98 vmax 700 bogging/dropping cylinder

yamaha06

New member
Joined
Feb 1, 2009
Messages
28
Age
36
Location
Canada
Hey, I have a 98 Vmax 700, the sled has always ran great but is having major problems now and I cant figure out whats going on. Sometimes when I start the sled it will seem like its running on 2 cylinders and I will go to take off and it will bog maybe pop and then when I get up to about 60 km.h It will start to bog again and the only way I get get it going is to pin the throttle. The carbs have been cleaned and set up, I have put new spark plugs and caps on, I checked all wiring for rub throughs, did find one on a wire under the engine so I fixed it but it did not solve the problem, I cleaned those contacts where the fly wheel and stator are not sure what there called, I have also checked the stator but its to cold in my garage so the readings are about 20 ohms low, I know it should be checked at 68 *F but my shops only about 35*F, so any help is greatly appreciated, and the problem comes and goes sometimes if I turn the sled off then start it back up it can run fine for like 20 minutes or so but the problem always re occurs.
 
I have a 97 and was having a similar problem. I did everything I could to the carbs and the wiring. I even cleaned out my exhaust system and still no luck. I then went back to basics. I need Air, Fuel, Compression and Exhaust. The sled checked out fine, so I decided to completely siphon the fuel out of the tank. To my surprise, just under a quarter of my tank was a gas / water mix. I drained the carb, put in some fresh non ethanol fuel and it has been running awesome since. Hope this helps.
 
Alright thanks for the reply I will have to check that out tomorrow. Where abouts are you in Ontario btw?
 
Yes I have done a compression test and everything tested fine, I had this problem with the sled last year but did not have enough time to get it fixed, but anyway last year I took the coils into the yamaha dealership and was charged $5.00 a coil to get tested for them to tell me all the coils were bad, the owner said that if all of them were bad there is no way the sled would run so they were not much help at all, but I was also told that if one coil was bad the sled would not run because there all wired in series?
 
I am in the worst part of Ontario! (i.e the GTA) lol. No seriously I like where I am but it is nowhere near as nice as the places I visit.

About the coils, they are wired in series. If you have a weak or intermittent spark, the first thing you should do after checking plugs and plug wires is to check the connection between the coils. I have had this issue, as the salt gets in at the coil connections and corrodes the wire at the connector. It looks totally fine until you take the rubber off and see the copper is a blue powder and the resistance of the wire is near infinity.

Also, just playing the odds........ Chances of losing 3 separate coils is kind of low, but it could happen I guess!
 
lol I hear ya, Im down around the London area, there are plenty of beautiful places in Ontario, I love it up North wouldn`t mind moving there especially with the snow they get. What should the resistance be on the coils anyway, Im having a hard time getting my hands on a service manual, and the dealership will be a while before they get one in.
 
Primary coil resistance at 20 deg C is 0.05 -0.07 ohms
Secondary coil resistance 2700-3700 ohms. Let me know if you need anything else.
 


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