Hi Niels, I think that is a Poulan leaf blower engine. The 012487 and 012481 part numbers on the crankcase and cylinder are Poulan numbers.

Just a note on the quality of Poulan engines – these engines are not a model of best practices in small engine design. They are low cost throwaway consumer grade engines. They last a few hours doing a great job and then they are worn out, either in the bore, or the connecting rod ends have huge wear.

Taken many apart over the years, only to find the above problems. But since you can get a replacement chainsaw or leaf blower with a new engine from many hardware stores here for about $150.00, no one fixes them, and parts are hard to find anyway.

Hi Niels – here's a parts diagram for the engine I think it is.

Dave – many saws and leafblowers only get used a few hours a year, so it can take many years to get to the end of a 50 hour engine lifespan. For many consumers this is just fine, and was what the machine was intended for. I'd be happy with a cheap saw or blower that lasted 14 years!

Hi Niels, The diagram was from a small engine parts place in the US called Jack's small engines, as I recall. I was looking into fixing a leaf blower of this kind in the summer, and looked it up.

Could be that some or all of the parts for these engines came from Taiwan or PRC to Poulan and Homelite etc. originally.

I could not see anything at the imgur link you sent, just FYI.

Good luck with your project.

How is that design going to be better than a Briggs and Stratton type four-stroke? What's the advantage? And will the inherent overheating and warping of the side-valve combustion chamber and exhaust valve/seat be exacerbated in an engine that fires every single stroke, with no "cool down" intake stroke in between? (Us old Harley-Davidson side valve performance tinkerers think about such things!)

1 per cent oil mix in a two-stroke bottom end and cylinder? That sounds pretty radical. Is it possible with synthetic oils?

MZ had engines reliably running at 100:1 on synthetic oils before they suffered from German reunification. They were looking for ways to reduce emissions as regulations tightened, but didn't formally adopt the leaner pre-mix as it was felt that accurately administering the smaller quantities of oil was likely to be problematic in the real world. The adoption of Mikuni dosing pumps on export bikes reduced emissions compared to premix bikes – the effective ratio on the pumps was around 32:1 at full throttle, but leaned off to around 70:1 a low speeds/ throttle openings, compared to 50:1 on premix versions. My wife always hangs back if she is following me on a premix MZ after prolonged town running, as the over-lubrication puddles in the crankcase & clears (smokily – for a couple of hundred yards) when accelerating when the restrictions clear. No visible smoke at higher speeds with modern oils, though.

Nigel B (two stroke fan since 1976)

Come a long way since I first threw a leg over a BSA Bantam two-stroker.

BSA Bantams are mirror image MZs – with the quality engineered out !

The second most produced motorcycle engine of all time, the DKW RT125. Given as war reparations to BSA (who didn't really want it !) & Harley Davidson & widely copied by many others (including the first Yamahas). The DKW factory was dismantled lock, stock & barrel & taken to the USSR as part of reparations, where the RT125s designer – Hermann Weber – died in a Russian labour camp after the war.

Nigel B

My brother used to have an MZ. Every other biker he met said 'does the job'.

My first pillion ride was on an MZ (running on paraffin) with a spare rear wheel somehow perched between me and 'Spam' who was steering the thing…

Neil.

I prefer the TS250s to the ETZs (250 or 251) – less peaky power delivery & more economical, but the disadvantages of 6v electrics and drum brakes. I had one of the last DDR-era produced ETZ251s, (in a fetching shade of beige) rescued from my brother-in-law, who had bought it new but then lost interest & left it festering in a damp garage. Build quality had rather gone down hill by the end of the DDR, though. Didn't keep it long, though did do a round trip to the Ace Cafe for the first "Red October" East European bike day on it – near 400 miles in the day & a long way to go for an expensive, indifferent burger !

My late friend Mark Dicker was Classics Officer for the MZ Riders Club & he reckoned that the ETZs would disappear before the earlier bikes due to frame corrosion – the area of the frame that the footrest bar bolts to rots off. The frame is used as part of the inlet air system & heavier dust accumulates at the bottom of the frame – this gets & stays damp, causing the frame to corrode from inside. The TSs used a similar intake system, but the tubular frames were heavier gauge than the sheet steel box section on the ETZs, so they last better + the tube is blanked off with an easily removed plastic plug that enables the dust to be cleaned out. The ETZs have (IIRC – it has been a while) a welded on closure with a small, easily blocked, drain hole. May be worth checking this area on your tidy bike ?

I have 6 in various states of assembly & function – 3 off TS250/1, and ES250/2, an ES150/1 and an ETS250 G5 ISDT Replica , of which only the oldest TS250/1 (which I have owned for 29 years) is running. So many projects – so little time !

Nigel B

Not all two strokes from the 60’s era had to be smoke generators, I had an Ariel Leader 250 two stroke in that era which I ran on Filtrate colloidal graphite as the lubicrant in the fuel, I can’t remember the exact ratio of lubricant to fuel but seem to remember it was 100/1, the exhaust was clean with only a trace of blue smoke. Ah those were the days.

Dave W