Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50

[edwardmorris]

Anyone on the clutch bell detachment issue?

What about this? does this look right or is it damaged (part to the right)?

[MCRider]

Anyone on the clutch bell detachment issue?

What about this? does this look right or is it damaged (part to the right)?

They are all essentially usable, no matter how much the ramps are worn. IIRC they are NLA, so good used ones from eBay are your only hope. A less worn one may give a better feel. How many miles on that one?

[edwardmorris]

Thanks for tip Ron, found a "Near new" one off of a bike with 8K miles on it. As for my junker, I have no way to tell how many miles since the gauges and numerous other things were not original to the bike. My guess based on the condition of the jugs and gear box is moderate use maybe around 15K??

[RRRToolSolutions]

Ed, you're looking at my absolute favorite clutch. Why Yamaha, Kawasaki, and Suzuki didn't copy that or something close I do not understand. It is the best clutch design of any bike I have ever worked on. Period. Even other Honda models used the crappy old pushrod through the case system and still do.

Be very careful when installing the outer basket cover. All 4 bolts have to go in slowly and evenly. I've seen dozens of broken basket covers just because the person failed to install it straight and perfectly aligned.

Regards, Gordon

[edwardmorris]

Thanks Gordon, still tearing it down and washing up parts as I find pockets of time between work and shoveling (graaahhhh). That's interesting about the clutch, thanks for sharing. I have the groove widened bearings but I can't seem to figure out how to get the basket off the primary sprockets. Any suggestions? Kickstart mentioned a criclip but I can't find it. I'll add the pic here again so its not forgotten in the page fold.

[edwardmorris]

Picked up refaced valves today, look so much better.

I'm about to give up on the damned clutch basket, just won't come off and I haven't seen KickStart around for a while.

@Ron, I saw a post where you'd mentioned that you were able to pull all the bearings off the mainshaft, but I couldn't find the page on the Phaedrus thread. How did you do it?

[HondaMan]

Picked up refaced valves today, look so much better.

I'm about to give up on the damned clutch basket, just won't come off and I haven't seen KickStart around for a while.

@Ron, I saw a post where you'd mentioned that you were able to pull all the bearings off the mainshaft, but I couldn't find the page on the Phaedrus thread. How did you do it?

If the seats in the head are nice and even, a short time of lapping with some Fine compound should put a nice line of seal on those new faces.

Sorry about the circlip OM confusion earlier: I thought you were asking about removing the basket assembly from the mainshaft. That's where some have a circlip that I was talking about.

I'm curious: why do you want to separate the primary sprockets from the basket? That's sort of a "let sleeping dogs lie" kind of thing unless you're after something special.

[edwardmorris]

Picked up refaced valves today, look so much better.

I'm about to give up on the damned clutch basket, just won't come off and I haven't seen KickStart around for a while.

@Ron, I saw a post where you'd mentioned that you were able to pull all the bearings off the mainshaft, but I couldn't find the page on the Phaedrus thread. How did you do it?

If the seats in the head are nice and even, a short time of lapping with some Fine compound should put a nice line of seal on those new faces.

Sorry about the circlip OM confusion earlier: I thought you were asking about removing the basket assembly from the mainshaft. That's where some have a circlip that I was talking about.

I'm curious: why do you want to separate the primary sprockets from the basket? That's sort of a "let sleeping dogs lie" kind of thing unless you're after something special.

I'm trying to get to the bearings so I can install my freshly groove widened SKF ones. I should probably start a separate thread for that issue....

[BPellerine]

valves look good ed way  cheaper than new!bill

[edwardmorris]

valves look good ed way  cheaper than new!bill

Yep. They only billed me for shop time because they said they had to take off next to nothing after I'd already cleaned them I hope these lap well and not overheat.  I haven't inspected them all but I did let the shop know I needed minimum 1.0mm left and they seem to have not lost any of it...

[BPellerine]

I think they will be just fine I have never had a reground valve fail on the street in my old bikes.bill

[Kickstart]

Picked up refaced valves today, look so much better.

I'm about to give up on the damned clutch basket, just won't come off and I haven't seen KickStart around for a while.

@Ron, I saw a post where you'd mentioned that you were able to pull all the bearings off the mainshaft, but I couldn't find the page on the Phaedrus thread. How did you do it?

Sorry... I might have given you some bad information.  For my bike, 75F model (as well as the 76 and later K models), there is a circlip that holds the basket on the spline of the primary gears (number 15 in the picture below):


It doesn't appear the earlier models have that circlip.  I'm not sure how the basket is attached.  Does it just pull off?



EDIT:   Ah... here you go.  CycleRanger has a post with pictures on how he removed his with a GearPuller:
http://forums.sohc4.net/index.php?topic=97244.0

[edwardmorris]

EDIT:   Ah... here you go.  CycleRanger has a post with pictures on how he removed his with a GearPuller:
http://forums.sohc4.net/index.php?topic=97244.0

Thanks Chris, I did see that thread during my hours of searching, and the only problem with that approach is that I already have the cases apart and blasted clean. I suppose I have no other way than to button it back up with the main shaft in and try using a gear puller. Again, thanks for the reply!

Lots of snow yet again, and lots of work, still tearing down and cleaning itty bitty parts here and there as I find time in between. Painfully mind numbing tasks (especially cleaning small parts and electrical stuff), but they're coming off the to do list so no complaints.

