The city of Nice seen from the surrounding hillside bathed in sunshine

Home Ren's Biking Blog

How To Get A 125 Engine To 100,000 miles

Blog Date 9 June 2023

Getting any motorcycle to 100,000 miles (miles, not kilometres) is not a common event, well not here in the cramped confines of the UK. In fact it's not that common for a car to make it to the big 100 here. I live in a small country where most folk's commute is a few miles and many journeys are considerably less than 10 miles. As such save for travelling executives and delivery vans, big miles in short time periods is uncommon here at least.

The odometer on Ren's CBF125 reads 99,999.9 miles
Oooooh the excitement! 

According to such trustworthy sources as "the internet" and "forums" most engine wear occurs at cold startup. I'm being facetious, most engine manufacturers and mechanical types would agree with this too. If perhaps you cold start your engine 10,000 times but each time you only travel 3 miles that's 30,000 miles. If you were to cold start your engine 10,000 times but each time you travel 10 miles that's 100,000 miles. For the same number of starts, equating to the same number of trips, it's likely the 100,000 mile engine is only a little more worn out than the 30,000 mile engine.

Plus if an engine is not allowed to warm through fully and run for a while - this can cause condensation in the engine leading to that "white frothy coffee" in the oil. Not good. Also any petrol contamination in the oil is not heated enough to evaporate it away leading to thin oil. 

My long suffering 125 was fortunate(?!) enough to have enjoyed(!?) comparatively long journeys. There was almost 10 years of commuting 3 days a week on a 25 mile each way route. There were many weekends away covering from 50 to 300 miles. There were plenty of tours where 100 or 200 miles would be covered in a day. Even commuting to visit Sharon is a 25 mile run, my shortest regular ride would be to mother's some 10 miles off. 

The CBF125 in the Netherlands complete with camping luggage
I'd consider riding the 125 to The Netherlands as a "reasonable run".

Regular use also helped. This not only keeps the battery charged and the brake mechanisms moving, it keeps splashing the oil around the engine helping with those harsh cold starts and not giving any rust time to form. Unless you're garage is temperature and humidity controlled or you "winterise" your motor at the end of each ride I imagine even the thinnest film of surface rust forming within the barrel's walls causes some wear. The longer it stands, the more rust will form.

The old exhaust on the 125 covered in rust at the header
It might not rust inside... it has rusted outside.

I doubt most folks ever notice. The swish Ducati that only gets ridden 5 times a year will never build up the mileage for anyone to become aware that each time it's started another few microns of barrel just shoot out the exhaust as rust. We only notice if the bike isn't used for 5 years and the motor's seized.

My bike also enjoyed(?!?) regular servicing. Initially the oil was changed every 2,000 miles, I started to eek this out to 2,500 later in life but this is still the recommended interval. Eventually it started to burn so much oil it was treated as a total loss system, receiving fresh oil weekly before it ran out. Admittedly the tappets never quite received the same tender love and care, and this came to bite me in terms of poor running over the years but as soon as they were adjusted normal service was resumed. I wouldn't mind but "doing" the tappets on the CBF125 is not an onerous task, I'm just lazy.

The oil filler on the CBF125
I've poured A LOT of oil into this hole recently.

Luck must surely have played it's part. I was unlucky to have suffered a cracked clutch basket ring gear but I was lucky that the crank and the cam and the valvetrain and the conrod and the gearbox and the piston etc etc were all good to begin with. Even with Honda's good build quality reputation anyone can suffer that one random badly made gudgeon pin circlip, feeble valve collet, or incorrectly fitted oil pump gear spring. Poop happens, I was lucky with this engine.

Finally, and most importantly, I kept the damn thing upright (mostly). I'd argue with a little care and a sprinkling of mechanical know-how most modern motorcycles could make it to 100,000 miles. I wonder how many engines actually die such that the bike is irreparable rather than end up in a ditch, under a bus, or otherwise mangled? I did drop it once or twice but nothing serious. Getting it stuck in a muddy bog at night and having to drag it out with the security chain mustn't have helped. 

