Topic: Getting my K0 back on the road

[MauiK3]

The baffle/no baffle situation would also affect jetting

[PeWe]

My CB750 K6 used 17:48 during long rides to Italy, France and Spain in the 80's.
2000-2300km one way.

It had good response when passing cars on Autobahn or curvy roads in the Alps.
Passenger too.
17:48 or 18:48 not much difference in rpm, but better working engine/gearbox with 17:48. It act like transmission is made for 17:48 as I have felt it.
It had 836, ported head and cam.
My almost stock K2 has 17:48 too.
19 front means less clearance to case.
I use thick x-ring 530 chains.

My K6 has 18:48 now but that with 970cc,  much more torque.

If bike feels like it revs too much, the exhaust might be too loud for the rider?

[WideAWAKE]

I got a 48 tooth and some 120s on the way.

Rookie move not checking what I had and what they should be stock.

If the bike had a little more grunt it would seem like it would pull the current set up. It does cruise at 70 super nicely in 5th though, Just gotta drop down to 4th to pull past that.

[WideAWAKE]

Swapped out my rear sprocket to a 48 and put in a 120 main… WOW! What a wildly different machine.

I didn’t quite understand the whole “worlds first superbike” when I went for my first few rides.

Now I get it!

I had a little pop on my exhaust as I let off the throttle so I went a half tub in on my air screw and that all but took care of it.

With having no baffles I think I need to bump it up one size on the pilot jet.

I also found a correct set of carbs on eBay in Germany of all places. They were labeled at 78-82 so someone had something mixed up but they would have been a bargain at twice the price.

Hopefully have em next week, I’ll get em cleaned and sort out my jetting.

[WideAWAKE]

Carbs finny showed up - unfortunately Ace Ventura was the delivery man and they arrived with the rack mount cracked in half. The upside is that it should be an easy fix, and then being so cheap, I can’t be too upset. Although I have contacted the shipper to see if we can work something out.

Was nervous if they had internals since the listing didn’t show them.

Pretty much spotless insides.

Got em torn apart, blasted and prepped to go back together.

I’ll get the rack welded back together this weekend.

Not really looking forward to synching these up but it should be worth it as the carbs are my last incorrect part.

[WideAWAKE]

More pics 

[Stev-o]

How the heck the mount get cracked?  Not packed good??

Otherwise the carbs look good Mark.

What blasting media do you use?

[MauiK3]

Maybe walnut shells?

[WideAWAKE]

Carbs were basically put in a an oversized box wrapped in a few sheets of brown paper.

I’m surprised that’s all that got damaged. It’s a long trip from Germany.

I use extra large baking soda

I think it give a close to original finish. Clean and not too bright.

[PeWe]

Prepared to be welded and grinded. Possible without much trace.

I have got my Mikuni VM 29 rack shortened by cutting it, twice, a 10mm wide piece removed and welded together. Very well aligned.
I had to use a little valve lapping paste for the throttle rod to move freely in its bearings fastened on the rack.
These carbs have not that need of alignment.

[WideAWAKE]

Prepared to be welded and grinded. Possible without much trace.

I have got my Mikuni VM 29 rack shortened by cutting it, twice, a 10mm wide piece removed and welded together. Very well aligned.
I had to use a little valve lapping paste for the throttle rod to move freely in its bearings fastened on the rack.
These carbs have not that need of alignment.

I got it welded up. Just need to clean em up. Shouldn’t be much of a trace at all.

The upside, I got a reply from the seller who offered a £150 refund. So that puts me all together just under $250 with shipping for the carbs. A score for sure, Even without the refund.

Even though I feel these carbs are really a step backwards from the push/pull set up, I like that they are correct.

[WideAWAKE]

Can anyone confirm that the later (non 28) carb tops did NOT have a gasket.

Mine do not have one. I’ve seen rebuild kits that have them, and those that don’t.

I saw the question posed on the sandcast forum but there was no answer, just a poster saying his 28 carbs had em and a few other later sets he had seen did not.

