Topic: Highest mileage on a SOHC?

[cyclezirk]

73 CB750 - 61,287 miles

[skamania19]

If the odometer is right, my '77 750K has 43,200.

[ofreen]

The 750 turned over 100,000 miles today.  Think I'll reward it with a new oil filter.

[Blue-Ace]

Oh man it sayd  miles not km, than 75.000 - 100.000 is a bit much. Im at 81.000 km's or 50625 miles now

[byidesign]

My 82 cb650sc just turned 140,324 mi, only had it apart once,to freshen it
    and two clutches in it. hasn't let me down yet.

[jaknight]

 

     After reading these posts, I guess my '74 CB750 K4 is just a spring chicken; not in the "running" yet at all.......... it just barely clocked over 24,000 original miles........

     ~ ~ ~ jaknight ~ ~ ~

[nickjtc]

Mileage unknown, since a PO smashed up the speedo and replaced it with a non-new one. Shows 65,000km+ now.

If you look in a horses mouth apparently you can get a sense of how old it is by the wear on it's teeth, or somesuch.

SO, assuming a bike has been ridden and maintained 'normally' is it possible to make a guess as to it's 'maturity' by indicators such as engine compression? My gut feeling is that Sophie has done fewer kms than indicated, just by the way she rides.

Any thoughts anyone?

[ofreen]

SO, assuming a bike has been ridden and maintained 'normally' is it possible to make a guess as to it's 'maturity' by indicators such as engine compression? Any thoughts anyone?

'Normal' still covers a wide range of behavior.  There are a lot of variables.  Short trips or long trips?  Is the rider smooth or is he ham-handed?  Given that oil changes are done at similar mileage intervals, but how much time has passed?   How was the bike stored?  Inside or outside under a tarp (maybe not even a tarp)?  Has it lived in a dry or damp climate?  Have there been long intervals where it hasn't been run?  Have the owners kept it clean?  Another factor with these bikes is the passage of time. 

I've had the same question as you, but the only one I can go by is my own '75 750F, and that is because I know the answers to all those questions above.  At over 103,000 miles, the engine is still all original and uses very little oil.  I do not have to add oil between changes, which are at every 3000 miles these days.  I have not had to change a tappet clearance in years.  I haven't had to adjust the clutch in decades.  It still has the original cables.  The engine has no significant leaks.  I synced the carbs many years ago when I bought the tool, and never have had to do it again.  It behaves as if it will continue to run indefinitely.  I take good care of it, but I don't baby it.  It has been a pretty good motorsickle.

[loonymoon]

I posted some history on another thread but can't remember where. Where? where? Oh where was I?  Bought the machine new in 1972 for commuting as was tired of my 2 stroke Kwacker smoking & loading up in low speed traffic.  The Kwacker was great for canyon thrashing but lousy for low speed commuting.  The 350F was nice for its intended work but rather anemic in our mountainous locale.  At about a couple of years old & maybe 25,000 miles or so the engine locked up, in a turn of course.  Only minor damage to either of us but upon taking the engine apart I found the primary link belt chain had started to come apart due to defective link pivots & jammed.  I was stamped "Hyvo" & Made in USA!  the replacement was Japanese & has served since without problems.  Since I had the motor apart anyway & oil was leaking from the head joint some experamenting was done.  I researched interchangability with other Honda fours & found that the crankshaft, rods & wristpins are in common with the 400F, as are the camshaft, valves & rocker box.  Cases, cylinder. pistons & head are different.  I measured 350F cylinder liners & compared with 400F pistons.  If bored to maximum over bore of the 400F pistons the engine would yield 425cc.  The original bore was 47mm & the maximum would be 52mm.  The large bore make the cyclinders thin at the bottom but I compared with my BSA B50MX, (500cc scrambler), with the 545cc kit & found it to be about the same.  The BSA engine gave no problems in open desert scrambles except being difficult to start, at least for me.  I turned the outer crowns of the pistons to prevent contact with the stock head.  Replaced all the gaskets, etc & several rocker arms due to flaking of the hard surfacing of the pads.  It looked like hard chrome facing.  Was astonished at the increase in low end torque & geared the bike to reduce the RPM at 70MPH from the original 7,000 to 6,000, about the same as a 400F.  Another 25,000  miles or so & a lot of oil leaking from the head again due to the rubber seals around the oil restrictors sqaushing into the overlarge hole in the head gasket.  Made up supporting rings surrounding the seals to confine them & they now hold up for many 10's of thousands of miles without leaking.  Also more of the rocker arms were damaged & some cam wear evident.  Having the head off again gave the opportunity for more enging development.  I replaced the trimmed pistons with unmodified new ones & chamfered the edges of the combustion chambers to match the piston profile, which yielded a perimeter squish band similar to more modern design.  While the heads externally had the smooth appearance of die casting the ports obviously were cast using sand cores as they were all rough & irregular.  Machining marks in the ports showed that they had been milled a short distance at both ends but nothing touched deeper.  Using a porting tool, riffle files, coarse & medium abrasive strips & a lot of hard work I blended the contours & surfaces inside but did not change the shape or size.  The improved engine ran better but was restricted with the original exhaust & air filter.  Experamented with various 4-2 systems but found the 400F pipe & a large  unrestricted muffler gave the best all around results.  Replaced the stock, restrictive air filter material with  Uni-Filter foam cut from bulk stock.  Naturally, all this made the carburation lean but upping the main jets cured that but at a cost of about 10MPG.  Had to upgrade the clutch to a Barnett 400F racing unit as the 350 could not hold the power.  The change is astounding!  On a steep grade with a headwind the original motor could not pull top gear.  Now with taller gearing it pulls the same grades at part throttle & cruises comfortably at 80MPH although top speed has only increased a few, from 92 to 98 but I have seen 100 on the clock on occasion.  The big change is in widening the power band.  It will pull full throttle from 25MPH in top with modest acceleration 'til 5,000 when the pull is strong & gets better with the revs up to 11,000.  That's a useful power band greater than 2 octaves!  No, it can't keep up with my 750 Bonneville but the performance compares well with my G12CSR but is more reliable.  Since then I've rebuilt the starter solenoid switch a couple of times & replaced the handlebar controls.  Replaced the cam chain twice using the rivet on link from the CB450 twin motor.  Replaced cam chain tension blade & guide twice.  Recently  a top ring shattered taking out the piston & liner too so replaced all that.  Replace the oil pressure sender to many times to count but no other major parts & has never left me stranded although my buddies think I'm a maniac.  I tell them the truth:  I learned to ride in Germany & ride like any European & they consider the pace as fast cruising.
Long & wordy, but we are talking 33 years & almost 200,000 miles here with a lot of experiences.
Cheers, Don Pscycle Madden.

