Topic: CB750K6 -76 project back to life with more updates

[PeWe]

I checked the fork today.
Last oil replacement in September 21 -  2022, refilled with 170ml Motul SAE 10 synth.
Wirth progressive springs must have SAE 10 independent of what used before.

I guessed this should be less than the progressive spring description 160mm from top, completely collapsed fork without springs.

Removed horns and collapsed fork today.
Had to fill another 10ml to reach 160mm from top. So rather close.  Both legs were equal.

Used a syringe with hose with a total lenght of 160mm from the syringe bottom.

Fill oil and suck it back in which will give an oil level of 160 mm from top. The fork caps are 23mm deep so they will compress some.
This is with fully collapsed forks so air gap inside will be greater.

Added a little since oil was recently replaced, 2360 km ago. No need to replace it again.

A little amount of oil followed springs up.
 I know now that 180ml oil minus oil followed springs -->175ml  in each leg is the amount to fill. So it was rather close.

I added an additional washer for a little bit more pretension. Before 1mm thick washer, added a 2.6 mm washer, totally 3.6mm. 

*** EDIT: Better handling without washers, better in corners. ***

Fork caps  hard to get in there despite fully stretched fork.

I'll see how bike will feel next season.
Hopefully stable as it has been before.
No wobble during heavy acceleration when fork will feel lighter, stable when passing 200 kmh on a straight road too

When everything is working fine, good power and high top speed verified so I can continue to ride in legal speeds most of the time.

[andy750]

Thank you Per great info! You give me such great ideas!

[PeWe]

Thank you Per great info! You give me such great ideas!

Hi Andy,
You have 3 months to prepare your bike.
I also get lots of ideas and useful knowledge on these forums.

I got the fork verification done this weekend thanks to the comments I got.
I had to know asap.
I should have verified the amount of fork oil vs level in fork when doing it before.

I had guessed rather ok when changed it last time.

[BenelliSEI]

PeWe..... thanks for your posts! I always get inspired to try something different!

[PeWe]

PeWe..... thanks for your posts! I always get inspired to try something different!

Your are so welcome John!
We all share ideas and how to do and not do things.

Yours and the other guys comments helped me with energy how to get the last small things done

Only a small thing left, connect the voltmeter to ignition 12V and see the important voltage not via ign switch.
//Per

[PeWe]

Fixed an electrical issue I was not aware of!

It started with change connection of the voltmeter between the gauges.
It had an anoying voltage drop of 0.3V, closer to 0.5V below 2000 rpm compared with voltage over battery.

Connected an extra wire from one coil to the voltmeter.
WTF! Now 1V drop!

I thought it must be the relay after testing another ground connection.

Replaced relay with a new I have. That sucker did not work at all!!

Another used relay, same drop.
Disconnected all bullet plugs before and after the hanging fuse between battery and relay.
After relay and plugs to wire going to coils + another to the Dyna-S. Cleaned fuse for Dyna-S feed too. Electrical connection spray.

This did it!
Plugs corroded due to splash of water. I had used rubber vulc tape to seal the bullet plugs. That tape more like warm chewing gum and very sticky.
Cleaned that and used only 3M electrical fiberglass tape.

Measured again and only 0.1 as max drop before start and at idle.
At 2000 rpm and up very small difference. Battery poles vs voltmeter on bike.

Engine must work better now when the Dyna coils and Dyna ignition get around 1V more!!

Another reason for a visit at the Dyno in April or May if the shop has time. He is usually very busy. End of season easier.

This with better needles can give a cleaner and maybe stronger running engine.




Not much at a little higher rpm. 13.59 vs 13.6V= OK

[BenelliSEI]

Per..... nice detective work. It’s all in the details!

[PeWe]

Yes, it worked out as it should. A happy ending of that day.

I can now see when those plugs will get bad contact. The contact spray might help it to last longer.
Inside left side cover is not that protected for electrical connections hanging there.

Honda has not much there, the few well encapsulated.

I had a bad contact in my horn switch a few years ago. Opened the left hand switch, sprayed horn switch while operating the switch with power off.

Still work fine without hesitation.

[BenelliSEI]

I’ve had the same frustration with a horn!

The worst was an intermittent mis fire that eluded me for weeks. My Cb750K8 ran perfectly, BUT, every so often it would stumble for a few hundred yards, then completely clear up...... it took me 1/2 that summer to solve it. The main fuse (center of the stock housing) was getting warm. Over +40 years, the plastic housing around the fuse clip melted, and shrank back a bit. This gap loosened the clamping on the fuse. 99% of the time it was OK. On day I tested the coil power when the fuse was “loose” and solve it.....

[PeWe]

Intermittent electrical gremlins are not nice.
I had an ignition wire with intermittent conductivity.

New wires, Dynatek grey graphite leads (broken inside/ bad connection with plug cap)
 I did not suspected the leads since they were new with coils and Dyna-S.

Over a half season making carb jetting confusing. With smoothbore 29's and next TMR32. 2014-15.

When it became worse easy to detect.

A good idea to have extra parts to test with.

[BenelliSEI]

Intermittent electrical gremlins are not nice.
I had an ignition wire with intermittent conductivity.

New wires, Dynatek grey graphite leads ( beoken i side lf bad connection with plug cap)
 I did not suspected the leads since they were new with coils and Dyna-S.

Over a half season making carb jetting confusing. With smoothbore 29's and next TMR32. 2014-15.

When it became worse easy to detect.

A good idea to have extra parts to test with.

Yes.... NGK plugs that fail a few minutes from new, is a great example!!! Never assume.....

