Topic: Build of CB750 K2 1975 - Europe had K2 until 1975 - Engine started feb 17 2019

[PeWe]

Started to fill the case with parts. Transmission in.
The final drive shaft did not fit first, the outer ring could not enter the groove in cases. I had to hammer the double ball bearing in a little bit more on to the shaft (about 2mm). This did it almost, had to hammer the inner bearing deeper into the shaft too (1mm). Yes, hammered the inner races with a socket and heavy dead blow hammer.

I tested to assemble the upper case to check that all 3 rings + final shaft ring fits grooves in bearings and case. Worked fine, tight fit.
It is different to assemble parts together that never had been together in an engine before.

The old type of clutch I'll use had 7 metal discs in! It started with metal instead of fiber. One too much.

CMSNL show same strange thing, start with metal, 6 pcs + 7 fibers that does not match 7 fibers!
K3-K5 clutch match the basket

It will get 6 metals + 7 fibers. Start with fiber, end with fiber as my K6 clutch that has same hub model.

Edit: Photos with crank and BMW cam chains as Primary chains.
Cam chain is the Yamiya "Yoshimura type" DID something...

Alternator rotor tightened with a cheap strong electric impact wrench for car wheels. The alternator rotor flew in place while I was standing on the crank laid on a wooden plank. Crank wrapped with cloth as dirt protection. Bolt with thread locker. It needed to be tighten some for seat completely on the cone.

[PeWe]

Struggled with the neutral switch today after crank assembly. Found out that I miss the washer that lock it in place. Need to make one.
183 O-ring to be fitted in case first, then the switch in, lubed o-ring helps.

Cases to be closed when gear assembly is finalized and working gear mechanism that need the neutral switch to be in correct position. I need to check oil pump too, open it, look inside replacing the seal, o-ring etc in the pump kit I have.

[PeWe]

Small steps forward today.
Gear shifter mechanism OK, shifted all gears.
Made a print of the neutral switch lock bolt and its  to make an oval washer with flat end. Washer 20mm od with 6.5mm hole should probably fit with a little filing on one side. Make one of small piece of 1-2mm thick alu will look good too and closer to stock look. 9mm from center of the M6 bolt to flat side of neutral switch.
Metal scrap bin at my jobs lab tomorrow.

Final shaft got the oiler plate for auto chain oiling. Stock bike must have if this need to be used in the future. Now plug it.

I was not sure if I wanted to restore the oil pump. After I had opened it for inspection I have to fix it!
I remember the oil pump i fixed before and the tricky oil seal. I have to find a good procedure to remove the old one. Dremel last time was too risky.

[Terry in Australia]

Looking good Per, keep going mate! Cheers, Terry.

[PeWe]

Thanks Terry!  I have the winter soon here to assemble the entire bike.
You will soon have summer and your CB750 project will soon run on the streets!

I have some orders to do,  DSS and Yamiya + the local tire shop

[PeWe]

Did the oil pump itself after work. Extreme violence to remove the stiff seal. Not too much damage, sealing surfaces enough under the new seal to not allow oil creep under seal.
The rest of the oil pump swimming in naphta bath so the stopper will come out and replace the rubber behind it.
I need to order a new oil pump repair kit from Vital, good stuff to have on the shelf.

[Stev-o]

Looking good Pewe.....

[PeWe]

Thanks Stev-o!
This is rather fun but there are some unknown status of the parts that need to be taken care of. All parts have not been together before, except for crank with its rods.

I found a magic cleaner in the Motorex chain cleaner. I saw that the oil pump had some dirty channels and used what I have. The Motorex chain cleaner wiped the dirt away and revealed a shiny alu surface! Must be good for very dirty carbs too. It should be fine for o-rings since it is made for o/x-ring chains. I cleaned the dirty oil pan and it shined within a minute!

Did the oil pump today and mounted it. There is a hard sound when rolling the sprocket at the kick starter that tell me to take out the pump. 2 of the 3 countersunk bolts keeping the pump together are too long. I took a chance that it should not touch any sprocket, pump or kick starter.
The 3 bolts are rather hard. I cut one of them 2 mm after a lot of work due to lack correct tools.  I need a better grinding tool, the files I have are junk. Bolts are high tensile 10.9
60mm long, need to be max 58mm. Perfect replacement of the crappy original X bolts.
http://www.ebay.co.uk/itm/M6-6mm-HIGH-TENSILE-SOCKET-CAP-COUNTERSUNK-BUTTON-DOME-ALLEN-BLACK-BOLTS-SCREWS-/111837901896?var=&hash=item5fa6c79137

The other 4 + 2 X bolts got hex heads. One of the 4 under the strainer needed a higher headed bolt, hex with collar since the socket was not thin enough.

The oil pan have also a tight place where a hex head could not be used since the alu is too close.
Only bolt possible is a allen head! Close to the oil bolt at the triangle.

I had a plan to use OEM bolts were visible including JIS bolts holding all covers except where hex bolts are stock.  I have to use allen heads all around the pan then.
Maybe the CB750 stock purists will look under and find allen heads!!! Like looking under a short sexy skirt and find......

