Minsk 125. CCCP era 2-stroke commuter of the people.

[A100man]

Not tempted to try a nice Jap built Mikuni?
____________________
Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[stinkwheel]

Well that was all drama free. Both carbs are in very good condition, no varnish or anything. just a bit stiff from lack of use. They could probably have been bolted on and just worked. Stripped them both anyway, blew through all the jets and passageways and gave everything a good clean. Put anti-seize on the screw threads and gave them a wipe of ACF50.

The older one:

https://lh3.googleusercontent.com/pw/ADCreHcnUK6QmIwZhsOE5e8q536-PYEk4ebpZ9Tpb2RnVjXzRhWbR8TmTjlryVWnQlHRrmQXKiIkeZFTjZybLyba2mWSokRtq-7sH3jmLNFNd6vktEg1Tx3EXfVPz8xMZI44uXeML8X0fYZ6_DdsqwNmbnDp=w489-h870-s-no

And the newer one:

https://lh3.googleusercontent.com/pw/ADCreHfKG1DRnGnZJyFYG5jSqJPXPMO-OEWdlJ5-e7-rbNFir14Uhw3cKMNJqL-EqrnRPmRNG8KLRJs455hUlaUpK-VANesRIV9j5LkJZaC11L6urh7BXzhbL5NDYgQAYwM_fwecPMXBPwBhFWVNaPJqvoMH=w489-h870-s-no

Classic bit of soviet engineering, no wasted materials, you don't need the centre of the slide so they are just bent brass sheet.
https://lh3.googleusercontent.com/pw/ADCreHfZYN3aum36P_eoqGZX8lRuYx09tIDK7XIPJUn0Sg9XzPBkI2EXSGl5h5I-QZ9eb4tZwPkGV79Jch5FY8fgwxTZYkGU27kOfKcc6mr3i_pV00D_p_NirlSyWj_Ta1rfEeqj5-5VLdms3J_Tapx3bXWi=w1547-h870-s-no

Holy mother of god though, the concentric one weighs a ton. They did not fuck about with unecessary machining after they cast this fucker. It weighs in at 904g which will probably put it over a kilo when full of fuel (the other one is 604g). You could murder someone with it. It's 150g heavier than the huge TM32 on my enfield. I actually checked it with a magnet to see if it was made of steel.

https://lh3.googleusercontent.com/pw/ADCreHdNgAF883DwolqKfgCnMByPoKZlEFsjZcnr03r6lqRFNlmEBCt83y4c3RSAdxzGuWYqYp544DsdAWgTyUYdJo7pnCmfEnW76JbAy4tVYT5-MHCCDhRPkyEXjHtJzOmw4Po5TKzIAXAjM0iHQiZYWrME=w1547-h870-s-no

On the pros and cons side of the two, the concentric is a lot more spohisticated. It's got a choke and it has a needle jet. Both have ticklers . I'll still probably fit the older one though.

Seperated and unmasked the engine casings before the paint went fully hard. Pleased with how these came out.

https://lh3.googleusercontent.com/pw/ADCreHd179nZAnd1yLI_cGzksR8xoD-dLfrzO1EBKi-he0mzgR1FBKpGOAtFh9wjVYu04-sQAby1sfMoIezlb9PyUreZGXHbUHMbWofQ4AmgVm6tCzHxb2bSydYHglHFZpY3CMvQ_S2d0A410Pfl5KpCAtQK=w1547-h870-s-no
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

[struan80]

What will you do with it when it's complete?

[stinkwheel]

[struan80]

Very cool mate.

[A100man]

[stinkwheel]

The seat was a nasty mess, bodged home fitted cover. Which in fairness is only marginally worse than the original seat covers. Seat base is salvegable though. A bit of tinworm and a few splits but mostly solid. I'll rivet patches across the splits and repaint it. I don't think my welding is up to stuff this thin. Might have a bash at brazing the splits if I'm feeling keen.

