Topic: Terry's new new redneck K0 "Special"..........

[PeWe]

3ohm coils will not drain battery quicker?
I had Dyna 3ohm coils with Dyna-S ignition. Battery drained rather quick at first test ride with headlight on as we must have here. (Good to be visible too)

I went back to shop and traded them in to 5 ohm version for 20% off fee. Then no charging issues.

[Terry in Australia]

No problems here Per as we don't have that stupid "Lights On" law that other countries are stuck with. We did have it, but it was thrown out a couple of years later. I'm happy to argue that car drivers don't see motorcycles any better in daytime if they have their lights on. Regardless, I don't ride in the city so five minutes after I leave my self storage facility I'm doing 60 MPH, and no issues with battery drain.  

[grcamna2]

No problems here Per as we don't have that stupid "Lights On" law that other countries are stuck with. We did have it, but it was thrown out a couple of years later. I'm happy to argue that car drivers don't see motorcycles any better in daytime if they have their lights on. Regardless, I don't ride in the city so five minutes after I leave my self storage facility I'm doing 60 MPH, and no issues with battery drain.

Terry,only 60 ?

[Terry in Australia]

No problems here Per as we don't have that stupid "Lights On" law that other countries are stuck with. We did have it, but it was thrown out a couple of years later. I'm happy to argue that car drivers don't see motorcycles any better in daytime if they have their lights on. Regardless, I don't ride in the city so five minutes after I leave my self storage facility I'm doing 60 MPH, and no issues with battery drain.

Terry,only 60 ?

I try to stay legal until I get on to my favourite back roads Bill, then the only things I can hurt are cows and Kangaroos......

[Alan F.]

K0 cams seem rare and pricey, I wonder if there's anything close for less? I'm sure I'll find a way.

I've been researching CB77 pistons and came up with something interesting. CB77 and CL77 pistons seem to command high prices, above $100 without rings is pretty common. And that's not just for 4th over either. Anyway as it turns out the earlier CA77 uses the same rings and wrist pins as the CB & CL did. And OEM pistons and rings are available in 4th over for around 1/3 the cost. Then I found this to bring it all back home: http://forums.sohc4.net/index.php?topic=63688.0

I was also wondering what you're running for an ignition advancer?

Thanks!

[Terry in Australia]

I read that one page linked thread and while I agree that super-expensive forged race pistons are great for race bikes, I can't see any problem running the cast CB77 pistons in a stock CB750 Alan, I've done around 2500 miles on my K0 so far with no issues at all.

I've got a spare K0 cam here, just for fun tomorrow afternoon when Spotty and I get back from CX500 scrounging I'll measure it against a stock 750 cam, and a mild Andrews street cam I have here, and see what differences there are, if any. I'm guessing there'll be more lift than duration, but who knows? An F2 cam might work well, I put one in my K1/K2 bitsa 836cc (with Cruzinimage pistons) engine after I pulled out the Megacycle 125/75 and it worked very well.

I'm using the stock Honda ignition advancer, the Kokusan ignition uses stock advancer.

[Alan F.]

Thanks Terry, I agree with cast pistons being alright for a street ridden bike. Stock pistons were cast as well, it's just a little higher compression.

Do K0 cams have a small rectangle casting protruding between cylinders somewhere? I've found one on eBay for ~$160 but it is discolored as if it had been overheated, but doesn't look worn.

Stock advancer being Tec 300?

[Terry in Australia]

Yes and yes mate, you're a good parts hunter!

[Alan F.]

Thanks, I've actually found one for $75/free shipping now that I know how to identify them, I'm hoping the seller will answer some questions but I'll probably buy anyway, it's much nicer than the discolored one I'd found.

So that leaves head porting and sprocket ratio? I'm sure there were many small differences that when combined make your bike so much fun.

Besides those early carbs, which i'll probably pa$$ on in favor of later round tops that I already have, and the Kokusan ignition, which are available here. I'll run 5 ohm coils since I already have them.

This will be the bike I'd ride in '25 if I'm lucky enough to go along. It'll be my K3.

