New to DTT, rebuilding my first cafe build...1982 CB650SC

[TolChock]

Hello DTT,
last year I decided that I wanted to try my hand at a garage built motorcycle. My thought process was to make my mistakes on something relatively inexpensive and move up to some kind of hot rod. At the time I didn't realize that cafe racers were so popular i just know I liked the raw aesthetic and simplicity they evoke.
So, doe eyed and naive i started what I thought would be a very simple process of taking a bike, stripping it and putting all the cool cafe kit on it. It turns out I was wrong... I picked up a bike at a fair price that I thought would be a good platform (1982 CB650SC nighthawk), the engine seemed strong and it was pretty straight except for a bent fork pipe...anyway, straight away started pulling stuff off and ordering new parts. The first thing to go was the air box and all of the plastic garbage. New headlight, markers, tail light, clip on's seat cover, speedo, and air pods were the first things that I did (aside from the obvious i.e. tires fluids brake pads etc.) I had a hell of a time getting it to idle and played around with jets and air fuel mixture until I could ride it. The carb's have just been bench synced. I rode it this way for a week or two until I decided I needed to fix some oil leaks that the P.O. had band aided...New cylinders, pistons, rings gaskets and seals were installed (first time installation for me). The bike runs but is lazy 1st thought 3rd gear, and seems to run better at high rev's in the upper gears, it doesn't seem to pull through all gears as it should.
Build/Rebuild:
So, being semi neurotic, I now have it down to a rolling chassis. My plan it to re-do the gaskets and seals (some bolts stripped the first time) and replace all engine bolts repaint. I have restored a flat bottom tank from a '76 CB750 that I will use to have more of a classic look. I have chopped the rear part of the frame and have welded in a hoop, and am in the process of fab'ing a seat.
All of the frame, paint and accessories etc. I have a good understanding of. I would like some input as to how to get the most out of this engine with the least amount of money. The first thing I thought was to get a Dynojet stage 1-3 kit. I would also like to do something different with the exhaust...keeping the old pipes. Photos are attached. I would appreciate any input, tips, trick, snide remarks whatever (lets just not have the filter box vs pods debate! cant find a box and have the pods!).

Somethings that would be super helpful are:
-List of all engine bolt sizes used and any washers nuts etc. and source
-tuning advice
-exhaust modification tips i.e. where can I chop, how long baffel, packing etc.
-trick tips to get more power/speed/smiles!
-any experience with using different size main drive cogs

Cheers!
Tolchock

 

[my-79-750-k]

Once you get the jets right, it'll perk right up with the acceleration, just don't expect it to be a crotch rocket. Check your timing, wires, plugs, coils, stator, wheel bearings, etc. The thing with jets, you need to do all of your mechanic stuff first before setting them. Get the engine cleaned up, adjusted, etc, then figure out your exhaust, pods, timing, etc. Then set all your air/fuel screws at factory settings. Search on here for the carb tuning thread, LOTS of info on jetting in there. It'll get you close. Once it's good enough to ride, start your plug chops and fine tune it.

As far as changing the sprockets go, I imagine you'll be getting a new chain anyway, you need to get new sprockets as well. Stock gears are 17 front/38 rear. I'd keep it stock until you get it running, then see where you want the power, either more down low for around town and spirited city driving, or better cruising comfort with lower rpm's. Then adjust your ratio accordingly. Keep us posted.

 

[TolChock]

Thanks Jewbacca...
Sound advice...I have gone though the exercise that you detail at least 3 times trying to get the motor to perform to its potential. I realize it wont be a crotch rocket but I do expect it to run consistently through all gears. I have been told that just changing jets, air mixture can only get me so far when using pod filters and that a dyno-jet kit is really the only solution, especially so if I intend to modify the exhaust. I'm looking for a second opinion or someone with experience with similar issues. I will continue to browse the forums here. Thanks for the reply!

 

[Fox]

Hey Tolchock,


Your bike is looking great! Really like what you did with it. I'm impressed at how far you've gotten with no previous motorcycle experience. Had a few questions for you. Is that your custom fab'ed seat? Have you thought about chopping your fenders, the rear one especially?

As far as nut and bolts go for engines, I've got two websites that I've heard are great McMaster Bolt store and this one, Bolt Depot . I would recommend you take a look on eBay though. Here's an idea of what to look for. Full Bolt Kit I can't vouch for them because I haven't used them yet, but whenever I rebuild my engine, I plan to use a similar kit. It's worth looking into.

I can't tell you about the baffling and such that you need, but you could consider just buying custom/new exhaust. When I was looking for the bolts I came across this one. 4-1 Exhaust

I will be keeping an eye out for how your jetting issues go. I plan to do a similar style project, so I'm interested as to how you remedy the situation. Keep those updates coming!

 

[TolChock]

Fox,
Thanks...Unfortunately I have learned by making many mistakes. The photo is what the bike looked like Sept-Dec. Its now spread throughout my garage (hope fully I dont end up with any extra bolts).

The seat pictured I purchased on ebay (look up cafe racer seats), they provided the foam already molded to fit my stock seat pan with a new cover. One thing to consider...its hard to get good/straight lines if your seat pan is a 2 up, even with the custom foam and cover. I have just finished a new seat pan which will sit lower and flatter with no bump. The rear fender pictured is one I pulled from a '76 CB750 and chopped, front is stock.

I have welded a hoop on the back of the frame which I will tuck a snubbed off fender under.

The current build when don will be:
-Modified frame rear
-custom seat
-new paint (frame engine fenders etc.)
-complete upper rebuild (jugs up)
-add tach
-restored flat bottom '78 CB750 tank

I am also ditching the pods and putting the air box back on. Once i get max performance stock, I will think about performance mods.

I will update my photobucket as I go.

As far as hardwear and other random parts, I am lucky enough to have a local salvage yard with lots to choose from (they also have a web store http://grimcyclesalvage.com/ and are willing to pull what you need).

 

[TolChock]

Progress pics...

 

[TolChock]

forgot link
http://s1172.photobucket.com/albums/r570/tolchock5/1982%20CB650SC%20custom%20build/

 

[Fox]

Tolchock,

Haha well, that's good! You've gotta remember, it's not a Cafe unless it's apart more than it's together.

I gotcha. I wonder what we would do without eBay? I haven't started on deciding on parts or anything, even though I really want to. I know once I pick them, I'll want to buy them, but I want to make sure the bike is 100% reliable and, as I've taken to saying, running like a top. I'm pretty sure I'm going to try my hand at making my own seat when I get there. There's quite a few guides out there, and it doesn't seem to difficult. Key word is "seem". Is that what you meant by custom seat?

The welded hoop is a good idea. I'll probably be doing the same thing. I'm only going for a one seater, no chicks on the back of my ride. Thinking of a hump seat. May do flat. We'll see how I feel when I get there. Same with the tucked fender. I'm considering mot having one at all, but I can imagine my bike getting really dirty really quickly.

What are you thinking of as far as a paint scheme? A possibility is that you could just keep it raw. I saw a thread for a guy that did his and kept it all raw metal. It actually looks pretty sick. Here's the thread. http://www.dotheton.com/forum/index.php?topic=25730.50

Good idea on the pods. Unfortunately the guy before me already put some aftermarket filters on, so I've got to deal with that. I have the stock ones in a parts box, but they're rusted and nasty. I could put them back on, but I'd have to spend a few hours cleaning them up. Not exactly what I'd like to do.

You lucked out on that hardware bit. Nice find.