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

[edwardmorris]

Ed, it's kinda tricky 'cuz you got two screw holes and the actual fuel outlet hole...so what I have done is make a little metal plate, drill it for the two screws and then screw it on with some rubber(I cut a piece out of a heavy duty rubber glove) or gasket material sandwiched between the plate and the tank.

Great idea! I should have enough crap around the house to rig it up. Thanks!

[Terry in Australia]

Have fun with the electrolysis Ed, I've done it but it was so slow I gave it the arse and used phosphoric acid (the stuff they put in Coca Cola, chrome polish etc) and it removed all the rust in a couple of hours.

Be aware also that you need plenty of ventilation with electrolysis, as you're also creating hydrogen gas, and any spark can cause it to explode. If you're a smoker, or there's a furnace in your basement, be very, very careful......... Cheers, Terry.  

[edwardmorris]

Have fun with the electrolysis Ed, I've done it but it was so slow I gave it the arse and used phosphoric acid (the stuff they put in Coca Cola, chrome polish etc) and it removed all the rust in a couple of hours.

Be aware also that you need plenty of ventilation with electrolysis, as you're also creating hydrogen gas, and any spark can cause it to explode. If you're a smoker, or there's a furnace in your basement, be very, very careful......... Cheers, Terry.

Good looking out Terry, I'll leave it out in the garage and keep checking in between work shifts. I picked up a nice steel rod to use, already have a good batter charger, just need to go get me some salt and rig up a nice petcock hole blocker.

In the meantime, I picked up the goodies from the machine shop! Everything looks cleeeeen, but my damned cell phone is on the charger. Pix coming up in a few hours...

[edwardmorris]

Here they are! I feel bad handling these in dirty gloves but oh well, I'll be cleaning them compulsively anyway

[edwardmorris]

The head got resurfaced on the house, rider-to-rider deal and the fins cleaned up nice.

[edwardmorris]

The cylinders are done with 0.001" clearance and cross hatch hone. He was impressed with the yamiya pistons, said he'd never seen all four measure the same. Resurfaced and clean fins

[edwardmorris]

AND FINALLY the icing on the cake! Perseverance is all it took. I found a shop all the way out in Lowell IN, Midwest Accurate Grinding, and they widened the grooves on my SKF replacements! They are a very nice business. Of the three bearing I sent them, one of them (pic 3) already was the correct size so they called me and let me know they didn't have to work on it. Pricing was reasonable too.

After chatting with them, it turns out that the bulk of the work is in "setting up" for grinding. Once its set, they can grind out as many as you need, so if you'd like to save, have multiple sets done together. Its about a 40min drive and they don't work on weekends, so I just shipped them my set and they shipped it back in a 5 day turn around time. If you're looking to get some done, give them a call.

[RRRToolSolutions]

Hi Ed, Gordon here. I've had dozens of cases, heads, and cylinders beadblasted over the years. You have to visualize that the blast material is sandpaper inside your engine. You have to get it out. I have a large plastic storage bin that will hold a crankcase.
 
I start off with a very high-pressure nozzle and wearing safety goggles, I blow into every hole, crack, and corner. Do not run the tap through the holes unless you have a damaged one - the tap removes tread material. Make sure every threaded hole is clean.

I then soak the casting in solvent (I use gasoline outside, but it's not proper nor safe) and I rock the bin side to side, soak some more, rock, soak, rock - until every piece is what I think is pure metal. I then remove it and blow with high-pressure again.

Lastly, I fill that same bin with hot-soapy water. I mean I get buckets of hot water out of the tub faucet and Dawn dish washing soap and soak/aggitate those castings again and again. I then take them to an outside drain and lay them on the bin's lid and run my garden hose over them and then blow again with the high pressure. I let them dry and and only then do I feel they are ready for assembly.

Please note that even after all this cleaning, the first oil change is something I do at 100 miles. There will still be some media in the filter.

Best Regards, Gordon

[SOHC4 Cafe Racer Fan]

Hi Ed, Gordon here. I've had dozens of cases, heads, and cylinders beadblasted over the years. You have to visualize that the blast material is sandpaper inside your engine. You have to get it out. I have a large plastic storage bin that will hold a crankcase.
 
I start off with a very high-pressure nozzle and wearing safety goggles, I blow into every hole, crack, and corner. Do not run the tap through the holes unless you have a damaged one - the tap removes tread material. Make sure every threaded hole is clean.

I then soak the casting in solvent (I use gasoline outside, but it's not proper nor safe) and I rock the bin side to side, soak some more, rock, soak, rock - until every piece is what I think is pure metal. I then remove it and blow with high-pressure again.

Lastly, I fill that same bin with hot-soapy water. I mean I get buckets of hot water out of the tub faucet and Dawn dish washing soap and soak/aggitate those castings again and again. I then take them to an outside drain and lay them on the bin's lid and run my garden hose over them and then blow again with the high pressure. I let them dry and and only then do I feel they are ready for assembly.

Please note that even after all this cleaning, the first oil change is something I do at 100 miles. There will still be some media in the filter.

Best Regards, Gordon

Gordon,
Even with that cleaning regimen you still find media in the first oil change! Yikes.

[BPellerine]

your stuff looks great ed!nice to have some pretty stuff to look at I bet!bill

[Terry in Australia]

Looking good Ed, just to add emphasis to Gordon's words, i.e., the need to thoroughly clean all of the castings that have been blasted, including your cylinder block.

I put each casting in a tub full of hot soapy water and use a range of gun cleaning brushes, tooth brushes and even pipe cleaners to make sure that every hole, slot, oilway, etc is thoroughly clean.

I haven't used the "solvent dip" that Gordon describes (because I have a fear of exploding) but I can see the benefits. The main thing is not to skimp on elbow grease and lots of flushing with clean water and poking a high pressure hose up every orifice in every casting. You'll be surprised at how much grit comes out.

You'll need to clean, dry and lightly oil your new bores after thoroughly washing the cylinder block to avoid flash rusting, but you can't leave it out, but it has to be done too. Cheers, Terry.

[edwardmorris]

Thanks guys, it is somewhat in the lines of what I had in mind I have a good compressor with a tiny nozzle attachment that should be handy for all the tiny nooks and crannys. I already have large bins that fit the cases (I cleaned them up with simple green before getting them blasted) so definitely doing the hot soapy water soak a few times. Not sure about a gasoline soak but I can flush everything passage with some mineral spirits (which I've found is as good a degreaser as diesel) and then hot soapy soak again. I tend to get obsessive when it comes to cleaning anyway so hopefully I'll clean it out well.

Looong snowy day, but small good news though, Yamiya got the K2 sets back in stock again so electrolysis is on the back burner for now (I know I know, big dreams, small wallet :p but I think I'll be able to save by the time I'm ready to ride this thing).

Only had a little bit of time today to work on a couple things. Cleaned up the alternator cover after removing the coils. Once again, the impacta came in handy and again with my luck, there was one bastard that wouldn't budge. BUT, I have the big beast as well and it whacked it right outta there.

Now am I not seeing it or looking in the wrong place? Where is the circlip to detach the basket from the primary drive?

[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.