[Terry in Australia]

That sounds like a bargain Alan. I bought my K0 frame and cases from a guy in Brisbane, nice guy, but not stupid. He'd "find" some parts that he knew I'd need, so I'd offer him a figure which he'd invariably accept (because I probably offered him too much) then he'd "find" some more stuff and we'd go thru the whole process several times rather than him just pulling everything out and me making one offer for the lot. I'm sure it cost me a lot more by doing that, but I'd wanted a K0 for a long time, so I just ponied up the dough. In reality it was a pretty cheap build, I paid more for my Z1-B bare frame than I did for all of the K0 parts that I bought from him.

The humidity is really bad in Queensland and the cam looked very rusty in the pics so I told him that I wasn't interested in buying it but if he didn't want it I'd take it for free, but when it arrived and I cleaned up the lobes on my wire wheel attachment, it was actually quite good, so I used it. I got my money back from him last year when I sold him my mint VFR750 for $2K more than I paid for it in 2016, he loves the VFR as much as I did, so it was a win/win.

The head appears to be a stock K0 head, I don't know what differences, if any there were between the K0 and K3 head, apart from the obvious extra bolt hole in the later heads. I was saying in Don's K0 thread that there were at least 3 different K0 heads, mine is actually a late sandcast K0 head. (yes, the "Sandcast" K0's had 2 different heads and the diecast K0's had another head again)

I can't remember if I'm running 17/48 or 18/48 but I suspect that it's 18/48 as it pulls 4000 RPM @ 60 MPH which is what it should with 18/48. You're right about the 4 cable carbs, they're great, but expensive. I've got a spare set here that I've been trying to sell for less than the ones on my K0 and didn't receive a bid on Ebay, even though they're perfect. I might have to put them back on with a lower starting price, even though I'll be losing money. It'll be great if you're able to come along for some of my Route 66 ride, it is much more fun riding with mates.

[Alan F.]

It's hard to feel bad when it ends as win/win.

I've been wondering if I need an early cylinder head or if my K3 head will be fine as is?

I should just bolt it together and call it a learning experience if I need to tear it back down, that's how everyone does it right?

[seanbarney41]

Don't overthink it.  All this stock swapping around really makes miniscule differences.  Facts are that any decent running cb750 is a pretty fun ride.

[seanbarney41]

...well, I bet those pistons will do something

[Alan F.]

When Terry said it was the most fun 750 of the 14? He's had, it kinda caught my attention.

[Terry in Australia]

Yep to all of the above, my K0 really is the nicest CB750 I've owned, and I've owned more than 14, and less than 50 (probably) over the last 45 years. Sean's quite correct, all of the components listed will only add a little difference, I think the main things on my bike that really made a difference are the 120 main jets, K&N airfilter in the stock K0 airbox, high comp 61mm pistons, electronic ignition and coils, and the Delkevic 4 into 1 pipe.

All of these things have just made my engine just a bit more enjoyable, it loves to rev and when ridden reasonably responsibly, returns good fuel mileage. The downside (not for me, but it might be a consideration) is that it'll run like sh1t on anything but the highest octane pump gas here, and will "ping" monotonously on anything else to the point where it's just no fun to ride. I only ran "standard" fuel in it once, and as I wasn't far from home I turned around, dumped the fuel and filled the tank with 98 RON (93? in the US) and it purred like a kitten. Hopefully the weather will be better tomorrow, I think I need to go for a ride.......

[Alan F.]

Ah the K&N, I forgot that. Thanks.

[PeWe]

KN filter in stock airbox has better flow than the paper version so main jet need one step bigger?

My K2 can have good use of one. It runs well with K6 carbs, needles 4th from top, mains 115. Pistons CI K7 61.5mm with better compression, K7 cam. Stock K6 head w race springs. Prepared for KHD cam that made pistons to kiss the valves.
Not compression enough to  ping on our 95 E5 fuel. It get Shell V-Power +98 E5.

K6 airbox might need additional holes to give the KN filter enough of air. Earlier airboxes have larger air opening if I remember correctly.

[Terry in Australia]

Yep thats a good point Per, the K0 airboxes breathe better than the later ones, I remember reading an article where Russ Collins was punching holes in a stock K1-6 airbox for better flow. The stock air filter is a great secondary choke, buy a K&N.

