350/400 miles before rebuild

[scottly]

How many miles are the wee Hondas getting before any major engine work is required? A fellow on the US forum, Ofreen, has logged over 170,000 miles on his F0 750 with the original engine. Who has the most miles on a baby four?

[K2-K6]

Not my own bike, a friend's example when they were more contemporary, reached 120,000miles without rebuild. It was, by that time more compromised as it sounded the traditional rattle/tinkle signature they give out when the camchain "horseshoe" gets stuck from gummed and baked oil residue.

From recall, starter motor replaced but no other notable problems. Serviced regularly, but not with such absolute diligence that may have given more life, potentially.  It didn't fail in the motor, more put out of use by replacement with a newer bike alternative.  I didn't get to see inside it, but bores / compression etc appeared to be in order from how it started and ran.

Certainly, I feel that oils used then were more prone to gumming effects, with black sludge typical in many an engine in that period, along with typical (of the time) British outlook of extreme suspicion in what were relatively low mileage interval for oil changes. Thsts also accompanied by an economic leaning of "how much is that going to cost" generally echoed around dealer service desk conversation 

170,000 miles is certainly a pretty high watermark for the one mentioned in thread title.

[Sesman]

John web,eh is the man to answer the longevity question.

[Deek]

I bought mine new in 1977 and it was my only vehicle for the next six or seven years.
Through that time I was riding 10-15,000 miles per year.
In a fit of youthful ignorance or enthusiasm I stripped the engine at 40,000 miles.
I replaced the cam chain as a precaution and, unnecessarily, had it rebored and crank clearances checked by SEP in Kegworth. I then put it back together. It's not been opened up since.
There were periods when, er..., the speedo drive didn't seem to be working and it's had 3 speedometers but I know the mileage I was covering at the time.
That engine has definitely covered in excess of 120,000 miles in total. The oil has always been changed at 1500 mile intervals and it's not been thrashed. It still sounded ok to me before it went to the back of the garage ten years ago. Needs a cosmetic rebuild but I should also replace the primary drive to improve the transmission slack.
I have a couple of other engines but can't verify the mileage on those.
There must be others out there with higher mileage than mine.

[scottly]

Perhaps I should rephrase the question:
What is the minimum mileage that can be expected from the small fours before major work is required?

[Oddjob]

Depends on the model, depends on what you define as Major work.

30-40k approx for an internal chain, after that they can start to get clattery. Again, depends on how hard it's ridden and how often the oils changed. I've got a 500 with 263,000 miles on it and it's had just the chains replaced and rings, is that major? No rebore, no clutch, no gearbox bits. It's very tired now though.