a crap shoot as to where your problem is directly.

You mentioned a parts sled. Is there a fuel pump? If so, swap it out. Heres the good and bad, but it will point you in a specific direction. Bad is you need to pull the carbs, again, to access the pump replacement. Good is you will be able to rule out some things with the carb rack removed.

When you get the carb rack out while carefully keeping it as upright as possible, get it to a safe area and turn it upside down. You need the bowls in place and in theory, full of fuel. In the upside down position, you should see equal amounts of fuel exiting the overflows. The overflows are located on the right hand side of each carb, and the mag side will be slightly obscured by the cable mounting bracket. Watch carefully, and if needed, refill the carbs via the supply nipples and recheck.

If one carb flows more fuel out, either the overflow is obstructed, the fuel pump isnt filling that carb, floats are whacked, or the inlet needle and seat needs attention.

Back tracking just a bit, do the carb test prior to swapping the fuel pump, but plan on swapping the fuel pump with a known good one while you have access.

I doubt a clutching or electrical issue at this point because neither will create a one cylinder issue. Follow my advice. I have a feeling I know who you once were, RR. One shot deal on this one.
 

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If one carb flows more fuel out, either the overflow is obstructed, the fuel pump isnt filling that carb, floats are whacked, or the inlet needle and seat needs attention.
I will try this today and report back. Luckily I have a brand new fuel pump in my box if things go there. I assume you mean the lesser fuel flow carb would have the issue (likely the pto side in this case)? I have adjusted floats in the past but carbs have been on and off a few times since so I will make sure those are in spec as well.
 

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well plenty of fuel flowed out of the mag side carb, few drops to none flowed out of the clutch side....so we aren't getting fuel. Of course the pump I have is not the right one...got to love CL. Any way I can test the pump to determine if it is working? I have another on the parts sled but was told it is bad hence the new replacement the guy gave me when i bought it.
 

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Discussion Starter #951
You can turn the sled over via the pull rope or e-start with the carb feed lines unhooked and see if both lines spew fuel equally. Or, if you have a mighty vac type hand pump tool, you can hook it to the impulse line and watch for the same results.

Bear in mind that just because the pto carb didnt flow much, doesnt mean its not getting fuel, but could also indicate a plugged overflow as I mentioned previously, and its actually getting fuel but vapor locking.
 

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okay just tested it and both lines are spewing ample fuel equally. went to dump carbs again and mag side dumped fuel and clutch side didn't dump any.

Is that sign of vapor locking? I don't understand how the carb isn't taking on any fuel at all... What do I need to test with the carb?
 

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Discussion Starter #953
Use some extra fuel line attached to the inlet nipples on the carb and fill each one. The fuel line needs to be higher than the carbs and the carbs in an upright position. Once the lines have filled and hopefully filling the float bowls, remove the bowls while carbs are still upright and see if both bowls have fuel.
 

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alrighty she is running on two! Turns out that it was the float, while within spec height wise, still keeping the needle valve from allowing fuel through. So much trouble and error for a simple fix.

Now the carb is leaking but I think its either the float needle assembly or the bowl gasket. Boy is this sled fun when it makes full power!

Thanks for the help shes running great....just piss poor MPG with the leaky carb...will fix that and be back on the snow in no time!
 

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I also have a question about a phazer. It has new pistons and rings and I have it running fantastic. The only strange thing I noticed is that the clutch side spark plug is much hotter to the touch than the mag side. Why would that be? Both plugs are both light brown and it runs very well. I tried new plugs and the same thing. I am just worried about it if I go for a longer ride. Any ideas? Thanks
 

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Discussion Starter #956
I also have a question about a phazer. It has new pistons and rings and I have it running fantastic. The only strange thing I noticed is that the clutch side spark plug is much hotter to the touch than the mag side. Why would that be? Both plugs are both light brown and it runs very well. I tried new plugs and the same thing. I am just worried about it if I go for a longer ride. Any ideas? Thanks
PTO side will be slightly hotter due to the distance from the fan. Things to be sure of is the fan belt and tension, no critters have nested under the cylinder head cover obstructing air flow, and that all the associated ducting is in place. This includes the shield above the y-pipe and seems like there is one other on the mag side.

I would pull that cover off the top first, two #3 phillips and a 10mm headed bolt securing it plus a few tabs with rubber grommets. Watch for those grommets!
 

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Wow, did you nail that one! Of course I have had the cover off and changed the fan belt and everything is clear but the bottom shield above the y pipe? I didn't remember that because it didn't have one! Checked out the fan shroud breakdown on yamaha parts house and sure enough I'm missing a bunch of pieces. The air isn't getting to that side properly as a result. Thanks for your help!
 

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I just bought a 2002 yamaha sx viper 700 triple drove it for about 100 miles and it started to back fire out the exhaust I found that middle cylinder has close to no compression im not going to give up I wanna order a wiseco engine rebuild kit with forged pistons but I need torque specs on anything that needs torqued down and also patterns to tighten bolts right and maybe any advise u would have for a first timer I am pretty mechanically online but havent had the pleasure of owning a yahama yet to tear into one but I have 3 kids and wanna do this right the first time ty for your time
 

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Discussion Starter #959
First and foremost, you need to figure out the root cause of the problem. Could have been bad fuel, dirty carbs, etc. The list can go on. The pistons should tell story.

Secondly, and almost if not more important, when you tear it down, dont let the coolant sit on the bearings, rinse them with fuel and apply 2-stroke oil liberally.

As for your wiseco theory, I wouldnt be a subscriber to adding a forged piston along side two cast pistons. You may rethink this scenario slightly. You can save a few dollars with aftermarket gaskets kits, but you mat not want to scrimp on piston and rings.

When your ready to dig in, we are here to help.
 

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I've been rebuilding a blown motor on an otherwise good Bravo that I picked up for cheap. I came across a few questions:

1. I had a hard time removing one of the pan head screws that attaches the stator to the crankcase. Its head stripped and I had to use vise grips to remove it. Should I retap it to clean out the loctite and then replace it with an allen head machine screw? It's a M8 x 16 x 1 screw. Will there be enough clearance between the screw head and the flywheel magnets? Would a hex head flange bolt work better? Any thoughts?

2. More importantly, I'm curious why the piston holed in the first place, and I'd like to root that out. The owner said they were towing and it overheated, so it could have been sheer abuse, towing under load at low speed. While I have the motor all apart, is it worth it to disassemble and check out the oil pump? It looks like oil's getting delivered, as there was oil in the carb from pulling it a couple times. I will change out the gas for mixed on the first tank and start it with the oil cable pulled to test it. One of the screws on the oil pump drive had worked loose and the case was loose on the one side. I didn't think that would affect anything at first, I'll look closer to see if it looks like the drive pin skipped out of its slot or something.

3. Am I going to have to press the flywheel back on or do some sort of freezing sorcery? It was pretty tough to get it disengaged. It seemed very hard for something that sits on a woodruff key.
 
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