Author Topic: K2 / F1 build from Maribor  (Read 2608 times)

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Offline gsb

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K2 / F1 build from Maribor
« on: January 15, 2021, 10:25:14 AM »
Hi,
Im novice in bike building.This is my first project -dream when i was15 and see cb750 four ....now Im 54.. 8),For daily Im working in medicine.Im from Slovenia -Europe .I have read forum passive for years ,then buy a book from Hondaman -Mark Paris .I have buy my donor bikes in Germany  :K2 frame with papers and another F1 bike from 1976.As first i have take off cylinder  and head . It was realy a pain -very rusted screws .As next i have clean head ,cylinder and carburetors.Tank was also dented under paint..For new build i will use k2 frame with F1 motor. For build  i have boldor fork 35mm. Carburetors were rebuild  with main -115 ,slow 40 jet .I have buy Wisseco 836 kit for rebuild.As next i have buy old seat  -rebuild from local shop here.As first i will send some pictures from build .Thanks for help and advices.
gsb
« Last Edit: January 15, 2021, 10:27:09 AM by gsb »

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #1 on: January 15, 2021, 11:23:29 AM »
Hi,
Here is part II mit pictures .Engine was very dirty -i have find local shop for vapur blasting to clean the head ,clyinder and other pieces .Primary chains were buy in Germany -IWIS -i have found it here im forum -from Messner Moto same brand as CCC.Filter box rebuild with new brackets made from V2A and all V2A screws.I build also new special screw in filter box -original was not there.Starter solenoid was not working - splint was broken -Thanks Hondaman -in the book was manual to repair it.
gsb

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #2 on: January 17, 2021, 10:37:13 AM »
Hi,
Here part III .Carburetors are complet finished .I have buy electronic ignition in Germany by Fourever -Classic-Parts.Ignition is working with stock coils and stock advancer.Mounting points are the same as original plate with points.Setup manual is included (LED timing indicator on baseplate).Now i rebulid advancer (TEC 300)
 -clean and oil all parts.I have read about stiffnes of sprigns if they are ok i dont know yet while engine is not finished .
gsb

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #3 on: January 24, 2021, 08:45:12 AM »
Hi,
Advancer is finished -I leave the springs for now -they snaped very good and smoth after rebuild .Now I prepaired head for rebuild .Head is from F motor 1976 . I try to remove 8 exhaust studs .At first I heated litle bit local with propan gas and then slowly out with wrench .Two studs are broken  :-[ Tomorow i take the head to metal shop from my brother to weld new nut and try to get 2 studs out . Today i try to fit exhaust flange -there is a gap 3-5mm without coper gasket in  ? Is that OK or is posible  F head had shorter mounting points .. i have no K head to compare .Thanks for help.
gsb

Offline BenelliSEI

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Re: K2 / F1 build from Maribor
« Reply #4 on: January 24, 2021, 05:17:12 PM »
Gsb..... Something does with that exhaust stub stack. The head you are using had studs. The later exhaust systems used 1/2 shells and a clamp down retainer. Two holes in it lined up with the studs, pulled down by nuts and washers.....  the actual end of the exhaust pipe is flared, and clamped down against the copper washer.

On the earlier K heads, those exhaust stubs are held in place with two large Phillips head screws. Without the copper gasket, they should sit right down on the posts. Not sure you can just “mix and match”. Let’s see what others say.


Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #5 on: January 25, 2021, 09:34:55 AM »
Hi,
Studs are all out -it was very dificult with last two. So i dont know what to do with gap ? I think to put a washer under ?

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #6 on: February 18, 2021, 09:39:06 AM »
Hi,
Cylinder head decked and ready for rebuild . I rebuild gauges now ,first is finished ,with tacho there is problem -silicone oil for damping must be refiled  for smooth action .I have ordered 50000cst silicone oil  in RC -cars shop. Here some pictures.
gsb
« Last Edit: February 18, 2021, 09:41:21 AM by gsb »

Offline PeWe

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Re: K2 / F1 build from Maribor
« Reply #7 on: February 18, 2021, 10:02:46 AM »
Very inspiring restore!
It is a nice feeling to assemble clean and refurbished parts.

- Do you reuse the old rings that clamp together the gauge halves?
The new aftermarket rings are of a rather hard material.