So that's how you get a 125cc motorcycle engine to last 100,000 miles. Longer journeys, regular use, oil changes and luck. LOTS of luck. 

The Honda CBF125
And you know what, I still love this owd dawg.

Advertise here - contact

Reader's Comments

Upt'North ¹ said :-
Luck,.....yes I spose, we all need luck.
But.......I think it got there because of love and care ( but never a sponge ). Fresh oil every few months also helped I'm sure. With a bore and new piston and rings it might do it again.....might?
11/06/2023 13:27:03 UTC
Ren - The Ed¹ said :-
I have considered either re-barrelling and re-pistoning the engine, or replacing the whole motor with a low miles used one. The problem is the rest of the bike. Is it worth the effort and cost when things like the fuel pump may be on their way out, the frame must be getting rather crusty, and the electrics are tired? I could spend £400 on an engine, or I could put that towards something with more life left in it.

12/06/2023 12:54:42 UTC
nab301 said :-
Nicely done Ren , so has it just been dumped in the corner of the shed or will it get a well deserved place in the natural history museum?
12/06/2023 13:09:22 UTC
CrazyFrog said :-
Great achievement for the little Honda!
12/06/2023 18:56:00 UTC
Ren - The Ed¹ said :-
Let me tell you a little story nab301.

With around 99,700 miles on the Honda I went to Blackpool Honda, on the poor beastie. I was sniffing around the machinery when of course a salesman, sensing my interest, pounced. Long story short I casually dropped in the details of the CBF125. He scuttled off outside to look and came back in all beaming. Why they'd LOVE to have this bike off me, they'd put it on a plinth as an example of the stunning longevity of Honda's wonderful machinery.

He wasn't willing to talk actual figures, not unless I wanted to trade it in. I have an interest in the CB300R which I raised. We never settled on a price but eventually he emailed me back - offering... £300 off a new 5,000 pound CB300R. SOD OFF! I'll get £300 trade in on a Kwakker or a Yammy. They've no intention of sticking it on a plinth. If they did it'd only be there a few months before the next new model needs the space.

I am regrettably under employment once more - and working but 2 miles away - walking distance. The CBF125 is presently performing "local" duties such as going to mother's or trips to town for stuff.

I have not made a decision. Ideally yes it would be nice for the long suffering 125 to be ensconced in a nice warm museum as an "interest piece". If I knew, for sure, that someone was interested in it for some kind of collection or display then I'd happily take a few quid for it. If I knew someone would make good scientific use of it then the same. However I suspect, even as something of a rarity, that it has little value to to anyone then it'll get used a while longer and, sadly, probably scrapped.

Thanks CrazyFrog. Wanna preserve a clapped out 125? Now with only 50 miles?

12/06/2023 20:18:16 UTC
Upt'North ¹ said :-
Ed, I can only recall taking one vehicle to over 100,000 miles, a 96 Ford Escort 1600 petrol. It was probably the best (in a few ways, not all) car I've ever owned. I sold it to my mechanic/mot guy when I changed it for a new motor and they used it for a loan car. It felt good letting him have it, he had afterall changed the front suspension arms at every mot for around 5 or 6 years. In the end he would order two in just in case, although it always was the case.
I can't say I've ever truly regretted selling a vehicle, you just move on, the Beemer will get swapped this year after over nine years of ownership (if Hyundai ever make its replacement) and there'll be no tears.
I was surprised to read you're considering the 300, isn't it too close to your 500, or is the 500 going too. Your thoughts on Blackpool Honda seem spot on, salesmans b.....ks.
But no surprise there at least. Although I am surprised they had the interest to talk to you, from my own experience of bike showrooms in the last year or so they don't seem to give a damn.
What about arranging a Batty Get-together where the culmination is a viking burial. Not yours, the 125.