[PeWe]

Fixed the long bolts in Oil pump. Had to buy a bench grinder  to fix them. A machine I have needed for years. It has a wet slow moving stone too for sharpening things.
 Always need to fix the thread start after grinding to not let the sharp start cut the alu like a cutter. This time correct tool, otherwise using a nut exercising the threads where grinded.

It took longer time than needed since one thread was bad. Noticed when tighten the oil pan bolts with 8Nm. The bad one did not torque anything. off with pan and fixed the thread. Having a Time-sert kit is needed when working with these bikes.
Oil pan on and used an old oil bolt. Will be a newer one with washer after first oil change.

I'll fix the neutral switch lock washer before  upper case on. I'll mount the APE case studs before too just for sure. Threads are unknown, looked good when cleaning the case. But you never know.

Note! I had Loctite 272 on the insert only to fasten it permanently in the alu case. All other red goo used on gasket and inside thread insert for assembly is Red Line assembly lube

[PeWe]

Assembled the upper case today.  Ugly neutral switch washer yesterday.
Several steps forward, 1 backward, had to order a time-sert M8 kit since the rear thread in lower case behind clutch was bad and gave up at 15Nm.  I'll probably need M8 time-serts for one or two exhaust spigot/studs threads. I'll do the cheaper helicoil copy. I changed my mind and cancelled the order since the block can not be drilled for insert, will be too much hole and little alu left.

I used an M6 bolt with nut to tighten it together for sealer. 12.5Nm is probably max for an M6.

Starter motor went in while at it. Need the washer for motor sprocket shaft on alternator cover side.
Pistons on kitchen table for ring assembly. Not much left until cylinder and head is there. I need a new longer cam chain slider since the short (correct for K1 stuff I have) has thinner pegs make it to rattle in upper part of cylinder.

[Terry in Australia]

Looking good Per, I like your grinder, I thought about buying one like that years ago, but my old Kmart bench grinder that I bought 35 years ago just keeps going, so not this week.....

[PeWe]

Hi Terry. I have missed a bench grinder for long time. I have not tested the slow going water wheel yet. I'll grind knives that need to get a better angled cut.

[PeWe]

Got a few missing parts today. washer for starter gear (OD 40mm, ID 12.2 mm, 1mm thick) and the cable guide inside the alternator.
Also got a used long cam chain slider in good shape. The shorter model has too thin pegs that fits in the cylinder upper groove. The longer has a nice tight fit.

I changed my mind to fix the M8 threads on the rear side of the block. I'll use a longer M8 bolt with washer and nut. The block has not enough of alu to hold up for an insert. some grinding to make it to fit plus some additional layer of engine paint.

New harness for charging system+ neutral sw and one for oil pressure sensor from Yamiya did not hurt either.

[PeWe]

Block met Mr Grinder, same tool as the other bike, K6 upper case met to be able to swallow the JMR billet block big bore sleeves.
Painted a little too.

Update:
M8 bolt with nut  in place and tightened 15Nm. Strange that I have not ruined the threads on my K6, that thread is short, easy to think an M8 bolt can be torqued rather hard.

[PeWe]

I did some kitchen job today. Pistons got the rings mounted. They are really hard. Cruzinimage 61.0mm pistons.
Piston rings - My nails: 1-0. 

This gave me a bright idea!
I started to think about the strong spring force of the rings and how fast they must break-in (or wear the bores). This ended up in oil thoughts  .
I might not need to use 10W-40 oil for break-in, better with 20W-50 and get a smoother gearbox.

Checked my stash of bike oils and noticed I have:
6.5L 10W-40 Mineral
4L 20W-50 Mineral
1.5L 10-50 Full synth of same brand as the minerals
+ a lot of Red Line 20W-50 full synth, too good for this stock K2 build.

Break-in with 20W-50 Mineral.
I'll mix the rest of the minerals with full synth, about 2 part mineral, 1 part synth oil, my own semi-synth!

This must be a good subject of future oil threads.
NOT about this or that single oil, the magic mix that work fine with smooth gearbox, finding neutral when warm, lubricate the cam with rockers and not finding scratch marks at next inspection.

The first oil fill in a cleaned and restored engine is about 3.5L. Oil change around 2.4L
First oil change after 20W-50 mineral: 0.7L 10W-50 full synth + rest of the 20W-50 mineral + 0.2L 10W-40 mineral.
Next: 0.7L 10W-50 full synth+ 1.7L 10W-40 mineral
Next will be Red Line 20W-50 (1 bottle, quart) + 1.4L mineral oil until my mineral oil is gone. Then continue with a good recipe!

I'll might continue to give my k2 stock engine a cheap 15W-50 semi synth mixed with a cheap full synth, all bike oils.

[Stev-o]

Wow...you started your own oil thread!

[SOHC4 Cafe Racer Fan]

Wow...you started your own oil thread!

Break out the popcorn!

[PeWe]

Wow...you started your own oil thread!

Break out the popcorn!

I have after I wrote my ideas found a cheap but probably good lubrication for my CB750
20L container for less than the cheapest mineral I have used. 4L for a little more but still low price.