[jerry h]

Hi Ed,
Sorry I didn't go back to re-read everything, but is that bearing bad, or do you have some reason to think its bad?   I know you spent some money to get the special bearing grooves cut etc, but sometimes one can do more damage fixing stuff that's not broken.  Don't ask me how I know this.

[Kickstart]

EDIT:   Ah... here you go.  CycleRanger has a post with pictures on how he removed his with a GearPuller:
http://forums.sohc4.net/index.php?topic=97244.0

Thanks Chris, I did see that thread during my hours of searching, and the only problem with that approach is that I already have the cases apart and blasted clean. I suppose I have no other way than to button it back up with the main shaft in and try using a gear puller. Again, thanks for the reply!

Lots of snow yet again, and lots of work, still tearing down and cleaning itty bitty parts here and there as I find time in between. Painfully mind numbing tasks (especially cleaning small parts and electrical stuff), but they're coming off the to do list so no complaints.

I don't think you need to put it back in the case to use the puller... try to find a large socket with an OD that's about the same as the primary gear spline section... but smaller than the basket spline/teeth.  Then put the puller on that to push against.

At least, that sounds good in my head... not sure how easy that would be to do

[edwardmorris]

OK, so few updates to post, I'll start with the micro polished crank. I took it to the shop and they were able to use an electric impact to get the stubborn bolt out, then Gordon's rotor puller worked like a charm to get the rotor off. Took it apart, everything looks good, little to no wear, but that's my novice eye.

[edwardmorris]

Had to use the big fat impact driver to get it apart, and notice the flat hammered marks on the countersunk screws. Do I need to impact tighten them? I have it put back together after cleaning.

I asked my machinist if he had a good bearing puller that he could loan me, and he just offered to pull them out for me. I told him about the stuck clutch bell and he said he had tools to get it out. And sure enough, I have it all apart now. How do these gears and dogs look?

[edwardmorris]

More. Needle rollers are gone too.

[edwardmorris]

Cleaned up the kickstarter and final drives.

While cleaning the alternator, I noticed pic3, is this bolt made of plastic???

[HondaMan]

Had to use the big fat impact driver to get it apart, and notice the flat hammered marks on the countersunk screws. Do I need to impact tighten them? I have it put back together after cleaning.

I asked my machinist if he had a good bearing puller that he could loan me, and he just offered to pull them out for me. I told him about the stuck clutch bell and he said he had tools to get it out. And sure enough, I have it all apart now. How do these gears and dogs look?

Those gears look happy, no troubles there.

[HondaMan]

Cleaned up the kickstarter and final drives.

While cleaning the alternator, I noticed pic3, is this bolt made of plastic???

Are you referring to the little plastic "locker" bit on it? Some of the bikes have a little nylon lock nib bored into the side of the bolt. These are sort of like the nylon-lined "locking nuts" you can get for bolts. This feature is interestingly on some of the engines and not others, over their years. The early sandcast engines had some history of loosened bolts that led to electric starter problems (no grip) which then damaged the tapered end of the crank. This was an expensive warranty repair, which led to bigger bolts, then bolts that were Loctited in real tight, and once in a while, bolts with the nylon lock nib in the side of it. That's why they are so #$@! hard to get out.

[Terry in Australia]

Looks fine Ed, as far as your gears go, they look good, but there's no real way of saying that the dogs are OK unless you've ridden it, as they wear pretty evenly. If it continually slips out of gear under power, they're worn out.

You can get them under-cut by most good machine shops, here's a youtube vid for your entertainment pleasure............

Under-cutting dog gears.

[RRRToolSolutions]

Ed, those dogs look good to me as well. I don't see rounding, chips, or wear on any of them. Undercutting has it's ugly side too. Forget about finding neutral and shifts require even more pressure to get the dogs to turn loose. The same angles that "pull" the gears (dog ears and holes) together now want to keep them there. That slight friction between the clutch plates caused by the oil transmits small amounts of energy to the gears to load them against the dogs. For the street and non-race use, I would never again have a transmission undercut. Only if every 1/10th second counts and you don't mind killing the engine to find neutral does undercutting really make sense for me. Count on increased wear of the shifter, the drum, and the shift forks too - more force means more wear.

Things are looking good! Gordon

[edwardmorris]

Are you referring to the little plastic "locker" bit on it? Some of the bikes have a little nylon lock nib bored into the side of the bolt. These are sort of like the nylon-lined "locking nuts" you can get for bolts. This feature is interestingly on some of the engines and not others, over their years. The early sandcast engines had some history of loosened bolts that led to electric starter problems (no grip) which then damaged the tapered end of the crank. This was an expensive warranty repair, which led to bigger bolts, then bolts that were Loctited in real tight, and once in a while, bolts with the nylon lock nib in the side of it. That's why they are so #$@! hard to get out.

Yikes! It makes more sense that its a nib, I thought the whole bolt was plastic/nylon because at the point of the nib, the zinc plating is starting to peel out, much like chrome in a can spray for plastic toys does. I'll have to remember to tighten this back up lie a #$@! as well, to the right torque.

[edwardmorris]

As for the gears, thank you all for the input.

Here are some pix of the countershaft (page 9 of this build thread)

http://forums.sohc4.net/index.php?topic=126735.200

Please review again since its been a while. I am not sure if I need to get it undercut, especially since the cost is prohibitive to just do 1-2 undercutting. I don't plan on racing so I'd rather save the cash for something else.

I'm very glad that the mainshaft looks good (here) and if the countershaft ones look good too, then I'm going to skip the undercutting. Hopefully by using the right weight oil + additives, the shifting will be smooth for a daily rider.