As an aside The B is off on its first jaunt tomorrow, wee bonny Jockland for a few days. It'll be a kind of get to know you tour, but I feel I know it pretty well by now anyway. Talking of Jockland anybody heard from Jim and TI.

13/06/2023 09:14:35 UTC
CrazyFrog said :-
At my current rate of mileage, being a retired, leisure motorcyclist, it'll take me over 30 years to put 100k miles on my little CB125F! I doubt I'll be riding for long enough to challenge your record Ren, sadly...
13/06/2023 09:15:49 UTC
Ren - The Ed¹ said :-
I'd like to say I don't get attached to my motorcycles Upt', but that's not entirely true. I have a level of affection towards the CBF125 due to having shared so much of my life with it. However, yes, it is merely a collection of various lumps of metal arranged such that it can be used as transport. The character I imbue upon it is simply a construct of the human tendency of pushing our feelings on to otherwise inanimate objects.

I shall be a tad sad to see it's demise, but I'll get over it just fine I'm sure.

Regarding the CB300R - the reason I haven't taken the plunge yet is as you say - while it's not the same as the CB500X they are in a similar class. It's a little smaller and lighter, only a little less rapid and it is a lot of fun to ride. But yeah, why get a small mid-range bike when you already have a mid mid-range bike?

It's there though. In my mind. Dagnammit. I fear I have a touch of Glyn's problem.
13/06/2023 19:58:06 UTC
nab301 said :-
Ren , as you've already figured and i've mentioned elsewhere on here, running costs of the restricted Honda 500 are similar to a 250 if ridden at 250 speeds. Even Enfield quote 100 mpg as the official figure for their 350 (20BHP) Hunter and other variants which probably translates to 90 mpg in real world conditions. I reckon you'll pick up a second hand 125 Honda and carry on as normal , you know it makes sense!
15/06/2023 11:23:43 UTC
Ian Soady¹ said :-
I find that when I bother to check, all my bikes except very small ones have done in the region of 55 mpg whether near-1,000cc "adventure" or cooking 500 singles. I believe that it's far more to do with riding style* than the bike / engine type.

*Style not being a term generally applied to me.....
15/06/2023 12:34:43 UTC
Ren - The Ed¹ said :-
I too found most of the mid to large bikes I owned used to return around 55 to 60 mpg Ian - that's why the CB500X returning around 80mpg is quite refreshing. The CBF250 and CMX250 Rebel would return around 90mpg and the 125s at least 100, usually 120 to 140 mpg.

As for the "bother to check" attitude! How very decadent, how terribly bourgeoisie. The proletariat and socially aware gentlfolk ought to know their consumption and be encouraged to use less. This is both environmentally beneficial and reduces the profits of the oil tycoons and/or oligarchs. Or in real terms if you're not checking you fuel usages you've got too much money.
17/06/2023 06:21:39 UTC
Ian Soady¹ said :-
Funnily enough I do check the consumption on my car religiously, noting mileage, quantity and price at every fill. Probably because the car is used for necessary journeys whereas bikes are as you imply mainly for pleasure use.

To put things in perspective my near 2 tonne Land Rover does almost 30 mpg, some of the time towing a 1.5 tonne caravan. Makes 50 mpg on a 200 kg bike look a bit feeble!
17/06/2023 09:02:28 UTC
Ren - The Ed¹ said :-
It is quite ridiculous how my one ton Astra estate returns 57-60 mpg, about the same as a SLR650. I'm of the opinion motorcycle development has been driven by Performance Bikes magazine and not my own favourite (non existent) magazine Tightfisted Motorcycle Monthly.

