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

[PeWe]

Another small step forward today after work.
Ignition coils with wiring complete.
A NOS horn mounted too. The K2 horn look good and sounds OK too. I was lucky to find a NOS with a minor dent almost invisible which made the seller to sell it for a affordable price.

I'll bolt the blinkers that look sad. I'll use the bolts I have until I get Honda correct parts I have ordered. 
Need a new drill ~1.7mm for the 2:nd hole for the new frame serial number plate rivets. I could do one until it broke.

[trigger]

I was just flicking through the pictures this thread and noticed you have a 1971/72, K1/K2 head and barrels on a 1975 K2. Are you aware that the european 1975 K2 had the later barrels and head ?

[PeWe]

Yes, the engine is not the original. This is a parts bike. Only frame, tank and battery holder+electrical stuff on it belongs to the registration.
Everything else found here and there and leftovers from my K6. The NOS fenders were bought for my K6 just for sure while still available for OK price.

Cyl and head K1 as told when buying them from a friend that has refurbished them. My plan was to use an old ported head and 849 or 900cc cylinder.
I changed my mind when I saw the fresh cylinder with new pistons. Head that had freshly cut seats and repainted. Gaskets surfaces decked. Then I knew that I'll go stock 736cc.

I have read about mixed built CB750 engines where Honda used what they had using K1 parts on K2.
 
I have seen K2's here with dashboard where blinker lamp is "Flash", Neutral is "Neut". Maybe some K2's got the later with "Turn" and "Neutral" as what I have available now and seen for sale claimed coming from a K2.

[PeWe]

About stock looking engine this bike once had...
I add some old pics I got from a PO that had the complete history since the bike was new with 1:st registration.

It has been a very modified bike that got 970cc (later 998cc) MTC pistons, RC327 cam, Weber carbs replaced by Smoothbore 29, modified F2 valves 34/29, Campagnolo wheels and ISR brakes. Goodies that fell off during the bikes way in the history and other owners. It must have had closer to 100whp.

Here the older pics.
I was told it was brown from the beginning. K2 means Brier Brown. That made me to decide to make it brown again. I saw a Peugeot 3008 in shiny sparkling brown last spring in Benidorm, Spain I immediately found to be the color my K2 will get and now have.

Pic 3 show the original dashboard like I have some of. It is extra fun to get the complete history of the bike as I got when a man called me soon 1 year ago asking me to sell the bike that just was a frame I've bought.

The K1 head the bike has now look much older when knowing the CB750 details 

[PeWe]

I found a problem to be corrected. Brake pedal hits the no 4 pipe. It is a straight pedal, not a curved outward shape as my K6 has.
I had no exhaust on when the pedal was mounted and brake adjusted.

A brake pedal is ordered and to be shipped from USA for a happier life on a bike.

[Terry in Australia]

About stock looking engine this bike once had...
I add some old pics I got from a PO that had the complete history since the bike was new with 1:st registration.

It has been a very modified bike that got 970cc (later 998cc) MTC pistons, RC327 cam, Weber carbs replaced by Smoothbore 29, modified F2 valves 34/29, Campagnolo wheels and ISR brakes. Goodies that fell off during the bikes way in the history and other owners. It must have had closer to 100whp.

Here the older pics.
I was told it was brown from the beginning. K2 means Brier Brown. That made me to decide to make it brown again. I saw a Peugeot 3008 in shiny sparkling brown last spring in Benidorm, Spain I immediately found to be the color my K2 will get and now have.

Pic 3 show the original dashboard like I have some of. It is extra fun to get the complete history of the bike as I got when a man called me soon 1 year ago asking me to sell the bike that just was a frame I've bought.

The K1 head the bike has now look much older when knowing the CB750 details 

Nice! I like the forks and brakes on the race bike Per, it's a pity you didn't get them!

[PeWe]

Terry, wheels and brakes disappeared 3 owners ago. The guy that gave me the complete history sold that separate. Later or direct after the entire bike with 998cc to a guy that replaced that big bore to stock together with the head that was opened for the big wide domes. Hello compression, where are you?? !!  Bike did not run that good. I think it was the slightly oil weeping big bore cylinder that made him to make that crazy decision.

