Hi all this is my first time posting here and I need your help. I have a 2000 Road Star that I purchased (used) a couple of months ago with 17,000 miles on it. The bike has all kinds of performance mods added to it like the Dyna 3000, K&N BAK + Rejet, Big BUB jug hugger drag pipes with tips. I have not had the engine apart so I dont know if the engine has custom cams or had any modifications to the engine itself.
When I first purchased the bike it ran very smooth for a big bike and especially when I found out it's engine has no rubber mounts. After riding the bike for a few weeks I started finding little routine maintenance things to fix like a clutch cable, oil change, gear oil, etc.

The vibration issue started on a 2 hour ride one night down the beach. When I started the ride the bike was running great and by the time I arrived home again I had this nasty vibration around 1800rpm.
I tried everything I knew to find the culprit. I took the bike in to a Yamaha mechanic and had him sit on the bike and rev the engine to 1800rpm and he could feel it himself. He took it for a test ride and could feel it, but after an hour and a half of labor cost his final verdict was it's a Road Star and they vibrate. The only thing he told me that he said would fix the issue was to put different pipes on the bike.
I know at this point it's something with the engine because I can sit in neutral not moving and rev the engine slowly up to 1800 and feel it throughout the entire bike. The headlight shakes so violently that Im afraid it going to shake itself off. The bars shake so bad you cant see the mirrors, The seat vibrates so bad your butt goes numb. It's become very uncomfortable to ride the bike not to mention it's in my head and bugging the crap out of me.

I know these bikes vibrate, but not to the point it hurts. It only occurs at 1800 rpm and no where else on the power curve. It just so happens that 1800rpm is where I spend a lot of time cruising on the back roads.

Can the short drag pipes really cause things like this? I'm afraid to take the mechanics advice and put a different set of pipes on there because I'm afraid I'll spend money on pipes and it wont fix the problem.

Also, I checked the Dyna3000 settings and everything is set correctly with that. I have reached the end on my line and cant think of anything else to do. All I know is this issue just started recently and it's not normal no matter how much the Yamaha guy trys to pass it off as normal.

Any help would be greatly appreciated guys. Thanks

Here is a pic of my bike


Post edited by: Snacky, at: 2005/05/31 10:55

Post edited by: Snacky, at: 2005/05/31 10:55<br><br>Post edited by: GRAM, at: 2005/05/31 15:06

Every Road Star has a vibration at approximately the RPM you are speaking of. It roughly correlates to the torque peak of the bike, as it occurs just below it.

Since torque peaks are different for just about every Road Star, the rpm range of this vibration is slightly different for every bike.

With EGA testing, I also saw another correlation. One that tends to explain the problem. On 99% of the Road Stars I have tested, there is a large difference in EGA values between the front and rear cylinders RIGHT where the vibration is worst. Above that rpm the combustion values even out. Below they get progressively worse coming off of idle and get the very worst at the point of greatest vibration.

Looking at a Road Star, it is opbvious that the intake portions of the mix (air/fuel) path are fairly equivalent. The exhaust seems to be making the same number of turns as well, but the front cylinder exhaust ends up making a complete 180 degree turn from its intake flow direction, where the rear does not. I suspect this may contribute to the problem.

EGA testing shows normal burn characteristics for the rear cylinder. The front cylinders however get very very lean up to and including the largest rpm of that vibration.

This means that the front Cylinder is pushing down on its piston with quite a bit more force (leaner, and more explosive mix in the front). I personally think this is the root of the problem for most of us.

Things that could potentially make this problem worse are things like vacuum leaks in the manifold, and carbon buildup in the rear cylinder's valves (which would make the rear cylinder burn less efficiently and exert even less force).

Hard to tell if this would help from your post, but I think with that number of miles on your bike, there is potential for the rear valves to be a little carboned up. Most jetting guys like to set the pilots a little rich, and given the scenario I have outlined above that would have a greater consequence on the rear cylinder than the front (remember that the front is leaning itself out as soon as you start to open the throttle).

There is a real inexpensive way to try and reduce them, that I have seen work wonders for more than a few bikes with your number of miles on them.

Go to an Auto Parts store and get a bottle of &quot;Marvel Mystery Oil&quot;. Put the Marvel Mystery Oil into a large water spraying bottle (like the cheap ones you can get at any Wal Mart). Start your bike up on the sidestand, in nuetral, with the Air Kit removed.

Start your bike up and get it slightly warmed up, to the point that it will idle without the choke/enricher on.

Spray the Marvel Mystery oil into the carb with the bike running. Too much at any moment will stall the motor, so take your time, and rev the motor mildly through that vibration point and back down to idle again (while spraying). This is easiest to do with two guys working on it.

It will smoke so bad that your neighbors will think your house is on fire (NOT kidding). Keep doing this for about ten to fifteen minutes. If you have carbon built up on any of your valves, you will feel the bike begin to smooth out after about ten minutes or so. If this does anything at all for you, you can be sure you had Carbon buildup. No way to stop it, short of leaning out the jetting too much (like a stock Road Star), but at least we can do something about it.

It would be worth trying for the cost of a bottle of Mystery Oil. I have seen it solve more problems than I ever thought it could.

Also, if this does work, get in the habit of doing a Techron gas shock treatment about every other oil change. It does just about the same thing, on a much smaller scale.