[PeWe]

Plugs I have
Ordered from UK before Brexit.
Denso last order 30 plugs for £48 with shipping, NGK a little bit more. Triple price here.

I have at least 50 Denso and 30 NGK. Plus a few sets of NGK 5kohm caps + HT leads. I like the stiffer model that will stay in Dyna coils.
Soft very flexible will easy glide out off the coils causing bad contact with bangs and no contact when gliding out.

Wind and water during cleaning will hit leads and help them out.
Done that several times until I found stiffer leads were much better.

Upon that a bunch or two of pitch black sooty very little used plugs. I might try to clean them in a small ultrasonic cleaner.

No fake plugs so far.

[PeWe]

I have to improve splash protection for left side under side cover.
Not only the extra wirings with hanging fuses for headlight, horn and igntion relays.

 Schottky rectifier too.
 I did seal it with silicone but the splash of water with dirt can be decreased.
Find out how to stop it without less cooling air flow for rectifier.
If it comes from rear wheel or front or both.

[PeWe]

Time for spring, soon!
A longer ride with plug readings of 1&4 at the side of the road.

When done make it louder!

When I ordered my Hindle 4-2-1, I ordered the short muffler too just for sure

My butt need to get road feeling of the current setup before the baffle change.

The shorter might affect the backpressure in need of a little richer needles.

I'll see if bike will become a cop magnet as in the 80's

It will end at the shock as my old 4-1 shown in the first post of this thread.

[PeWe]

I could not wait that long when I know how easy a muffler swap is.
Test idle in garage with minor revs.

It is not that loud as I thought.
Need a road test to hear.

My old Alfa 4-1 is a little bit shorter.

[grcamna2]

The alfa pipe:is that a straight-pipe with no baffles ?

[PeWe]

No, it was delivered with 2, one really silent not usable, no flow but good at vehicle inspection back in the days when that was actual.

The other sit inside, rather screaming loud.

Hindle has a much darker tone with better flow,  a large hole all the way.

[seanbarney41]

Thanks for those pics PeWe!  The Hindle is looking very good!  I have been reluctant due to the Ripple Rock Racers website having kinda average pics, but now I might have to get me one of those!

[PeWe]

It works well too.
My old 4-1 was louder with less flow. Sharp tone but still nice sound if in race mode Cops stopped me several times in the 80's and gave me tickets for the nice song

I'm happy that I ordered both mufflers back in 2017.
I knew that order once again with oversea shipping should cost too much for an extra muffler.
Maybe I got a package deal too

They have another tip too.

The angle of the pipe will skip passenger foot peg.
I have added a frame mounted from Yamiya just for sure.

The few times my wife will follow, she prefer the stock K2.

I'll hear how it will sound at next ride when crusing in low city speeds as well as good acceleration.

Photo as this one beside a Shell gas station 75km away from home and a cafe another 70km in that direction, but the shorter muffler.


Last ride November 12. Z1-900 mirrors that allow me to see the road behind me, not my arms only as stock CB750 mirrors.
Combination with lower bar and mirrors.
Stock Honda mirrors must show more with higher US style bars.

[PeWe]

Got the auxilary lamps today.
Ordered after November darkness rides.
https://www.amazon.se/gp/aw/d/B0B3J58TJX/ref=ya_aw_od_pi?ie=UTF8&psc=1

Did not see much on wet pitch black country roads. No moonlight either.

They fit better than expected. I need to grind just a little to make it fit around fork tubes.

Tested with an extra battery. Measured  just over 1A each so they will not drain the charging system.
2.2A extra.

My H4 LED takes only 40W at HI so just a little bit more than std H4 60W.
Now total of ca 65-70W when auxillary are lit with HI.
5 or 10W LED parking lamp included. Off with LO.

Weekend job.
Adjust angle with inside mounted bolts.
On-off switch included. Might be good to not use them if not really needed or switch off  first when blinding meeting traffic. Or switch on to blind AH's!!





#
Switch not that weather safe. Need some tape or silicone to protect against the worst wet.
It will sit closer to left hand switch. It can be replaced later on.


#
I have a new slim Honda CB750 K2 headlight on-off switch possible to use. Will look better.
EU K2 bikes had beside LHS when RHS had Parking-LO-HI (PLH), not on-off.

My K2 has now OFF-LO-HI.
It has not got the NOS EU RHS switch I have.

K6 got Hi-Lo on LHS switch, LHS have off-P-Headlight.









#
Edit: The cheap switch delivered with lamps is not that bad. Feels rather stable.
Not that much stock look, but for practical use.

[PeWe]

Lamps on. Had to massage the brackets a little with a flapper grit 60.
Fiberglass tape around the fork tubes as chrome protection.

Connect them next. Final adjustment during a dark ride.
Test with additional battery.

[BenelliSEI]

Those look bright!

[PeWe]

I'll see when riding how far they will lit.
Hopefully a little bit brighter in total and much wider light pattern. If they will extend the light a bonus. These are the low wattage versions.  15W max.
90W each will make daylight!

The last November rides  in total darkness on wet roads that made it even worse were not fun nor safe.
The right one is directed a little bit more to the outside of the road to see animals a little bit better before they jump from right side.

[PeWe]

Auxiliary lamps completed with switch and own 5A fuse. Short circuit here shall not kill the headlight.

Telephone lense does not like blinding light
Switch work fine, not bad at all!

I look forward to a ride in the dark to see how far I can see. Can I ride fast enough when dark?
Pitch black country road  with dense spruce forest  close to the road on both sides.
Or open fields with curves which is even worse.

Even 70kmh felt too fast when the sharp curves came closer in the countryside.
At least a wider beam will help on a curvy road.

[grcamna2]

The lights now on both sides will certainly help