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

[BPellerine]

these bottom ends seem pretty tough so your stock head should get you a lot further along.and be easier to deal with.hope things go better!bill

[Terry in Australia]

The engine I just rebuilt was trashed by a PO, so I had to replace around 50% of the larger components, but my experience is that generally, most CB750 engines that I've opened up have been in pretty good condition overall.

Sorry about your woes Ed, if you need funds to buy a good used head I'd be interesting in buying your K4(?) head, cam, springs etc. Cheers, Terry.  

[edwardmorris]

Thanks Bill and Terry for your kindness. I'll be able to save up as I start racking up hours with the new year. What is upsetting is the time I'm losing. And of course, when I have it on the road, all parts left over will either go back to members here or to my next project if I may dare dream so. Damn that sexy black and polished engine of yours Terry, that's going to drain my wallet next winter I tell you!

Some good yet expensive news, I've secured a K2 head that came right off a running bike, should be here next week sometime. Also have a stock cam and springs coming in soon from Whaleman, can't wait for the goodies and can't thank you guys enough. I will keep it moving along. I lost a day today because we got buried in the snow here, had to keep shoveling every so often to be able to have the car get out easily if needed. Still battling the mess the old gasket left on the jugs that are inside the house. The last few bits are pretty stuck on there and really testing my patience. As I clean it up, I notice a few very minor gouges at the corner that was giving me a hard time when I was taking it apart. Its from the chisel extension I had to use to pry it open then but it doesn't look too  bad. I'm sure sanding it is out of the question, so suggestions welcome on how to fix (if at all it needs to be fixed).

@kickstart I haven't had time to look into the crankcase yet, its in the garage which was blocked all day by about 18" of snow that I just got done shoveling out of the way. Soon though, hopefully.

[Terry in Australia]

No worries Ed, have you got access to an oven? I heat my oven in my garage to around 200 deg C and shove the cylinder block in the for an hour, then the sleeves will just fall out.

I've got a 3M nylon "strip disc" on my sander/polisher that will remove the old gasket material in around 10 seconds without removing any aluminum, and I soak the cylinder block in Acetone, or layer on some paint stripper, which will remove the paint, grease, carbon, dead mice, etc.

Then I just heat it up and drop the sleeves back in again. If you've gouged the gasket surface with your chisel (I hate chisels) you can carefully file the gouge, just don't go lower than the gasket surface. I had to do the same on the black engine due to the incompetence of another "Chiseler"...... Cheers, Terry.

[calj737]

Ed - take a piece of 400 grit sand paper, use a wood block, and sand in a pattern at 45 degress to the gasket surface. The flat, wide block, and angular motion will prevent any damage to the aluminum and remove the remnants promptly.

The gouges, so long as they're on the outside edge of the machined surface, won't hurt you. If they're bad, follow Terry's advice. If they're cosmetic, leave them be. The gasket seals from the inside edge.

[edwardmorris]

Don't have an oven Terry, the wife bakes a lot and will kill me if I taint hers with engine part The head gasket came off clean with just some residue behind that scrubbed off pretty easy. Its the base gasket that is being stubborn, so I think I'll be able to manage without getting the sleeves out. I will pick up a few things on my way home today to gently remove the rest of it. The gouging isn't bad, and thankfully is only on the outside edges of the one dowel corner. I suppose I can carefully sand/plane that out using a wood block and super fine paper like Calj suggested. I've been searching around here and many have suggested sanding the mating surfaces as smooth as possible IFF they aren't warped. If there's warping, no choice but to find a machine shop that won't scream as if they saw a werewolf when you bring in a motorcycle part. The crankcase and jugs definitely have paint on them, so its good to know I can use a paint stripper to clean the outsides.

Had to go to work today at -11F, but hopefully it will warm back up to 0F and i'll be able to get some stuff done when I get back.

[Terry in Australia]

No worries Ed, if you've got room in your basement/shop, an old oven is a handy tool for not only dropping sleeves, but also for curing engine paint, loosening valve guides, curing powder coating etc. I bought a small one on eBay for 2 bucks and used it until I scored an industrial oven which has much more room.

