Evo engine vibration.......ugh..again!!

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Aug 28, 2020 | 02:30 PM

#31

1340beaver

6th Gear

Joined: Aug 2020

Posts: 11

Likes: 0

From: Yorkshire

Quote:

Originally Posted by 1997bagger

If your a engineer then rattles, vibrations and some road wagging is going to drive you crazy, Tequila usually helps.

Alignment can cause engine vibrations due to binding up the engine mounts instead of floating freely, laser levels on the rotors with beams projected onto the ground comparing the 2 together but the rear wheel is offset to the left for some strange reason but this the process they use, gets timely and expensive. So many non simple hidden items on a Harley come to life, wish you well on this repair

yup, done all that.. I have a wider back wheel and chain drive, but tested the lot.. make the mounts lose, let it settle and so on.. its in line... the reason its out if I'm honest.. my BMW GS is in for some work doing... bay be I've just got too used to the Bema and zero vibes

Aug 28, 2020 | 05:13 PM

#32

98hotrodfatboy

Seasoned HDF Member

Joined: Mar 2010

Posts: 21,093

Likes: 7,622

From: Poolville

Sorry sometime auto spell gets in the way..... Shouldn't... Their to picky... We're not going to the moon.... Just cruising down some 2 lane blacktop..

Aug 28, 2020 | 06:12 PM

#33

Mattbastard

Grand HDF Member

Joined: Nov 2009

Posts: 4,315

Likes: 1,663

From: Tampa

Quote:

Originally Posted by 1340beaver

yes, but I'm an Engineer and like things to be right (or at least better) than they are LOL... things like this just drive the **** out of me until I fix em.

Will try live with it.. but it may be in bits before long if I can't

Ok, you're an engineer, so am I. My first Harley was a 1996 Sportster. Rigidly mounted engine to the chassis would buzz the hell out of my hands at anything above 65 mph. I researched the hell out of a fix and the only thing I could come up with to make the vibrations go away was get a Dyna, or a 2004 and later Sportster because that's when they went rubbermounted. Undeterred I gave Darkhorse over $800 to rebuild and balance my crank to the pistons I had. What did it to? Maybe make the vibrations a little bit less but they were by no means gone. The only real fix was put the vibes up past my highway speeds with a 55T rear pulley, but then I lost a lot of torque out of the hole. I ended up just selling the bike because much of my riding was on interstates.

If you decide to research it you'll eventually come across something called the difference between primary balance and secondary balance. The reason the 45 degree V-twin can NEVER be in perfectly smooth balance at ALL rev ranges is because of this. It's exactly why the Twin Cam Softail went to counterbalancers, and the Touring, Dyna, and Sportster models are all rubbermounted engines.

Also, everyone who says their Evo is smooth is either never going faster than 60 mph, have a lot of nerve damage in their hands, or full of ****.

Aug 28, 2020 | 07:43 PM

#34

1997bagger

Seasoned HDF Member

Joined: Aug 2008

Posts: 5,080

Likes: 2,152

From: Ohio

Quote:

Originally Posted by 1340beaver

I'm sure its my crank, I measure through the timing hole a bit back and measured 0.40mm on the edge of the fly, so thinking it may be twisted?... but if it was it would not be good 1000-200 and 2500 to 5000... top end its like silk

Evo's don't have any problems with the crank twisting, they just break ask Hotrod. If the crank was out it would be a paint mixer with more RPM's. If your crank is damage you can do the run out test on the cam sensor side like a TC and not guess before splitting cases.
Something as stupid as a exhaust muffler not sliding in the rubber mount can vibrate bad enough to break air cleaner support brackets. Is the bike properly tuned, is the primary chain stretched and too tight, you have a chain final is it set for the weight of a rider changing riding height.
You may want to ride a Shovelhead for a while and jump back on your bike, you'll be ok with vibration then. lol

Aug 28, 2020 | 07:54 PM

#35

Roadghost

Road Warrior

Joined: Jul 2014

Posts: 1,479

Likes: 638

From: Up North

It's because it's not a counterbalanced engine. It's supposed to shake. If it doesn't, it's not a real Harley.

Aug 29, 2020 | 02:47 AM

#36

1340beaver

6th Gear

Joined: Aug 2020

Posts: 11

Likes: 0

From: Yorkshire

Ive had lots of pre-rubber Spoties and my last big HD was a Shovel, all better that this. over the lets say 500 rpm band where it is, its quite harsh for sure. Its RPM related so it's not after the clutch. its sure as hell not a buzz...
I'm checking the voes works right today as it around the point that happend... I'll check the spark, and it can backfire a tad on over run but thats with the silencers in so will take them out see if it reducec...

but it literaly can shake my feet off the pegs it i hold it there.....

What about measuring the side of the fly through the timing hole... I get 0.4mm TIR... anyone know about this

Aug 29, 2020 | 06:16 PM

#37

Mattbastard

Grand HDF Member

Joined: Nov 2009

Posts: 4,315

Likes: 1,663

From: Tampa

At that rev range the oscillation of the engine is combined with a spring action of the isolators which exacerbates the vibration you feel in the bike. That hardness of the rubber in the isolators is designed to allow smoothness at specific ranges without allowing the engine to flop all over the place at lower RPMs, and if Harley engineers did their job they went with a certain hardness such that at cruising RPM ranges the isolators absorb the engine vibrations, not multiply them. Is your bike smooth at 3000 rpm?

It's PHYSICS, and unless your isolator is so worn out the engine is bouncing off the frame you're just hunting for an issue that doesn't exist.

Aug 30, 2020 | 12:54 AM

#38

Beemervet

Ultimate HDF Member

Joined: May 2006

Posts: 6,590

Likes: 444

From: Ohio

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Aug 30, 2020 | 01:32 AM

#39

Sharkymcmetalmouth

6th Gear

Joined: Jun 2020

Posts: 12

Likes: 1

From: Centralia, IL

Quote:

Originally Posted by 1340beaver

To what extent? my feet kind of vibe off the pegs and it can make your eyes blur if you hold it there.. but the bars and mirror is fine?
Was reading this last night in bed (sad I know)... but does sound interesting

http://granbygarage.com/gilroy/techi...0Balancing.pdf

If I held it in that range where it vibrates, it would be a miserable ride for sure. But if I drop below or above that range everything smooths out nicely and I have no issues.

The only time I really notice it is when I'm slowing to turn or if I'm moving through town traffic and I'm slowly accelerating.

But as I said before I'm never in that range for long and my bike is completely stock and only has about 14,600 miles on it.

Initially, I thought it might be exhaust issues but after looking everything over and not seeing any glaringly obvious issues, I believe it's just a quirk of having an older Evo.

I'm not too concerned about it, I've just been checking my critical fasteners a bit more often and making sure I blue loctite the bolts I don't want falling off.

and I guess as a disclaimer, I'm not a mechanic, I'm just military trash that enjoys riding Harleys and trying to keep them running myself.

Aug 30, 2020 | 03:10 PM

#40

1340beaver

6th Gear

Joined: Aug 2020

Posts: 11

Likes: 0

From: Yorkshire

Well, i set my timing today (34 deg all out), and it goes well Ive got to say. And as you point out at cruse speed its not a problem. think my problem is around town at 30 and 40 mph. its best to ride under the vibes, but then from 40 in 4th to get through the vibes isnt that bad I guess. In 5th I'm kind of okay by 65 / 70 mph so can cruise at this all day and above....
I've just come back from a 30 mile test ride and feel just a little tingley....
See how she goes then.. if they are all the same

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