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1999 Vmax Sx 700 Triple Help

N
Mar 7, 2018
5
0
1
Hi I have a 1999 Vmax Sx 700 Triple. The engine was replace by a previous owner so it has unknown miles. It is a red top 700 triple. Fist when I was having trouble with my sled I was bogging out every time I went to go full throttle. I did a compression test and it came 90 psi in each cylinder. So I went to a dealer bought new gaskets, pistons, and rings. Took the engine apart and put the new parts in. When I put the new gasket on the top, I cut the ribbit holding them together and took the middle layer out to build more compression. When I put everything back together, I did another compression test. It came out as 100 psi in each cylinder. I figured it was bad seals in the crank. So we bought a known good crank from a sled that had bad pistons. The sled that the crank came from was a 2001 sxr red top motor. I switched the cranks. Putting everything back together I noticed that the plugs from stator was different. So I took the recoil off my original crank. I've own this sled for 2 years and its the first time I've taken the recoil off. When I taken it off I noticed the fly wheel nut was missing. So I think this is the reason why my sled wasn't running right. But any way I switched the plugs from the stator. Now every things back together. I took the sled down the street and back. Now it sounds like its running on two cylinders. The cylinder furthest from the PTO side isn't firing. So I put a never been used BR9ES spark plug in. Still sounds like its running on two cylinders. So I did another compression test and i'm still reading 100 psi. Am I doing something wrong? Everything is torque to specs. I put in new gaskets for everything. Carbs have been cleaned recently.
 
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N
Mar 7, 2018
5
0
1
pilot jets very small sure they are clean

Ya there clean, but that wouldn't be my problem if I only have a 100psi of compression. I did some research online and they say to take a feeler gauge and put your rings in the jug and see what the space between the openings of the rings. Dose anyone know what I should have for space between the rings. Im not shore if my jugs are bored out. Could I go with oversize rings? Or do I try running it on the trail to see if the rings sit in?
 

Givemeaboost

Well-known member
Lifetime Membership
Nov 26, 2007
991
157
43
Great Falls, MT
You've got compression and spark. Check the reads. It's got to be a fuel problem.


Ken..........
 
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..SNAKEBIT..

Active member
Lifetime Membership
Jun 24, 2004
306
35
28
Iowa
I think most guys are not concerned with the compression, every gauge reads different if they are equal I would say ok.
should be something with THAT cylinder, just saying IMO I would pull carb and chk reeds
 
i just bought a 1998 yamaha 700 triple(after my 99 yamaha 500 VMAX blew up). i was riding it and noticed some backfireing and dogging out on low RPMs, then i went through the engine and the fuel vaccum was part way off and the exaust was leaking due to lack of springs holding it together. well i fixed those 2 things and was wondering if the dogging out was normal or if there is somthing wrong with it. matinence tips would be nice
 
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