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

[PeWe]

That's the model I used on my cracked inlet rubbers. 9mm wide. 32-50mm

The newer softer models of Honda carb boots  get  "mold" pattern after the clamp's "thread".

But, the reason was probably overtightened clamp. Easy to tighten more when warm. It just digged deeper into the rubber.

[Terry in Australia]

Yep, the thing to remember is just because you can crank the hose clamps tighter, doesn't mean you should. I used all new OEM rubber insulators on the K2 bitsa 3 years ago and only just tightened them enough that they wouldn't rotate on the spigots. I've had those carbs on and off way too many times due to dud engines, but the rubber manifolds are showing no damage at all.

[Don R]

 I love this bike, it looks like the K1 I sold to DSS a few years ago.  I used 2013 accord tiger eye pearl brown paint with the k2 stripes. I plan to build another one.
 It's in the river runner build thread. pic on page 3.

[Terry in Australia]

I love this bike, it looks like the K1 I sold to DSS a few years ago.  I used 2013 accord tiger eye pearl brown paint with the k2 stripes. I plan to build another one.
 It's in the river runner build thread. pic on page 3.

How much did DSS pay you Don? I bet I would have paid way more.....

[PeWe]

I love this bike, it looks like the K1 I sold to DSS a few years ago.  I used 2013 accord tiger eye pearl brown paint with the k2 stripes. I plan to build another one.
 It's in the river runner build thread. pic on page 3.

Thanks Don!
Yes, the brown is not a bad color!
I had not planned it, but when an  earlier owner (2 owners before me) called about the bike  (the registration + frame I had bought) I got full history.

It had been brown from the very beginning, Briar Brown.
So I got thoughts to make it brown again as delivered from Honda which felt good.

When I saw a Peugeot 3008 SUV on a sunny parking place in Spain I felt a Heureka moment. The brown really sparkled!

The tank I had bought  a few years earlier from same guy had been part of the bike too.
The repaint layers verified with the older owner.

I ordered the paint and the rest is history.

Brown metallic in a redish tone is nice! 
On top of that into black is a nice color too.

[SOHC4 Cafe Racer Fan]

Per,

I gave this bike a nickname -- Sexual Chocolate.  Great highlights in the paint, especially in the sun.  More subtle than a rootbeer flake.

[PeWe]

Sounds delicious!
Sunshine make it alive.

[PeWe]

Replaced battery today. The old had suddenly died. Not even 1V ! Charger did not like the status.

Before replacing, checked resistance between disconnected + cable and ground. Shortage!
I thought it was the rectifier with a diode that had got a short.
Disconnected the connector from rectifier, same problem.
Disconnected fuse in my additional plus cable to ignition relay. No short. 10A fuse that did not blow, lower current leak drained battery.

Creep current via the relay connectors, flat sockets or inside. It changed when I squeezed the connectors, moving cables.
This happened when relay was not activated.

Replaced relay, insulated each connector better with electrical fiberglass tape, shrink hose around the relay and connectors. Sealed in both ends and more tape.
Might have happened at last wash a few days after last ride.
It ran fine Feb 28.

[Jimcg]

Glad you found both the problem and what caused it before bike season starts for real. 🙂

Also good for others to keep in mind if similar things happen.

/Jim

[PeWe]

Yes, strange current leak shorten the battery draining it, not blowing the fuse.

I'll flip the relay too so connections are faced downwards, no eventual moist to accumulate on the flat area where connections are. Relay was bone dry, still a short.

But that small relay is not designed to be water and dust proof.
Typical auto relays 12V 30/40A for additional headlights on cars  are better sealed.
My K6 has that kind of relays. Take more space.

[PeWe]

Time for an update....
This K2 got KN airfilter today in stock airbox. Had to fasten the rubber sealing in upper airbox with glue.

This better flowing filter can hopefully improve a little. 4-4 have good flow so the  restriction is not there today.

Started the bike and notified again that I had forgotten that it would not start without FULL choke despite some  starter and ign off before.
My K6 with acc pump carbs have spoiled me.

This bike got an ignition issue last year in September when point 2:3 decided to declare war. It might have got a physical bump by a dropped tool or similar.

