Hi guys,

Well I've been putting up with excessive vibration now for some time with my 81 / 80" shovel. Riding the twisties and normal riding is ok but when I get on a h/way and open it up to 110kph it vibrates like nothing else. Looks like I've got 4 mirrors and the tank dash unit is vibrating like crazy. I usually back off to around 100 - 105 and watch my mates roll away. 

I noticed recently when I adjusted the pushrods that the front exhaust rod had a very slight bend in it. Bike came like that, no doubt incorrect adjustment by someone else prior to me buying the bike, 12 months ago. 

Would that very slight bent rod be enough to cause the vibration at speed that I am encountering? Or would it be something far worse like an unbalanced flywheel? WTF, how does a flywheel become unbalanced?

I can eliminate tank clearance and caliper bushes: About 6 months or so ago, I remember adjusting the fuel tank up as much as i could because it was almost resting on the top of the motor (front). I've checked and it still has clearance, just. Plus I had new bushes replaced in the front forks where the calipers are attached, so all good there. 

Any feedback or comments would be appreciated, thanks.

 

Lots more to check,.....steering head bearing, motor and tranny mounts, swing arm bushes, wheel axles..ect ect.

I would also replace that bent pushrod.

Hi Bob, I replaced the steering head bearing already, checked motor / box mounts for torque (all good), haven't done or checked swing arm bushes, I have replaced axles and bearings. Thanks 

Have purchased a new set of rods which I am going to do soon.

did the bike vibrate like this before, or is this a rebuild that ya just got going?

Hey Bob, well it did vibrate before but I think that was because the front rocker cover had the tank bracket resting on it. Shit design in my opinion.
Come to think of it, when I did lift the tank, it still vibrated but not as bad.

Just came back from a ride and can definitely put it down to an engine issue as opposed to the frame, bearings, bushes, front end etc.
I noticed when I revved it to 2,800 in 3rd gear it would also vibrate. Going to change the push rods tmrw and see how I go.

Bike was a barn find about a year ago, it had a hard life for some time with very little attention given to it. Cost me a bomb so far (but worth it).

Hey Dave, 

Are you referring to the bracket that holds the tank on the underside at the front, or the top one.....or the bracket between the pots at the top (red arrow in the pic)?

 

 

I had an 79 fxef with a snapped top mount exactly as KiwiDave points out.

my guess would be that top mount cracked too the red arrow one, happens a lot.

So I pulled off one tank tonight. Bugger me, the top engine mount bolt was as loose as. 

Going to replace the bolt with a new one. Looking forward to winding the old girl out and moreso just looking at one pair of mirrors and enjoying speed again.

Thanks for the heads up and comments fellas, much appreciated.

 

Good to hear you found an easy solution. With my shovel, I go around and check/tighten bolts and nuts on a regular basis. Remember, Loctite is your friend.Its just the nature of the beast.

Well I fitted the new top engine mount bolt then took the old girl out onto the h/way and got her up to speed. It was quite noticeble the difference going through the gears, enjoyable to say the least.

I did however find it still throwing out some vibration at 2,800rpm and above. Nowhere near as before but its still there. Wondering if I've now got 'normal' shovel vibration or do the members here cruise at speed with next to nothing.

Cheers 

Well I fitted the new top engine mount bolt then took the old girl out onto the h/way and got her up to speed. It was quite noticeble the difference going through the gears, enjoyable to say the least.

I did however find it still throwing out some vibration at 2,800rpm and above. Nowhere near as before but its still there. Wondering if I've now got 'normal' shovel vibration or do the members here cruise at speed with next to nothing.

Cheers 

no mate, that's it, they buzz.

Even though 110km/h don't seem like a lot, a stock shovel runs best up to about 100 (unless you start tweaking it) - I've had my bike chewing along with full packing and passenger @ 180km/h pretty much stock (apart from changing the engine sprocket * see below) but vibrations comes and goes - I do not encourage you to ride a -81 shovel on these speeds though - things WILL come off and vibrations is normal - there's a few things you can do to improve things though (assuming there's no other issues with bearings, frame, wheel alignment, engine balance * such as the non aligned pushrods etc) ...

I had my -81 shovel since new and one of the first small things I did to improve vibrations were to change the engine sprocket (alt rear sprocket = your choice)

This made a biiig difference to it while being brand new

With this setup I still experienced excessive vibrations at some speeds, but it also disappeared at higher speeds

The latest thing I did to get rid of most of these issues were to upgrade the cam to an Andrews J-grind (.405 lift that require no mods to the rest of the engine) along with replacing the stock ignition module for a crane HI-4N and a Crane single fire coil

Perhaps worth mention that I also threw out the primary chain and replaced it with a Primo belt (closed trans cover (pretty much bolt on) - saved a lot of weight and other hassles *and oil leaks " border="0" src="/DesktopModules/NTForums/themes/_default/emoticons/smile.gif" />
I also got rid of the hydraulic lifters - replaced with S&S solids (again saves time and hassle)

All up, this have made a 100% improvement overall - I still have vibrations - this is normal - but I can ride very comfortable at much higher speed without loosing half of my bike or being forced to go over the entire bike after a run tighten every single nut and bolt " border="0" src="/DesktopModules/NTForums/themes/_default/emoticons/smile.gif" /> - still things drops off or breaks on occasion - its normal
If you want you bike to last as long as I had mine, you need to ride it at a more gentle speeds - my ideal cruse speed sits between 90 - 110 (going over this for a long time gets a bit painful over time and the chance that things will break increases 10 by an exponent of 10#)

Do yourself a favor and keep it gentle and you'll enjoy 35 more years * - regular maintenance is a given though

Great that you found the issue. What gearing are you running on your tranny and rear sprocket. Taller gearing will mean lower rpm's at highway speed and less vibration.