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

[seanbarney41]

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........

+1, I have always done the same, no need for heavy duty studs

[PeWe]

I used the std studs before. No problem with 28 Nm. I felt some flex. I did in steps too. 10, 15, 20, 25 and finally 28 Nm. The heavy duty studs are more rigid, no flex at all. I have no other studs than the APE set.
I have also done a 2:nd    torque a day after. My K6 got ISO std forged collar nuts. A little bit higher and 13mm socket. Ill might use Honda std on this build.

[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.

I could not resist to buy a 4L bottle. I should have bought the 25% cheaper 20L container if I had not seen a label like ”OK with  catalysator” which means not max amount of Zinc and phosporous stuff that  cam and rockers like.
I’ ll mix with Red line 20W-50 that has plenty of it, 2,5 %

[PeWe]

APE studs mounted in case. Next step is cylinder on. Hopefully no broken rings. 
Need to find some fresh rubber straps holding the base gasket.
I'll torque head nuts 20 Ft lbs (27Nm) The std nuts have hard time with higher torque

EDIT:
I noticed that the "Complete" gasket set from DSS  has not the important o-rings. Base (2) and head -cyl (+ eventual 8 o-rings for new headgasket on old cyl-head)+ 18x3 between cases and neutral switch + o-rings for oil lines.. Yamiya's kit has more o-rings. good idea to have extra of all o-rings.

I have some o-rings I have ordered earlier.

[PeWe]

Cylinder went on today. 
Stiff stock 61 mm piston rings did not cause any problems.  "Vibrated" down the cylinder over the rings with a screwdriver stucked thru the piston pin, moved it heavily forward-backward which made it easier.

Stopped by a CRAP head gasket!! I did not notice how crappy the DSS "complete" gasket kit really is earlier since I had all o-rings separate and used big bore head gasket. I have 2 head gaskets that look exactly the same from 2 DSS gasket kits, not a single bad quality then.

The head gasket supplied in the kit is not possible to use in a serious build.
I have seen egg shaped gaskets before, but not like this! Plus the hole for outer M6 bolt at cyl 4 misplaced, the hole need to be grinded off at least 2mm to exhaust side.  I compared with 65mm gaskets I have, Cruzinimage and Yamiya, both have much better fit.

I had several std head std gaskets from all gasket kits I have used since the 80's I gave away a couple of years ago since I had no ideas building a stock bore.

Have to find an MLS head gasket with circular 61 -62mm holes for bores. Here a gasket that hardly cover the sleeves upper wide area.
I have 65mm and bigger gaskets with ROUND holes, but I'll loose compression.

[PeWe]

OK, I gave up and used the std fiber gasket. MLS for 61mm bore will take long time to get. Probably only CycleX and Dynoman that sell them.
Head went on today, added 8 additional o-rings since the gasket is late model with 8 wide holes, cyl-head early model.

[PeWe]

Torqued head nuts for 3:rd time 27Nm (20 ft lbs).
Head and base gaskets compressed, marks on nuts show deeper settings each time.
I have to do a 4:th time to verify that gaskets are fully compressed and will not leak with no further re-torque after some use. Remove cam and holders is boring for tightening nuts only.

[PeWe]

I found my stronger glasses (4x) and checked a bag with o-rings once again. Found the correct o-rings  4x2mmm I knew should be there somewhere.
Yamiya gaskets kits have most of the important o-rings with both late and early o-rings under cam holders.
Re-torqued head again. I hope the fiber gaskets have compressed enough and will keep tight, no leak.

Cam mounted. So easy with stock stuff, no need of cam timing!!    Valve adjustment left.
Stock valve lash 0.05 / 0.08mm feels very tight. Will the lobes get enough lubrication?  I'll start with 0.1/0.1 mm.

I have adjusted my hotter cams  0.1/0.15 mm since many years. Last cam 0.25/0.25 mm (should be 0.3/0.3mm)

I hope I used Redline ass lube and not Loctite hi torque/temp!