After some fiddling I gave up, called my nearby shop and asked about Dyna-S in stock.
Really sure that they have one?
They guy which I know since the mid 80's as a biker went to grab one, the last unit in stock. Popular part. I arrived 5 minutes later.
Went back home, installed it in 15 minutes. Bike has fused feed wire for ignition since before.

Set the plate in the middle position, started the engine and fine tuned a little with ignition strobe lamp.
Since the advancer springs are cut, ignition can be set at idle 1000-1200 rpm.
Full adv at around 2600-2700 as my K6 that also idles nice with an even good throttle response after that.

I did not follow the complicated instruction Dyna has written which is more like a fault tracing guide for a faulty unit ended up setting ignition at full advance only with no respect for idle and very important take off revs that will make bike to a bad and not fun to ride bike in the city when wrong.

It ran better and more evenly after that, especially after 160kmh


Fresh filter produced this year and oiled, ready to be installed. Huge box for the filter.

[PeWe]

Total waste of time today!
I had to replace the fork boots/gaitors due to my wrong choice purchasing sh!t aftermarket rubber boots to save a few bucks.

They cracked after max 3 years use. I should have replaced them 2 years ago when I noticed the cracks.

They cracked and swelled even faster when they got fork oil splashed inside. I lubricated the fork seals upper part for longer seal life.


Today real Honda fork boots/gaitors. Hopefully better.
I expect at least 100.000km/10-15 years.

It took an hour to take it apart, over 3 hours together.
Removed seal clips for rust removal, cleaned the fork lowers.

Seals got a special seal grease I have got from my job. Special project to make oil seals to live longer.  Mostly rotating shafts in seals.



Special seal grease a colleague recommended

[PeWe]

I had to check the oil pump relief valve spring.
Cold start oil pressure has been  80PSI that felt high.

My K6 has around 70PSI direct at cold start.

It was a post about this spring. Comparison between Honda stock and new shiny spring, part of the oil pump rebuild kit a forum member sold, Vital Motor sport.

- The spring that sat in pump was Honda stock.
So I had to change to the shiny spring in the rebuild kit.

- Now lower cold start pressure, around 70PSI that feels safer.

This will not affect pressure when warm. This is the max pressure.
Normal when warm is around 40-60PSI during cruising/speeding.

My K6 also got rebuilt pump. It must have the oil rebuild kit spring due to the 70PSI pressure when cold. 20W-50 oil.

[PeWe]

When checking/replacing the oil pump relief spring I measured the primary chain slack.
65.45mm

Not bad after 14192km.
BMW timing chains as primary chains.
Ca 0.50 mm more than new that  is ca 65 mm.

[PeWe]

Replaced the stock points cover.
Honda cover cost too much to be used.
One of my 2 SOHC covers feels like an upgrade.
The bike is a SOHC not printed  anywhere on bike until now.

My first cover from 4into1 a few years ago is on.




#

The other with smaller text ordered last year from Germany.

#

I have also ordered blank covers from Vintagecb750 when ordering other parts.

[andy750]

Per I am liking those covers! Very nice!

Reading through your earlier posts I also changed to a K+N filter years ago for both my K2 and K4 and would not go back. A yearly wash and oiling is all they need.

Thanks for all the great info as usual!
cheers
Andy

[PeWe]

Hi Andy!
It was this thread that encouraged me to order.
http://forums.sohc4.net/index.php?topic=194726.msg2280264.msg#2280264

I have seen them at 4into1.

The other parts with shipping helped me to decide.
 

[PeWe]

Replaced both tires.
The wheels too
I have extra wheels so I mounted the tires  before use last winter.

It is enough to remove wheels and back again. Wrestling with tires off and on again without pinching the tubes takes time and energy.

Move the disc and front axle.

The new tires will hopefully last long. Michelin Road Classic stock sizes, 4.0-18 and 3.25-19.



#

The old rear tire Metzeler ME77 Perfect  did not last long 3831km.
It must have wrong spelling on its side, Defect is a more correct name.

Uneven pattern left. 1/3 flat, the rest more with 2.25 mm as most.
Tire had no run-out affecting the ride when new  nor when replaced.

Must have been strange production.
'
Pressure as CB750  Shop manual say for K6 add-on pages.

Front 32PSI / 2.2BAR
Rear 40 PSI / 2.8 BAR