Today I went for a ride out to the Mississippi river taking a round-a-bout way through some nice country putting about 400 miles on all together. The temperature when we started out was in the low 50's and probably never broke 60 all day which is a lot cooler air temperature than the bike is used to. There should have been no fuel quality issues, happened in all four tanks of fuel from today, all fuel was name brand premium.

Under hard acceleration after the V-boost has kicked in and around 7,000 rpm in fifth gear, it feels almost as if the clutch was pulled in, the tachometer races to about 9,000 rpm and stops during which there is an interuption in acceleration. When the tachometer hits about 9,000, the reading on the tac drops back to just above 7,000 and then it starts pulling again (feels like when a clutch is let out) and the bike performs from that point on as usual. It only happens in the highest gear. In lower gears, the bike goes through the power band with no interruption in power. That is why I tend not to think the problem is not in the drive train for if it were the clutch or some other worn hard part, I would think it would do it any time the engine hit 7,000 rpm regardless of the gear it is in, but I could very well be wrong because I have never worn out a clutch in a bike before. The bike otherwise runs fine and pulls hard off the line. To describe it another way, during that brief window at 7,000 rpm in fifth gear while accelerating, it kind of feels like when your carburators are affected by elevation, the rpms are there and can rise, just no engine power. If any of you have experienced that, that is what it feels like. I was wondering if it could be either floating valves, possibly an rpm related electrical spark issue, or maybe a carburator/V-Boost issue? The bike is in otherwise good health and is well looked after, it currently has 64K miles on the odometer. I ride it hard but I don't beat it. It is however getting older and I was wondering if any of you folks had ever experienced similar or have any ideas.

Much appreciated,

Chas

I think it's clutch slippage, from the symptoms you decribe. My Venture was acting similarly, seemed it had an automatic transmission in 4th and 5th when grabbing a handful to move into the fast lane on the freeway. The revs would pick up, but the speedo didn't move up near as fast. I replaced the friction plates, and the problem was lessened somewhat. Sooo...I went back in and replaced the spring...no more slippage! I believe just putting in a new spring would have eliminated the problem. My Max slips a bit in the higher gears when really getting on it, so I will be fixing that this winter.

The diaphragm spring is relatively cheap, and simple to replace! It took me about an hour, mostly due to scraping off the old gasket, removing & replacing the footpeg. Is good to have a torque wrench for re-assembly!

I've noticed that same thing my '2000 vmax, but ONLY in high gear with vboost switch on at slightly slower speeds and wide open, feels just like the clutch slipping then gradually hooking back up.. personally I don't mide as long as it don't do it in the lower gear higher speed like dragging style acceleration, which it doesn't. I love spanking my buddys 22k victory with a 280 rear tire.. Or better yet the tricked out Vrod (P.O.S.) with an extra 10k of performance parts that barly pushes 105hp...LOL

BikerJ0e wrote:


BikerJoe,

You make it sound so easy. I am mechanically inclined, built my old Mopar engine from the ground up. I just don't usually mess with motorcycle engines and usually not transmissions. I have an old VMAX manual I down loaded off of the Internet a few years back. Is this something I should try or just take it to the dealer. I would like to save the money if it is something I could do myself. So you are pretty sure that is what the problem is?

Thanks,

Chas

Chas

I'm a shade-tree mechanic myself, and found it very simple. I used VMOA discount to get a new spring from University Motors in Fargo. They are great people to work with on the phone, and sell for just a bit above cost (10% I believe).

This site has a lot of info on it, but the article deals with complete replacement: [url=http://vmax.lvlhead.com/tips/clutch.htm]

Basically, just lean bike on side stand, remove right rider footpeg & brake lever, remove clutch cover screws and cover. There are 6 bolts that hold the spring in place, just take them out and replace the spring.

I punched holes in a cardboard template and plced the cover screws in it as i removed them (to keep them arranged in the order they go back in, as a couple are different lengths).
It's good to have a new gasket on hand, the old one will undoubtedly come apart, and I put a thin layer of Yamabond gasket sealer on one side of it when i put all back together.

You will want a torque wrench for sure, as the bolts torque to about 7 ft.lbs, you don't want to strip out the aluminum they thread into!

I was careful not to let any crud fall into the open motor. Didn't loose a drop of oil during the procedure (bike on side stand).

I can't see an honest shop charging more than 90 minutes for the job, but they all seem to have "adders" for rags, disposal, etc.

The only scarey part is being sure you don't over-tighten the fasteners!

Karma for you Joe, very nice help!

I'm not a mechanic, but if revs are going up and speed isn't...either the back tire or the clutch is slipping. I first noticed the issue in 5th gear, but over a summer it became noticeable in 4th and 3rd. Ventures and Maxes are notorious for this problem. Some owners have even put 2 springs in, the "double-D" mod.

It is a simple procedure, you can do it for sure. You're not out much if that wasn't the problem.

It worked for me. Of course it's always good to research stuff like this, and get others' opinions!!!

Thanks Bad! I'm sure anxious to ride my 09. I've never ridden a bike with a clutch designed to slip LOL

BikerJ0e wrote:


SAme here!

mustangfe wrote:


Who ever modded that vrod was a fool. Ive personally seen those bikes put over 160 HP to the ground with the right mods and dyno tuner.