Topic: how to remove front drive sprocket? Break chain first ??

[dboblet]

After researching the forum I finally managed to get the blasted sprocket cover off.  Not an easy chore since I had to drill off the rear screw head then turn out the screw a bit of a bit of a turn at a time with a pair of pliers once I'd pried the cover out enough to reach the screw shaft.  But I've got new screws to replace the old ones so no worries. 

I 'thought' I'd just be able to slip the sprocket off, chain and all, but no clearance for this on the 78 cb750f with the 630 chain.  I'm going to replace the chain anyway so I might just file off one of the links and open up the chain to pull it off, but I was wondering if there is a way to remove the sprocket WITH the chain?  Seems too tight a clearance from what I can see.

Incidentally, I'm doing a 630 to 530 chain conversion at the same time.  I'll post how that goes with pics when complete.

[Bido]

I have a 78 F3 and can get off the front sprocket without removing the chain it just took me a little time leave the chain on the front sprocket but remove it from the rear I am also running a 630 chain and a stock sprocket. If the sprocket is larger than stock I don't know if it will work.

Good Luck
Bido

[scondon]

I 'thought' I'd just be able to slip the sprocket off, chain and all, but no clearance for this on the 78 cb750f with the 630 chain. 

  You can do it, just get a lot of slack on the chain and work it until you're blue in the face. That's what I did, man was I happy when I arrived at the "magic" position and everything popped free

[dboblet]

blue in the face.... Magic moment.... seems like a lot of the work on the 750 is all tight tolerance just manageing to get the part to the right position at just the right angle with just the right amount of slack at just the right moment... and most important, with just the right amount of determination.  One could wonder if a lot of this was engineered this way or just a lot of luck... a whole lot of luck.

[andy750]

Perhaps its different in the later bikes but I can push my rear wheel forward, get some slack in the chain and take the front sprocket on/off easily. Done this on a K4 and K2.

good luck
Andy

[scondon]

Perhaps its different in the later bikes but I can push my rear wheel forward, get some slack in the chain and take the front sprocket on/off easily. Done this on a K4 and K2.

good luck
Andy

   The 630 chain makes for less clearance at the front sprocket,Andy. Sliding the sprocket off the shaft has the chain banging against the case. Another plus for ditching the 630 for a 530

[GammaFlat]

About your screws in the sprocket cover.... I've put a screwdriver to several 750's and every one of them had both screws "wobble" on the way out.  I think the screws were bent a little. 

I did not have trouble getting the screws out, however.  Even if the head is a little damaged, you can use a #3 phillips to get them out.  I use a #3 bit and have had "zero" trouble.  The correct bit/head to use is actually a JIS (Japanese Industrial Standard) #3 which is hard to find.  Most folks (including me) try using a #2 phillips (the most common size that everyone's familiar with) which is a bad mistake.  You will end up sorry after stripping screws that are stubborn at all. 

I am very interested in your 630 to 530 conversion.  Please keep us posted.

[andy750]

Perhaps its different in the later bikes but I can push my rear wheel forward, get some slack in the chain and take the front sprocket on/off easily. Done this on a K4 and K2.

good luck
Andy

   The 630 chain makes for less clearance at the front sprocket,Andy. Sliding the sprocket off the shaft has the chain banging against the case. Another plus for ditching the 630 for a 530

Ah well that explains it Sean....another reason to get an early K bike 

I hope the ridings good in CA just now 

cheers
Andy

[dboblet]

as for the screws, both screws had obviously been removed at least once before with the wrong tool.  The heads were damaged so that no screwdrive could work well.  An impact driver got the forward one to start turning but the back one didn't have enough meat to do anything but raise my blood pressure.  Once I got the head drilled off I still had to remove the screw shaft to get the cover off so I slid the cover as far away from the case as I could and used a pair of pliers to grip the screw shaft from under the bike.  Of course the screw was loose then so it turned easily... about a 1/16 of a turn per attempt.  It took a while but I'm good at persistance, even laying on my back on hot pavement in the sun at noon when it's 113 degrees outside. 

[David]

About your screws in the sprocket cover.... I've put a screwdriver to several 750's and every one of them had both screws "wobble" on the way out.  I think the screws were bent a little. 

I did not have trouble getting the screws out, however.  Even if the head is a little damaged, you can use a #3 phillips to get them out.  I use a #3 bit and have had "zero" trouble.  The correct bit/head to use is actually a JIS (Japanese Industrial Standard) #3 which is hard to find.  Most folks (including me) try using a #2 phillips (the most common size that everyone's familiar with) which is a bad mistake.  You will end up sorry after stripping screws that are stubborn at all. 

I am very interested in your 630 to 530 conversion.  Please keep us posted.

Thanks for the tip on the JIS screwdrivers.  I will order some before I foul up the screws.

[Rosinante]

I have a '78 K.  The front sprocket has one bolt, in the center.  The chain seems LARGE to me, so I suspect it's the 630.  I can see the sprocket is worn.  From the discussion above, it sounds like I MAY be able to wiggle the chain and front sprocket out without breaking the chain.  I'd appreciate comments on this, particularly if someone is certain this is impossible.  My plan is to hit the nut in the center of the sprocket with an air wrench if possible, and a regular tool if not.  While the chain is still on both sprockets.  Anybody want to warn me against this plan?

I ended up removing the shift linkage cover in order to get the sprocket cover removed.  I determined it is impossible to remove the sprocket cover without first removing the shift linkage cover.  Why didn't they make the sprocket cover just a LITTLE smaller so this would not be necessary?  Any thoughts?

And finally........As some of you know I am getting back into motorcycling after a 25-year hiatus.  When I had a CB750 back in the seventies, I bought an impact driver.  It was, and is, an ESSENTIAL tool for dealing with these screws on these motorcycles.  As is a good selection of bits that fit properly and have square edges so they bite the screw head well and fit deeply.  I am tempted to start a thread, just to alert/remind everyone of the importance of this tool.  Is that silly?  Does everyone already know this?

[OldSchool_IsCool]

I am tempted to start a thread, just to alert/remind everyone of the importance of this tool.  Is that silly?  Does everyone already know this?

Often discussed, widely known.  It's usually the 2nd or 3rd tool any SOHC'er will buy!