[non_car] Minsk 123Cc

[fairway1 5]

I recently purchased this motorbike off eBay which I'm in the process restoring along with my 309 + 205.

 

Its a 123cc 2 stroke Minsk. They are a Russian bike (also sold in the UK under the names Neval or Regent) with an eye watering top speed of around 60mph. 8-|

 

They wern't particularly popular when they where on sale in the UK from the mid '70s to the late '80s, mainly because they where so far behind the times compared to bikes by Honda etc which where also on sale at the time and the fact they where so basic and the Communist build quality could have been better. The exhaust smoke from these bikes is comparable to that of Del boys 3 wheel van. They where and still are extremely popular in Vietnam, Afganistan, Thailand, Iran, Russia and far Eastern Europe. They where really made for off road use, or dirt track use. They where never made for long distance or high speed in mind. They are however very comfortable and quite small.

 

If I'm honest, those downfalls are something I've really started to like about the bike, everything is so easy to work on. You could remove the engine, strip it & rebuild it in under an hour - and I'm not a qualified mechanic! To this day parts are easy to get and are cheap (can't get parts in the UK anymore though, but parts can be easily sourced online from Europe and shipping isn't too expensive, i.e a complete new engine inc postage would be around £120).

 

My bike was first registered by a chap in Healing, Grimsby, North Lincolnshire, in June 1987.

 

It was used untill June 1990 having covered 2,500 miles, when he decided to remove the cylinder head to de-coke it. For some strange and unclear reason, this never got done, and the bike sat in his garage, untouched, under a tarpaulin sheet untill 2011.

 

The owner, now retired for some years with failing eye sight decided to clear his garage out with the help of his neighbour, a chap called John.

 

He found the old Minsk exactly where he left it 21 years ago & was going to let the next passing gypo or rag & bone man take it away. John stepped in & said the bike is far too good to scrap like that & offered to sell it on eBay for him. After having it explained to him exactly what eBay was, the elderly owner agreed. I was the second bidder and won.

 

The bike is basically all there, however it's absolutely filthy and I was told it had NEVER been washed! The cylinder head was in bits in that hideous white back box which I promptly removed. I now use it as a parts bin in my garage.

 

 

 

 

 

The bike even came with original old style log book, both tax discs still in the holder from '88 and '89, original bill of sale and written recept and original owners handbook! The tyre hand pump under the seat had never been used as had the original tool kit supplied with the bike in a leather holder in one of the side storage tins.

 

 

Clean up started.......

 

 

Edited January 12, 2012 by fairway1

[fairway1 5]

 

 

 

 

 

 

 

 

[fairway1 5]

Hi all,

 

Been a good while since I updated this thread, thats pretty much that untill recently, progress has been pretty much nil. I've been working abroad for a while & my 205 has been taking priority over the poor bike but I've pulled my finger out & been cracking on with it lately

 

 

 

 

Back in November '11 I stripped the engine down (without removing it from the frame) and fitted a new piston (old one had a nasty crack up one side), new rings & new gaskets. Unfortunately, at the final stage of reassembly; screwing the cylinder head down on top of the cylinder, one of the four threaded mounting posts the head is screwed down with snapped (see pic, left bolt).

 

[fairway1 5]

I wasn't too worried because I knew I'd soon manage to source a replacement, or even have a new one made. It was around then I had an enormous stroke of luck in coming across a used Minsk engine on eBay. It was complete and came with carburettor attached (the slightly later, more reliable carb they used) and some spare gear selector rods and spare clutch + throttle cables. I spoke to the seller online & he knew very little about the engine (he had to e-mail pics to his local bike shop just to identify it), its history or it it was even a runner, only that it had likely once been used on a racing go-cart. I was the only person to bid and inc postage by courier the lot came to just over £17! I was very pleased with that purchase because theres been a fair few bits I've needed to rob off it since

 

 

 

From late Nov '11 to May this year, progress on my bike had been pretty much nil due to working away a lot and work to the 205 taking priority in my free time, but being home from work for 2 weeks off I knew I needed to pull my finger out & get cracking with it. I completely removed the engine from the bike (which took all of 10min) so I could clean the frame & those hard to reach places and to work on the engine at home, which was where the spare engine was.

 

 

 

 

 

 

(Spare eBay engine on the left)

 

I removed the cylinder head (again) and replaced the snapped head bolt with one from the spare engine. After replacing the head I gave the engine casing a good clean with white spirit.

