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Motorcycle Repair/Making one of my 305's a Sunday rider


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I have a 305 Dream, two 305 Superhawks and a 250 Scrambler. About 10 years ago, whenever I would come across one of these bikes that was in non rust bucket condition, I would buy it.  The 250 Scrambler is supposed to be on the cover of one of your manuals?

It is original down to the paper clip like loops on the handle bar levers cable adjusters.  But I am not the expert here.

What I could please use help with is this.  I have gone to some trouble to get them titles.  The whole bond thing, and swore I did not steal it back when I was 9 years old.  I have raced motorcycles all my life.  And would love to do this myself.  But I have sold my time, and work over 53 hours a week.  So.

I would like to find the most competent person I can, and have them take on the mission of making one of these bikes a weekend rider. I would like to find someone that knows these bikes to the point of not just rebuilding the motor, but what state of tune is best and rebuild the bike to that sweet spot.  I am not interested in a "Concours" example, I want a hot rod!

If we were talking about a 1973 CZ Coffin tank 250 or 400, I could tell them what we need to do.  Hope this example makes sense.

I would very much want you to be involved.  And so I am writing to ask if you take on this type of work?  And if not, would you consider steering me in the direction of someone solid that would love to help me.

Thank you for any help you may be able to provide.  I have read your writings and you write very entertainingly, which I do not believe is effortless, and when you are also being informative at the same time.  And thank you for your time.


Charles, thank you for the compliments concerning my writing and expertise around the 250-305s, which have been a specialty for me in the past 25+ years.

Your choice of platforms will dictate some of the parameters involved in the final decision. If you are tall and muscular, you might not fit the CB77 chassis very comfortably. If short-legged, then the Scramblers might be too tall for a comfortable fit. Early Scramblers have insufficient SLS brakes, so you have to move up to a later CL77 with DLS brakes on both ends for safe street riding. I think we'll leave the Dreams out of the equation as they have pitiful suspension, brakes and only a single carburetor to breathe through.

The 305 engine can lend itself to some mods which will increase the power, however there are a lot of inherent limitations to their designs. Valve sizes really can't be increased more than a millimeter and the ports are really sized for a 250cc engine to begin with. There are cams and valve/spring kits out there as well as some forged pistons to improve reliability. Electronic ignitions can help keep the spark timing in check and are available from several sources. You are going to be stuck with the clunky old 4-speed gearbox, unless you want to invest about $2500 in a Nova street 5 speed gearbox, but that precludes the use of the kickstarter I believe. There is a guy in Australia who had offered "short block" motors that have 6 speed CB360 transmissions and stroked crankshafts to stretch the engines all the way out to 500cc in full race trim. Obviously, this kind of work costs thousands of dollars, as well.

You can't go too crazy with high compression pistons for the street, as they tend to seize if not finely tuned and kept from overheating. There are oil coolers and racing oil pumps from Italy for very serious applications.  My friend Tim Mings, who is a master builder of N/Z600 Honda cars, has been racing CB77s for many years and currently has a competitive bike that has a $5k front brake assembly on it. He works with Les Barker up in WA, who can conjure up all kinds of trick parts for hi-performance applications.

Other than a 350cc kitted engine with roller camshaft in a CB77, I generally have been rebuilding the bikes to stock specs in order to contain the costs involved with aftermarket goodies. It takes about 6 hours of labor just to reassemble a stock engine and parts like primary chains are scarce and expensive.
You must have a really good crankshaft to start with, of course. The rest of it can usually be sourced from eBay sellers parting out engines or the aftermarket venues. All of my main suppliers of vintage parts are seeing a steep downturn in the demand for 1960s vintage parts/bikes now. I am 67 years old and most of my peers are in the same age group. We have all "been there, done that" with the old bikes and few of us are still doing any extensive amounts of restorations or repairs nowadays.

I do have one remaining set of NOS head and cylinders which were bored to .75 which are all ready to go for a stock engine build. I've pretty much burned up my CB77 spares in building up the last half dozen bikes since 2011 or so. Just rebuilding a stock engine runs from $1200-2000 depending upon what you have to start with and what needs to be refreshed. It looks like you have a good Z-1 Kawasaki there.... won't that work for a thrill ride for the weekends?  :>)

Bill Silver

Motorcycle Repair

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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