Topic: CB750K2... Ol' Sarge project

[onepieceatatime]

Just got a K2. I would love to say that I plan to restore it, but there is too much missing for me to spend the time and money to track down all of the parts that I'll need.
The frame has been cut, so I will do some more cutting. I want to Kong it, and build a rat bike. I would rather have one of the K0-K6 bikes in original shape than the K7(s) I have yet to finish, but I'll work with what I have.
Here is what I have of the K2.






I have a lot of CB650 parts, so my tentative plan is to use 650 handlebar controls and entire front end on this bike, if measurements work out.
I will be building the wiring harness from scratch, I need to find a rectifier/regulator for it. I'll have to figure out if I can use CB650 coils, or if I'll have to track down a set of CB750 coils. I'll be building a custom oil tank, probably a custom rear fender and seat. I have an old 550 key and switch that I think I can make use of. I'll probably use the Lester wheels on this build, but it did come with a spoked rear and a hub for a spoked front. I have a pair of old tail lights from who knows what car (they were in the trunk of a '64 Thunderbird when I bought it years ago) that I will probably use for brake lights/rear turn signals. I haven't decided if I will use one of the random fuel tanks I have sitting around, or try to find something else for it. I want to ditch the chromed swing arm, so I'll probably use the one from a K5 that is laying in the garage. I do not have an airbox, so I'll see if I can track down one of the breadbox air filters.
I guess I'll see how the build morphs from this plan as I go.

[Pielz]

Badass! I'll be excited to see your progress! Also I found the sissy bar funny. "Honda Motorcycles" in the Harley style badge. 
 
Those solid rim wheels are cool too. What are they?

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[onepieceatatime]

Badass! I'll be excited to see your progress! Also I found the sissy bar funny. "Honda Motorcycles" in the Harley style badge.

I have a taller one for my CB650 too

Btw if you're not gonna use the rear fender and brake light setup that came with that, I'll buy it from ya

Let me make sure I don't need it for one of the K7s. I think they are both in good shape, but want to be sure. If I don't need it for one of them, I'll trade you for your old Jardine exhaust.

[onepieceatatime]

Those solid rim wheels are cool too. What are they?

Those are Lesters, like what is on my black K7.

[Pielz]

Badass! I'll be excited to see your progress! Also I found the sissy bar funny. "Honda Motorcycles" in the Harley style badge.

I have a taller one for my CB650 too

Btw if you're not gonna use the rear fender and brake light setup that came with that, I'll buy it from ya

Let me make sure I don't need it for one of the K7s. I think they are both in good shape, but want to be sure. If I don't need it for one of them, I'll trade you for your old Jardine exhaust.

I had edited my post immediately after realizing it probably wouldn't be interchangeable with a k7 lol but if it is I'll 100% trade that jardine for it!
 
And nice I love the look of them!

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[onepieceatatime]

I started mocking parts up today to get some idea of if the parts will work or look the way I want.
CB650 forks and kick stand, CB750K7 steering stem and triple trees, CB750K5 swing arm, battery box, rectifier, regulator, starter relay, engine mount brackets and bolts, and handlebar clamps, CB750K2 handlebars and rear fender, Corbin-Gentry seat, Lester wheels. Unknown brake lever, maybe CB650.
The kickstand will not work as is. The tab for the spring is on the opposite side as the one on the frame, and the stand is a bit long as the bike currently sits. I'll probably still use this one, just modify it as needed. The forks will not work for this build, they are too short. I do have CB750K2 (I assume) lower fork tubes that came with the bike, but the uppers are trashed, so I will probably buy new uppers and rebuild them.



I have 3 sets of nasty round top carbs. They will all need a very good cleaning, and hopefully I can get a couple good racks put together... a project for later.



I have a chrome CB750K2 swing arm (again, I assume) that came with it, but do not plan to use.



I do not plan on using that seat for this one either, as I will be altering the frame.
I think I'll end up taking the passenger peg mounts off, because I don't see this as a bike I'll have anyone on riding with me.
I have a cleaner set of shocks from a CB650, I'll see how the size compares and probably use them.

[Pielz]

Sweet!

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[onepieceatatime]

A bit of google time has revealed that the random tail lights I was thinking about using are from an 1949 or 1950 Lincoln Cosmopolitan.

They seem to be a bit of rusty gold.

[onepieceatatime]

I started to rebuild the forks that came in the box of parts with new stock size upper tubes. The internal parts do not match the parts diagrams for a K2. They look more like K5 forks. When I get them put together I'll compare size to the set that is on it now, and if they are taller, I'll put them on to see how it sits.

