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

[PeWe]

Valve cover finally on. That took longer time due to a bad thread that showed up now. I missed one when I checked all threads when head was on the bench. Time-sert inserted.

Valve cover showed a nice surface when I cleaned it. Old alu look and covered by good clear coat. Breather cover is an old ugly chromed one. It will look OK under the tank. I might find another one in the future. New valve caps, aftermarket from DSS look exact as the old Honda CB750 caps  New Honda cap look different! Thicker cap.

I had problems with DSS  NE gasket set again, this time the valve cover gasket that has a bad fitment. I used another gasket I have, thicker,  the entire gasket fits much better and all holes aligns.

I'll order gaskets separate since I have most of the o-rings which often are not included anyway.

I have prepared the bench with my old K6 carbs. I'll dismantle them and let them swim in naphta for a while since they are covered by old slimy fuel residues from sept 1990.

[Terry in Australia]

Yeah mate, I wondered if someone had re-drilled it for a hot cam rather than slotting it, did anyone make a "16A" cam? Interesting.......

[PeWe]

Russ Collins had sprocket with several holes for various degrees of cam timing.
But those were placed closer to each other as I recall.

[PeWe]

Started to clean my old K6 carbs that were parked with fuel sept-okt 1990. No cleaning since then
Time to fix them.
I'll try Cruzinimage carb repair kits. Will not use all parts. Needles worked fine back in the days and will hopefully work OK again.
Main jets are 110 wich might be a good start.
Work a little every day will make the bike ready for street in April, I hope.
I need to fix my leaking fork on my K6 and replace the 4-4 with a 4-2-1 plus remove center stand that the K2 need better.

Cleaning will take a week cleaning them one by one in the jar with naphta.

[Terry in Australia]

What pipe are you going to put on your K6 Per, a Hindle? I think I'll buy one eventually.

[PeWe]

Morning Terry, Hindle 4-2-1.
I need to fix the right fork tube first since it has a scratch and leak. I have all parts, need to do it.

The bike look good with the 4-4 but I want to squeeze all power out of the engine.
I'll soon have another bike  with stock look. It might get the new Honda seat I bought for my K6 a few years ago.

[Terry in Australia]

Good choice mate, I've been a fan of Hindle's since I saw them on GSXR1100's back in the 1990's, they've got a good rep, and aren't too expensive. Cheers, Terry.

[PeWe]

1 carb is cleaned.
Naphta bath 48 hours softened up the dirt, not much cleaner.
Sprayed EGR carb cleaner- blown  with compressed air, more spray and brushed all dirt.
Still dirty and corroded-  1 hour in 12.5% vinegar helped. Compressed air again.
More EGR carb cleaner spray.
Used most of the parts in the cruzinimage carb restore kit except needle, air screw (too different look), needle clip and main jet.
Main jet 115 will hopefully work with No numbers 4-4 and drilled airbox for more air.

[seanbarney41]

Pewe, Mikuni jet size numbers are not directly comparable to Keihin.  Somewhere online I have seen a conversion chart.  You should probably just buy some Keihin jets.

[BobR]

1 carb is cleaned.
Naphta bath 48 hours softened up the dirt, not much cleaner.
Sprayed EGR carb cleaner- blown  with compressed air, more spray and brushed all dirt.
Still dirty and corroded-  1 hour in 12.5% vinegar helped. Compressed air again.
More EGR carb cleaner spray.
Used most of the parts in the cruzinimage carb restore kit except needle and main jet.
Mikuni mainjet 115 will hopefully work with No numbers 4-4 and drilled airbox for more air.

 Running (Keihin )115's in my K4 with a drilled airbox and 4 into 1 exhaust. Runs great. The conversion charts Ive googled put a 115 Mikuni jet the same as a 130 Keihin which sounds way large. Bob

[PeWe]

Ok, news for me. Thanks guys!
The old jets were also Mikuni, stamped 147.5!!!  That with pods, 836, ported head, cam and 4-1 plus real fuel
I think it is a good idea to order some Keihin jets then.
Struggle with jets when I can avoid it seems to be a better idea.

Jet conversion list as you mentioned: http://www.jetsrus.com/FAQs/FAQ_mikuni_vs_dynojet_vs_keihin_sizes.htm

I have ordered 115 and 120 keihin jets. 110 keihin look alike is included in cruzinimage restore kits.
I used the cheaper white nylon dynojets back in the 80's, nothing mentioned about size difference.

[Terry in Australia]

I didn't know that about Mikuni vs Keihin jets either Per, that's interesting! I installed a Mikuni HSR42 flat slide carb on my Harley Sportster last year, and because of the freer breathing air filter I've been drilling out the stock 160 main jet until I think I've got it right, using some metric jet drills in .5mm increments, I think I'm up around 180 now? I did drill another one out to 2.05mm and it ripped at high RPM, but burped and farted down low. I've got some old Sudco CB750 carb rebuild kits here, and stole the 125 mains for my bitsa bike, it starts and runs fine, but I haven't put any miles under it yet. Cheers, Terry.  

[PeWe]

Did one more carb today. I decided to not use cruzinimage air screw since it look too different, brassy thick head. My stock are OK

[PeWe]

All 4 carbs cleaned. Needles adjusted back to stock, new pilot jets and float valves. Waiting for keihin 115 mains and top seal since one is lost and not possible to order anywhere.
Edit: Found the seal that could not be reused since its dry and brittle, cracked when I tried to press it into the carb top.