All I can sa y is wow....  Any ideas how many miles a 350 stock engine will do without a rebuild before it starts to go seriously wrong.?

[nickjtc]

See ofreens reply, above. I see no reason why the motor shouldn't last a long time if it is not flogged unmercifully and the maintenance (especially oil changes) is done in a timely fashion.

[ic455]

Got mine with 31,621 on the clock, put about 5 on it so far, many more when I get it running right!

[ofreen]

The 750 rolled over 105,000 miles today on the way to work.  Still running strong.

[nickjtc]

The 750 rolled over 105,000 miles today on the way to work.  Still running strong.

Congratulations.

[sandcast2356]

What can you say for a 1969 that doesn't even have the odometer any more...prolly at least 1,000,000 miles or so.

[ieism]

My 550f speedo is at little under 50.000 miles now. I'm thinking about a rebuild next year.

[Kamal]

When I got my 76 K6, it had about 45K, that was about 7 years ago now.  Since then, I removed the speedo, commuted with the bke for a couple years, and have consistently rode the shift out of it....

So, I'm thinking it has in hte range of 70K miles now.

Kamal

[Stormer]

My 400F has 37.500 Km, but dont know its entire hystory.
So, for real, may be lots more.

[hoodellyhoo]

only 8022. Should go up a bit once I get her running.

[ic455]

Just picked up a '78 550K with about 11,500 on it.  Goes well with my 750 K6 that has over 30,000!

[S-Dog]

My 75 cb750k has  whopping 5600 miles.... yeeehah

[Jugghead]

hodellyhoo,
your 350F looks in pristine shape, those guage faces are immaculate!
my 73 CB350F (built 9/72) has 13,000 miles and is in its best form since i got it 3 years ago.
I get 44 miles/gallon and have never hit top speed yet.  I hit 80mph and 8000RPM and either run out of accelleration room, or run out of cajones.
 ( i am too chicken)
mine is just starting to get good.  hopefully she will last 100,000 before I have to open up the engine
hopefully.

[clarkjh]

I just rebuilt at 32,000ish.  I have put about 1800 on since May.

James

[kpier883]

Broke 18,000 on a recent trip.  At 75 to 90 mph it will use a quart of oil in about 4 tanks of gas.  I used three quarts on a trip a few weeks ago that covered 1500 or so miles.

So I don't know if the odometer is actual mileage or not.  CB750 - 1974

[754]

I voted 25-50. But I remembered my speedo says 60K I think, and it had 3 or 6 when I got it, but I put the speedo on my chopper as well.

 I stopped running a speedo back in 81 I think...

 One of the guys I rode with in 74 had 69 K I think on his 71.. Iknow that by about 80 or 81 him and his brother both had around 200K plus on the 2 bikes..

[Bob Wessner]

I modified the poll to allow folks to change their vote. Over time, member's bikes might accumulate mileage that would move them to the next category. This way, it might become something of an accurate archive of the mileage these bikes are capable of.