I managed to close frame upper triangle today with brackets I made. Used old alu bracket for passenger footpeg I used with RC 4-1 K7 model the first years of the 80's. Really hard 5mm thick alu, probably Dural. PITA to saw. So I did a tour to the shop and bought a tigersaw, AEG US400XE 400W small variant perfect for this. Cut 2 pieces, drilled and threaded the holes, M6 only. No space left for M8. Holes already done in frame decades ago.

Frame got its serial number plate riveted to frame where it should sit. They are available as new aftermarket exact as Honda made them. Only number left to stamp which I have done a year ago.
Bike got its registration plate too. It has become a real bike again!

I'll paint the fork upper bridge next, 2K spray can. I'll do 3 bridges, 2 K3-K6 model and the K2 bridge. My K6 has a repainted one that will loose the paint direct when brake fluid hits it.

Edit: Added one more pic to show that front sprocket cover is there.
There is another future project in the background, an old K1 bottom end with frozen rods. Hopefully some rust only or minor obstacles. I have cylinder, pistons, head and cam for it. Bearings and chains with tensíoners  too   Good to have an extra engine! lets see what I'll find when open it.

[PeWe]

Begin of next step in the project. The K2 upper fork bridge that got some stripper and brush today. Dashboard and another bridge to be sanded before 2k paint.
Gauge restore comes closer.

[PeWe]

Prepared 2 other upper fork bridges for 2k paint. 3 dashboards sanded.
Best to paint as much as possible when 2k spray can paint must be used asap when activated

[PeWe]

Finally an important step forward!
Painted the upper bridge and dashboard.
Paint need to cure a little bit more. Until then I'll mount the electrical switches on handlebar with cables routed inside.
Paint look really good.  https://www.spraydosen-shop.de/index.php?a=336656&bewertung_anzeigen=1

I noticed when I have applied one layer black on the shiny brushed aluminum, it looked like anodized as I thought these parts were treated as stock. The alu was shining thru the paint that looked black-dark brown.

Handle bar soon on and throttles checked so air box can be mounted plus all electrical stuff in headlight. Soon only the K2  speedo and tacho to be assembled with new faces, crimp rings, silicone damper oil etc...

New shiny bolts.
I was close to use the later style K3-K6 bolts for dash board. Horrible!!    K2 spacers assembled to avoid cracked upper bridge.
New big nut and washer in Honda bags wait to be with the team. 

[PeWe]

Handle bar with switches, cables inside. A gap between controls and grips. I'll see if I'll adjust handle bar or do nothing.
Blinkers connected and tightened.

[PeWe]

Air box wrestling fiddling the box on carbs. Box got new paper filter and rubber seal.
I got some memories about how nice it was to remove the box and use pods 35 years ago. 
I had the rubber stacks in wrong angle at first attempt, 180 wrong.
I could not get the box brackets to fit ears on frame. A black strap on each ear work too.

Some connections to do.

I used vinyl shine on air box after the photo was taken, look better. Spray can from the 80's
Some dirt sat  in the plastic

[PeWe]

Bike got correct brake pedal. Some testing to make it to sit correct. Brake shoes might have been more worn than I thought. I like the old Honda marked shoes that most likely has good old asbestos.

All electric stuff connected and work!
(After some issues and fault tracing thanks to bad blinker relay and dashboard bulbs.)

It should have worked direct without fault tracing if the new Yamiya crappy blinker relay(s) should have worked. Upon that really crappy LED bulbs I installed in the dash board!
All worked for a minute or 2, Oil pressure stopped lit, next neutral. Measure the conductivity and voltage on the headlight bucket connections showed that bulbs must be failing. Same with blinker relay.

Replaced bulbs with old fashion wolfram bulb as the bike expect to get. Working. 

Bought a cheap (4€ blinker relay for cars that had same round size as the Yamiya/-Honda rubber mount.
Worked direct!
I did not try other bulbs in the blinkers with more wattage since the blinkers are new Honda blinkers sold by Yamiya so their relay should work. i tried 2!   I saw that the bulbs are all one thread bulb, not as rear light with 2.