It must be a good idea to test before bringing a 20L container home to the garage. I have to wait until next year
Q8 Moto SBK Racing 10W-50
http://pds.q8research.com/sheetcommercialpdf.php?id=179&taal=E
http://pds.q8research.com/safetysheets/B/B/English%20(US)/Q8%20Moto%20SBK%20Racing%2010W-50.pdf

Blending my own is still interesting.

[PeWe]

Started the piston assembly after work. Did only one, too tired, no hurry and eventually make a mistake.
The Assembly lube notes on the cap reminds me to change oil shortly when running, after 50 km as my last build. It might contain antifriction stuff that need to be flushed away from clutch. Good for an assembled engine that will not be started in months.

Pistons marking, the arrow does not match the valve pockets. The arrow point forwards to exhaust, right? The valve pocket is alittle bit wider on that side, not on inlet as I expect.

I did not use the Cruzinimage pistons G shaped circlips, I use Honda. I have a feeling hat the G shape can get loose easier. Maybe I'm wrong.

[Terry in Australia]

Block met Mr Grinder, same tool as the other bike, K6 upper case met to be able to swallow the JMR billet block big bore sleeves.
Painted a little too.

Hey Per, that's an interesting looking "grinder" in your pic, looks like a holes saw with teeth on the sides too? I'll have to get me one of them! Cheers, Terry.

[PeWe]

Block met Mr Grinder, same tool as the other bike, K6 upper case met to be able to swallow the JMR billet block big bore sleeves.
Painted a little too.

Hey Per, that's an interesting looking "grinder" in your pic, looks like a holes saw with teeth on the sides too? I'll have to get me one of them! Cheers, Terry.

Hi Terry,
Yes, that tool has been very useful. Found it in a tool shop when looking for tools grinding the upper case, grabbed it just for sure and it looked useful. Less than 10 USD. Fixed the alu cast under the bolt hole in a few sec. The upwards teeth grinded upwards too in a sharp angle while it ate side ways too. It eats alu really quick so be careful. It must be found on Chinese sites since it is cheap.

[PeWe]

Did all pistons after work and car wheel change. Ready for case studs. After that cylinder and head on.

The head and cylinder have smooth surfaces, MLS would be fine but I have fiber for free with the gasket kit. The frame will have frame kit so re-torque is not difficult, especially when I'll use std cam with std sprocket. No cam timing, just bolt on.

But MLS is handy, no additional tightening of stud nuts after 500-1000 km. Base gasket is fiber though, so an extra job with torque wrench will happen anyway. My K6 has both MLS and RCS base gasket, no need of remove cam and cam towers to tighten them again.
I'll tighten 28Nm, (20.65 ft lbs). Maybe no hurry for tighten again after some use. I'll do a re-torque after a month on bench. Cam holders etc will wait while I'll work with the frame making a rolling chassi.

Honda did a design mistake. It should be possible to tighten the 16 head nuts without removing the cam, cam towers etc. And removable frame section too.

[SOHC4 Cafe Racer Fan]

Block met Mr Grinder, same tool as the other bike, K6 upper case met to be able to swallow the JMR billet block big bore sleeves.
Painted a little too.

Hey Per, that's an interesting looking "grinder" in your pic, looks like a holes saw with teeth on the sides too? I'll have to get me one of them! Cheers, Terry.

Hi Terry,
Yes, that tool has been very useful. Found it in a tool shop when looking for tools grinding the upper case, grabbed it just for sure and it looked useful. Less than 10 USD. Fixed the alu cast under the bolt hole in a few sec. The upwards teeth grinded upwards too in a sharp angle while it ate side ways too. It eats alu really quick so be careful. It must be found on Chinese sites since it is cheap.

Looks like a dental torture tool.

[PeWe]

Block met Mr Grinder, same tool as the other bike, K6 upper case met to be able to swallow the JMR billet block big bore sleeves.
Painted a little too.

Hey Per, that's an interesting looking "grinder" in your pic, looks like a holes saw with teeth on the sides too? I'll have to get me one of them! Cheers, Terry.

Hi Terry,
Yes, that tool has been very useful. Found it in a tool shop when looking for tools grinding the upper case, grabbed it just for sure and it looked useful. Less than 10 USD. Fixed the alu cast under the bolt hole in a few sec. The upwards teeth grinded upwards too in a sharp angle while it ate side ways too. It eats alu really quick so be careful. It must be found on Chinese sites since it is cheap.

Looks like a dental torture tool.

A little bit bigger.. Ø26x60 mm
Torture for lower parts...
The engine look like a surgical operation. I had to cover it completely since I know how madly the circlips want to jump down there.

[Terry in Australia]

Honda did a design mistake. It should be possible to tighten the 16 head nuts without removing the cam, cam towers etc. And removable frame section too.

Whenever I build an engine Per, I torque the stud nuts to 20 ft lbs (8 ft lbs first run, then 12, 16, 18, and finally 20) then leave it overnight, back them all off and re-torque them to 20 ft lbs again, and they don't leak. I know that 20 is way more than you'll read in your workshop manual, so I think Honda made a mistake with their specs too........