Topic: Senior project for high school - 78 CB750K

[Restoration Fan]

Are you sure the splines on kick shaft arent simply stripped?

+1 for Pamco, Pete gives rapid results on customer service questions. My 750F runs great with it.

http://www.dynoman.net/bikepages/sohc/index.html
CB750Supply.com VintageCB750.com BikeBandit.com should get you rolling.

Showing off a little now, here's by recent engine rebuild thread. http://forums.sohc4.net/index.php?topic=93209.msg1603613#msg1603613

I'm not sure what's going on with the kick starter shaft yet.  We got the clutch cover off but we couldn't get the clutch basket out yet.  We tried taking a screw driver and tapping the nut with 4 notches to try and get it to come off, but the entire clutch basket keeps turning...even when we try to hold it.  It looks like we'll have to try and run by a Honda store tomorrow and see if they have one of the clutch basket removal tools.  If they don't, I'll order one off eBay.

However, I took a photo of the shaft and it does appear there is something broken on the shaft there.

[calj737]

An air impact will remove the 4 screws. Just "break" each of them to allow release of the torque somewhat easily. The "ears" are very easy to crack due to uneven pressure.

[Stoli]

Even with the correct socket, you will need to find a way to keep the clutch basket from spinning to remove the nut. An air impact would work for that as well. I believe Cal was referring to the 4 bolts that hold the clutch spring plate (not sure if that is what it is called) on. There is a spring behind each bolt and if you don't unscrew them evenly (1 or 2 turns at a time) the spring pressure can skew the plate and crack it. Typically you won't need too much force to free those 4 bolts so I would just try a socket before you revert to something like an air impact on those. Too hard to control the rate (but that might just be me). 

The pic is a little fuzzy to me. Is that a big chunk missing from the kickstart shaft?

[Stoli]

At a glance, it looks like the shaft is worn where it would contact the bushing in the clutch cover. Is that correct? That would explain the intermittent nature of the problem. The clutch cover bushing helps to keep the shaft aligned properly so the gears line up. If the shaft is allowed to wobble, then the gear would get skewed and not properly engage.

If that is the case, you need to inspect the hole in the clutch cover for wear as well. At the very least, it looks like you will need to replace the kickstart assembly (at least the shaft) which you should be able to find a used one on ebay for short money. If the hole in the clutch cover is ovaled, you will need one of those as well. Hopefully there is no damage to the gears but you won't be able to see that until you remove the clutch basket.

[Stoli]

I was doing some work on my clutch today so while I was in there, I snapped a few pics to show you what you will find and what to look for after you get your clutch basket out.



You will be able to rotate the kickstart gear (large one) to inspect it. It's normal direction of travel is counter clockwise. Notice that it turns the oil pump, so it is kind of an important part. When the engine is running, it is driven by the mainshaft via a gear on the back of the clutch basket (see pic below). There is a linkage (can't see it because it is on the other side of the kickstart gear) that allows the gear to spin freely on the kickstart shaft when the engine is running. When you kick the bike over, the linkage engages the shaft to the gear and spins it counter clockwise - that turns the main shaft (via the clutch basket gear) which turns the crankshaft via the primary chains.



You will want to give all three of those gears a thorough inspection.

[Restoration Fan]

You guys are awesome!
Stoli,
Man, I can't thank you enough for taking the time to post those photos and explanation.  I showed that to my son yesterday and he said, "Oh.  That's pretty simple.  That guy is really good at explaining this stuff." 

To clarify, we were able to get the four bolts off and the springs off the clutch basket with no trouble.  It was the center locking nut that has the 4 little tabs on it that we were having trouble with.  (Shown in center of 1st photo).
We tried tapping a flat-head screwdriver with a mallet to see if we could get it to turn but it appeared to start making a notch/indentation in one of those tabs so we decided to wait and get the tool designed for that job.

Interestingly enough, I took a new photo of the kickstarter shaft from a different angle and I'm not seeing that "damaged" area that was visible in the other photo.  So I'm anxiously awaiting the ability to get the clutch basket out myself as well just to see what's really going on there.

[Restoration Fan]

Slight update.  I went to Cycle Gear in Alpharetta, GA today and picked up a clutch tool.  It wasn't the kind I was looking for, but I was hoping it would work.  (Photo of tool below).  Long story short, we still can't get that clutch lock nut off.  So I went in and ordered a tool from online made specifically for this specific purpose.

