engine vibrations

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23 Mar 2022 20:06 #864249 by woodyvale
engine vibrations was created by woodyvale
Might be a daft question, but how 'buzzy' is normalish for one of these engines.

I'm gradually putting more miles on my rebuilt GPz11 unitrak and getting used to how it rides again.
It revs well and seems to perform pretty well but it certainly seems to be pretty 'buzzy' as I'm rolling along.

Mirrors and levers vibrate, fairing buzzes, pillion footpegs vibrate when the bikes revved and so on. I realise its getting on for 40 years old now so I'm not trying to compare it with newer machinery but I wouldn't describe it as 'smooth'.

Its had all the engine mount rubbers replaced for new and all the bolts are tight.
Throttle bodies balanced
Rebored to first oversize with wiseco pistons
New camchain

Just trying to rule out any dramas with the motor that are in effect just the way they are. I never had one of these bikes when I was younger so don't have a reference point when they were new.

So does yours vibrate much - ooo er! 

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23 Mar 2022 20:29 #864250 by Ojisan rider
Replied by Ojisan rider on topic engine vibrations
From what I can remember, I didn't feel any vibration from my bike, which is smaller 750. I did have some vibration from tires been old (No thread at center of the tires. I think PO didn't know how to ride). What I mean is that I didn't feel I had enough vibration on mirror or the handlebar. I had a chance to ride friends Ninja 600 and Rebel 250 and I was surprised just how much the bike vibrates. 600 had enough small vibration that my hands were numbed after maybe about 15 minutes into the ride. Rebel 250 was even worse. My feet felt like f someone was tickling me.

I also have 89' ZX-7 but never had any problem with vibration. But that bike has less than 3500 miles on it, even to this day (I'm restoring it to ridable condition now along with my KZ).

But then just like exhaust, one man's loud is another man's music. So I or you may feel it differently. But then again, you have a bigger bike.

82' KZ750-R1 cafe racer style. Clip-on, Rear set, Fork-Brace, Mikuni Flat-slide (forgot the size), Kerker.
84' GPz750 (basket case). everything are in pieces.
89' ZX750-H1 (ZX-7 Ninja). Resurrection project are on going with my KZ750. Everything is stock.

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23 Mar 2022 20:34 #864251 by RonKZ650
Replied by RonKZ650 on topic engine vibrations
I had a new GPZ1100 in 1982. The only vibes were right at 50mph in 5th gear, and whatever that RPM was in lower gears as well. It should be smooth without hardly any vibration at most speeds from the rubber mounts.

321,000 miles on KZ's that I can remember. Not going to see any more.

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24 Mar 2022 02:50 #864257 by Scirocco
Replied by Scirocco on topic engine vibrations
GPZ1100 UT cranks are known to get twist and out of balance.

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30 Mar 2022 13:59 #864553 by DFIGPZ
Replied by DFIGPZ on topic engine vibrations
yep common problem on GPZ1100 than and thrust bearing failure , my 84 GPZ1100 only has 14k miles and it had the dreaded thrust bearing failure , I installed a NOS Crank after having sent to pearson and having needle thrust bearing installed the trued & welded,done many in shop days under warranty .

1984 750 Turbo

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06 Apr 2022 05:53 #865033 by daveo
Replied by daveo on topic engine vibrations
Anyone know what percent of ZX1100A (83-85) engines had these crank problems, and were the ZN1100 engines plagued by them as well?

1982 KZ1100-A2

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06 Apr 2022 21:05 #865070 by woodyvale
Replied by woodyvale on topic engine vibrations
What would common symptoms be of an out of true crank or thrust bearing failure. Knocking from the bottom end?

Mine seems pretty quiet.

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