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[onepieceatatime]

I have been gathering parts out of my bins, and buying some other parts to get this thing together.
A pair of 3.5" dual element LED headlights with rock guards and a set of 7" headlights from a 1940s military truck that I plan to convert to LED.
Reproduction Harley hinged rear fender. It will require some modification to fit the frame.

Frame section cut out of a junk K5 frame that I can use with a frame kit to replace the missing part of the K2 frame I am using.

'77 CB750 Hondamatic fender and pedestrian slicer to go on the front.

1500 round 7.62 ammo cans for hard bags and a place to mount the Lincoln Cosmopolitan tail lights as turn signals, and a Model T tail / brake light.

Some badges that I will find somewhere to mount on the bike.

Two petcocks with bungs, brass gas cap with bung, and two NOS Army water buffalo air tanks, to be turned into a gas tank.

Air horn, center stand, and an assortment of gauges that I will use in some combination.

Reproduction Cadillac bullet lights for the front turn signals and amber LED strips to make side mount turn signals.

And an old Kevlar helmet that will adorn the sissy bar as decoration once Ol' Sarge is completed.


I need to find a good (or rebuild-able) front brake caliper assembly, a breadbox air filter, a set of turn out mufflers, and I would like to find a set of Henry Abe 7-Star wheels for it. I decided to keep the Lester wheels, but for my K7, if I can find a decent set of 7-Stars.
I will end up building a custom wiring harness, and I have a set of RC 836 pistons and rings I am thinking about putting into this engine. If not the RC, I have a newer 836 kit that will be used. I also have a Lockhart oil cooler to use on it.

[scottly]

Those forks in the first pic are not K2; they have the K3 and up caliper mounts.

[onepieceatatime]

Those forks in the first pic are not K2; they have the K3 and up caliper mounts.

Thanks! That makes sense, since the internals didn't match the K2 parts diagram. I just bought a set of 4" over upper tubes to rebuild them with.

[scottly]

There is nothing left of the original tubes for the frame kit clamps to clamp on?

[onepieceatatime]

Nope, they were cut at the weld on the front downtubes. I had a junk K5 frame that I got with a parts lot that had those tubes though, so I cut it at the welds, and will weld it on the K2 frame, then cut it again for the frame kit.

[scottly]

Got it. PM incoming.

[onepieceatatime]

I did a bit of work with a weld in frame kit that I had, and the section of K5 frame that I had cut out.
None of it is welded yet, I have more cutting to do and didn't feel like setting the welder up tonight.


Then I did a little more frame cutting. I used a diamond cutting wheel on my angle grinder, because I need some new sawsall blades.
When I get the new blades, I will be able to finish those cuts and remove that section of the frame to lower it into its new position, and weld it in.



After that, I pulled the swingarm off the frame, removed the cup washers, collars, and end caps. The collar did not want to move, but my shop press convinced it.
I had a spare swingarm pivot bolt, because I plan to upgrade my K7 as Hondaman describes in his book, and I decided to investigate the chrome swingarm that came with the K2 frame. When I tipped it sideways, the collar slid right out, covered in fairly fresh grease. There were no endcaps or cup washers with the chrome one though. I'll try to clean up the gummed up grease on the one set later for that K7 upgrade and use the nice ones on the K2. I still have to clean up the inside of the swingarm to see if the bushings are any good or need to be replaced, and try to find a set of the felt washers.

[onepieceatatime]

That swingarm collar is pretty pitted, so is going into the scrap bin, and I'll buy a new one for the future K7 upgrade.

When I got the K7s, I paid $500 for both, with a bunch of extra parts and this K5 thrown into the deal.


It has been the donor for rectifier, regulator, swingarm, and frame sections for this K2 build. Today I decided to check out the engine, and was surprised that it turned over easily by hand. I figured that it would have been seized from sitting outside with no exhaust for an unknown number of years. The PO told me that he had gotten it from a scrap yard, for the scrap cost of the metal when he bought the K7 projects.

I figured if it would turn, it might be a good base to start building with the 836 kit, and if not it may be a good donor for parts for the K7 that I have yet to open up, but someone was certainly into before, as evidenced by the orange silicone and black jugs and head.

There were 3 different kinds of spark plug in it.