[Terry in Australia]

Looking good Per, I see you've got plenty of that red sh1t everywhere, I presume that it won't make your clutch slip? I always use imperial feeler gauges to do the valve adjustments, so .002" and .003" respectively. Cheers, Terry.

[PeWe]

Hi Terry, I have also thoughts about the red lube and clutch.  I'll do an oil change after the first 50km ride on 10W-40 mineral oil that is not a good oil for CB750 (gearbox feels hard and mechanical), only for initial break-in of rings. Another change again after additional 1000km, then with oil filter and mix with full synth getting semi.

I'll use Barnett clutch springs, std CB750 has not that much rwhp either. It will get the clutch plates that my K6 (almost double hp) got a slip with except for the outer with wider tabs that does not fit the older basket. I'll use a new CycleX plate.

I have a friend living on the countryside 25 km away from me. Perfect for test rides and ignition check/adjustment on a warm engine.  Half distance is OK for 150-190 kph riding if not too many slow going cars (90-100 kph) will block the road. Then a few km curvy country road with pine trees close to the road. Risk for deers too making it more exciting when twisting the throttle.

First ride with this will be a few accelerations to 6000, 8000 rpm followed by decelerations when warm and I have reached the smaller road.

It will take about 6 months for starting it so using oil only now might cause bad lubrication the first 30 seconds at first start-up.

0.002"/0.003" is closer the Honda spec of 0.05/0.08 mm. I do not trust that small play. If using double play on IN will reduce lift a little  I'll start with 0.1/0.1mm (0.004"), check again after some use.

[PeWe]

Plugs in (Denso) to cover the holes were things will fall if given them a chance.
Alternator and shifter covers went on. Took longer time since I had t repair one thread with time-sert and use longer bolts for other weak ones. Gasket had bad hole alignment too, one hole had to be cut wider. I do not recall I had that problem with Yamiya gasket kit. I use old covers to start with. I have all 3 NOS, alternator, gear shifter and chain sprocket cover.

I'll use an old ugly chromed chain sprocket cover.

I have changed my mind about JIS bolts after I had to fight bad OEM bolt holding the field coil in cover.
Allen heads it will be all over. Honda made a mistake with JIS, I'll not get the old bolt struggles back again. Got some flashbacks today.

Time for cleaning the bench and work to get a rolling chassi. Need to order new tires in std sizes. 3.25-19, 4.0-18. Have really fresh stock wheels looking like new.

Need to find a fresh valve cover. I had planned to use the valve cover from my K6 and use a old cover with cam holder bolts on the K6. I do not want to remove tank again for the cover only. I had removed it several times a year and risk for harming the fuel lines and petcock.

[01Thomas]

Hello Per
What BMW are these timing chains from? I know you've listed a part number but that doesn't look like a BMW part number to me; more like a supplier p/n.

regards
Thomas

SNIP

Primary chains will be BMW timing chains (VAICO V20-0251).

SNIP

[PeWe]

Hello Per
What BMW are these timing chains from? I know you've listed a part number but that doesn't look like a BMW part number to me; more like a supplier p/n.

regards
Thomas

SNIP

Primary chains will be BMW timing chains (VAICO V20-0251).

SNIP

BMW 530 d,  184 HP,  [E39],  Production: 1998/08 - 2000/09,  Engine code: M57 D30 (306D1)
Original partno: 11 31 2 248 729

You can find more about prim chains in this thread
http://forums.sohc4.net/index.php/topic,154183.100.html

[Terry in Australia]

That engine looks great Per, I'm just hoping I've got enough gaskets to fit my shiny covers to my repainted engine!

[PeWe]

You might have a forgotten gasket set somewhere?
The Honda gaskets look better than the gaskets I used form DSS set. Hondas are slimmer, well shape and probably holes aligning better.
http://www.yamiya750.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=gasket&inc_subcat=0&sort=20a&page=1

All 3 side covers and maybe the oil pan, cam chain tensioner and valve cover too. If not adding sealer they can be reused if covers are lifted.