Be careful with the sanding, even with a wide block it's easy to "round" the gasket surfaces, that's why I use the strip disc, it's fast and only removes the old gasket, and not the aluminum. Don't bother with fine abrasive paper, all you'll do is polish the old gasket. Cheers, Terry.  

[edwardmorris]

No worries Ed, if you've got room in your basement/shop, an old oven is a handy tool for not only dropping sleeves, but also for curing engine paint, loosening valve guides, curing powder coating etc. I bought a small one on eBay for 2 bucks and used it until I scored an industrial oven which has much more room.

Be careful with the sanding, even with a wide block it's easy to "round" the gasket surfaces, that's why I use the strip disc, it's fast and only removes the old gasket, and not the aluminum. Don't bother with fine abrasive paper, all you'll do is polish the old gasket. Cheers, Terry.

I'll keep an eye out for an oven on craig's list. I've done inspection passing electrical work around the house but never messed with gas lines so a little apprehensive about that. I can have someone install it for me though if I really need it.

As for the gasket, I picked up some acetone and I had some 1000 grit sand paper at home. First round, wet the surface with acetone and scraped it off with a credit card. Then for the really stuck crap, I just wet sanded with the 1000g and wetting with acetone itself. Made my life easier and it looks pretty clean now. I'll post some pix after dinner tonight.

I did look at the strip disc, looked a bit too coarse so didn't try it yet.

[edwardmorris]

Here they are. I washed it in my poor man's parts washer to get as much of the dirt and crud off from in between the fins. Its going to need a few more rounds of that. I have no idea why I don't have any WD-40 around the house, so I dabbed the sleeves with some motor oil and put it aside for now. Moving on to pistons tomorrow and dive into the crankcase as we're expecting to warm back up to freezing (0C).

[Terry in Australia]

Those gasket surfaces look great Ed, good job! Yep, lots more work required on the finned areas, but I've no doubt you'll get it squeaky clean too. Cheers, Terry.  

[edwardmorris]

Thanks Terry

I went through the first step that Hondaman listed on what to look for with the countershaft. From what I can see, all the gears, dogs, slots etc. are in good shape with you nicks, dents or any other obviously visible damage. Shift forks too, look alright. But, I'm the noob, so I'll let the experienced eyes be the judges here. Not the best pics but I can take more at different angles if needed. I've looked as best as I can and I think I'm good here. Only thing I couldn't get out was that damned thing with the roller drum. How does that come off? The neutral switch also hasn't fallen out even with the bolt and plate removed. Is that what is still holding the roller drum in? What to do?

[edwardmorris]

More

[edwardmorris]

Last pic is what I want to remove next. Any suggestions on removing the kickstart, oil pump and the roller on this side of the case?

[Kickstart]

Man... following your thread is making me feel lazy.  Nice effort here.

Yeah, that neutral switch in the bottom needs to come out for the gear drum to slide out.  You may have to pry the neutral switch out a little with a flat head screwdriver. That's what I had to do to get mine out.

The more experienced here will know better, but the gears and dogs look OK to me... but I think you should get some close-up angled shots of the dogs, especially on the 2nd gear dogs (I believe the C5 gear - the one that you had to pull out the side to get the secondary shaft out).

Also try to get some close-up pictures of where the dogs contact on the mating gear (witness marks).

The fork shaft looks like it has some shiny spots... you might want to mic that to see if there is any significant wear... again, others would know better than me.

[edwardmorris]

I'll try and take some close ups of those two gears. I didn't take any that way because you basically need a video to see all the teeth. I went through all of them and, to me at least, looks like all the edges are actually sharp with no nicks or dents anywhere. If I should use a mag glass to be sure, then maybe I'll find some. I'll look through again and maybe take pix of the worst spots on their circumference.

