View Full Version : Supermeg and Vibration

10-15-2008, 07:11 PM
Just wondering if anyone else has experienced more vibration with a Supermeg 2-1 on a touring HD. I installed a 2-1 a month or so ago and was trying to eliminate a vibration issue that was felt between 2200-2500 rpm. Tried removing and adding discs, running open and closed end caps, changed motor mount etc., all with no real diference. Finally put the stock headers and mufflers back on and the vibration is much less. It is still present but no as pronounced and at the same rpm range. Also a lot more vibration with the 2-1 compared to the stock set-up while ideling in neutral. Last set of pipes before the 2-1 was V&H True Duals with Cycle Shack Slip-ons and I didn't feel any vibration with those pipes/mufflers.

So I assume the vibration is just something inherent in my engine and with the 2-1 and modified stock 2-1 it is more perceptable than with a True Dual setup.

Anyone else found this to be true and do you know anything that can be done to reduce the vibration? The motor is otherwise stock at 88" with carb rejet and aftermarket air filter and backing plate.

10-16-2008, 08:38 AM
Have you tried going back to stock or milder jetting? The jetting required for the true dual set up may be a little much for the stock or 2:1 headpipe combos.
The pilot jet may be involved with the idling issue. Was timing changed for the true duals?

10-16-2008, 07:21 PM

I have not changed the jetting nor the ignition. It has the stock non-adjustable ignition. Jetting is kinda basic for stage 1 bikes. The more I think about it and the more I research, I think it may be an internal problem with my motor. Possible flywheel/crankshaft issue because it runs great with no hesitation, spits, sputters, coughs etc. and the vibration is present at the same rpm range regardless of the pipe (stock or Supermeg) used.

I talked with the delaer today about checking crank issues and was told to "just ride it" as the expense to tear it down just to check for a problem is cost prohibitive. Since no one else has experienced anything similar (a lot of guys have the Supermeg on the web group I frequent) I really think it is the motor and will just ride it and see where it goes.

10-22-2008, 08:52 PM
Just read in the last thread about crushing the diffuser discs when torquing more than the 15 in-lbs. I definately tightened mine down a lot more than 15 in-lbs, probably more like 5-7 ft-lbs.

I bought the pipe used, as well as one for my wife's softail. Both seemed a lot tighter than 15 in-lbs when I first removed the screws to change the number of discs and I just tightened back to where I thought they were without reading any torque specs.'

No doubt I have crushed some or all of the discs and possibly they may have been crushed when I got them used to begin with. Anyway, I just ordered 3 sets of 12 and replace all of them on both bikes.

Any possibility that if crushed, the increased exhaust restriction could be a contributing factor to my vibration issue? I only bring it up because the True Duals with Cycle Shack Slip-ons was not restrictive at all and I didn't feel any specific vibration with that set-up. The stock is suppose to be very restrictive and I felt some vibration when I put those pipes back on. Assuming the discs are ruined, just wondering if possibly the Supermeg with closed end cap and only one outlet is as, or more, restrictive than the stock mufflers with 2 outlets and thus the reason I feel more vibration with that pipe.

The new discs should arrive in a few days and I'll know either way.

11-20-2008, 09:45 PM
Just an update and finally an answer to my vibration problem. Got the new discs installed and no change. Finally broke down and took it in to the dealer. They were convinced my crank was bad but checked the runout and it was only 0.002, so well within spec. They looked at everything and noticed the aftermarket engine guard I had seemed to vibrate more than the stock guard on a similar bike so they took it off and no more vibration at all.

Ok so why did the guard that had been on the bike for 18K miles only start vibrating after I installed the Supermeg? The engine guard has built-in footrests that can either be folded out or can be stowed in to provide 2 different foot positions. I knew the guard had always had some vibration but it never was felt in the frame like I felt it after swapping to the 2-1. When the footrests were folded in they would vibrate along with the guard itself and after 18K miles they began to rattle when they vibrated.

Well here's the deal and I feel like a fool for the time, energy and $$ wasted trying to "fix" the problem. I installed the 2-1 and rode the bike maybe 10 miles and didn't notice anything unusual. Then about a week later and not having ridden the bike since the 2-1 was installed, I headed out of town for some mountain riding. Just before pulling out of the driveway I decided to tape the footests down in a secured position so they wouldn't rattle. Two pieces of electrical tape on each side and they were secure. So off I go and after riding 250 miles on the interstate at high speed (above 3000 rpm) we pulled off on a 2 lane mountian road and that is when I really remember feeling the vibration at 22-2500 rpms. When I got home from that trip (about 1000 miles) I began my search to find the problem which I thought was pipe related. Efforts included, removing and replacing the 2-1 several times, putting the stock pipes back on, changing the front motor mount, checking the torque specs and integrity of all motor and frame mounting points, playing with the number of discs, and finally taking it to the dealer under the assumption that I had an internal engine problem. Funny thing is that when the tech rode it, he had a co-worker ride it as well and he called me to let me know they too thought it was the crank and wanted my authorization (let me know it would be $) to check the runout. When that was found to be in spec they started looking elsewhere and noticed the excessive vibration with the guard - which I knew had been vibrating like that since it was installed 18K miles ago - and why I never suspected it as a possible cause. Once the guard was removed no more vibration. Put the guard back on and the vibration returned, removed the tape securing the footrests in their secured position and no more vibration. For some reason when the footrests were secred and not allowed to vibrate independently from the guard itself, the vibration was transmitted through the frame in some sort of harmonic way with a peak resonance at about 2300 rpms.

It had absolutely nothing to do with the pipe and everything to do with the 4 pieces of 6" strands of electrical tape. All along I was thinking it's gotta be the last thing I did because it wasn't vibrating until I put the 2-1 Supermeg on. It had absolutely nothing to do with the pipe! Yet I was fixiated with the pipe since I thought that was the last change I made when in reality the LAST change was adding those pieces of tape to get rid of a high pitched rattle that had been present for some time but recently got worse during a 5400 mile cross county trip we did this summer.

At least now I know my crank is good and I can finally say without reservations - I love this pipe! And I can't wait to do more extended trips without having to wear earplugs or turn the radio on full volume to hear the music over the loud pipes that the Supermeg replaced.

11-21-2008, 07:34 AM
That's a very good story, thanks for sharing it with us. I'm glad you found the problem AND you're enjoying the pipe and your bike again =)

11-25-2008, 04:06 PM
I can assume that over torquing the screws holding the disc's in can and will flatten them, thereby altering exhaust flow?

Oooops............ my bad!

Time for new ones I guess.....

11-26-2008, 07:15 AM
Yes, only 15 INCH pounds. After the discs are seated, another 1.5-2 turns should be more than enough. You can order the disc packs at our online store or Summit Racing is another good source for our Universal components & accessories;