[Terry in Australia]

Thanks Per, I've got a huge box full of gaskets that I've collected over the years, mostly for Honda's, I'll need to go thru it and see if I've got what I need, if not, I'll pay Yamiya an e-visit......

[PeWe]

I'm sure the old CB750 gaskets sets were sold cheap for 15 years ago.
Different now when all CB750 SOHC stuff sells for more than double than the later bikes NOS and used parts.

[01Thomas]

Thanks for the BMW cam chain data, Per.

[Terry in Australia]

I'm sure the old CB750 gaskets sets were sold cheap for 15 years ago.
Different now when all CB750 SOHC stuff sells for more than double than the later bikes NOS and used parts.

Before EBay, everything was expensive, I remember paying $90 at a Honda dealer for a points cover for a CB350F I restored in 1996, then $30 plus postage for one for my K1 in 2004. I bought that box of gaskets for 50 bucks and there were maybe 10 or 12 NOS OEM Honda sets (mostly CB350/450 twin) but I've added leftovers from many builds since, so it's a good source if I only need a couple of gaskets. I reckon there's probably 20 CB750 head gaskets in there that I've never used as most of my rebuilds have included big bore kits.

[PeWe]

Terry, you might need the std head gaskets. I gave 5-6 away 2 years ago before I knew that my K2 engine cases should get stock cylinder and not ported head.  I had thoughts about DOHC 900 rods, 836 or 900cc, ported head and a nice cam I have on the shelf. I need to find more parts for another engine

I gave the new head gaskets to the guy I got the cylinder/head from
But they might been bad as the DSS gasket I used, oval/eggshaped.

Strange, I have never seen an 65/65.5 mm gasket like that. MLS gaskets have perfect fitment except for the rivits that can be between the mating surfaces and need to be removed or making dents in the surfaces where the rivits are.

[PeWe]

Thanks for the BMW cam chain data, Per.

It was Messnermoto that started the thread with good information about Primary chain alternatives. It was easy for me to order a set or 2

[PeWe]

One step forward again! Clutch went in really smooth without any problems like searching for tools, bolts, nut or other small idiot things that will make a half hour job to several hours. 

It got the slipping plates and Barnett CB750 springs used in my K6 earlier this year except for a new CycleX plate placed in the middle for extra grip.
K6 has one plate with wider tabs replaced by the CycleX plate, K2 has 7 equal.
Many ponies less will not cause any slip, hopefully

Cover will soon cover it. Need some minor cleaning first.

[PeWe]

Clutch cover mounted and clutch lever adjusted today after work. 

Found an old plastic bag with a good looking TEC ign plate. It has TEC points but only 1 TEC condenser. I found another plate not TEC aslo mixed condensers, 1 TEC and another. I might have mixed them in the middle of the 80's. Strange, I know I used to replace the complete plate.

I'll fresh up the TEC plate and give it NOS TEC points and NOS Koyo condensers really old. Hondaman's ignition will hopefully like the setup and let the spark from new Dyna 5 ohm coils.

Valve cover need to be polished a little, not too much. Old alu look without corrosion is OK.

Found an old cam sprocket too. I do not know what it comes from. Maybe original K6?

[Terry in Australia]

I think that cam sprocket is earlier Per, but not sure? Why are there two extra holes drilled in it? All my solid sprockets only have 2? Cheers, Terry.

[PeWe]

I think that cam sprocket is earlier Per, but not sure? Why are there two extra holes drilled in it? All my solid sprockets only have 2? Cheers, Terry.

Hi Terry,
It might be an old tuning sprocket? I compared with a Falicon sprocket with slotted holes. Possible to make both sprocket to align, both holes lined up fine with the outer ends of the Falicon sprocket slots. Sprocket marked 16A. Maybe a mystery to be solved in the bike thread?