help with 97vmax 500

bluebullet

bluebullet

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Joined
Jan 28, 2004
Messages
558
Age
65
Location
Augusta, Maine
Here is the story. Yesterday after sled was started it took a long time to get it to come to idle. Had to stay on throttle to keep running. Left and made it about 5 miles and sled ran normal once good a warm. Speed was only about 30 -50 mph came to a stop and heard a pop ( not a backfire) and no power. shut sled down nothing obvious could be seen. pulled the plugs and no metal and looked tan in color. put new plugs in anyway. Sled would start and idle but poor throttle response and just enough power to limp along around 10 mph. got the sled home and went to see if it would start and took quite a few pulls with hardly any compreasion. ( pulled like a sled without plugs installed) Tore apart this am expecting to find hole in piston or decentagrated ring at least somthing? Everything looks good? I have posted some pics. Any help would be appreciated. Reeds look good? Maybe a ring stuck ? All the rings are free and rotate. Head was tight nothing loose when I took apart. I thought I had lost compression and usually easy to find problem. The carbs will be cleaned before I put all back together.
Thanks Blue
 
More pics

more pics. I can take more detailed if someone see's somthing? Thanks for helping! Terry
 
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Daman, about 6500 miles on motor. Just bought the sled last fall and I am sorry but don't have that type of info. What is the update? The only mode I know of is the Vforce reeds were installed last year. How can you tell if a reed is bad? the petals all seem flexable and will move and no holes or cracks. My buddy seems to think they might be an issue? Will they effect compression? I did poor some Yamaha lube down each cylinder after I put it in the shop? Still had no compression after. There is no scuffing or hardley any scratching inside the jugs. What will effect compression other than mechanical seal between intake and exhaust of the motor? Gaskets, rings. Thanks for responding.
 
Boy this is weird,everything look's fine...lol


bluebullet said:
What is the update?
Click to expand...
in '97 there was a problem where the ring pin could fall out and if that
wasn't bad enough it would let the ring spin then it would catch
the exhaust port,,but you having that many miles on her it would have
happened by now.
bluebullet said:
How can you tell if a reed is bad?.
Click to expand...
they need to lay flat,held up to a light you don't want to see light through
no crack's either,on a stock motor OEM reed's are as good as it gets
bluebullet said:
Will they effect compression?
Click to expand...
My SRX had a reed not sealing good and comp was right up there still,so
probably not on that..

dunno, about the only thing i can suggest is look everything over good
again, and since you have it apart you may as well freshen it up now,
mic your pistons new rings,new oem reeds, light hone..

none of your rings were in line(ring end gaps lined up) were they?
 
Rings rotate

Thanks guys for the input. I can tell you that the rings will rotate on the pistons. Could one of rotated to the notch thus loosing compression? How coul an electrical issue prevent compression. I think we will put new rings, light hone jugs, new gaskets and put it back together and see what happens. Keep the info comming please. I used a flashlight and can't see any light threw either reed.
 
bluebullet said:
I can tell you that the rings will rotate on the pistons. Could one of rotated to the notch thus loosing compression?
Click to expand...
When compressed in the cyl. the rings cannot spin,if they do they will
catch the ports and bam junk cyl's, there's a little pin that's in the ring
land that sticks out just enough to keep the rings from spinning in the
ring land.

the ring end gaps must be opposite or off set from each other to enable
seal compression,if lined up comp will just flow right through them into
the case.
 
more pics

O.K. my camera isn't the best. Here are a couple more pics. Are the pins in the piston notches? It looks like they are in there. the rings all look good to me? Thanks Terry
 
Well, I am looking for atleast one new piston or even used, Wife doesn't want to put $200-300 for a new top end if That's even the problem. I created a obvious one yesterday while taking the primary off the crank spun and one piston caught the end of the bottom case and broke bottom off piston. so anyway I know I have a problem! We are trying to save money and buy a house plus I don't think she like the sled anyway! I just want to get it back together and see if compression is back or not! Anyone got any used or new pistons kicking around? Thanks
Blue
 
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