I saw that you have the better chain to be used as primary chain.
- Have you found a master link to that chain?
To be used when rivet the chain together after cut from 72 links to 68.
« Last Edit: February 18, 2021, 10:11:42 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #8 on: February 18, 2021, 12:43:13 PM »
Hi  PeWe,

Most  I know about  motors is from forum here and some German forums. Yes parts must be clean -I work in medicine haha.It will be easier to buy all new  or finished ,but i like to work on old parts ....

-Yes I reuse old rings -I have also read the new are very hard , so I use rubber hamer and straighten the rings on one end litle bit to fit but is very hard to close the gauges.

- Yes chain is from Iwis Germany -information is from here from Messner-Moto .Chain will be shortened to 68 links by mechanic who bored cylinder and rebuild cylinder head.He did that on some racing motors without problems .
Number of chain is - Steuerkete SWAG G68HPF­2 - two pieces for 86 Euro.

- I will post some pictures when silicon oil come in house how it works  on tacho -now the needle is turning back without damping.

gsb
« Last Edit: February 18, 2021, 12:48:52 PM by gsb »

Offline PeWe

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Re: K2 / F1 build from Maribor
« Reply #9 on: February 19, 2021, 03:18:31 AM »
My K6 has same chains if the info is correct in MessnerMoto's thread about primary chains.

I bought mine ready to install from Classic Cycle City for a higher price.

They have not got much more slack after 28.000 km. Mostly with 1005cc around 90-93whp.
I measured + 0.5mm. slack 65.5mm a little bit under 65 when installed. I think first start gave som intital value when moving.

It would be fine with master link. I found a similar that is a little bit wider.  But only in USA with expensive shipping and customs.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #10 on: February 20, 2021, 12:26:40 PM »
Hi,
My bike will not have so many Hp so it will be fine with chain. Today silicone oil with 50000cst arived. I bored small hole in damper 0.9mm with Dremel. You must bore carefuly there is brass tube inside. With injection I fill the damper. I have closed hole with normal silicone. OP finished. Here are two videos from before and after refil.
gsb

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #11 on: February 20, 2021, 12:43:58 PM »
Sorry here are the files
gsb

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #12 on: February 21, 2021, 12:57:17 PM »
Hi,
Gauges are done. I think is ok. Now I prepaired frame for build. I have buy a lock holder but it seat not right on frame. What is with second hole?  Must be alighnet with hole on frame?

gsb

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #13 on: March 05, 2021, 08:51:24 AM »
Hi,
I take frame outside before painting to bolt on parts .I have two swingarms  -one F1 and one from K3 .F1 is 1,5 cm longer and shock mount point is also 1,5cm back.I will use drumbrake.Colar on drum side is missing .I dont know corect size ? For build i will use fork from boldor 750 -i have two of them.Original K fork that I have  is 75cm long .Boldor  fork is 78cm long. I put also two pictures from same forks build in cb 500 with Kawaski z 750 brakes .That setup worked ok .My brother cut some horn holder plates from thin V2A and Titan .They look very nice.Here some pictures.
gsb

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #14 on: April 12, 2021, 10:26:22 AM »
Hi,
Zylinder return from rebore for wiseco 836 kit. Head also rebuild - one  valve and valve seat replaced. Head and zylinder decked. I have removed all zylinder studs 🤪.Primary chains HD Iwis shortened from 72 to 68 link. Now mechanic will open cases...
gsb

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #15 on: May 23, 2021, 10:29:40 AM »
Hi,
Some parts are back and overhauled.I,m also rebuild control lights -with led,s .My control panel was not complete -without wires and light,s ,so I have used  some rubers from medicine botles for injections -they fit perfect to my control panel.I have no spacer on brake side of rear hub.How wide is the spacer -dimension ? Thanks for help. Here some photos of rebuild parts.
gsb

Offline Gamma

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Re: K2 / F1 build from Maribor
« Reply #16 on: May 23, 2021, 01:47:31 PM »
Here is the spacer on my K6 hub

Offline gsb

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Re: K2 / F1 build from Maribor
« Reply #17 on: May 23, 2021, 10:54:17 PM »
Hi,
Thanks Gamma for help. I have some parts laying around from F1. Must see if anything fits.
gsb

Offline MauiK3

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Re: K2 / F1 build from Maribor
« Reply #18 on: May 24, 2021, 09:05:10 AM »
Nice progress!
1973 CB 750 K3
10/72 build Z1 Kawasaki