Nothing special about doing the job on a cb-1. The only difficult thing is getting the race off the bottom yoke and you can usually drift it away rather than use a proper puller but you'll need patience and a chisel or screwdriver you don't mind wrecking.

Old Haynes tip is use a bit of threaded rod and the old race to drive the new races into the frame. Really works too

Other than that, the only things linking 3&4 would be the fuel rail (could have a blockage but seems pretty unlikely) and the air intake which allows the slides to rise (but that wouldn't make a difference at low revs).

Humour me. Check the leads.

If you were to connect the coils wih the left coil to cylinders 1&3 and the right coil to cylinders 2&4 (as opposed to the correct order which is left is 1&4, right is 2&3) then you'd get cylinders 3&4 not firing as you describe. They'll warm up anyway as the engine is aluminium which is pretty good at conducting heat.

I got myself some vessel screwdrivers. Made in Japan,  but there was something about JIS no longer being recognised so they don't necessarily write that on the packing - still made to the same recipe though and work like a charm.

Ebay search vessel megadora and you'll  it.

Drop a pm to pod70, he has a load of spares and is usually happy to help out.

Welcome to the fold! We definitely need pics of your -1 and the 35!

It may be worth checking his work on the carbs. If any seals weren't replaced (some are sure to be nla) then look to these guys: http://litetek.co/Carb_Kit_Honda_CB1_NC27.html
Tried and recommended.

I wouldn't want to trust slightly leaking boots. There are now some cheapy replicas on ebay, could be better.
Look at this on eBay  http://www.ebay.co.uk/itm/232342370235
Not tried but worth a look.

The air screws may need tweaking. Should be 2.25 turns out at sea level i believe. Best check me in the manual though.

The idle seems quite high so a lot of guys set it lower. Should be 1300rpm +/-100, it won't be happy lower.

If he's rebuilt the carbs they may need balancing.

Looks great, well done.

I've a little bit fallen for mercedes brilliant blue, saw a wagon in that colour in the local dealer window. One day when time and money permit,  i would like to get the body done in that colour.

Glad you got her back

For me its showing 3rd party blocked.

You may find your cache holds the image for 24h, so your looking at a cache version from the photobucket hosting site?

The other possibility is more sinister. Perhaps they're hiding what they're doing so you think your posts work when really they aren't.

Yeh same here. Really crappy thing they're doing.

Those take 110 and 140 like the cb-1. The cbr isn't significantly lighter so don't see why it couldn't work. It's probably a good place to look, and the 5 spokes look decent.

The cbr disc is 296, not sure you'd find a bigger disc to fit. 296 should be ok though.

Just be mindful of trying to get more than you paid for. Those chinese exhausts  made of thick steel and very heavy then sticker / hydro coated with carbon look film which burns off. The demon exhausts look to be the best vfm in the budget end of the market. They offer so many styles you're bound to find something you like.

You can adjust the screws without a long driver but i reckon you'll save scalded fingers from trying to do it with the engine fully warmed through.

Do these prices seem cheap? I can't see a Picclick UK link in the drop down menu. Maybe BREXIT killed it already...!

https://picclick.es/Motor-recambios-y-accesorios/Motos-recambios/Escapes-y-sistemas-de-escape/Silenciadores-Silenciosos/

Too cheap,  chinese crap.

Have an eBay search for demon stainless exhaust. Lots of sizes and designs,  cheap, made in uk, comes with baffle.

There is a silencer in the link pipe. It's much like a simple glass pack construction,  held in place by two plug welds in the link pipe, which are visible from the outside. I'm pretty sure it's not about performance! It reduces the pipe diameter quite a lot.

I'd say it's for noise but also to help keep the size of the silencer itself smaller.

I've seen a few cb1s with one-off link pipes. A lot including one I owned were quite ugly and full of tight S bends, but a good job can be done. Seems the trick is to cut pretty low and remove that silencer, giving enough space for a gentle curve.

If you're changing stuff, consider using a cbr900 rear hanger. Squashes up the passenger legs but if you don't often go two-up, it's worth it for the extra clearance you gain, as the silencer is carried a couple inches higher.