I do have a question though.  Behind that nut is a piece of aluminum or metal with several tabs.  Two of those are intentionally bent down between to form a sort of tab stop between 3 cylindrical tab stops. (shown in first photo).  The question is:  am I supposed to bend those up and THEN try to remove the nut?  Or do I remove the nut and then that whole little metal piece just slides out because it's no longer held by the nut?

[Stoli]

The tabbed washer behind the nut is there to lock it in place. Any tabs that are bent forward (into one of the 4 slots in the lock nut) need to be bent back before the nut can be removed.

[70CB750]

Since you are getting the clutch out, you should consider to drill the basket for better oil flow.  More information here:

http://forums.sohc4.net/index.php?topic=78643.0

[Restoration Fan]

The tabbed washer behind the nut is there to lock it in place. Any tabs that are bent forward (into one of the 4 slots in the lock nut) need to be bent back before the nut can be removed.

I suspected that might be the case and started to bend them yesterday.  But my son stopped me because we weren't sure that we weren't going to break the washer.  Thanks for the info.  We'll give that a try this afternoon.

Also, we'll definitely drill out the clutch basket to improve the oil flow and since we also have the oil pan off of it right now, we'll probably go in and replace the O-rings on the oil pump as well.  Many thanks for the link. 

[Stoli]

Last time I checked, those washers are still made by Honda and available anywhere that sells OEM parts. Part number 90431-292-000. Around $2 I believe.

Did you download or do you have the '78 CB750 Honda Shop Manual for K8 and F3?

[Restoration Fan]

Last time I checked, those washers are still made by Honda and available anywhere that sells OEM parts. Part number 90431-292-000. Around $2 I believe.

Did you download or do you have the '78 CB750 Honda Shop Manual for K8 and F3?

I do have it.  But it doesn't mention bending the tabs.  It just says to remove the tongued washer after removing the nut.

[Stoli]

That's the 69-78 manual. It's a must have, but there is another manual out there specifically for the K8 and F3 models. I find it a little better if you are working on a K8 like yours. They changed a few things over the years, especially in '77 so the manual you have can sometimes be a little confusing/misleading. It contains supplements for the different model years but not as detailed as the K8 manual. I just did a quick search and the links I found to download the K8 manual are all broken so if you can't find it, let me know and I'll see if I can get my copy online for you to download. The file is rather large so can't email it.

[Restoration Fan]

That's the 69-78 manual. It's a must have, but there is another manual out there specifically for the K8 and F3 models. I find it a little better if you are working on a K8 like yours. They changed a few things over the years, especially in '77 so the manual you have can sometimes be a little confusing/misleading. It contains supplements for the different model years but not as detailed as the K8 manual. I just did a quick search and the links I found to download the K8 manual are all broken so if you can't find it, let me know and I'll see if I can get my copy online for you to download. The file is rather large so can't email it.

I just went on eBay and bought the K8/F3 manual so that I could have a printed copy and because I couldn't find a version online anywhere (well I did find one that might be available but it required the download and installation of literally 9 pieces of adware that I wasn't willing to corrupt my computer with). 

If you do have an online copy, I would love to have that as well but my copy is supposed to be delivered by Saturday otherwise.

[madmtnmotors]

I just went on eBay and bought the K8/F3 manual so that I could have a printed copy and because I couldn't find a version online anywhere (well I did find one that might be available but it required the download and installation of literally 9 pieces of adware that I wasn't willing to corrupt my computer with). 

If you do have an online copy, I would love to have that as well but my copy is supposed to be delivered by Saturday otherwise.

The link to the manuals is in my signature:

http://www.sohc4.net/cb750k-manuals/

[Stoli]

Thanks for the link but I think that is the manual that Resto already has. There is a manual specific to K8/F3 bikes.

[Restoration Fan]

Thanks for the link but I think that is the manual that Resto already has. There is a manual specific to K8/F3 bikes.

That's correct.  I have the overall manual for the 69-78 SOHC's and I ordered the specific one.

By the way, Stoli, I just went back and looked at your first bike.  Dude, you do incredible work.  Unfortunately, I was 100% certain before looking at your bike that I wanted Logan to do a pure restoration back towards being as close to original as possible.  Now you have me thinking of some mods.  Damn you! 