I also removed the fuel tank from the bike as there was a lot of crusty, dried oil stuck to the bottom of the tank. I flushed it out as best I could first with white spirit and then with parafin.

I then went on to clean the fuel tap. I read in the manual that there was a very fine metal gauze filter inside which are easily clogged up. Mine was no acception, but along with various bits of dried oil & black gunk there where some gold paint shavings - I'm guessing overspray that managed to get inside the tank from when they painted it during manufacture or perhaps paint chipped off the filler neck by metal fuel pump nozzles.

The fact the paint chips where still in there tells me this filter has never been off and cleaned and I'm willing to bet this crap in the fuel tap started to affect the bikes performance and probably lead to the previous owner to take it off the road in 1990, thinking the engine needed de-coking (when it actually wasn't that bad & wasn't due to be done.)

[fairway1 5]

I removed the base of the carb & flushed it out with parafin. It absolutely f***ing stunk when I first opened it up, the petrol had dried over the years and it was full of oil that had gone as thick as treacle and there was a sort of oil 'skin' growing up the sides (it reminded me of the 'skin' you'd get on a pot of gravy thats been left to cool and not stirred). I suppose I was too excited about getting the bike back together & getting it running because I perhaps wasn't as through as I should have been and didn't clean it or strip it to the extent I should have, which I found out later (will upload pics later)

The rubber fuel feed pipe which runs from the fuel tank tap to the carb was cracked & weeping fuel so it was replaced with a new pipe and a pair of new jubilee clips for about £3, courtesy of Pirtek in Hull. (will upload pics later)

Finally, I drained the gearbox oil (only 500ml capacity), replaced the sump, filled & swilled with neat petrol (as recommended by the owners handbook), drained again, allowed to dry then filled with some fresh gear oil. The owners manual was very vague about exactly what grade of gear oil should be used, only stating, '....replace gearbox sump and fill with appropriate oil.' so I just used the first can of car manual transmission fluid I came across & hoped for the best. As the design of this bike, especially the mechanical side of things had hardly changed from the 1950s, I expect if I was to fill the gearbox with a tin of Tate & Lyle it would probably wouldn't harm it

 

Anyway, with the engine etc refitted on the bike and a few drops of petrol down the sparkplug hole for good measure I gave it a kick start. On the 3rd attempt it fired up. I was well impressed because I've never removed / stripped / rebuilt ANY engine before and it was great to hear it burst into life after 21 years layed up in a garage under a tarpaulin sheet

Unfortunately the bike conked out about 40 seconds later. Cutting an allready long winded & boring story shory, the bike would refuse to start without either a few drops of pertol down the spark plug hole or a squirt of carb & choke cleaner in the air intake. When it did start after doing either of these things it would quite happily rev and tick over for about 40secs before dying again.

 

This morning (17/06/12) I removed the carb off the spare engine & fitted it onto my bike. Hey presto it fired up on the first attempt, tick over spot on and revs exactly as it should do and no conking out or any hesitation. Fantastic

 

 

 

 

Its a 2 wheeled environmental disaster!!

 

 

Carb from spare engine now on the bike

Edited June 18, 2012 by fairway1

[fairway1 5]

I still plan on throughly stripping the old carb down and cleaning it out meticulously this time and fitting it back on the bike as I prefer things to be original where possible, and theres still lots of jobs to do i.e the brakes need adjusting & maybe new shoes fitting, rear tyre has a slow puncture, chain needs tightening etc but my next main jobs are;

1) I've misplaced a gasket or a large metal washer or something that should go in where the exhaust screws into the cylinder block to make it airtight. Without the gasket it spits out a very small, fine mist of unburned oil and smoke.

 

 

2) I have no idea what this black stuff is thats leaking from the bike and I can't tell where its coming from. It's either just unburned oil thats dribbling out of where the exhaust screws into the cylinder block where that gasket is missing (see above), or its coming from the gearbox, which I doubt because I put fresh oil in there and fresh oil does not look like that.

 

 

3) Disappointingly, none of the electrics seem to work apart from the horn (intermittently). Probably just a loose connection or plug somewhere & nothing serious.

[fairway1 5]

[muddatrucker 125]

Cool, I'd have one of these! paint it olive green with white stars on! did Top Gear use one of these in one of their specials?

[fairway1 5]

Cool, I'd have one of these! paint it olive green with white stars on! did Top Gear use one of these in one of their specials?

 

Yes, Richard Hammond rode one on the Vietnam Special. If I remember correctly his Minsk was the most reliable of the three bikes..........?