[PeWe]

KN filter to be ordered.
Hondaman has also mentioned drilling holes in the airbox.
I think my K2 can reach 60whp. One 58whp dyno so far.
Terry, your K0 is probably in the +60whp area.

[Terry in Australia]

Thanks Per, I’ll never put it on a Dyno but I wouldn’t be surprised if it was good for 60 at the wheel, it feels just as quick as my K2 Bitsa with 836cc Wiseco pistons and Andrews cam. The K2 also has 120 mains, a K&N filter, Delkevic pipe and Kokusan ignition. I better take one of them for a ride.

[Terry in Australia]

Rode it! While I've always said that putting Ohlins shocks on a CB750 is like putting a Mink coat on a 10 dollar hooker, I could definitely use some better ones on the ol' K0, the Ebay cheapies which are just as awful as the OEM items, but with stiffer springs, and were  were overwhelmed on several occasions when I found some really deep potholes (one mid-corner that I wondered might throw me off, but it didn't) so I might have to think about reburbing some old Koni's that I have here, or just ponying up for some new Ikons.

I went to my favourite Bakery/Cafe but it was closed to all but takeout today. I asked why, thinking it had something to do with Covid and laughed when they told me that the table cleaners hadn't showed up for work today. That was OK, I wandered over to a bus stop where 3 other bikers were sitting. I asked if it was OK to sit with them and they welcomed me like a long lost brother. There were 3 guys ranging in ages from the oldest, 64, to the youngest, 25. The 64 year old was really excited about my K0 but the other two were only mildly interested. The 64 year old told me that he had a K2 back in the day.

He'd been away from bikes for the last 20 years, so bought a 2006 Harley 1200 Sportster from a mate who was too ill to continue to ride, 6 months ago. He said, "Hey you know about bikes, tell me what this thing is?" And he pointed to the "pop top" oil tank cap. He said, "What, it's got an oil tank?" and I immediately realised that he'd never checked his oil. Anyway, he was selling it, he wanted to buy a "Big" Harley so he could take his wife on the back. I was gonna ask how big his wife was, but decided against it. Anyway, I showed him a few things on his bike that he had no idea about, so he was happy. I checked his oil and it was fine.

All things considered, I had a great ride, it was a beautiful day, hardly a cloud in the sky, and I didn't see a cop for the whole 130 miles, so I rode like a maniac. I won't say how fast, but I got the absolute worst fuel consumption today. On my last 130 mile ride I had to go on to reserve at the 128 mile mark, today I conked out at 118 miles, as I was coasting down a hill, so I didn't turn the fuel tap to "Reserve", I just coasted down the hill with the engine off, and rolled into a gas station to fill it up. My best ever fuel consumption on the K0 was 63 (Imperial) MPG, todays "Danger Ride" had it down to 38, but that's OK, it was still great fun riding at "Go straight to jail" speeds.

K0 Sunday 9 Jan 2022  1 by Terry Prendergast, on Flickr

[PeWe]

A $10 hooker with mink coat will charge you 100!!

Not good to roll with engine off.
I read about it in a thread Hondaman commented about the final shaft roller bearing. It's lubricated by the running engine.

I got thoughts about my long rolling in the alps back in the 80's. Over 100km/h, engine idling for around 10km. But I did not get any problem.

Maybe if towing it longer distances.

[Terry in Australia]

Not good to roll with engine off.
I read about it in a thread Hondaman commented about the final shaft roller bearing. It's lubricated by the running engine.

I'll call bull#$%* Per, I had the clutch in and was just coasting, and I seriously doubt that I risked any damage at all, I've only done it a thousand times over the last 50 years or so....... without ever damaging anything.

[PeWe]

I have rolled a lot too. I got some thoughts after reading about the final bearing and towing the bike with motor off.
It might been when discussing early single row bearing and later double.

[Terry in Australia]

Yeah, I wouldn't be too fussed mate, we all know that just riding your bike is eventually gonna wear it out, but who fcuking cares, I'm still gonna ride mine.