Bike should be ready to be started IF only it has a working Oil pump. NO flow at the oil galley despite 1 x 20s + later 1 x 10s pumping with the electrical starter.
I'm really happy to have used Redline assembly lube for crank, cam and other moving parts when assembled the engine. over 1 year ago. Project photos show a big sprocket on kick starter shaft is good news too...It SHOULD work

Next is to remove pipe 3-4 and oil pan. Remove oil pump and prime it really well. I do not drain all oil from oil tank before to see how it will flow with pump away. Maybe use extra thin oil to start up the pump with... It has Motul dino 10W-40 now.

Update: I had to drain pump again in a deep oil bath, releasing the nut on relief valve letting bubbles out. I opened the other 2 bolts keeping the leak stopper valve to vent out a little air too. Made sure that oil could flow in. Pump could now suck better when my thumb blocked one of the 2 holes for oil lines and rotating the sprocket. Same on the other hole rotating in the other direction.
Conclusion: Only drain pump in oil and rotate the sprocket is not enough to get all air out.

My earlier engine reworks with pumps usually cleaned pump with degreaser (naphta), then a little oil. This made the solution thinner and most likely easier for air to get out, never a long running on starter to get oil flow by the pump.

Oil flowed nicely out thru the oil galley that will get an oil pressure gauge to supervise the oil quality/viscosity when hot.

[PeWe]

Started it today!
It ran on 2 cylinders only, 1,4.
I said to my self, OK that's the frakking yellow wire to coil 2-3 that is disconnected, tank must be lifted...    BUT, I'll test a new condenser first. Replaced the 2-3 condenser and fired it up direct on all 4!!  Its really nice when correct things are not working, easiest to fix!

It sounds nice with Yamiya No number 4-4 with diffusers with no wool and stock airbox that I have not used since 1983 on my K6. It responds surprisingly well on the throttle. Stock engine with a K7 cam that probably is a degradation compared with K2.

It need road tests to fine tune air screws that now are 1 turn out.
Main jet 115
Needles: clip at middle position 3:rd from top.
Fine tune ignition too with timing lamp and dwell meter. Now only static timing plus a 2mm retard of the plate. (Advancer advance some at idle compared with static)

It got my Freedom Green metallic tank set to start with, I do not want to scratch my new painted Brown metallic K2 set. It look now like a K1, K2, K4 bastard. For USA riders Euro K2 has K1 genes too (rear light, fender and blinkers). K1 cylinder and head.

It will get the brown K2 tank set when I have done the initial break in rides and the mandatory vehicle inspection.¨

Only tacho and speedo left to repair and add to the bike. I look forward to a not that dirty repair.

[strynboen]

ready for spring.?.ve have sun and nice +10 deg,in denmark(but it can not hold..shure ve get dirt back.).but nice as long it holds..have veteran insurence on both bikes..so no riding before 15 marts...need a new gel battery for the 550..the biltema one..have a small crack in the casing..replace it..so no leaking can damage the bike..

think it is a lot hotter here dovn in the low land..

[PeWe]

It is very convenient to have the bike ensured all year around, ready for a ride whenever possible. This bike has been insured for many years despite its in parts, finally a frame only used on the street 1991 as last date.
I guess that end of Mars can be riding days here as last year.

I have to do the vehicle inspection when the weather allows it. I guess early April will be fine. After that, no more vehicle inspections ever. My blue K6 is always ready for a ride as long it is functional. I pay full ensurance for both all year around. The K6 cost more  around 100 USD/year. This K2 60 USD/year. Not expensive as before.

If used or not, ensurance is needed if something happen to itin the garage.

I look forward to have 2 functional bikes. Good to have a ride when replacing tire or doing some service/repair or upgrades.

[PeWe]

K2 Tacho & Speedo restore/build initiated.
New faces are white and rather transparent. Old Honda (ND) not. I painted the rear side with blue/green metallic spray. I'll see if this will be OK, no lamps shining thru the faces.

The old gauges function tested with a drilling machine. It must run counterclockwise to move the needles and trip meter.

[edwardmorris]

Are those replacement faces from Marcel? They are drop in replacements and work fine, nothing shines through and looks solid day or night, I have rebuilt a few sets and they all came out great!