[BenelliSEI]

Just an FYI, the bracket was probably broken when you bought them. It is very fragile and breaks when pulling on carbs, to get them off rock solid, old intake rubbers. Despite being extremely careful, I’ve snapped a few.......

Use the gaskets. I was having all kinds of issues sync’ing my K0 carbs (settings were constantly changing and wandering), until I put them in. I used a later style and punched out the centre, offset hole to suit. HUGE improvement.

[WideAWAKE]

Benelli - thanks for the heads up about the carbs.

I’ll fit some gaskets. Seems funny, the earlier carbs seem to have em, these don’t and then later ones do.

As for the bracket, I know it was in One piece when it shipped, but nonetheless it definitely seems easy to snap. That pop metal was a pain to weld too haha.

I did manage to get it back together, flat and not terrible looking.

When I get my mill set up I may pull it at some point when it needs maintenance and machine the pockets a little cleaner. Figured I’d leave some meat on em so it doesn’t snap again.

[PeWe]

That repair look good!

[WideAWAKE]

Thanks PeWe!


Got the carbs all back together and ready to swap out. Hopefully this weekend.

They have one small screw float bowl and 3 big ones… I’ll probably just use 4 big ones until I can track down the other 3 small ones.

They look to have a steel screw as well and not a brass one. Don’t know how that first into production. The guy selling them had a lot of later F style carbs for sale. Idk.

I also used a 4 oring brass fuel T instead of the 2 oring ones that were in there. I know the 2 oring is correct but I don’t wanna have to pull all this apart if they leak at some point in the future.

I’ll stash the originals away.

[BenelliSEI]

Nice work. The carbs and bracket look.good!

[WideAWAKE]

Thanks!

Got em mounted and kicked it over.

They seem much more aggressive than the later carbs I had, even with the same jetting.

I havnt synched em with gauges yet but I like em so far.

Hopefully I’ll get to that in the next day or so.

[Stev-o]

Thanks!

Got em mounted and kicked it over.

They seem much more aggressive than the later carbs I had, even with the same jetting.

I havnt synched em with gauges yet but I like em so far.

Hopefully I’ll get to that in the next day or so.

Good job Mark!   Do you have sync gauges?

[WideAWAKE]

Stev-o - yes I have a set of gauges.

Got em mounted and hooked up, I swapped in 42 pilots in my old carbs cause I was pulling more air without baffles and was getting some potting on decel.

It seemed real rich with these carbs and it would appear that the slides on these 4 cable carbs have much less of a cutaway.

Swapped back to a 40 pilot and it idles much better.

Got busy with a few other projects and havnt had a moment to get gauges on them yet.

Leaving town for a few days and hopefully next week I’ll have em dialed.

[WideAWAKE]

Carbs on - synched.

Bike seems to smoke quite a bit.

Never smoked with the later carbs.

Any ideas??

40 pilots, 1 turn out, needles in the bottom clip.

Slides seems to be much richer than the slides on my later carbs and the set of k1 carbs I have.

[WideAWAKE]

Quick trip around the block finally.

Smoking seemed to go away.

Runs fantastic! Seems much more “emotional” with these carbs on. I like it!

[Stev-o]

Runs fantastic! Seems much more “emotional” with these carbs on. I like it!

More emotional, huh?!  Dont believe I've heard that one before!

[WideAWAKE]

Runs fantastic! Seems much more “emotional” with these carbs on. I like it!

More emotional, huh?!  Dont believe I've heard that one before!

Haha seemed to be a good word.

More raw and aggressive. A much more appealing deep gurgling at idle that goes to noticeably quicker acceleration. It smokes a bit on start up haha … emotional haha

I really didn’t the carb change would do much and if anything I really thought I was going backwards but I’m pleasantly surprised with the swap and glad I did it.

I believe the carbs I originally had were off a k5. The only thing that really seemed different were the slides.

I built a set of K1 carbs I was gonna put on but found these K0 ones so I went that route.

The k1/K5 carbs seemed to be the same internals but I never ran the K1 carbs so I can’t confirm if they performed any different than the K0 or K5 carbs.