75 CB360 - bad omen "yatagarasu" build

MiniatureNinja

Member
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OK here we go. I bought this bike in February last year from the second owner, who in an attempt to rekindle his youth decided to "cafe" the bike and had a younger friend 'help' him do so. It was quite a mess, I don't know why he chose to chop up an otherwise perfectly good bike.

I never intended to document anything or make a thread so I didn't take many pictures of anything but we are starting over this winter making this thing proper so you guys get yet another cb360 thread (thanks PJ)

the bike ran well, even with velocity stacks and no exhaust (and I mean no exhaust, the guy cut all but the first 9 inches of bend off the pipes and left it, I dunno what he was going for.
the first thing I did was put exhaust on it. the electrics were whack, but the bike ran and rode well, i rode it all summer only ever catching on fire once.

so here we are now!
before I rode it I did some things, I changed fork fluid, changed oil, PO said it was recently "maintained" whatever that meant. Tires on the bike are shit Chen Shen or something. Gonna have to fix that. Everything else is as follows. FOLLOW ALONG!



yes, this is where I am right now. in my back garden, with nothing but a tarp for protection and some less than stable work surfaces! But hey, its fun. friends are helping with welding and the larger machining tasks.



this is what the under seat looked like after it caught fire (charging system not up to snuff, not my wiring!)



new rick's kit - should fix that





chopping down the rear (will add hoop here as soon as I get new tuffside seat in so that it can match well)



comparing clubmans and clip ons. these clipons are trash, I ordered better ones




drilled some holes. may drill more to clean the rest of the rotor these holes will just leave grooves I fear



engine out



new valves are in order. debating the extra $50 each for 1mm larger intakes


rest of the engine is in remarkably excellent shape. pensioners are the OLD style, and look very worn. will replace.
I am planning to bore the engine out using tried and true methods of the GS850 pistons, which I already have in hand, with rings and new hardware. copper gasket, some mild porting to clean things up. stay tuned, Lots more to come. Now that I know I need to make a thread, I will do better with pictures
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Awesome. The ebbs and flows of CB360 threads on DTT. It's nice to have another upswing.
 

whynot

~~~If it ain't raining, I'm riding~~{iii}?~~prost~
Interesting build.

I don't suppose you can do this same trick to a CB350 twin can you?
 

MiniatureNinja

Member
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WhyNot said:
Interesting build.

I don't suppose you can do this same trick to a CB350 twin can you?
the 350 i believe uses a 15mm wrist pin, where the cb360 and gs850 both use a ~16mm diameter wrist pin.

so short answer is - anything can be done with enough money
long answer is - it's gonna take a lot of money to do that
 

whynot

~~~If it ain't raining, I'm riding~~{iii}?~~prost~
MiniatureNinja said:
the 350 i believe uses a 15mm wrist pin, where the cb360 and gs850 both use a ~16mm diameter wrist pin.

so short answer is - anything can be done with enough money
long answer is - it's gonna take a lot of money to do that
lol....thanks
 

adventurco

Nick Ol' Eye
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Definitely drill out the rest of the rotor, it will squeal like a piggy and gouge the pads if you run it like that. Ask me how I know ;D
 

crazypj

Split personality, I fake being smart
The extra 22cc is best bang for the buck ever.
Oversize intake valves are a good idea but not 100% necessary, all my engines so far are running stock valves.
Cheng Shin made in last 5~6 yrs are OK particularly at the price point and far superior to some of the overpriced crap out there (the price of one nice square Firestone will probably get you 3 Cheng Shin OK tyres)
 

MiniatureNinja

Member
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crazypj said:
The extra 22cc is best bang for the buck ever.
Oversize intake valves are a good idea but not 100% necessary, all my engines so far are running stock valves.
the valves im only debating because "while it's apart" still up in the air - gaming computer components are stupid expensive right now so i have decided to put that stuff on hold, opening up the bike budget some - carburetors is what I am really worried about tackling probably gonna pick up a jet kit from common-motor.com bike had symptoms of running lean and i imagine that the larger displacement, porting, and exhaust that i plan on making will require more fuel

one question: do I have to split the case? it's never been open before, bike had pretty low miles on it and shifted flawlessly. I'm wondering the pros and cons to splitting the case
 

irk miller

You've been mostly-dead all day.
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Don't split the cases unless you know the transmission and/or crank are a mess.
 

crazypj

Split personality, I fake being smart
No need to open case unless you really want to have a look inside or kickstart return spring breaks. All the 'important' stuff you need to do can be done with just the covers off.
If you want to run K&N wit stock carbs they cannot be just jetted but need extra stuff done to them (and for road use modified stock are almost always superior to Mikuni VM) The only thing that as to be changed is secondary main jet and that is totally dependent on the exhaust system more than extra 11cc per cylinder. the extra 'vacuum' is self compensating with stock carbs. Trek is using smaller than stock primary mains (65?) with stock bore and I'm pretty sure he won't need to change back to originals (68) with the 378 he's doing
I've never seen a broken transmission in a 360, it's designed for more power tan bike can ever make (unless you get into full turbo/supercharger, nitrous, etc) Same goes for crank although parking bike in a lake for a few months would probably screw the bearings pretty good. Small ends can get scuffed if left idling but even that takes a long time plus dirty oil
 

crazypj

Split personality, I fake being smart
WhyNot said:
Interesting build.

I don't suppose you can do this same trick to a CB350 twin can you?
You sorta can but it's more work. I think GS 550 pistons work or it may have been Kawasaki 650? (been a long time since I did one)
It's a little more expensive but easier to get a Todd Henning kit for 350 although I can't remember if CR is a bit higher than you want for road gas?
Biggest issue with 350 compared to 360 is the offset stud spacing so you have to bore block offset to get major capacity increase plus you then ave to use same offset on crankcase top. 360 will got to a 70mm bore but 350, never going to happen unless you weld all the stud holes then make a new block and head
 

MiniatureNinja

Member
DTT BOTM WINNER
crazypj said:
No need to open case unless you really want to have a look inside or kickstart return spring breaks. All the 'important' stuff you need to do can be done with just the covers off.
If you want to run K&N wit stock carbs they cannot be just jetted but need extra stuff done to them (and for road use modified stock are almost always superior to Mikuni VM) The only thing that as to be changed is secondary main jet and that is totally dependent on the exhaust system more than extra 11cc per cylinder. the extra 'vacuum' is self compensating with stock carbs. Trek is using smaller than stock primary mains (65?) with stock bore and I'm pretty sure he won't need to change back to originals (68) with the 378 he's doing
I've never seen a broken transmission in a 360, it's designed for more power tan bike can ever make (unless you get into full turbo/supercharger, nitrous, etc) Same goes for crank although parking bike in a lake for a few months would probably screw the bearings pretty good. Small ends can get scuffed if left idling but even that takes a long time plus dirty oil
thanks man. you still doing carb stuff?
 

crazypj

Split personality, I fake being smart
Yep but I'm really slow 6weeks to 3 monts turn around(too much other stuff going on plus (gasp) I'm getting older
You need to drill the 'extra' holes in rotor so they 'overlap' slightly, that way pads stay flat and rotor stays 'clean'
 

crazypj

Split personality, I fake being smart
Use a Yamaha rear mount and drill a hole for bolt/washer combo (or weld a tube/nut to frame) or weld CB piece to frame with original rubber mount. I don't remember how I did last one of mine when I swapped tanks
 

crazypj

Split personality, I fake being smart
Velcro won't hold it if you hit a decent pothole plus tank can move around if your 'using' it when cornering. Even stock mounts are marginal when your 'leaning on it' a bit ;)
 
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