VintageVmax.com

Hey Guys

Out for a good run today 320km or about 199miles with the wife on our 87 and 90 Vmax, but my sled (the 90) has been bogging alot - hesitation really BAD today off and on. I am steady playing with the throttle to keep the rev's up - if I don't do this, it wants to just bog and not go anywhere.

This bogging would usually occur going up certain hills - such as today - I had to get off the sled and run beside it while still playing with the throttle to try and get the rev's up so it would keep going and not hesitate. But now it's beginning to happen on flat ground..... And then there are times it will just fly, but again it's getting more throttle play then anything to try and keep the rev's up. Today's events even included a couple of times when crossing roads, I had to do the "Old Dog Sled Push" to keep it going - no I wasn't laughing but the wife was. I seem to have to play with the throttle even when it is running as it feels as thou the power is hesitating and not really there for the speed I am going (a real pain in the ass)

Even when Ive been stopped, and to get it rolling, I have to play with the gas to get the rev's up so it will even move. I even had to lift the back end up and had the wife rev the sled up to get it going with no resistance on the ground after we got gas at one place.

I know it is not the Gas since we run both machine together and the wife's 87 is running great (and thats the way I want it - hers running better if you all know what I mean) BUT! this is really starting to P*** me off now.

Could it just be time to rebuild the crank/motor and give up on this motor as it is the orginal?
Maybe other Clutch issues?
Maybe other Carb issues?
Maybe Stator issues?

Any input guys would be great! I am really stuck on this for sure. So any suggestion or lots of them would be nice to read.

Thanks Again

Paul

well, it could be any of those things. I'd start with the easiest things to see first.
Jack up the back of both sleds, rotate both tracks by hand, is yours any harder to move?
Next look over your clutches carefully. look for something like a broken spring, are the primary arms free?

If that found you nothing, its time to move to the engine. I would suspect carb, dirty carbs.Perhaps the easiest way to sort this out is to unscrew the caps and slides, and swap the carbs between sleds. If the problem is now on her sled, send her to the mall and go riding. Ok, that might prove costly, I would then clean the carbs. Carb cleaner and compressed air, blow out the jets and all passages. Now, put a clean piece of fuel line onto the inlet of the carb and blow gently by mouth. As you push up the floats by hand, the air should stop flowing Put everything back together and give it a shot.

If we still haven't got anywhere, I would wait until dark, or turn of the lights, start her up, the sled, not the wife. Look for stray sparks from the plug wires, or anywhere electrical

Now if were still batting zero, I would go to the bar, and drink heavily, because next comes the OHM tests.
Try the above and let us know what ya got

Thanks Bob for the info. Every little bit is going to help for this one as it really has me stumped.

Paul

Hey Guys

Started checking the sled today. When I open the hood I notice some Gold Dust Filings on top of the Cylinder Head. I took the cap off the spark plug on the clutch side, and it was stuck onto the spark plug pretty good. As I looked at the plug it had 2 small grooves in it at the side of the tip about 1/2 on it. I also notice that the cable wasn't pushed on very tight either. So I guess (I hope) this is where I was getting that bogging issue by it serging with not the right amout of spark getting to it. Is there anything else that may cause why that spark plug was worn that much with the 2 grooves?

The track on both sleds turn the same with ease as Bob suggested to try as well. I also have an extra set of carbs which I will get cleaned and set up from my mechanic buddy.

I started it back up and it seemed to idle better but, I will get it check by my buddy to make sure it is where it should be at.

Any other thoughts on this issue Lads would be good to read. And I am still wondering why the spark plug looked like that at the tip but the other side was fine. They both looked the same on the bottom as well but alittle rich as both were black and wet. The wife did say I was smoking alot more than normal. And by the time we got home we could really smell it on her Yamaha Suit as we had to hang it outside to air out for abit.

Thanks again

Paul

The secondary sheeve has a Bi-metalic bronse/copper colored bushing around the helix in which if bad could leave a gold colored dust.

It seemed to be the Spark Plug wire that you screw into the end of the cap that was causing all the trouble. Put a new cap on and trimed back the line to the CDI and screwed it back in and it sounded alot better right away.

I didn't have to play with the throtle at all, but it still bogged abit at time at the low end when I was driving really slow for abit when it was hot. Once I got it going it seem fine.

Thanks for the help

Paul

for the record i think you trimmed the wire to from the IGNITION COIL to the spark plug

that is the ignition coil or just plain "coil" on top of the airbox.... the cdi is buried down by the water pump

Your right my mistake

Thanks Tyler

When I had a problem running on one cylinder, I pull the muffler can to see and hear the pipes separately. If one carb is flooding out, there will be raw fuel spitting out the stinger.

By covering the end of each pipe in turn, you can listen to the sound of the other cylinder to determine its health.

If one cylinder is smoking excessively, you can tell which one needs attention.

Well theres always the spit test, almost as good as EGT gauges but very hard to do at speed

The new plug on the clutch side has the same 2 grooves burned into the tip and the cap was hard to get off again due to it melting and bonding to the tip of the plug. I am wondering if anyone else had this problem in the past? It is not as bad as before "YET" as the grooves are only small again but starting to get deeper, but it was still bogging at times going up some smaller hill inclines nothing big at all. Again the cap was changed as well from before.

So am I getting a stronger surge to that side for the spark? Again this is on my 1990 Vmax.

Thanks

Paul

Wet the wires, caps and coil down then start it in the dark and look for sparks comming from defective parts. There are resistive & non resistive spark plug caps and resistive & non resistive spark plugs. They way I understand, If I am right......(?) is they must be mis-matched so, if you have a non-resistive cap then the plug must be resistive as in BR9EV's ?

Go up to a 45 or 50 pilot jet.