[Stoli]

Thanks. It's a tough call to go stock or not. If your intent is to ride the bike often, have the option for an additional rider and do the occasional long touring ride, then I think stock is a better way to go. As soon as you start modding the seat, handlebars and pegs into a more cafe look, you start giving up a lot of comfort and often the ability to accommodate a rider. I am really happy with the two bikes I have finished thus far (project #1 and #3) but they are really just "around town" bikes. Not a lot of fun on the highway and not very comfortable to ride after a few hours in the saddle. They do tend to attract a crowd though, which was my goal. Of course, a well done stock restoration will attract a crowd these days as well.

I am currently on the road but when I get home, I will see if I can temporarily upload that manual to one of my servers so you can download it. I'll PM you with the link as I can't support the bandwidth of a bunch of guys hitting it simultaneously. Probably won't be until Thursday. I also have a pdf of the K8 parts (exploded views and part numbers) of every system on the bike. I got tired of going to the OEM sites to reference the parts one system at a time so I captured each and combined them into one file for easy reference.

Searching the internet by Honda part number can often be more productive than using the description and can save you money as well. Case in point - Honda often used the same part on different models and I have found that some parts are hard to find or very expensive if you find them by searching for "CB750 K8 ..." parts, but that same part might be sold much cheaper by someone that is parting out a totally different bike on ebay. You would never find it searching for CB750 parts.

[Restoration Fan]

Thanks. It's a tough call to go stock or not. If your intent is to ride the bike often, have the option for an additional rider and do the occasional long touring ride, then I think stock is a better way to go. As soon as you start modding the seat, handlebars and pegs into a more cafe look, you start giving up a lot of comfort and often the ability to accommodate a rider. I am really happy with the two bikes I have finished thus far (project #1 and #3) but they are really just "around town" bikes. Not a lot of fun on the highway and not very comfortable to ride after a few hours in the saddle. They do tend to attract a crowd though, which was my goal. Of course, a well done stock restoration will attract a crowd these days as well.

I am currently on the road but when I get home, I will see if I can temporarily upload that manual to one of my servers so you can download it. I'll PM you with the link as I can't support the bandwidth of a bunch of guys hitting it simultaneously. Probably won't be until Thursday. I also have a pdf of the K8 parts (exploded views and part numbers) of every system on the bike. I got tired of going to the OEM sites to reference the parts one system at a time so I captured each and combined them into one file for easy reference.

Searching the internet by Honda part number can often be more productive than using the description and can save you money as well. Case in point - Honda often used the same part on different models and I have found that some parts are hard to find or very expensive if you find them by searching for "CB750 K8 ..." parts, but that same part might be sold much cheaper by someone that is parting out a totally different bike on ebay. You would never find it searching for CB750 parts.

That would be great if you can upload the PDF to a server somewhere.  If you do so, I'll be glad to actually host it out to a public folder on Dropbox and make it available for anyone else who wants it.  I have several Dropbox accounts that have plenty of storage space that I'll never use up.

I did the same thing as you on the K8 parts.  I have those downloaded to a folder on my Macbook for reference because I got tired of logging onto sites on the internet and drilling down through Honda....1978...CB750K, etc to find the relevant pieces.

[Restoration Fan]

Quick update and a question. 
While we're waiting on the clutch tool to arrive (supposed to be delivered by end of the day today), we did some work on sanding down the frame and getting it ready for paint.  We should be ready for paint by tomorrow or Saturday on the frame but we haven't decided on what primer and/or paint to use for the frame.

A buddy at work was telling me that we should use a self-etching primer for painting the frame but I admit that I have no clue as to whether we need that or not.  What do you guys use when painting your frames?

Also, as an FYI, here's the paint we plan to use for the tank and side panels on the bike.  We're going to go back to the Candy Alpha Red color that was one of two standard colors for the bike in 78 and was the original color on this bike as well.  I liked this paint, not only because they can match the original color, but I like the rattle can (scroll all the way to the bottom for the diagram) that has the built-in hardener for the clear coat as well.
http://www.ct70paint.com/alpha-red.html

[SOHC4 Cafe Racer Fan]

I'm a bigger fan of powdercoating frames for increased durability and resistance to gas and other solvents. I'm sure some restoration fans will chime in on preferred paint selections.

For body parts, I've used VMR Paint with great results for accurate vintage paint.