[danyo]

Are those replacement faces from Marcel? They are drop in replacements and work fine, nothing shines through and looks solid day or night, I have rebuilt a few sets and they all came out great!

Recently I have rebuilt some k0 and k1 gauges using faces from Marcel. I know those are the best available replacements and I'm happy with the final results but also I had to paint them on the backside to hide shining through internals (see picture showing k0 unpainted tach) They look perfect otherwise.

Sent from my SM-N920T using Tapatalk

[PeWe]

Yes, I guess there is only one that can make them. Several that sells them.
They look fine and will hopefully work exactly as the old stock when new.

I have a K6 tacho with new face that almost blinds me when riding on a dark road. Bought as refurbished from Marcel a few years ago. Look perfect at daylight.
It has got the weakest bulbs I could find, still shining thru. Not the cozy illumination that the stock speedo has.
I'll open it, paint face rear and check if inner cover has the light blue-green color.

[PeWe]

I was just flicking through the pictures this thread and noticed you have a 1971/72, K1/K2 head and barrels on a 1975 K2. Are you aware that the european 1975 K2 had the later barrels and head ?

This might make it better? Photos below
Got a head today. Look good, 2 exhaust valves not good. I have 4 almost new ex valves to be used now.
I plan to give it a quick valve lap, new valve guide seals, sanding the gasket surface as I did with my K6 head. First  1-2 rounds of 240 grit paper, then 1-2 x 400. Paper glued on a board. Finally verify that all threads can get an M6 tightened 10Nm. It's so boring to find bad threads when head is tightened on the cylinder, engine in frame. (Franks kit)

I might use a newer block, my K6 block, before 836 now 849cc since a week or 2.
I have an old K1 bottom end in need of top end, K1 style will fit

I have to figure out what to do with my 2  836 cast piston kits (Actions Fours, RC) and 900cc cylinder with forged 67.5mm pistons...
Plus another early head, ported, now at the shop for refurbish and port improvements before the guy retires. He is now + 2 years overtime....
Good to have fresh spares in stock.

I have a feeling that this stock K2 will get a ported head (34mm F2 IN valves), my old 29mm smoothbores.... 
I must try to resist the modification devil. I have my modified K6 blue avatar bike.

[PeWe]

It look better now with gauges mounted. NOS Honda.
I continue with the restore of the old gauges as a later project. Crimping the rings so it look good need better tools.

Fact is that the K2 stock faces match Freedom Green Metallic really well!

[PeWe]

Adjusted carbs yesterday when I let it idle together with my other bike that was started for first time since parked last year.
Air screws on the Honda K6 carbs make huge difference at idle. 1 turn out ran bad, 1/2 turn out much better. I think this was how they were set in the 80's too.

It got an oil pressure gauge today which is a must.

[andy750]

PeWe your bike look amazing and I really like the Freedom metallic green. One question: where did you get the seat with the K2 pattern? Looks really good.

Cant wait to see your ride report for this bike.
thanks
Andy

[PeWe]

Hi Andy!
Thanks for the nice words about the bike.
I agree with you, Freedom Green Metallic fits the bike really well.
Bike is a bastard right now with K4 tank set never sold in Europe. But it look OK.

Seat is K2 replica from DSS £135 + VAT. It has steel plate bottom and look like stock Honda. Hinges is extra. https://www.davidsilverspares.co.uk/CB750K2-FOUR-1972/part_275786/

Honda stencile found on eBay. Text a little bit smaller than my NOS K6 seat. Paint used is Silver Vinyl spray, a few dusty thin layers.

I'll use the home painted K2 set in brown metallic later on.

Fun to have an extra set to be used now and then.

The winter and cold weather returned. I hoped to have a test run within a week. I have to book vehicle inspection. Last on the registration was 1990. After an OK inspection, never more needed on this old classic bike.
I'll put it back to original. It was rebuilt and registrated for that 1986.

Only the rubber hoses between pipe at the 1-2, 3-4 ends. I use oil hose cut in correct lenghts, cut open to be wrapped around afterwards and secured with a black cable strap.

I have new Honda that must be on before mounting pipes, fitted when assemble it and the black clamp around it.

Good to have 2 running bikes. My K6 need soon a new front tire. I can do the change without hurry later this spring.