CB400T Shitbox Build - Daily Driver
I'm a new guy to this forum as well as motorcycles. Let's kick this off with some background ---
My history with engines and wrenching etc. is in big block V8's, trucks, and Camaros. Not exactly bikes. I've rebuilt two ford engines out of trucks; one a 460 V8 (pictures attached), bored over and upgrades throughout, and the other a straight 6 which was a real turd. I have also rebuilt 2 small block Chevy v8s (the old 350), one of which was a shop motor the other was in a 1971 Z28 camaro. I have had the experience of removal, tear down, bagging & tagging, sending parts to a machine shop, fitting, checking clearances (plastigauge), then re-assembly. So far none of those projects have melted down. So far.....
I did all of the builds in my family workshop, which was a structural steel shop, where I had about 7 years of experience in fabrication and metalwork. I built the engine test stand, fabbed up a flat bed truck bed for the project, generally modified everything on the old truck we were messing around with.
So I basically have no idea what I'm doing, when it comes to bikes.
I recently moved from Michigan to Germany. I needed a bike to cruise around town on and also was in dire need of a project. First I found a workspace, which is literally a bomb shelter, and now found a bike (80,000 kilometers on the bike). I will be getting a TIG welder and some other tooling to do the (limited) fabrication on the frame. I bought the 1981 CB400T, from a guy who used it as a daily driver for 10 years in the city. It was used, maintained-ish, and now is going to be hauled over in order to be a less ugly (much more safe) daily driver for me.
Issues with the bike: It's a cb400.... so there's that. Hasn't been in any accidents, rust free, overall still in serviceable condition. Safety wise.... Here's my initial reaction after tearing the forks out.
Brakes; two discs in the front drum in the rear. It's got two solid front brake rotors, both of which are still service capable. From what I read on the internet (.....) it seems like the front rotors are safer and more effective in wet conditions when they are slotted and drilled. Is that true? Am I okay to stick with the stock ones or do I need to get upgraded rotors? The previous owner had braided steel brake lines put on it, which are in good condition. The master cylinder is in good condition, aside from cosmetically looking like shit. The brake calipers are in good condition and work well.
Engine; It has an obvious piston knock (skirt slap). It's unclear yet why, as I haven't pulled the cylinders off. It runs alright, dogs hard in the higher gears which could be a result of the carbs being dirty (haven't looked yet) or the oil rings are toast. It starts up fine, dies on idle if the throttle isn't revved a little bit, until it gets warmed up. I was going to test the choke but I couldn't because the cable is completely fucked up. IF they cyclinder is toast, I found a new one on this site (https://www.davidsilverspares.co.uk/...A/part_175587/) which also sells stock spec pistons as well. I'm not opposed to rebuilding the top end for fun, but I'm afraid if the cylinder is toast that the heads will need to be rebuilt as well. I've still got to inspect those when I pull it apart.
Drivetrain; The chain is toast. I will replace that. The sprockets look okay, but from what I read it's likely a safe bet to just replace them with the chain. The transmission and clutch work without flaw, it holds every gear all the way through, without dropping out or jumping, and shifts smoothly. I really don't want to tear into the bottom end of the engine, if I can avoid it. But, I have the manual so if the concensus is that safety requires a total rebuild of the crankshaft and transmission, I'll go through the whole fuckin thing I guess.
Frame; This thing is in very good condition - but fuck is it ugly. I haven't decided if it's worth the effort to rebuild the rear frame, just for cosmetics. I am kicking around the idea of just cutting off the frame behind the shock mounts, and then putting a hoop around the back to support the new seat. The only thing I wonder is if it will make it un-safe to build new mounts for the shocks, also the idea of getting the geometry right is intimidating. I have seen CB400t builds with a mono conversion but that seems like a huge waste of time to me, for a putt around bike.
Lastly, This is a budget build for me. I want to re-use as much of the original parts as possible, making safe to drive but still have some fun modding it up with custom fab work for fun. I like the cafe racer look and style, so I want to follow that overall design. I bought the book THE BUILD by Robert Hoekman Jr. as an intro the the aesthetic and process for building a cafe racer that doesn't suck. So now I'm appealing to you all for details. Follow along in this thread for updates.
Thanks in advance for your candid responses!Attachment 95255Attachment 95257Attachment 95259Attachment 95261