[Stoli]

I'm no expert when it comes to paint, actually I am not an expert at any of this stuff, but I'd be happy to pass on what I have learned over the past 2 years.

I get my frames powder coated but based on the nature of your project and seeing that you have already got the frame prepped, I think you will be going with a rattle can. There are plenty of guys who recommend that over powder so no worries there. As you know, or have already read, prep is 90% of any paint job.

When painting bare metal, you want to go with a self etching primer or a two part epoxy primer that says it is meant for bare metal. As I said, I haven't done any frames but I have done 3 engines and on one I used the Duplicolor self etching primer with Duplicolor engine paint over that. On another I went with the Duplicolor Engine Primer followed by Duplicolor Engine paint. On the third I went with a two part epoxy primer and left it at that. All three came out fine but of the three, the two part epoxy has stood up the best and  is the most resistant to chipping (and there is nothing on top of it!). The self etching comes in second, followed by the regular engine primer.

The difference between my engines and your frame is that you probably want to finish it with a urethane based paint (with hardener - like the paint you plan on using for the tank). I have read on an automotive paint forum that it is not recommended to go with an enamel based primer under urethane and the self etching primer that you find in a rattle can will likely be enamel based. Something about different expansion rates...  That said, I'm not sure you can get two part epoxy primer in a rattle can. At the end of the day, I'm guessing that plenty of guys have used the self etching enamel primer under a urethane finish with fine results. After all, we are talking about a motorcycle frame and not the hood of a car that is going to bake in the hot sun all day.

So far, my comments are probably not helping you narrow your decision, are they....

To muddy the waters a bit more, there are also urethane primers out there. Since money is not a predominant factor for you, that might be a consideration. Suggest you find the top coat you plan on using first, then see if the manufacturer suggests a specific bare metal primer for that paint. While on that subject, read the label regardless of what paint you use. I think the manufacturer knows best when it comes to things like dry time and sanding between coats and things of that nature.

[calj737]

I have seen numerous members swear by POR-15 chasis black as a DIY frame paint. They cite: easy to apply, great coverage, and very durable finish.

[Restoration Fan]

Excellent advice.  Thank you all.
Yeah, powdercoating would be nice but I don't have access to anyone I know or trust who could get me in immediately and we'll have the frame ready for primer by the weekend.

Also, MEGA thanks to Stoli for providing an online version of the 78 K8 F3 Service manual.  I was able to download it and put it up on Google Drive in a shared public folder.

Anyone who wants to download should be able to get at it with no needed security or passwords, but if you have trouble, feel free to let me know.  Here is the link:

78 HONDA CB750 K8/F3 SERVICE MANUAL LINK
https://drive.google.com/folderview?id=0B4nqeBb662mZZjZjTWdGRk9Qd0E&usp=sharing

[Restoration Fan]

And finally some progress.  So, once we got the proper tool, we had very little trouble getting the clutch basket off. 
For those who might need to do this on a 78, there are a few lessons we learned:
1.  Use the correct tool.  This one http://www.z1enterprises.com/ItemDetails.aspx?itemDescription=Oil+Filter+%26+Clutch+Hub+Spanner&item=MP08-0015 from Z1 Enterprises was $8.18 and it was going to take something like this or the T-handled tool that Honda makes to break the pressure on this nut for us because it was torqued on very tightly.
2.  The lock washer that sits behind the nut has a bunch of little tabs around the exterior.  There are also 2 larger tabs that are intended to fit between the 3 little cylindrical stubs.  You don't have to bend those to remove the nut.  They're supposed to stay there to keep the washer from spinning.  However, once the nut is tightened to the proper torque, there should be a tab somewhere on that washer that can be bent into one of the four slots on the nut.
If it's like it was on ours, that tab was bent so well into the slot that it wasn't readily apparent that it was in there stopping the nut from turning.
3.  Even after bending the tab out of the slot, we still couldn't break the nut loose without the correct tool. 
4.  Once you do get the nut and the washer off, remove the circlip but there's still a small slotted washer in there behind the circlip.  Slide that out.
5.  Finally, the clutch basket exterior itself may not want to slide right out.  But at this point, there should be nothing holding it, so get your fingers into 2 or 3 of the holes and make sure you pull evenly on both sides of the shaft; otherwise, it binds against the shaft as you try to remove it because it's a pretty tight fit onto the shaft.