Vibration during acceleration

[lvsloan1]

Hello, I am new to the trike world as of 1 month ago & I was needing a little info. I have a 1990 Yamaha Venture Royale that was triked w/ a Motortrike conversion around 1996 & has a 7.5 ford differential like the small mustangs had. My trike has 63,000 miles on it but was the only trike my wife & I was able to get due to our income, but sounds great mechanically as far as the engine, etc. My concern is when I am in 5th gear going around 40 M.P.H. & give it throttle to get back up to highway speeds, we have a vibration that lasts until we get to our designated speed (70 - 75 M.P.H.), THEN THE TRIKE IS SMOOTH @ any steady speed. Only have the vibration during acceleration.I think maybe the rear u-joint may have something to do w/ it as there is a very small amount of slack, not in the u-joint itself, but up & down inside the yoke where the caps rest. I greased the u-joint & the caps expanded a little but may still have a little movement but is so small I can't detect any. I know I can remove the driveshaft & check the u-joints properly but can't find a socket thin walled enough to get on the bolts cause the yoke ears are so close regardless which way I turn the shaft. Anyone think I am on the right track of locating the acceleration vibration? I even wondered if the driveline was timed wrong, maybe a turn or so off but can't get on the rear bolts to remove the driveline to try that. I talked w/ a man who does Motortrike conversions but he could only suggest these things that he was familiar w/ on the Goldwing since Motortrike doesn't offer a kit for the Yamaha since he has been in business in 2004.

Any help appreciated &amp; want to let ya'll know that this forum has already got me hooked as some of the things I have read have already helped! Anxious to get enough experience w/ my trike so I can help someone out in the future.<img src="images/smilies/shrug.gif" border="0" alt="" title="Shrug" class="inlineimg" />

[Bikerbozo]

If you want a thinner walled socket, just put it to a belt sander. Grind it down until it fits.

[slick rick]

.......If it got better after filling the cups with grease your on the right track....

[Baz]

Do you think you maybe lugging the engine a little ? 40 mph sounds to be far too slow to be in 5th gear. Drop it into 5th at say 50mph to see if the issue persists.

[Marc H]

Do you think you maybe lugging the engine a little ? 40 mph sounds to be far too slow to be in 5th gear. Drop it into 5th at say 50mph to see if the issue persists.

I tend to agree.At 40 in 5th you are lugging the engine.Thats why its smooth at 70.Try hitting the gas in 3rd or 4th at 40 and see if you have a vibration then.

[bongobobny]

Yup! Ventures like higher RPM's! Their power band isn't until the 4000 to 5000 RPM range! Try getting up to 60 before shifting into 5th and see if the vibration is gone or still there. There are several issues that can cause the vibration such as a dried out front universal joint, dry splines there, or possible clutch issues.<br />
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Come join us at venturerider.org for lots of technical info on Ventures as well as a great bunch of people there...

[lvsloan1]

Thanks everyone for the MUCH APPRECIATED HELP! When I accelerate in 2nd, 3rd, or 4th I can still feel the vibration but not as bad as when I lug it in 5th. When we got back from a round trip of 805 miles, the vibration cause me to lose a nut off the bottom of the radio handle in front of the cassette player. Since this was my first Yamaha 1300 w/ 63,000 miles on it, I was a little afraid of winding it too far. I have however, went to Amsoil synthetic 10W/40 in the engine & Amsoil 75w/90 synthetic in the rear differential. I'll remove the driveline and check the front u-joint also and lub the splines. AGAIN, THANKS TO ALL!

[bongobobny]

You can over rev these bikes, they have no rev limiter on them. Watch your tach though, they can handle 9000 without flying apart. You want to be around 5 - 6K when you shift. Shift out of first around 15 -20, 2nd around 35 - 40, 3rd around 50, 4th around 60 for the bike, but with the gearing on the conversion you might want to cut it back a few MPH.

[lvsloan1]

Thanks for that info on tach RPMs. Because of the 63000 miles on the trike & the fact that it has sit for a year w/o being rode, I was afraid of rerving it that much. I knew the redline shows on the tach to start @ 7000 & also I try to get better fuel mileage when I ride as it only gets about 24.5 MPG w/ the stock exhaust & air filter. Guess I'll work on this trike for awhile to get it all back in shape & REALLY APPRECIATE this info.

[bongobobny]

Yes, your real issue could be a multitude of things ranging from need for a carb sync, bad plug and/or wires, small vacuum leak, etc. Once you get it running right these are real beasts!! It is nothing to pop a wheelie with a 1st gen Venture!<br />
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For the carbs, try a treatment of Seafoam. 1/2 can per tankful and drive it like you stole it! After that I would then recommend a new set of plugs, and I also would not trust 20+ year old plug wires. There is a proper procedure for syncing the carbs. There are several members of both Venturers and ventureriders that are very proficient at this, and it makes your MPG go up and run cooler as well...

[lvsloan1]

THANKS bongobobny! Once again you have helped me have some things to do to improve this trikes performance. I KNOW it needs plugs & once I can afford it, I want to replace the plug wires. I can rev it in neutral & hold a steady 3000 RPM & I can hear a small stumble or miss pretty steady but is smooth @ an idle. That also tells me I probably have a higher resistance in the plug wires than the specs allow adding to this small misfire. I will check around this small town to see if anyone sells Seafoam but will probably have to go to Lubbock to get it. Well until later, have a great day & THANKS AGAIN for the help!
P.S. I want to sync my own carbs. If I can locate the procedure & feel I can do it, I will. Otherwise I will have to wait to get the money to take it to a Yamaha shop.