Spotty and I had a great day in his garage today. Somehow Spring has reverted to winter this weekend, with the temps in the low 50's, and pissing down rain that was getting blown into his garage's main door, just where we like to stop and have a cigarette during a hard day's tinkering. Anyway, we finally opened my new Yamiya exhaust system for my K0, after it's sat in my garage for most of this year. It was a bit like a scene from "Raiders of the lost Ark" as we both caught our breath when we saw how well it was packed, and how shiny the pipes were!
K0 Saturday 14 September 2024 by Terry Prendergast, on Flickr
Installation was straight forward, but would probably have been easier if I had the correct bolts for the footpegs. The bolts are 14mm OD, and the OEM bolts are "Necked down" to 12mm threaded section that protrudes through the mount on each side of the frame, but all I had were 14mm bolts. As an experiment I'd actually used my super dooper magnetic heating coil to soften the threaded portion on one of the 5 bolts I bought from an Ebay seller, then used my lathe to cut the old thread off the bolt, then used a 12mm threading die to cut a new thread a few months ago and it worked fine, but when I tried it on another, either I hadn't heated it enough, or the die was fcuked, because the second one didn't work as well and was a biach to thread, so I gave up and just used two 14mm bolts, after Don told me the overall length of the OEM bolts.(thanks mate!)
I was absolutely stoked, after some of the guys here told me that the insides of their Yamiya pipes weren't coated, but mine were, so hopefully they won't rot out like the originals did. On top of that, I happily discovered that the box contained new K0 style heat shields, and all the fitting hardware that apparently usually aren't included, even the joiners and clamps at the rear of the mufflers. The only things it didn't have were the two rubber bump stops for the stands, but Spotty ratted through a box of various rubbers, and we found two that will do the job, so fitted them.
K0 Saturday 14 September 2024 1 by Terry Prendergast, on Flickr
We'd installed the ignition (Dyna S ripoff from China) and I'd thought that the white wire connected to the yellow wire, and the black wire connected to the blue wire, so had reconnected them a couple of weeks ago. When we went to start it, it was sparking with a beautiful fat blue spark (with my little jumper attached to the battery) but wouldn't start, so I swapped the above mentioned wires around, and it fired right up, at around 5000 RPM! Fcuk!
I'm guessing that one of the slides is hanging up. Spotty and I had (we thought) routed the 1 into 4 throttle cables really well, so wondered if the tank was pushing down on the cables, so we released the rear of the tank and propped it up above the cables, but it made no difference, so next time we work on it we'll check the cable from the handlebars to the carbs, and if we can't find anything, we'll remove the airbox and see if I've somehow installed one of the slides backwards.
Regardless, it was running on all four cylinders, and has more compression than any CB750 I've owned, even those with high comp big bore kits, and I had to go find my jump pack so I could crank the engine over. Good thing was that there are no apparent oil leaks, and the pipes look lovely. I'm really looking forwards to a nice warm day so I can clock up some miles on the old beast. 
K0 Saturday 14 September 2024 2 by Terry Prendergast, on Flickr
K0 Saturday 14 September 20243 by Terry Prendergast, on Flickr
K0 Saturday 14 September 2024 4 by Terry Prendergast, on Flickr
K0 Saturday 14 September 2024 5 by Terry Prendergast, on Flickr
Terry….. Stunning! My pipes on the Sandcast came coated the same way. Sure you haven’t had them longer? Most people are reporting the new ones are just raw steel. Bike looks stunning. Check the barrel where the cables go 1-4. On one of mine the single cable end was not fully seated and prevented a decent idle. Did you remember the gaskets in the carb tops? Air leaks there can be a problem too…… Looks amazing, njoy that first ride! John D.
P.S. as potty’s shop looks like a great place to spend a day!
Thanks John, I bought them from a guy here in Oz who owns some beautiful sandcasts and I’ve been buying, selling, and swapping parts with him for the last 5 or 6 years. He imports several sets of pipes from Yamiya and then sells them on to guys here. Mine arrived with the internal coating, the correct K0 style heat shields and hardware, but no rubber bumpers for the stands, but Spotty had a collection of rubber bits and a couple of them fit the pipes, so all good.
This is the second set of Yamiya pipes I’ve bought, the first set came from a member here in Oz around 10 years ago who put them on his K2(?) and didn’t like them so took them off and put them back in the box. They weren’t internally coated, so I don’t know whether the current batch are coated or not.
Hopefully I’ll be riding it this weekend. Spotty’s 2 multimeter’s were about as accurate as the weather forecast, around 3 volts apart when we tested the battery. Spotty put the battery on his charger yesterday and said that the battery was reading 50%, so just in case it’s dead I charged up a cheap lead/acid battery that Spotty gave me awhile ago and was happy to see that it’s good to go if the 5 year old Motobatt is dead.
The well known carb “expert” in the US that I bought the carbs from in 2020 had neglected to install any of the gaskets that you mentioned and not being a K0 expert I raised the needles a notch because it was running really lean, then realised his error and found some old Sudco rebuild kits in my garage that had the correct K0 gaskets so installed them. That fixed the lean condition and made it run rich because I didn’t drop the needles. Didn’t bother me much, and was easy to warm up from cold, but we dropped the needles again while we had the carbs off.
We repositioned the throttle cable junction box and that sorted the high idle issue. I’m thinking that the current slightly funky running is possibly due to the battery condition, electronic ignitions don’t like batteries that are less than in premium condition, so We won’t touch anything else until we’ve got a fully functional battery installed. I went to a couple of chain auto parts stores yesterday to buy some new NGK plugs and neither of them had NGK or even the Bosch equivalent so I had to buy Autolite (apparently a Champion brand, oh God, we’re all gonna die….) plugs that are apparently equivalent to either D7EA AND D8EA! (Says so on the packet, so it must be true) If it runs well with a fully charged battery I’ll keep them for spares. We will know more tomorrow. (Long weekend, my favourite kind)