GRAM<br><br>Post edited by: GRAM, at: 2005/05/31 11:59

Wow Gram! that's some good info and thanks a bunch. Your the first person to tell me something that actually makes sense when referring to this issue. I will get some mystery oil this afternoon and try it.
I noticed that the Yamaha manual recommends a valve adjustment at 16,000 miles. Should I go ahead and pay the $300 to get this done?? I am not confident enough to do it myself.
I will report back if the Mystery oil does the trick, thanks again.

Its your call on the Valve adjustment, but with that many miles it would be a good idea. Be sure you do the Mystery Oil first, as any carbon built up around the flange of your valves, or seats, will affect that adjustment.

Also, If this treament helps at all it stands a good chance of fouling your plugs out (from loose carbon particles flowing through your combustion chamber). So if you see a difference after doing it, you might want to change your plugs.

GRAM

Gram, I did the Mystery oil treatment tonight at work just like you directed and the result was my plugs fouled. I had to remove the plugs and clean them then recheck the gap. During the treatment (spraying into the carb) the engine began to sputter and backfire through the intake of the carb as well as the exhaust. I backed off and ran the engine without spraying anything into the Carb but the engine ran really rough. I had a lot of smoke like you discribed but I soon noticed a difference in exhaust temps just by feeling the air with my hand. Rear cylinder started to run Hot and did not have the same amount of air being pushed out while the front cylinder ran cooler with more air being punched out the exhaust pipe.
After i broke everything down and cleaned the plugs the cylinders ran at the same temps and air exhaist. bike sounded much better.

After all this though I still have the same vibration at 1800 rpm. A aircraft mechanic at work said for me to run a little mystery oil in each tank of gas I get from here on out and over a period of time see if I notice the vibration going away. He said it could take a few hundred hours to see the vibration go away. He said after the vibration goes away to run a little mystery oil every other tank of gas or at every oil change.
I am wondering if a valve adjustment might cure the problem. Like you said if carbon is built up on one of the valves that could throw things off.
Would the Yamaha shop be able to clean the valves when they adjust them? or does this involve breaking down the engine completely?

I will continue to run a couple of caps full of mystery oil with each tank of gas and see what happens.

btw- The aircraft Mechanic I had look at the bike today at work is an old Harley guy and been working on aircraft engines his whole life. Even he said there was definantly something wrong and it felt like the cylinders were out of sync in some way. He agreed with you Gram that it could very well be a valve issue.

Post edited by: Snacky, at: 2005/05/31 23:00<br><br>Post edited by: Snacky, at: 2005/05/31 23:06

I just wanted to give a little update on my situation. On a hunch I took my BUB Stubbies off and inspected them. What I found was pretty interesting. Mounted inside the bottom pipe (front cylinder) was a venturi ( I guess it's called a torque cone?). Anyway, there wasn't one of these in the top pipe (rear cylinder) so immediately I start thinking about back pressure and the difference between the two pipes and how that missing venturi could cause a imbalance. It turns out the other venturi piece had popped loose somehow and made its way up toward the front of the pipe closer to the exhaust port. I remounted it to the rear of the pipe just like the other one and reattached the pipes and tightened everything down. Since doing this the bike has run a little better and feels more in tune. The vibration is still there at 1800rpm but it's not as annoying as it was before. It could be a combination of running some mystery oil with my fuel and finding the venturi issue, but so far the bike is riding much smoother than before. Thanks for all the help

Looks like you found the primary offender Snacky

Thanks for the follow up!

GRAM

Gram, just wanted to let ya know I have been running the Mystery oil with each tank of gas and even after finding the the part in the pipe and fixing that I still get the vibration. For a little while it looked like the bike was smoothing out, but what I found out was as I ride the bike seems to loosen up and the vibration kicks in.
When I first start up the bike and during the first few miles the bike feels pretty good, but after a few miles and the bike warms up it vibrates more and more.
I am dumbfounded by this and cannot figure out whatelse to do. I am considering selling the bike because of it and finding something more comfortable. I was considering putting some different pipes on the bike, but I honestly dont feel thats the problem and even with the pipes off I can feel the vibration kick in. It's just not magnified by the pipes at that point.
I talked to another Road Star owner over the weekend and he says he doesn't get any kind of vibration. I sat on his bike in neutral and revved it up past 2000 rpm and nothing. He sat on mine, revved it up and said &quot;Ouch!&quot; lol He is amazed I keep my hands from going numb. I told him they do go numb.lol

I posted earlier and said I think I found the problem, but I posted before letting the bike warm up.lol
I did not get the valve adjustment done yet, but that will probably be my last thing I try before selling it and getting a moped or something.lol

From all you have posted, I would really look hard at trying a different set of pipes, even stockers. You may have a set of pipes built on a Monday after a three day weekend. Would be a shame to let an aftermarket part make you sell one of the best cruisers made.

There is actually a scenario where your jetting could be causing this Snacky.

Once it is warmed up, and the vibration is going full blast, try holding the throttle at he worst point of vibration and see if your choke/enricher has any effect on it. Try everything from a very slight engagement of the choke to full on and see what happens. If it has an effect, you might be able to adjust your jetting to compensate.

Road Star front cylinder lean up real bad close to the RPM you are estimating. If one cylinder is lean, it is getting a more explosive mix (also hotter). There is a point on this spectrum where you could have a very explosive mix in the front cylinder, and one that is too rich on the rear. If the choke does anything to smooth it out, you should be able to move your clip on your needle down (closer to the tip) to compensate for the problem.

If you know your settings for your bike, you might want to post them.

Manifold (ported or stock)
Needle brand and clip position
Main jet size and brand (if you know the brand)
PMS setting

GRAM