CB350 wanting as much power as my wallet can afford.

Or spend $1000's less, keep stock, and enjoy riding it....

The man claims he has a wallet, if he wanted the fastest CB350, he wouldn't even mention cost.... 8)

This is a website devoted to modifying motorcycles.
Why is it every time a new guy asks a question every answer is "you can't do it leave it stock"
Just tell the guy what he wants to know sheesh

Make it run well & be reliable then find a big hill = 100MPH then you can ride it around town and say it did the ton.

I think it would be cool to build a 4 valve head for the 350, I think they had a kit back in the 70's at some point. combine that with a crank, special rods and pistons that could make 15k, and I think it would be pretty neat.

SONIC. said:

Just tell the guy what he wants to know sheesh

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What he wants to know, and what he needs to know are not always the same thing.

For anyone to become even moderately proficient at working on/modifying bikes, one needs to gain some experience, and have some successes. Waay too many first time builders get in waaaay over their heads. They fail at their first build, and never end up even being riders. Their projects end up being a pile of junk, sold off for parts to the next sucker who will never finish it either.

What are the chances he can modify it and improve it if he can't get it running well stock?


Sure , 4 valve heads and fuel injection and oversize pistons, new connecting rods and complete overhaul with new bearings will make it fast.

Did the op mention he wanted to empty his wallet and bank account?


He probably will balk at the price of a good head rework and cam and better valves.

The truth is a fast anything costs money.

Show me anywhere on this site someone with a genuinely high performance, rideable 350 that spent under $2000 to get there. Count labor, because the op is not likely a machinist.

You can make a fast 350, but you need a bit of resources.

The question of how do I make a 350 fast implies he does not have the knowledge, resources, or experience to do it, never mind cheaply.

I am not busting his bubble. He has no bubble. I doubt he even has soapy water.

A realistic answer to his question is what I said. Get it running well first. Then contemplate improvements. If you can't get it running well stock, you don't have the skill to hop it up.

I don't know the op, but if he knew how to increase performance his questions would be more about specifics, like cam grinds and duration.

My 69 cb350 stock would do the ton with a slight downhill run and a favorable wind. These bikes run well stock when well tuned. Carbs, timing, valve adjustment spot on.

Get there first.





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I think the best investment you could make if you're trying to make a bike fast is a wideband ego, an engine in good shape, actually tuned to hit 12.5:1 a/f ratio will be a lot faster than you think, once you're dead on with tuning, the thing is basically as fast as it's going to get, then start playing with better ignition, different air intake, different exhaust, overboring, camming, porting, it's an iterative process, frankly, I haven't seen any build on here that was finished by starting with rebuilding the engine for performance (unless it was someone who had done rebuilds many times before)

So many opinions and options and the OP is a self described beginner.

First step is to examine the bike form one end to the other and come up with 2 lists: What must be replaced to get it running safely. Things like tires, chain, cables and brakes etc. Next list what you thing would be nice upgrades. Then price both of those lists and decide on a realistic budget. For most of us, list 1 is more than we intended to spend on the whole shebang - especially when the motor is stuck.

If the budget covers that first list, great. Rebuild it stock and get it correctly tuned and then ride it all summer until the snow flakes reappear. Learn how to ride it and to maintain it.

Next winter look at list 2 again and see if that's a good way to spend your hard earned cash or decide if maybe a bigger or better bike might be a smarter investment.

Kemp said:

Go big bore. Should be able to get 435-450cc with liners with reliability. A megacycle cam one step down from full race, mild port work and 34mm Mikuni's will get you about 45hp at the back wheel easily. The bike will be a bullit!

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VonYinzer said:

What Kemp says is gospel. He knows, really knows, more about motorbikes than just about anyone. Fact.

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Only problem going that big, it costs big to pay someone do it
You can't just bore 326cc motor, it's going to need a crank swap (I know, I tried)
Even offsetting the bore won't get you a 435cc motor, the cylinder just isn't thick enough and the stud offset is just a PITA to deal with
It may be possible but it isn't practical unless you do everything yourself
Basic 1mm OS bore and clean things up, as I said before, ignition is way more limiting than ports/carbs/etc

AlphaDogChoppers said:

What he wants to know, and what he needs to know are not always the same thing.

For anyone to become even moderately proficient at working on/modifying bikes, one needs to gain some experience, and have some successes. Waay too many first time builders get in waaaay over their heads. They fail at their first build, and never end up even being riders. Their projects end up being a pile of junk, sold off for parts to the next sucker who will never finish it either.

Click to expand...

I seem to remember a certain CB350 around here somewhere that's just faded away after 3yrs work and a load of cash ;D (R....R...R...)

Not that difficult to go big bore. Powroll made 435cc kits back in the 70's. You do need to re-sleeve (LA Sleeve) for the big pistons and you do need to open up the top case to accept the larger sleeves. Wiesco makes a nice piston, thin ringed for a Kawasaki that fits the bill with the right dome etc for the 435 displacement. I think it would cost about $2500 to build this motor with cam, valve springs and retainers, HD studs, copper head gst, ported head, 34mm Mikuni's, piston kits and machining.

This motor should be quite reliable, will make it's max power at about 9500 rpm and will be a torque monster. Swarbeck pipes from the UK would round this beast out quite nicely.

I don't see anything wrong with wanting to build a wild CB350 for the street. Yes, a modern bike will kill it for performance but who cares. It will be yours and you built it.

What has a 435 big bore got to do with this thread? The OP is a noob with limited budget, not a big dollar pro who can build that sort of bike. Time to keep it real.

teazer said:

Time to keep it real.

Click to expand...

Why start now? 8)

^ LOL

Kemp said:

Not that difficult to go big bore. Powroll made 435cc kits back in the 70's. You do need to re-sleeve (LA Sleeve) for the big pistons and you do need to open up the top case to accept the larger sleeves. Wiesco makes a nice piston, thin ringed for a Kawasaki that fits the bill with the right dome etc for the 435 displacement. I think it would cost about $2500 to build this motor with cam, valve springs and retainers, HD studs, copper head gst, ported head, 34mm Mikuni's, piston kits and machining.

Click to expand...

That is equivalent of a crank swap
Powerol increased stroke by moving crank pin then heat connecting rod red hot to 'shorten' it by squishing
That creates all sorts of other issues
Max bore is still relatively small
$2,500 is not exactly chump change or something you find down the back of the sofa (unless your running a F1 or NASCAR team : )

thank you for all your help!

I was wanting to spend $2500 on the whole bike.

so I think I am going to keep the motor as stock as possible. I want the bike to get back together in the next few months so I need to get on the ball.

I have $3000 grand into my mostly stock bike. The builds nickel and dine you to death.

A good investment (investment is really the wrong word) is something like MikeXS aluminum rims. I spent $161 shipped for 2 new rims. Aluminum rims are lighter than stock, won't rust, and reduce rotating mass, so the bike won't have a higher top speed, but will accelerate a little quicker. I also put Buchanan SS Spokes on ($226 for 2 sets) to avoid rust and corrosion. My oringinal psokes were extremely rusty, and about 6 were broken, and another six or broke when I tried removing them. My build has the relace pictures, but I attached the front and rear finished....CB350 uses same size rims and spokes as CB360.

That post Reminds me of what my dad would say about harleys at the drag strip ( by drag strip i mean the bar) " if it dont run chrome it"

Unpolished ss and replaced rusty chrome wheels with aluminum.

Your father was pithy, but I am not sure how it applies here.

Lighter rims are a performance helper.

Stock 350 is faster than a stock Harley of the same vintage even with 2x the displacement.

Have another beer and settle down.

You know you love Honda.




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