Prying the neutral switch out with a screwdriver had failed when I was splitting the cases. There is a rubber gasket that keeps pulling the switch back inside. I know @Terry hates "Chiselers" but I had to resort to Pic 1 the chisel opens at 90deg so I just pushed the damned switch down far enough to get the roller out. Once the roller was out I pushed the switch out by hand.

On to the million dollar mistake, how do I deal with the broken screw in here? Drill it out?

[edwardmorris]

Oil pump is out, the screen had some crap in it but not too horrific.

[edwardmorris]

Only thing left in the lower case is the kick start gear assembly. That dowel style pin isn't budging and needlenose pliers aren't gripping it well enough to try and pull it out. Is there an easier way to pull it out?

[Kickstart]

I'll try and take some close ups of those two gears. I didn't take any that way because you basically need a video to see all the teeth. I went through all of them and, to me at least, looks like all the edges are actually sharp with no nicks or dents anywhere. If I should use a mag glass to be sure, then maybe I'll find some. I'll look through again and maybe take pix of the worst spots on their circumference.

Prying the neutral switch out with a screwdriver had failed when I was splitting the cases. There is a rubber gasket that keeps pulling the switch back inside. I know @Terry hates "Chiselers" but I had to resort to Pic 1 the chisel opens at 90deg so I just pushed the damned switch down far enough to get the roller out. Once the roller was out I pushed the switch out by hand.

On to the million dollar mistake, how do I deal with the broken screw in here? Drill it out?

Sorry... meant to say take pictures of the dogs, not the teeth, on the gears and where they mate up on the other gear.

Regarding that broken screw... that's a tough one.  Maybe try drilling out with a reverse drill bit if you have one, or just take it to a machinist.
Is there anything sticking out to grab onto?  I've never had good luck getting broken bolts out that were broken flush.  Every e-z out I've tried I ended up snapping off in the bolts. 

[Kickstart]

Only thing left in the lower case is the kick start gear assembly. That dowel style pin isn't budging and needlenose pliers aren't gripping it well enough to try and pull it out. Is there an easier way to pull it out?

Yes... use a large (8") Diagonal-Cutting Pliers ("Dykes")
Something like this:
http://www.homedepot.com/p/Klein-Tools-8-in-High-Leverage-Diagonal-Cutting-Pliers-D228-8/100020319?N=bm4r#.UsjGSfRDsuc

You grip the pin just enough for the pliers to get a good bite (but not enough to cut the pin) and then slowly push down on the pliers to leverage out the pin. Since the plier head is angled it works nicely as a fulcrum.

[MCRider]

Only thing left in the lower case is the kick start gear assembly. That dowel style pin isn't budging and needlenose pliers aren't gripping it well enough to try and pull it out. Is there an easier way to pull it out?

Many threads on this, many have struggled with it. My method is to grab the exposed part of the pin with smallish vice grips, squeezing the pin closed a little. Lever up on the pliar with screwdriver or tire iron. Rinse and repeat until its out.

[edwardmorris]

HA, thanks kickstart and Ron, I must have just missed your posts. I ended up searching and found the same suggestion (almost the same words from Ron's earlier posts ) and I got it out. With the greatest stroke of luck, the pliers kickstart mentioned were in my cheap 10 for $10 plier set kit. Worked like a charm!

Back to the gears, I hope these are the correct angles.

[edwardmorris]

and the mating ones

[edwardmorris]

Before I move on to the other half, visually, how do these look? From Hondaman's book (if I'm reading the book and these bearing right) this is the correct wear pattern. Are these replaceable?

[edwardmorris]

Where is everybody? 

Garage inaccessible again with all the snow. Since I'm stuck indoors, I decided to clean up the pistons. Did a preliminary clean, how do these look? There is definite pitting on all of them, worst are 1 and 4. Want be sure these can go back in before I do a compulsive clean all the oiling holes, ring grooves etc look great. The rings themselves look great, but I'm not even going to dare ask

[70CB750]

I would say pistons are fine and you could reuse rings if you put them back the way they were.  I was going to to that on the F, but one ring was broken - reringed it all.