32 year old mower.


Colin

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Hi,

Blackie's doing his thing putting lots of rain down again so I'm doodling.

Our Al-Ko 38BH 2.6KW BVS 143 petrol mower is now 32 years old and running perfectly. I service it each year at the end of the season and drain the fuel. Given its age and how miserable the weather is I've now got the mower on the bench just to tinker about a bit with it.

As usual with such tinkering it quickly escalates into a big job; I've worked on petrol engines for the last 55 years but never stripped a mower engine so a number of things are new to me; I'm used to points for precise spark timing but no points on this mower? Carb linkages have assorted springs etc. The spark on this mower is generated by a magneto; I'm used to Mag/Dynos from my biking days but all these had points so I'm on a learning curve and enjoying myself.

The top covers are now removed and yesterday afternoon I had fun removing the flywheel expecting to find points and condenser; my bearing puller didn't suit the size of the flywheel and not wanting to be brutal hitting it with an hammer I needed a way to gently remove the flywheel but it was proving more difficult than expected; I noticed three stopped holes around the flywheel boss; these holes measuring 5mm diameter and I was rather puzzled why these plain holes were there; I tapped the holes at 6mm then made a flywheel puller out of thick steel; had I resorted to using a hammer I'm sure a lot of damage would have occurred given how tight the flywheel was attached to the shaft; with the flywheel removed I was surprised not to find points but not to worry this is down to my ignorance regarding mower engines.

Whilst I'm tinkering and having got thus far why not remove the cylinder head and do a decoke and valve grind; I can also then check valve clearances and adjust if necessary. Everything will be thoroughly cleaned and the carburettor serviced too; this mower has given me a lot of service so time to give it a lot of TLC.

I've been browsing the web for spares but I'm just wasting my time; I can make a new head gasket and the original air filter can be washed clean so I'm not stuck for parts. :)

Kind regards, Colin.

50656


Flywheel removed.

50657


Over the years and given our rough terrain up the mountain the original wheels self destructed so I improvised; the two front wheels are castors and the rear wheels turned on the wood lathe from Meranti hardwood but just for fun I added the original tyres?

50658


There's the easy way to remove such a flywheel being brutal using a hammer causing damage or there's a gentle way to remove the flywheel; I never ever abuse machinery so the gentle way it was. Here I'm tapping at 6mm diameter to accept a home made puller/extractor.

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A piece of 3/8" thick black iron I had to hand being pressed into service; the flywheel was very tight indeed but was removed without it suffering damage.

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So far so good; at a glance the key looks to be offset; the magneto can be seen on the right; a lot of debris has already been removed so it's now ready for a good clean. This mower was expensive new but worth every penny and it owes me nothing.
 
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Thank you for the pictures. I had googled the Al-Ko 38BH 2.6KW BVS 143 petrol mower and found confusion. The governor seems to be an airvane design?
 
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Colin

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Hi,

Thanks DirtMechanic for your governor suggestion; much appreciated. :)

At the moment I'm unable to say what this mower has because we've just been enjoying horizontal sleet due to the terrific bursts of wind; Gale is in full force today and when it's not sleet Blackie's joining in with plenty of rain so I don't feel like getting a soaking wandering down to the workshop. For those unfamiliar with engine governors please see this;

https://www.briggsandstratton.com/eu/en_gb/support/faqs/browse/governor-system.html

I'm used to governors and automatic advance/retard; the bikes I worked on years ago had manual advance/retard; on the 600cc single cylinder bikes if the ignition wasn't retarded it meant a trip over the handlebars due to a violent kick back; some bikes were fitted with a valve lifter allowing the piston to be eased over top dead center. I'm not in a hurry but I'll know more once I get into the workshop.


I'm a dinosaur going back to steam power where governors were a very important safety device; such a great invention still used these days;

https://en.wikipedia.org/wiki/Governor_(device)

At the end of this month we here in the UK can enjoy the joke of the year once again when we alter the clocks and call it "British Summer Time"

https://inews.co.uk/light-relief/offbeat/clocks-go-forward-change-2019-when-date-why-bst-british-summer-time/

Brilliant sunshine now.

Kind regards, Colin.
 

Colin

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Hi,

I wandered into the workshop this afternoon in spite of the dire weather and enjoyed a session with this mower; A lot of time was spent cleaning removing debris and old dirty oil etc; I used brake cleaner; WD40 and paraffin; it's now looking a lot better; I hadn't realized how much debris had accumulated until I removed the covers.

What a big surprise though when the carb was removed to find so much debris in the carb intake and also in the intake port. The exhaust valve definitely needs grinding in but I'll grind both valves in as a matter of course; I'm delighted however at the overall excellent condition of this mower and once its reassembled it should give many more years trouble free service.

Kind regards, Colin.

50676


Not bad at all for 32 years old.

50677


What a dirty job it's been to clean the engine but well worth it.

50678


An incredible amount of debris in the carb intake; it's going to love me once its put back together looking like new.

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Exhaust valve on left definitely needing decoking and grinding in.


50680


Both ports will be decoked too.

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The valve chest with valves removed; more TLC needed. Amazingly the mower was running very well but will be even better once it's rebuilt.
 

