I promised to do a write-up when I finally finished rebuilding the starter clutch on my Nighthawk.
It's a task that would otherwise seem extremely difficult due to the first step - removing the engine, but my experience has shown that it is actually quite a simple task that doesn't require any special skills. I've never done it before and it took me an hour - and some of that was time spent fending off my cat who insists that I escort him to his food dish before he'll eat.
Why did I do this write-up? There are plenty of resources out on the web about how to rebuild the starter clutch on a CB650 Nighthawk - and while the bikes are very similar in look and design, the rebuild process just doesn't work on the CB700. But even if it does (and I didn't see how) pulling the engine is really not difficult and in the end the job is far easier than the arm twisting and joint breaking process described for the CB650.
Before you begin...
Get a copy of the service manual. While I didn't particularly find the manual very helpful for fixing the starter clutch itself - like all service manuals it was written by someone who knew exactly what they were doing and as a result plenty of things were left out that a newcomer just wouldn't know. That said, it still contains plenty of information needed, like pulling the engine itself.
Second, make sure you have good tools - 6 point sockets, socket extensions, good hex key wrenches, rubber or plastic mallet, gasket scraper.
Third rent or buy a motorcycle jack - it makes pulling the engine very simple
Fourth, order your replacement gaskets ahead of time. Oil pan, clutch cover, (if you remove it) cross-shaft cover, (if you remove it) shifter cover.
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Pulling the starter clutch:
Put the bike on its centerstand
1) Use the service guide/shop manual to direct you on how to remove the engine. The directions in the service manual are very specific and very useful.
a) Remove the tank, side covers, unplug the electricals
b) Remove the coils and the coil cover
c) Remove the carburators - not strictly necessary, however you do need to provide for ample room and the carbs and airbox boots will get in the way
d) Remove the frame stiffeners (coils were sitting on them).
e) Remove the exhaust and headers
f) Remove the alternator cover and coils
g) Remove a few other odds and ends, you'll know which when it comes time.
With the stiffeners removed the engine bay is really really accessible. This built-in feature alone will save your aching back when wiggling the engine out.
At this point stop working on removing the engine.
2) Drain the oil, remove the oil filter. Let the oil drain for a long long while.
a) Use an oil pan under the engine
b) Remove the oil hoses - they'll weep oil for an eternity, hence the oil pan under the engine
c) Remove the oil pan cover
d) Inside the oil reservoir are 4 things to remove
1: Oil siphon - pull it off
2: Oil filter spout - pull it off
3: Small oil pipe - pulls out (watch for a gasket on each side)
4: Large oil pipe - pulls out (watch for a gasket on each side)
With the oil pan off and the oil finally drained
a) Remove the clutch cover
b) Remove the clutch basket - consult the service guide, too detailed for this write-up (sorry) and it's really no challenge anyway.
c) Remove the ignition cover and ignition modules - important, they help hold the engine case together
e) Loosen the engine mounts
A word about supporting the engine. I specified a motorcycle jack because they're long enough to roll in from the right, and still give you a place to slide the engine away from the frame while it's in the air.
The basic problem removing the engine is that the lower frame is in the way. To get around this I put plywood on the motorcycle jack, then 2 2x4's under the engine, and a bunch of 2x4s on the right side of the frame. That way the 2x4s are taller than the frame and you can slide the engine across the 2x4s and out of the frame
Onward:
Stop at this point and place the motorcycle jack under the engine from the right side of the bike. Support the engine, to help take pressure off the engine mounts
Remove the engine mounts
Remove the right rear engine mount point (two bolts, rear brake sensor is on it)
Remove BOTH upper engine mounts (two bolts each)
Remove the lower front right engine mount (two bolts)
Wait!! What about the driveshaft and u-joint??
Don't worry about it - it pulls right out when you remove the engine. Okay that's a lie, it binds up and drags, but it does actually pull right out once it starts moving. I never did understand what the service guide was talking about when they mentioned pushing the driveshaft out of the way with a screwdriver ?? It separated from the U-Joint once the engine moved a certain amount.
So, you have the bottom of the engine supported on a couple of 2x4s. You have some more right on the other side of the right frame. Just slowly and surely slide the motor out. It really is that easy so long as you take your time, look what the engine is up against (the battery box is a pain in the butt), raise and lower the jack as you need to.
Once the engine is about 1/4 of the way out it's home free and it slides nicely out. Roll the motorcycle jack back away from the frame, lower it, take a 10 minute break.
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Splitting the engine case:
Generally consult the service manual about this. The directions are clear and accurate. Basically you're unbolting a ton of bolts, there are 4 on the top part of the case - one is deep in a well next to the transmission. You also have to remove the oil pipes. You also have to remove the clutch slave cylinder.
Once you have all the bolts removed, (you did remove the ignition right??) the case comes apart relatively easy. It's probably rusted a bit here and there, nothing a few taps with a plastic mallet won't cure. If it doesn't split right apart - you missed a bolt, don't force it for God's sake!
The starter clutch it located on the UPPER part of the case. To access it, turn the engine over on it's head (valve cover actually) and pull off the lower part of the case.
Since the clutch is out, the next step is relatively easy.
Again, consult the service manual, but basically you're removing a small cover over the end of the alternator shaft. Then you're removing a flange nut on the end of the alternator shaft. If you did step 1f way above, after removing the nut you can then slide the shaft out.
The starter clutch is that barnacled and crummy hockey puck looking object at the end of the alternator shaft. A piece of junk even when it was new no doubt. It falls right off once the alternator shaft is out.
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Repairing the starter clutch:
The service manual eluded that you could actually repair this. I don't see how myself, it was permanently pinned together. I think the instructions were for the CB650 clutch.
1) Take the starter clutch to your drill press and remove the heads on the pins or simply drill them out entirely. 8 or 10mm pins I believe (10mm I think).
2) With the pins gone, remove the cover on the starter clutch and replace the springs and rollers (if necessary)
The springs are real light. I ordered mine from Amazon - 3.52mm OD, 0.32mm Wire, 29.3mm Free Length, 0.16N/mm Spring Rating.
I did not remove the cover pins entirely on mine - just the heads.
1) Drill and tap the pins for a 6mm bolt (button head for low profile)
2) Reassemble the starter clutch - test the operation of the unit once reassembled.
Option 2: If you can't drill the clutch out, or mucked it up, or the unit is trashed in some other way. I have heard a rumor that the starter clutch from a 2004 Yamaha R6 will work just fine and is in fact a superior unit. Just what I've heard though.
No matter which option you chose, you're done. Reassemble the engine. Make sure you don't have extra parts. I reassembled mine 3 times before I got it right
Mostly because I was dumb enough to remove the transmission cross-shaft, the other because I forgot to put the oil port back onto the end of the clutch shaft.
Installation back into the frame is a bit more challenging - but if you go slow and steady it works. Re-lube the u-joint.