https://lh3.googleusercontent.com/pw/ADCreHdi4EPQEC91D2UC_Kbj6XD2JT1zNGTMioBHkO5G-kDgms32pJ6AYwmsiveH7M1logP8jJwJK68z62lnfvV3SgXHby_M5H9BdYvtaUtAMsbR09IdvWtVKOx0BHPaz-ISbdDJ1Pizpq1dB14i3Q7cdLyj=w1547-h870-s-no

https://lh3.googleusercontent.com/pw/ADCreHeMCh76O3BdzqpyZy8LvfqTSu1Q0mOXEq7e2Ep3ssCnD46p9GpxFqnzbtwluJpz3-amVKzBdYHkD3bH6DZFKxZODvtbMj_F5pFd7ZOcdrE8OaEFih2Qj7THzWLtnXUfxB5U8QMK6hv00vIPccmPk1Na=w1547-h870-s-no

Really nice condition seat foam though.currently drying out because it was pretty soggy.

https://lh3.googleusercontent.com/pw/ADCreHcSH3SAWMzyhJ39oTG5f_ddJHp5f_yRZZJxuy9v5bjoKR7_8Gm8RoT0YKjUzd1TD4O74nTfJYDGOlfbA4jTRJ8IU3MsfGtuC1YuZVCp_jkL-1ypPp6EK011nYb9PVQC2sqLHv7Y1FTU1LkCS3AppMwr=w1547-h870-s-no

Going to replace this skanky vinyl with some more modern stretchy stuff. It rivets onto the rim of the base so I'll use some nice stainless flange rivets. I think I'll need to put some sticky foam strip over the edge of the rim (or even gaffa tape) so it doesn't rip through the cover.

https://lh3.googleusercontent.com/pw/ADCreHc5V46taBkTukQsAzAXgXYT0lLo9uSK-Bfo4zg4K9qeEcK6Hl7Jltewswnvkf3nWZZ07rnvaqgraymZrwyKeV-7VUmVN_IpuLtbPWeBHL6_LeQDRpgrFhSHH__jdkWCFTIajp86zDH3F0SdBGnQa0QC=w1547-h870-s-no

Stripped the hubs and ordered new bearings. There's some cleaning up to do here but I've seen worse tinwork. I'll start with a pressure wash and work up from there. Maybe some rust killer inside the rim.
https://lh3.googleusercontent.com/pw/ADCreHcz6OBMrpZovLLgyUp3kXXeSlXmvWNSyLWBkH1LRjhENmtBEj84DIkua1FIrO2bKqYWpHhkzyrXixn_QnwuvhWpXXPT6UG2J7H8pFRmfnQA8uWz93tQMHw4iRhW_LCSVdVKvvnWkLDTx3cw0zhYUuMr=w1547-h870-s-no

Also removed the old tyres (no mean feat). One had a 1989 date code on.
https://lh3.googleusercontent.com/pw/ADCreHe_KNueE7qV05xMUhHeIy4zGSkYKaUg6RrDw6EvbdcNxE2QIXF2dZ1Zbq6J8-663sM9HHL8gIv3obM6uHupBmLUJOK9FjmKQprICdbaq3_fNHARCRcb3jUmMHcJJE_ekA7DF0EKjaHll_Nqt161SBD9=w1547-h870-s-no

Ordered some cheap and cheerful catspaw tread trail tyres for it.

Also got the tank out (which was for some reason wrapped in cling film). The paint will need re-doing.
https://lh3.googleusercontent.com/pw/ADCreHeESm6khMKNbsamRey4fnD6aUn-wfYO22Uc6SYGDyLFUc56hjPp7ngQRWl7CRR63nnzKu36TWIQrvkBWR_9-72k1dGUevTCcHi3OwBRmyVGjeyGlYaT7QZ8Zq9O4FIqGjqUeWvXW4-yiDRQjmp8VN8p=w1547-h870-s-no

There are a few dings in the tank. The biggest one is behind the seat so It can be ignored. The others are small enough I think they'll fil quite easily.

