1973 cb350f lightweight cafe

Well I wasn't looking for another project, but this just kinda fell into my lap. 1973 cb350f, hasn't been ridden for 2 years, 15k on the clock. I was able to get her to run (won't hold an idle just yet) and decided to go for it. Being that the sound of this motor is a personal favorite, I think it's going to jump to the top of the priority list.

Since these motors are by no means a powerhouse, the name of the game is weight loss! My goal is to rebuild the motor with some new goodies to squeeze a little more power out, and get as much weigh off as I can. I've seen build where 40 pounds came off easy, so I will set the goal of 50. With the combination of removal and replacing steel components with aluminum, I think is may be possible.

Additionally, I plan on doing a lot of riding on this one, so comfort is going to be a priority, so long is it doesn't compromise the look I want. I'm thinking to give her to minimal cafe look, going with a white and silver color scheme.

The first thing I will be doing is getting her to maintain an idle. She sat for 2 years with no gas, but there's is good spark, good compression, fresh battery, so I am convinced some cleaning of the carbs is in order. The bad news on this one is since I really wanna to go above and beyond, the budget I think I will need won't be available for a while, possibly even 6 months. In the mean time, as funds become available, I will move slow and steady.

I'm in - looks like a decently clean bike already.

The pictures lie!

A fair assessments is decent. So we now have an idle. Hooray!!! Now I cause all kinda of havoc!

Great bikes -- I'm in too.

I'm in cute muffler

I have 2 of them so I am in for sure !!

Lovin all the interest! Rode a few miles to see whats what. Some decent detonation going on. I took a look inside the spark plug hole, and the top of the piston is all cratered . Hopefully that is the extent of it. I already picked up a 3mm overbore kit so im not all that worried. My hope is there isnt any damage to the bottom end....

I have one, and I'm in to get ideals, and maybe help out some.

Love it, i'm in

Thinking out loud here, I've got a rebuilt set of cb750 SOHC carbs that I've had on the shelf for a year or two. If you're on a tight budget and going 3mm overbore I'll donate them to you if you pay for the trip over. Might help get more juice without having to buy too many components.

Finnigan said:

Thinking out loud here, I've got a rebuilt set of cb750 SOHC carbs that I've had on the shelf for a year or two. If you're on a tight budget and going 3mm overbore I'll donate them to you if you pay for the trip over. Might help get more juice without having to buy too many components.

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Hmmm. I may have to take you up on that!

I was looking at the keihin round slide cr26 's but that may do the exact same thing. The other thought I had was I am I fan of the mikuni vm carbs. Why can't I get 4 of those with 2 throttle cables and change out the petcock for one that will work? I was thinking the vm24's if I went that way.

These are the f2 carbs, they have metal slides instead of diaphrams and the accelerator pump

What's the outside diameter where it slips into the rubber mounts on the motor? Trying to see what I'd need to do to make them work.

And boom goes the dynamite

Ime in on this one too 8) great little mile cruncher & always turns heads, plenty of parts still out there too

So I'm playing with the lines I want for the bike. Granted I'm normally on a 175, but the front end on this thing goes on for days. How much can I lower the front end before the geometry goes to poo poo? I'm guessing I can throw the clips ons on above the tree, then take another inch out of the travel, that would be a 3 inch drop if I did both. If nothing else I guess I can try it and modify if it doesn't work out.

Tomorrows plan is to get the carbs off and motor out. I'm eager to see inside and get an idea how bad it is. No matter what the head is getting ported, but I really hope it's just a matter of that and the new pistons to bring her back to 100%

I wouldn't. These things ride great with stock geometry, IMHO. If you want clip ons you can shave a little off of the fork ears and mount them just under the top of the triple tree.

Well I guess the question now becomes which front end I will be using, stock or something else? The 2 options I have looked at are very different, but both have merits.

Option A

Give cognito moto a call and get a gsxr front end from them. This option undoubtedly gives me the most advanced suspension choice, and takes all the decision making out of the equation for the front end.

Option B

The modern honda rebel 250 forks are the same diameter, I think same axle diameter, but no idea on length. I can go to a local honda dealer and take a couple of measurements to verify. This give me new springs, shiny stanchions, and less headaches.

I'm actually quite torn between both choices. On one hand, I like the appeal of a nice inverted front end, big beefy brakes, and zero guesswork. On the other, the slimmer profile of a 33mm fork is sexy on a vintage bike. I've gotten really good at shaping the factory top triple clamp into an attractively contoured feature of the bike, and I think part of what makes building these so great is when things are made, not bought. I sure I will meet resistance from many of you on this one, but the other "advantage" (in my eyes at least) is with the 33mm front end, I can ditch the disk brake for the cleaner look of a front drum.

To me at least, the point of building a bike isn't always for the best performance available. If that was my top concern, for the 8 - 10k I'm spending to build, I could buy a modern sportbike and call it a day. So if performance isn't the #1 priority, then to me the focus is on the aesthetic. So I am willing to give up a degree of performance if need be. Besides, getting 50 lbs off will put the weight in 350 twin territory, and drums work just fine on them.

I guess the first step would be to go take some measurements and see if option 2 is definitely viable....

$8-10k and you're doing it yourself??

You're doing something wrong lol

1sttimer said:

$8-10k and you're doing it yourself??

You're doing something wrong lol

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I always buy the most expensive parts what can I say.... my 175 cost 5k.