Blummin leisure riders, pfffffft.
17/06/2023 09:21:37 UTC
nab301 said :-
It's all about aerodynamics Ren. My CB500R seems to average nearer 90mpg ( fully faired) which is why I mentioned above that it makes 250's redundant. Is that slight improvement over your 500X because of the fairing?
Recently, reading through the very informative book " Royal Enfield Bullet The Complete Story" by Peter Henshaw there is a decsription of a grp fully faired Enfield in the 50's that had a top speed improvement over unfaired from 65mph to 77mph while sat bolt upright and mpg improved from 102mpg to 126mpg at a steady 30mph.
Online searches reveal that the factory prototype fully enclosed "Dreamliner" Bullet had a top speed improvement of 11% and MPG improvements of between 25% and 35% depending on the speed.


17/06/2023 12:11:53 UTC
Ian Soady¹ said :-
Royal Enfield were far more innovative than generally credited. The Dreamliner was indeed an interesting project but was never really implemented. RE were more or less the first to use what becam the standard rear suspension with swinging fork and twin suspension units. ridden with great success by Johnny Brittain and others. At the time common wisdom was that a rigid back end was better for grip.....

Later on Steve Linsdell did amazing things with a Bullet based racer in classic events.

The company did have blind spots however and insited on using small diameter cycle thread fastenings into light alloy which did what would be expected when treated to the tender mercies of the average bike owner and stripped.
17/06/2023 15:14:04 UTC
ROD¹ said :-
Although the modern 500cc bikes you mention are very good with their fuel consumption, they offer the performance of a 1980s 250cc bike.
19/06/2023 08:25:01 UTC
nab301 said :-
But the only problem is, at 14500rpm the FZR engine would have a half life measured in minutes...
19/06/2023 16:17:20 UTC
Ren - The Ed¹ said :-
I can only imagine a 250 at 8,000 revs uses as much fuel as a 500 at 4,000 revs.

I'd never really considered aerodynamics nab301 - but as soon as you said it yes of course, it makes sense. Cars are "slippery" where as motorcycles (most at least) are lumpy, there's gaps between the screen and rider causing turbulence, save for full on sports bikes most aero is directed towards rider comfort not efficiency. This is another nod in the favour of feet forwards fully enclosed 2 wheelers.

I know the aesthetics grind harshly against our present eyes but just imagine how efficient something like this could be if "done right".

Posted Image
21/06/2023 08:06:53 UTC
nab301 said :-
Ren ,after a quick search, apparently the drag coefficient of a (naked) bike is approx double that of the average car or more akin to a flat plate ( obviously positioned vertically )..
23/06/2023 17:08:43 UTC
nab301 said :-
I forgot to mention whilst out for a bimble yesterday with some friends and travelling more conservatively than I would on my own, the 250 V Strom returned 105mpg despite some hilly terrain although admittedly for every ascent there is a descent...
23/06/2023 17:15:21 UTC
Ren - The Ed¹ said :-
105mpg nab301! That's much more than I expected - colour me impressed. This, well this doesn't help in my decision because such good ecomony (if ridden carefully) leans me towards 250-300cc rather than back to another 125.

I used to be indecisive, I'm not so sure now.
25/06/2023 10:36:30 UTC
ROD¹ said :-
Ren, I understand the dilemma.
I think I would start by asking myself how am I going to use the bike.
If you are going to use the bike for country lanes b roads and towns, buy a 125. A 250/350 will only get close to 125mpg when used very slowly.
A 250/350 has lower road tax than a 500 but used at legal limits in the real world they will not better the 500 mpg by much.
I feel that I have a good bike combination with the 125 and the 1150. If I am riding country lanes at 40 - 45 mph then the 125 fits the bill with 120 - 130 mpg, however going faster and using A roads will drop the mpg to around 85 mpg.
If I want to keep up with A road traffic the the 125 is not suitable as I need to thrash the bike to even try to keep up.
This is where a middle capacity bike makes sense.
My normal riding speed when traveling on A roads / motorways is around the national speed limit and the 1150 does this with ease, with plenty left for effortless overtakes. At these speeds the 1150 returns 57 - 62 mpg solo or with a pillion.
So ask the question, How will I use the bike?
25/06/2023 11:18:37 UTC
Ren - The Ed¹ said :-
You are correct ROD - but here, let me make it more complicated for you. How will I use the bike? Dunno mate. I shall write up my thinking and bring it to you shortly. Don't call me Shorty.
27/06/2023 07:39:20 UTC
Daf said :-
You did it! I'd be genuinely interested in seeing what the compression is like and how much ring/bore wear there is in the engine...