Fuel tap actually works but is well grotty so I'll leave it to soak in paraffin.
https://lh3.googleusercontent.com/pw/ADCreHfcctLBjkiTQnBX7iKi2ghMEUu1lJYoDZbagWfGmFTtf9zOHq26XXXYzqCcJ7gh1b2HJlPTOS-z4_kwUkJlJ4f9yt4GuW7Jqi614If33FhkqpJe1Q5-cUrsUipeEab1yoSRLMOa4j5Ycju7lSUnd-dG=w1547-h870-s-no

I'm going to try to make a graphic so I can get a tank badge made up. Anyone know the font? (I'll put a post in the general section) it looks ariel-ish.
https://lh3.googleusercontent.com/pw/ADCreHd_9DPu1zkEUX-L5Sps_UdR-_xiUIUx7INV10czYgon3bVxY3toBXHzgRJ_ojMJZ-Lx2CD9S2ozguDkrSmUakhqG3n8TyJo4o03mnyFyqGT2KYfnlrmZvML4RXTwtkmeMugHkvwUH0eBIk6ESkbFJPq=w1547-h870-s-no
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[virus]

that factory trials looks ace. deffo a win for old school side bowl carb too if the other one is that hefty. performance is adding lightness and all that.

[Easy-X]

Classic example of the downside of steel rims and tubed tyres. Damp gets in and then trapped behind two layers of rubber - tube & rim tape

On the DT, after treating the rust with the typical rust converter, I painted the valley of the rim with anti-corrosion enamel paint to try and head-off the same problem in the future.
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[WD Forte]

I doubt the exact font will be that easy to find so briefly fecked about with the image to see about
cleaning it up to create a template for vinyl or decal.
https://imgur.com/85adFJq.jpg
then I looked online to see if there were any preexisting ones to save time
I didnt see any Motobeno ones so far but a Minsk
one is available
I kinda like them as it says 'muck'

https://mxg.one/shop/minsk-stickers-set/

https://mxg.one/wp-content/uploads/2020/06/28.005-MINSK-1.jpg



I see they'll also make them to your own design so if the
motobeno image was cleaned up and distortion/curvature removed you could probably get those made
My own preference would be to go for the commie bastard look
____________________
bikers smell of wee

[stinkwheel]

It's going to be the Motobeno logo because a Motobeno with that exact dark blue tank with gold lettering was my first motorbike and the one I passed my test on.

I will be getting Як ты смееш! across the bottom of the numberplate which is Belarussian for "How dare you!". Given it runs on 25:1 premix.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Rob Fzs]

Seat base on my H100 was alot worse than that, managed to get away with spot welding some fresh sheet metal on the original with arc welder turned well down and then spot welding some upholstery back tacking strips on, never thought it could be done but came out well in the end
____________________
'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30> Yamaha RD350 YPVS F2 > Kawasaki ZZR 600 D1 > Yamaha TZR 250 2MA >Suzuki TL1000R > Yamaha TDR250 > Honda 929 blade > Suzuki SV1000 > Honda H100
Mod 2 Passed 09/06/2011

[stinkwheel]

[blurredman]

[Robby]

Two questions/ideas.

1. Does your workshop oven get hot enough for any kind of silver soldering with lots of flux? I really like the idea of putting parts together with some flux and brazing compound, putting them in the oven, and taking out a piece where the braze has been able to nicely wick into the spaces.

2. I assume this will end up being a bit of a mule. Any chance of a home-made expansion chamber?

[stinkwheel]

I considered silver solder. You can even just pre-assemble them then heat them with the MAPP torch. I've done it before by hammering the solder flat, coating in flux then wiring the joint together and heating away from the joint so the heat flows into it but it starts getting expensive. I don't think the oven would get hot enough even if the seat base would fit in.

Regarding a spanny, I'll probably fit the original exhaust at least initially. I had an idea that if I want a spanny, I'd fit an MZ TS125 exhaust. They are cheap and available and the engine dimensions are almost identical so the pressure waves should work. It would be in keeping with the origins of the bike as well as being the OG spanny designed by Walter Kaaden himself.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

I hate sheet metal work.

Here's one of the cracked areas. It's the hole the rubber goes in that supports the seat against the frame. The more I look at it, the more a square hole seems like an inhearantly stupid idea. You can literally see the cracks propogating from the stress-riser corners. I think I'll make these round and fit some blind grommets in them. It will have been harder to make too.

https://lh3.googleusercontent.com/pw/ADCreHeBu9ko1zDep5yuqF08iBaI33rfrOccW-JLmeCwpu8zlXCJnfxm6kl3LcZHvvL9iRIK2V0SanI2hhzs_mghvbDnJCQLd_aOrGRmyennnxTaX7rjcx8w5v5pUP3QTo9P3PzkCTSUjPa6XfUsbSeMo8Rj=w1547-h870-s-no