My cheap compression tester seems to have failed, indicating 60 PSI with nothing connected and the bleeder valve released, so I dug out my old Snap On compression tester. It is a bit harder to use as you have to press it into place while trying to turn the engine. It showed no compression, but I cannot be sure I was holding the tester tight enough. I'll have to get someone to help, or another screw in tester.


I pulled out the FSM to see how to check valve clearances. The tappet clearance is set too loose on both intake and exhaust. If I can verify that it has compression, I'll compare to the numbers I get from checking the K2 engine and decide which one to tear down and put the 836 kit into.

[onepieceatatime]

I couldn't stop for the night without knowing if the K5 engine would work, so I messed around with it a bit more. If there was a kickstart lever on it, things would have been easier. I discovered this by checking the K2 engine.
I had not looked at the K2 engine very closely up until now. As I was pulling the old dry brittle duct tape off the intake and exhaust ports and oil filter opening (no cover present), I noticed what appeared to be a strange threaded spacer sitting in one of the spark plug recesses.


Closer inspection revealed some bad news.

I will see if I still have the contact info for my welding professor from a couple years ago. He has his own welding shop, and can weld practically anything. He should be able to fix this up for me.
On the plus side, there is compression on the K2 engine all cylinders, but I still prefer to use a compression tester that will thread into the spark plug holes.

Moving back to the K5 engine, I was able to get a reading on the 3 and 4 cylinders, but not on 1 and 2.






The rings are pretty well stuck in the grooves on 1 and 2, but I could not feel any pitting or grooves in the cylinder walls. I will probably install the newer 836 kit I have, with the cylinders already bored to match the pistons, and see if I can find someone to bore these cylinders for my RC 836 kit. That will either end up in the K7 or in the K2 engine and eventually make it into this bike.
The head will need some clean up too, so either I have to do some more reading and learning, or I have to send it to someone smarter with more tools than me.

[onepieceatatime]

The rings are pretty well stuck in the grooves on 1 and 2, but I could not feel any pitting or grooves in the cylinder walls. I will probably install the newer 836 kit I have, with the cylinders already bored to match the pistons, and see if I can find someone to bore these cylinders for my RC 836 kit. That will either end up in the K7 or in the K2 engine and eventually make it into this bike.
The head will need some clean up too, so either I have to do some more reading and learning, or I have to send it to someone smarter with more tools than me.

I've been thinking on this some more, and with the cylinders in good shape, I think I'll check specs and just put it back together, replacing what needs to be. The rings have freed up on #2, but #1 sre still stuck, so they need attention.
What I do not have the experience to know, and hope someone can tell me, should I out it back together as is (once I get the rings on #1 free), give the cylinders a quick hone and put it back together, or hone the cylinders and replace the rings then put it together?

Also wondering if there is a preferred brand or brand to avoid for gasket kits.

[onepieceatatime]

I did a bit more frame cutting last night.




And a little mock up with the rear fender.


I ended up setting the fender a touch farther forward than this, but forgot to take a picture. I think that is how I will end up mounting it.

I also decided to pull the clutch cover from the K5 engine. The screws were pretty mangled and quite stuck, but my impact screwdriver managed to get them out.
Looks like some PO messed things up in here in the past, so I guess I am looking for a new lifter plate too.


I'm not sure if I'll work on the frame more tonight, or get to work on that Subaru engine that has been waiting on me to replace gaskets for a couple months. It will be nice to have it running again, and the garage space that the Outback is taking up back for projects again.

[onepieceatatime]

I did sneak in a little work on Ol' Sarge tonight, while working on the Subaru.
I had an old ratty, dented, leaky, terrible paint, failed liner CB650 tank that I cut up. I cut out the center channel to be able to use it in the fabrication on my fuel tank for this bike, and cut a decent front corner out of it to repair another CB650 tank with. Both tanks were cleaned out and left open years ago, no chance of residual fuel/vapors.




I'll clean it up more another day. Looks like I really need to clean the floor again too 
I took the steel bushings out of the swingarm tonight too. I have some shiny new bronze ones to go in, after paint or powder coat. I tried to use my slide hammer puller with no luck, so I carefully cut one with a hacksaw and broke it out. Then I dropped a socket and extension into the swingarm and put my shop press to work. That one came out much cleaner and easier.