As for me, the GW250 is still going strong. Minimal niggles for its age, and currently on 87,000 miles. It's returning about 81 mpg down from 85 when new. Compressions still much the same as when I bought it, and it needs a little oil (3-400 ml) between oil changes. All said and done I'm impressed - and I did have niggles when I bought it. I'll give you a proper write up when I get it to 100,000 miles which at current milage will be next summer!

11/07/2023 14:24:02 UTC
Ren - The Ed¹ said :-
It's a big credit to the Suzuki and yourself getting it to 87k! I do recall some early issue you had but I can't recall the details - so I look forward to your review.
14/07/2023 17:50:40 UTC
RobEll said :-
Well I finally took some advice and cleared out my long suffering garage, sold my expensive bikes and opted for a little Hyosung GV 250 Aquila which was running one of two cylinders for £500. A couple of plugs and chain/sprocket kit later and a home service, installed end can link pipes and I have a roadworthyish bike! I love it, it sips fuel and rumbles along just lovely. I did get in trouble with my long suffering wife as my 'bargain opportunity' arose on the Xmas run up, but much wine and chocolate later and the amber light was given. 15k kilometers now 16k and pretty cheap.I know, it's beginning to become a catalogue of parts but still less than £800 all in. Great job for commuting, bumbling around my local b-roads and taking in the views. The paintwork leaves something to be desired but it is in the rat-stages of life, and suits it well. I'm too lazy for chrome cleaning and I'll get around to finding out taking a photo when I can get off my lazy butt at some point. Love the blog Ren, all the best
16/07/2023 19:15:44 UTC
Ren - The Ed¹ said :-
That Aquila is the little, well actually not at all little for a 250, cruiser according to google. They're a big bike for a 250 so I imagine it's plenty roomy enough. What's the mileage on it now and how well is it running?
17/07/2023 08:07:29 UTC
RobEll said :-
Aye, she's roomy indeed for a 250, and runs like a super dream, really I had one years ago and feels comparable but with more vibes/character!? So much character that before fitting proper bar end weights I could see nothing in the tiny mirrors.. Best enjoys 50ish mph and happily cruising at up to 70 if needed but I have a shred of mechanical sympathy so keep it below 7k revs for the most part, it pulls cleanly to 11k or about a true 80ish but no need for all that palava. It's really grown on me, as has the frugality of a small bike. I keep looking over the fence and thinking, well I could have a shiny one with similar features, but for no less than £2k, God forbid! Got it with 15k and it's now around 16.5k kilometres on the clock, just over 11k in real money I think. I've no plans to get rid, besides the paintwork it's so iffy (in lacquered rattle cans job) I'd not get what I think it's worth. It's got life left in it but doubt that it'll ever see 100k miles
20/07/2023 17:55:27 UTC
RobEll said :-
Oh, and here it is... Pretty it ain't
Posted Image
25/07/2023 18:42:20 UTC
Upt'North ¹ said :-
Well, beauty is in the eye of the beholder.
But I get your point.
26/07/2023 11:21:16 UTC
Ren - The Ed¹ said :-
I'm liking them bags. Don't worry about it being all pretty and shiny RobEll, bikes are for riding and enjoying not for looking at.
27/07/2023 18:30:30 UTC
RobEll said :-
The bags came with it, but they do kinda suit it, bleeding bargain!
28/07/2023 21:42:45 UTC

Post Your Comment Posts/Links Rules



Add a RELEVANT link (not required)

Upload an image (not required) -

No uploaded image
Real Person Number
Please enter the above number below

Home Ren's Biking Blog

Admin -- -- Service Records Ren's Nerding Blog