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Cam chain replacement, l/h threaded nut

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Hey peeps,

I’m swapping my cam chain this weekend, following installation of new shims, and I’ve just ground to a halt. Here’s what’s giving me gyp.

The top cover’s off and the cams are out. Tensioner is out, oil and coolant drained, left hand cover off and the clutch has been removed (with a bit of cunning and an oil filter strap-wrench - no clutch-holding tool). All good so far.

Removal of cam chain is imminent. Here are some photos of what the Haynes Manual now says, may I draw your attention to point 21.3 and illustrations:

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Despite what the manual states, I can't get the chain guide back up the tunnel to remove it (and from the pics, it appears these photos were actually taken with the cylinder head removed, not what it sez in the book) and there’s not enough wiggle room to drop the cam chain off the crankshaft sprocket and out once the intake side chain guide is off its perch, so I’ll have to remove the primary drive gear to get access to the cam chain drive sprocket. OK.

I had a looky online and found Kyle Peterson’s take: https://www.youtube.com/watch?v=dO920_tj8GY  Roger and understood.

Back to the manual: to gain access to the cam chain drive sprocket, remove primary drive gear. It sez here: Undo primary drive gear nut (l/h thread - book torque of 150Nm or 101.5ft-lbs) and then remove the gear, making sure you don’t lose the Woodruff key from the shaft.

As suggested by pidmyster here: https://www.youtube.com/watch?v=5lUeAoXZmGE  in order to apply the necessary torque to the nut, I’ve jammed the balancer drive sprocket and the driven gear behind the cam chain drive sprocket, from above, with a copper coin and leant on the socket wrench as hard as I dare. It’s chewing the coin as expected, which locks the gears fine - but no movement from the fking nut. I’m hesitant about jumping on a breaker bar to get the nut loose. Anyone else had this happen? How much force did you have to exert to get the damn nut to turn? 

Plus, when it comes time to reassemble, I’m going to have to do the reverse trick with the coin, and gravity will not be my friend, as I’ll have to jam the gears from underneath, and there’s less room due to the internal casting web below.

Fck. Is there a better way to do this? :facepalm:

Edited by BLAM

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OK I see you are over your head.  The clutch nut is easily removed by putting the transmission in 5th and holding the rear brake.

The primary drive nut is LEFT hand thread.  Turn to the right (clockwise) to remove.  The ideal way to hold the crank is with the hex on the flywheel.

1st alternate is to use air or electric impact wrench.

2nd alternate way is to use a Motion Pro gear jammer in the primary gears. I NEVER recommend the use of a coin.

Frankly I do not know if it is possible to change the cam chain without removing the primary drive gear.

 

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Cheers, but over my head? Nah mate, simply being cautious! Due diligence and all that. Yep, well spotted, the 'r/h thread' was a brain-to-keyboard blockage, I'll edit the post to reflect.

The clutch nut presented no difficulty (it was only on at 50.5 ft-lb after all) but I'm being careful about the primary drive nut, simply because it's taking more effort than I expected to loosen it.

I know the copper coin thing is a hack (although the Haynes Manual suggests the very same approach), I have some lead lying about which may be kinder to the gear teeth. I just wondered if the Haynes crew were lying about getting the cam chain out past the drive sprocket...

Might have to invest in a mechanical impact driver it seems.

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Cheers, but over my head? Nah mate, simply being cautious! Due diligence and all that. Yep, well spotted, the 'r/h thread' was a brain-to-keyboard blockage, I'll edit the post to reflect.
The clutch nut presented no difficulty (it was only on at 50.5 ft-lb after all) but I'm being careful about the primary drive nut, simply because it's taking more effort than I expected to loosen it.
I know the copper coin thing is a hack (although the Haynes Manual suggests the very same approach), I have some lead lying about which may be kinder to the gear teeth. I just wondered if the Haynes crew were lying about getting the cam chain out past the drive sprocket...
Might have to invest in a mechanical impact driver it seems.

Do what Noble says. The primary gear has to slide forward to get the chain on. I have an aftermarket flywheel without the hex. I used the Motion Pro jammer on the primary gears. DO NOT jam the balance shaft gear, it may break. I've seen it posted.
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The hazard using coins, screwdrivers even rags to jam gears is not so much damage to the gears but breaking cases and/or damaging bearings.  A gear segment works well to jam gears. The Motion Pro jammer works the same as a gear segment.

When you get a good solid lock on the crank the primary nut will come off with seemingly less effort.

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Yep, fair enough. FWIW I went back out to the garage and tried with a thickish wedge of lead and bingo. Squeezed up progressively and locked tight. New cam chain is in and the reverse was easier than I predicted. I expect I was overly concerned about banging in 150Nm through the 3/8" drive socket and breaker bar, in the end I used a long-handled 1/2" drive torque wrench and it was all good. I found a place in NZ selling the jammer tool for $30NZD, I'll invest for next time. Cheers lads.

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Good point bro, I’ve always considered left of any bike to be true left, as if sat upon it, pointing the right way, reckon Haynes take a different view, the dumb fcks.

:rolleyes:

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I too just went through this exact process. I had to remove the stator cover and using breaker bar on the nut on that side of the engine I braced it against the footpeg so I could get the necessary torque on the primary gear nut to break it free. Took some time but it finally broke free, of course I had already done the locktite fix before so that made it even harder. Good to see you figured it out

Edited by Bm1997
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Hey bro, Yup the opposing torque technique was next on my list - as pointed out by Noble above, applying a socket to the hex nut on the flywheel end (and putting in sufficient turning force to overcome the 150Nm being applied on the other side - or better, locking it as you did) would prevent the crankshaft from rotating, and wouldn't cause any stress to the primary drive gear or balancer gear, or any bearings, or the cases. Next time I think I'll go that route, although I bought a gear jammer, just in case.

Cheers :ride:

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