But I had to stop there and work on this Subaru. My girlfriend has been driving my 1988 Chevy Cheyenne 3500, and would appreciate it if she could switch back to the car. It has around 220,000 miles on it so it is due for timing chain and components to be inspected, and began leaking oil quite profusely. I pulled the engine out a couple months ago to address the leaks, but never got around to doing anything with it. It is a 2001 Outback VDC with the EZ30D 6 cylinder engine. The valve cover gaskets, oil pan gasket, and timing chain cover were leaking oil. To replace the valve cover gaskets, the engine has to come out. I bought new struts, CV axles (the boots were torn anyways), tie rods, water pump (I'm going to be under the cover anyways, might as well), thermostat, spark plugs (you have to unbolt the engine mounts to change the plugs, so perfect time), and all required gaskets and some Yamabond 4 Marine, since I couldn't find Threebond 1280B.
I pulled out the 59 bolts from the timing cover (some surrendered easily, others met the dremel and impact screwdriver), and all the timing chain components look fine. I might replace the tensioners anyways. I have to pull the upper chain to pull the lower chain to pull the water pump.


I have a 2002 LL Bean Subaru Outback sitting in the yard with blown head gaskets (according to the friend that I got it from). I don't know if I feel like doing all this again, plus some, to get it going. It might find its way to the scrap yard instead.

[onepieceatatime]

Since I am waiting on parts for the Subaru, and I had a couple days off work, I made some more progress on Ol' Sarge.
I cleaned up some of the frame cuts, removed un-needed tabs from the frame, and cleaned up some of the factory welds to allow the rear fender to sit in a little nicer.



I ordered some 25mm steel tube to insert and weld into the frame tubes with open ends that are visible in the photo, to add strength, and to fashion my new top section of the frame triangle, and the tall sissy bar that I will be building.

I got the old bushings out of the swingarm, and have put the chrome swing arm on the bike for purposes of mocking things up.
I also did some more work on the K5 engine.
I pulled the clutch out, there was some debris around the basket that looks like clutch material.




I split the cases and found more of the same in the sump pan, the screen, the lower case below the crank shaft, and in the oil filter housing.






And surprise, there was no oil filter (or washer) in the housing.

The only bad thread I have found so far was on one of the oil tank lines. As soon as I touched the bolt, I felt that it was loose, and the threads all came out with the bolt. 

I also took apart the used front caliper I sourced from ebay, and got the stuck piston out with my grease gun.


I already have the rebuild kits for the master cylinder and the caliper, but did not install them yet.
I ordered new cam chain, and cam chain tensioner/ guide parts, and am waiting for those, gasket kits, a dial gauge, and some micrometers to arrive. Once I get them, I'll check tolerances on the engine parts, clean t he oil passages, and get this thing back together.

In the meantime, I did a bit on my K7 project.
This bike was sitting with no exhaust when I bought it, and has stuck valves.
Thanks to the weldless frame kit I just bought, I cut the frame to work on the top end in the bike.
Inside the #4 cylinder I found this:


It looks like twisted up leaves.
The cam chain tensioner has a lovely patina to it, so a new one is on the way.


Orange silicone on gaskets, which I could see from outside the assembled engine.


And the head.

#3 and especially #4 exhaust valves are stuck open, no cam present.

The pistons do not look all banged up, and the cylinder walls are pretty smooth, so hopefully all is well inside this engine too. Further teardown will have to wait until the K5 engine is back together.
The carbs are frozen solid, but I have a good rebuilt set I can put on the K7 once the engine is finished.

Once both of these engines are back together, or I can clear more bench space, I'll tear into the K2 engine and see about having the oil filter bolt bung welded back on.

[onepieceatatime]

On both of these heads, the oil restrictor jets are pretty well stuck in place. I have tried to turn the heads upside down and shake them out, but they will not budge.
Is there a safe easy way to get them out to clean the passages?

[RAFster122s]

The leaking gaskets on the Subaru motor sre often indicative of blocked Crankcase Breathers...excess crankcase pressures blowing out the gaskets. If the flame trap/crankcase breather is not maintained that is what happens on many motor designs.
Look into it...

[onepieceatatime]

The leaking gaskets on the Subaru motor sre often indicative of blocked Crankcase Breathers...excess crankcase pressures blowing out the gaskets. If the flame trap/crankcase breather is not maintained that is what happens on many motor designs.
Look into it...

Thanks! I ordered a new PCV valve for it when pulled the engine out, and will be replacing the heat/radiator hoses when I put it back in as well. I'm not familiar with a flame trap, so I'll google that and replace parts as needed. the order for the Yamabond 4 marine was canceled as out of stock, so I ended up ordering Permatex optimum grey, and hope that will be good enough.