Colin

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Hi,

Colin, am I correct in thinking that is a Tecumseh engine?
Thanks for asking Flatlander. :)

The details on the engine state Ecnamotors although given its age it could actually be Tecnamotor the "T" now missing so it could well be a Tecumseh ?

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I'll double check next time I'm in the workshop; I think it was made in Italy?

I've been looking for Ecnamotor getting nowhere and with you now asking I've just had a quick browse on the web looking for Tecnamotor and yes you are bang on Flatlander as seen here;

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Kind regards, Colin.
 
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Tecumseh went out of business a good few years ago, so spares can be difficult to get hold of. A while ago, I did have a contact that had quite a few, but dont know if he still has any.
 

Colin

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Hi,

Thanks Flatlander. No problem at the moment regarding spares and the engine appears to be in good condition so hopefully once reassembled it's going to last quite a while. The air filter can be washed clean and the head gasket is still in good order.

I've been browsing the web and found this which is just what I wanted;

https://www.scribd.com/doc/26830208/Tecumseh-Service-Manual

Kind regards, Colin.
 
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I'm a little bit surprised that you wrote that there were no points on the engine. The operation is similar to the old Villiers Flywheel Mag., which you should remember.
 

Colin

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Hi,

Thanks Flatlander. During my biking years I was a four stroke guy having little to do with small bikes with Villiers engines fitted so I'm not up to speed with the flywheel type mags. My big bikes had Lucas Magdynos;

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These had points and all the old cars I repaired whilst owning my own garage business also had points in their distributor; I'm unfamiliar with the type of ignition on this mower so I'm on a steep learning curve; however I still haven't noticed any points and the ignition is "solid state" so I'll look further into this because the ignition is self contained; I'm interested in how the timing is achieved; as I said in a previous post I've never worked on one of these mower engines.

I've been busy out of the workshop for most of today; I had a brief session this morning decoking the valves and ports; another short session late this afternoon I've ground in the valves and reinstalled them also the cylinder head is back on; tomorrow unless I'm wanted elsewhere I hope to make more progress; there's still a lot of cleaning to do especially the carb.

Kind regards, Colin

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Sorry about picture quality but it's been a black hole again and I'm trying to take pictures with gloves on my hands; everything seems to take forever. Here I've ground the valves in as seen by the clean continuous rings on the ports.

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Only basic tools are required for valve grinding.

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I chucked the valves in the Graduate lathe to clean them of carbon deposits.

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The ports and valve chamber cleaned using brake cleaner; the cylinder bore was wiped clean and oiled also the valve stems were well oiled; everything turns by hand with the valves opening and closing as they should; the cylinder head is back on; I reused the old but good gasket being unsure if I could still buy a new head gasket. I plan to resume work on the mower tomorrow but being retired I don't have as much time to play around as I would like.
 

Colin

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Hi,

You are definitely correct Flatlander; there's even a big label on the engine cover stating Tecumseh; I've just noticed it having now got the mower back together and have just fired it up.

I'm a little bit surprised that you wrote that there were no points on the engine. The operation is similar to the old Villiers Flywheel Mag., which you should remember.
No points but as I guessed I'm pretty sure the offset key is the method of timing the spark?

32 year-old mower?
Blimey!

I'm more than twice that!.
Nice one Sean; I too am more than twice that.

The mower sure sounds noisy inside the workshop when fired up so it was just a case of starting it and letting it settle for a minute before stopping it due to exhaust fumes. Once I get it out into the open I can make adjustments but it's a good runner and now ready for the next 32 years trouble free service. :D

The spark plug is a RJ17LM and the magneto coil gives a reading of 6K Ohms. The flywheel magnets are excellent; holding a screwdriver gently between finger and thumb at the handle end allowing the blade to hang down the blade is pulled towards the magnet from 3/4" away so all is well.

The decoke was straight forward the worst part was in cleaning all the debris off. It's now ready once again for the cutting season.

Kind regards, Colin.

50718


The "offset" key; I'm pretty sure to put this in wrong way around will upset the ignition timing; I could be wrong but I've not come across this previously? Has anyone knowledge of these key's in relation to ignition timing?

50719
50720


I should have gone to Specsavers Flatlander but I had this cover off before you kindly asked if it was a Tecumseh engine. o_O
 

Colin

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Hi,

How come I can browse YouTube and the web for hours looking for information but only finding the information I want after I've actually done the job; here we are with such a YouTube video; having only just completed the mower decoke I was correct regarding the key being in relation to the ignition timing; I wondered how the ignition timing was adjusted so now I know also please note the flywheel puller; my flywheel had three untapped holes so as shown previously I used these three holes tapping them at 6mm then made a crude but very effective puller; these jobs though keep my head working which can't be bad. :)

Kind regards, Colin.

 
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Colin, that sticker also tells me some other things. Its a solid state magneto. Somewhere in it there are transistors and equally horrid things! :D Also, as it was built in Italy, you'll probably be able to get spares (if ever needed) for it in Poland of all places. If you have any neighbours from that country, it may be worth getting to know them....:)
 

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