Stop holes drilled (because round holes don't propogate cracks as easily)

https://lh3.googleusercontent.com/pw/ADCreHfuBYqGIGm0gEYM-E71D3chm6MAjKCObe-PwA54QFpbm-qeA76AulBSZG37iN4ot2ofPUrcs_wBsKh29zIocjfMAgz1SKjadGky8rDGOIx8bPUILVRzKBx6IlFsYlRbKjYhGSgX3ZgsiLdFhbNKvQNY=w1547-h870-s-no

Brazed. Took all the heat my MAPP torch could muster and still went in a bit cold but it seems solid.

https://lh3.googleusercontent.com/pw/ADCreHcwHvL0YUcbYwPFQSpk93fB5Rfnkc7R1F2Ncehrnsr1o5qUUBfokmx6sxwq8VNRpckdO35DQwysanm1f9BhxuUm02q4KXTrMDMEF6JxVGHs-9xGSGBd-wYpKUUuEEjP-1oFOnjHcP8OudWM6FQyBEgW=w1547-h870-s-no

Ground out. There's still a bit of a stop hole showing but the crack is bunged up, there's a time to persist and risk making it worse and a time to call it good enough.

https://lh3.googleusercontent.com/pw/ADCreHeAZqOO7XNV1M2J1C1AR1rNWu4xzFMiQDlfKvaPTAFBdrYO6de6dDS_eZT_C0vVX7FA7yn89Qa8zc1g0hFBs5EkqqDa2HylZAPwY2e4V0-qyd55fCngREOP9P9omHBorFEO2qF7cCZtwBcb8zhy-1q2=w1547-h870-s-no

Also had a go with the stick welder. This was hard. you had to make sort of a drip of weld then let it cool then run another drip over the top of it and work up like that. That said, it's 1.5mm sheet steel and you shouldn't even try to stick weld that. I'd have been better with thinner electrodes but I have what I have just now.

https://lh3.googleusercontent.com/pw/ADCreHf3bOaZfsVBzxYr1j2n4FA5Z-eCTR5Tu633hK7KjoX7DoK4dLRTBICfxnUtDmlYaimEDO-MfQDhxtaUODS3s7ZsTW_9xv07a5LWFSnBoGiYs3MST3y41flhOu75x6eJ10uK9S56ZaGRoadRKMwZRG7m=w1547-h870-s-no

Looks terrible but there's no more flex there so mission accomplished I think.

https://lh3.googleusercontent.com/pw/ADCreHevymHdi1SKFjbpzmGZ3O0fDgQlaiHcNtFB5gWzBeTzo1-eVNsWtS5l6pQBCDFXuhX6S7U8hJC8FOTKuQEVV87MB9v_33dYXcGsV6S89UvkMI9gq504PrLjFgVPZwZCesag-em4PwYdCGV4avc9o6Bg=w1547-h870-s-no

That hole is supposed to be there, it split through a rivet hole. I won't say I didn't make more holes though.
https://lh3.googleusercontent.com/pw/ADCreHfcaw0tn8IRDCUJYXK-65nxTWowNwpSsW1fSVE7TP-0zyHNWY-CksMCcWBV6W9UnG5Wpghlb2UOBZcv1Obv0KpQgPuO6TiUGFuaG8jgf5WoQBC5ehucCTyMqL5eksrVR3bc54YAFJghrQKB5YFOKhAt=w1547-h870-s-no

I have asked Santa for a scratch TIG nozzle for my welder and some bronze filler rod. That would be ideal for this kind of thing.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[A100man]

[stinkwheel]

Did the whole seat base with phosphopric acid to stabilise any rust.
https://lh3.googleusercontent.com/pw/ADCreHex6LKLk8tB978GYmZ837cTW6dYZnrA1_UU1LqoxtjdxGlv_f52RIpiHyxgioKPWvtiJYxltSU6RJ-MFOOdpd1tzcmGgNpDq3rNSrw4MkzlXGUFUWbnkemusrdcVQ897OYHE2OQUkJusqHd44w23623=w1547-h870-s-no