I'll use Viton o-rings as top seal. 4 x 2.5mm must be OK. Tested 4 x 2.0 that wobbles around a little
Still separate and will set the float heights before assembly. The cruzinimage carb kit float valve washer is a thin metal washer, Honda used a thick fiber washer which will affect float height too when it will sit lower.

I have found the reference of the float height setting.
http://www.hondachopper.com/garage/carb_info/float_levels/float_levels.html

[PeWe]

Mains 115 keihin style mounted.
The needle jets have used Mikuni jets before so the threads are not that tight. I punched a mark where the main jet meet the needle jet which hopefully will squeeze them together better. Main were tightened but I had thoughts about vibrations make them to loosen up.

Adjusted the float heights that all were close, might have worked as they were. Made my own tool

[PeWe]

Assembled the carbs today. Spent time to adjust the choke linkage for perfect synch, total lift and close on all. Almost, no 4 does not close 100% at full choke. But so much choke is seldom used. All lift completely when off.

Bench synched them and ready for use. I think I'll fix the spring, it is very hard. I'll look for a softer one.

[PeWe]

No updates this week either. Christmas, New year and a cold have kept me out from the garage. Last week I have been on a warmer place with sunshine, free food and drinks west of north Africa, Gran Canaria. Beer and Sangria perfekt after breakfast. The sand on current beach feels like blasting sand must be perfect for bike jobs
#$%*, my glass of Sangria is empty!
I miss my garage now and then.

[Stev-o]

Is that Morocco?  Looks very nice, good for you!  How did you swing FREE food & drinks?!

[Terry in Australia]

Nice Per, is that one of those Sh1thole countries that the bloke with the tiny hands is talking about? I'm not too sure about that black sand, but the rest of it looks pretty good!

[PeWe]

Canarian Islands.
Gran Canaria is one of them.Tenerife, Lanzarote and Fuerteventura other of the 7 islands. Belongs to Spain and part of EU and therefore OK to use my phone as home.

Perfect climate for biking all 365 days. Seldom too hot and never too cold. Book holiday with all inclusive is rather common. Flights, hotel with  3 big buffets as breakfast, lunch, dinner and meals between as hamburgers, pizza with free drinks, alcohol or without as much as I can drink and eat from 06:30- 22:00

I must find a way to migrate.... with my bikes
Climate sucks at my latitude 100 km west of Stockholm.
I sent a sunny photo to a friend  an hour ago, I got a photo from my town with snow, ice and complete darkness.
We’ll go back home tomorrow

My garage is the positive thing and update this thread with my K2  build. Fix my leaking right fork tube on my K6. Probably K6 first replacibg the tube + seal. Dual brakes make extra work removing the wheel. It will get a new handlebar too.

[PeWe]

......the bloke with the tiny hands....

Terry, who is that? A leader of a country?
Both I and wife laughed at that funny expression

[Terry in Australia]

Ha ha, well I probably shouldn't mention his name because it might start a fight and cause your thread to be shut down Per, but he's got his own tower, and his name's not Eiffel.......

[PeWe]

OK, I thought it could be one of the candidates.
But I like that guy. He is welcome here and all of us that are concerned about their belongings and beloved.
I need some days in the garage and make this K2 build great again!
Back to bike talk

Edit: I forgot to mention that I'm back home to the darker and colder place called home (but warm inside). Today's job is showling snow on my driveway, 20cm thick layer, about 25m2.

[Terry in Australia]

Yep, I read about the Islamification of Sweden recently and thought, "Why the fcuk would desert people want to live in Sweden?" But who knows, the world has changed so much since 9/11, I'm just glad I visited Europe before it turned to sh1t.

We've had a bit of a heat wave (over 100 deg F) here over the last couple of days, but it's gonna be a bit cooler today so I need to take an airbox to the Post Office to send to a bloke in Sydney, then pick up some K&N air filter oil, I tried my un-oiled filter in my K2 bitsa a few days ago and it was hard to start even with the choke on, so it's getting too much air, I need that "Bolt on choke" to get it working right.

Have you got a snow blower Per? If I lived anywhere near snow (and I never would, unless I was in jail there) I'd have a snow blower, one of the few engine powered devices that you could enjoy in that weather without risking death!    

[PeWe]

Yes, the change started to escalate from 9/11. It look like the working people must go south, after too many not working going north...
I look forward to more biking weather

Terry, the area to clean from snow is not enough for a snow blower.  Around 6m x 5m in front of the garage (minus where the car is parked) + 5m path from front door to a garden shed. The snow job yesterday was easy snow, not warmer and sticky that is heavy and will stick to the shovel as it is glued to it.

I'm currently investigate the type of handlebar switches my K2 build need. I have the later 73-76 models but the earlier K2 look different with an additional slim ON-Off switch on left side. Important both side switches are made for internal wiring in handle bar.

I'll probably order the  handle bar switches from Z1parts that has a nice complete set of meters
https://z1parts.net/honda-gauge-set-cb750-cb550/
Look not that differernt from K2 except for the plate and Top Fork Bridge. The fork has the later version that these meters will fit. The bike will not be an absolute K2.
Did CB550 really have same tacho gearing as 750? I have a late CB500 tacho that look as a CB750 tacho with green face but NOT same gearing, it show much more rpm than a CB750 since I have tested it. Red line start later too.

Switches, K2 style
https://z1parts.net/35250-341-672-CB750K2-Left-hand-control-switch/
https://z1parts.net/CB750-CB400-Right-Control-switch-35300-300-674/
I'll see if I must have this one: https://www.davidsilverspares.co.uk/CB750K2-FOUR-1972/part_105021/