cam drive gears

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rigsby
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Bike owned: NC 30, gsxr slingshot, benelli
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cam drive gears

Post by rigsby » Mon Feb 05, 2018 11:12 pm

I have nearly completed my engine rebuild, the cam drive gears have had the quietner gears removed and the pins have been tack welded back into place. The gears are the original ones that were always fitted to the race engine but due to a big end failure i have installed a good condition crank from a road engine i had spare. The gear assembly's were marked faintly front and rear so installed them back onto the correct cylinders. After torquing the cylinder head bolts i noticed that the front gear assembly had slight play i.e i could rotate the gear for and aft slightly i checked the crank pinion and the play was between the lower gear meshing with the crank, the rear cylinder gear when bolted down has no play at all.
Firstly am i better using the drive gears from the road engine even though they have the quietner gears on as the bottom gear will be mated to the crank gear better or am i over reacting.
I am not sure whether the slacker fitment is how it should be or whether the tighter fit is correct, either way they dont feel the same one has slight movement the other gear has none.
It worries me that the person who removed the quietner gears didnt get the gear exactly in the right place before tack welding i.e either lengthening the mesh of the gears slightly or shortening.
Any advise will be greatly received

Ian

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CMSMJ1
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Re: cam drive gears

Post by CMSMJ1 » Tue Feb 06, 2018 8:58 am

Has been a long time since I was in the guts of the motors - but is there not a bolt that locates the gears int he back of the head? It is bolted to the frame that holds them gears from the inside of the V? Is that in place?

I might be bonkers - nearly 10 years since I did my motor*


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Neosophist
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Re: cam drive gears

Post by Neosophist » Tue Feb 06, 2018 4:58 pm

yeah the cam gears should be bolted into the head by 1 bolt...
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vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

rigsby
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Re: cam drive gears

Post by rigsby » Tue Feb 06, 2018 10:13 pm

Hi,

Thanks for prompt reply, i fitted the m6 securing bolts too. The assembly wasn't moving in the cylinder heads it was the way in which the lower gear meshed with the crank pinion. Once torqued down the front gear meshed with the crank pinion correctly in line etc its just that the way in which it meshed with the crank pinion was a bit sloppy/loose where as the rear gear assemby meshed to the crank with now slop at all possibly tight?. It worried me that they didnt mesh the same as these gears were not originally paired with the crank i am now using and also they have had there quitener gears removed, if the person who removed them didnt get the lower gear spindle or pin in exactly the right position before tack welding back into position this may be the reason as to why one has more play in the mesh than the other or as im using a different crank they may have worn differently?
As i dont know how much play is expected in the gears i have opted to air on the side of caution and fit the other gear assemblys i have which still have the quietner gears on also these were the gears that originally ran with the crank i am now using.

Thanks

magg
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Re: cam drive gears

Post by magg » Fri Feb 09, 2018 8:57 am

Cannot speak from personal experience but OEM service manual identifies F and R gear trains, just a thought..

RVF
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Re: cam drive gears

Post by RVF » Mon Mar 12, 2018 8:43 pm

With the quietening gear removed the back lash must be set by lowering or lifting the gear train. In most cases it will need lowering. We try to run between 15 to 20 microns back lash. Measure the backlash every 90 degs of crank rotation and take the average to calculate how much the gear train needs to be adjusted.


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