Made the square holes round with a step-drill.
https://lh3.googleusercontent.com/pw/ADCreHcNz9QfsZaDC9YxphsSIsIB8xtN0XMbtpE9Dn7jloWFUIA6JCAo6Xphi7CMNbJW9ND5ZELwOu1cE2jY4FCY9_ZTnSqGpXrGwbuMrrhZyh5eh0obZt9DKJTv27SlKZtdv8apqM0ziP_63jb6t_52V8d2=w1547-h870-s-no

A coat of zinc based primer.
https://lh3.googleusercontent.com/pw/ADCreHdqre1dfs9rtyA3pmfAXcgbdFKKvKUl5CllqEniLRmZKpV-HsWack4-9qG7t9Zcxu3w5OQFHrsm41o8zWiHKo1kCSdzQhl3qHmXx5ExtFvArdhblr6oCYRudmtoJMPNgfqV8edp2M66_UqWuBA4Z4M3=w1547-h870-s-no

I'll order some blind grommets/chair feet for the rubbers and some edging strip to go round the sharp edge of the sheet metal so it doesn't tear the vinyl.

Also been cleaning wheels, which is tedious and messy.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Easy-X]

I think the phrase is "best of a bad job" Square holes though, asking for trouble!
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[A100man]

[stinkwheel]

[Robby]

When I did my 250 I took the wheels apart to make cleaning easier. I also re-painted the hubs and (home) zinc plated the spokes while I had them apart.

If I was doing it again, I would measure the runout before taking them apart to find out what "good enough" is. As it was, getting them true enough to the workshop manual spec didn't take too long. The difficult bit was making myself stop and not chase perfection.

[stinkwheel]

Aye, wheel building is an exercise in knowing when to stop.

I want to get the last few bearings and seals ordered because lack of them will hold up production.

There's one in the rear hub/sprocket carrier. A bit oddball because it's a QD rear wheel and the chain is enclosed.

https://lh3.googleusercontent.com/pw/ADCreHfNxG23W-GzBM3Yp7KtbpzJBCPRCN_UrWaNsR_teg_oAM-Ho7juZkv2G56KNpIn_AhOeB7W0rgo2tZwT1AA-U9wsl02lhVg0QarXVuBF9MVWWDn_GlxIz2Ty7OkhQubCRNC_P7yMFaGH7HGyu9KUSuS=w1547-h870-s-no

Three of these four bolts sheared off on my old one so they'll be being replaced.

https://lh3.googleusercontent.com/pw/ADCreHdEWkHl7U6di1OlCBLoMP_yRo_d47Q6-xDrTbqbDD15SmTYJKysq_AjYRevWg0P7fCCb_jklhE4TZ1PYb-JXzL0VuWhj8ARNB-xpHA9iDbl9fl1UKvvV5qTOpFOC3SabirodK-VM0LRr51X4jVfUUot=w1547-h870-s-no

Relatively straighforwards. The metal shielded bearing had a standard 6000 series part number on it but it's incorrect. Came up as £150 each but then I looked at the size and the part number they have is 100mm OD so I just measured them. They have a 6 where there should be a 4.

https://lh3.googleusercontent.com/pw/ADCreHc2iDjaCrgCFlcsxI7by3c4ppWhXq4Kkr7vdeeSx9on6Ujoo9dxYkHVKnwANOzHlK3hKdyiE01LwSNyGpETBoR7a0X2LClCqBOwaIBetw6Gnn6JDTOldSnJLRfss_5EVvhgBvMczKIBSyLxUnI7Rbvm=w1547-h870-s-no

Also want fork seals. The stanchions aren't chromed, the sliders are, go figure? Makes it easy to give them a buff up though, no chance of sharp-edged pitting to tear seals.
https://lh3.googleusercontent.com/pw/ADCreHdKg9SouJGaCOaFzGc94rgkEi3OWFmDirUI811Vxp6-ZhzvGukktdMu_n8EWIp-gNX-UZC9b4brHuUhT4sIvx0ZQOVo2uu66Ks2cNN49_r7LH24s4qC8lwiA73cGfZdW0KU1kbg0e5OEdPd7r4-Se5F=w1547-h870-s-no

It's a straightforward damper rod setup with a non-anchored damper rod. the fork is retained in the stanchion by a screw on collar which contains the fork seals. Plain iron bushings.

https://lh3.googleusercontent.com/pw/ADCreHdBCdYrGiGqUiVJjVb6rflzHNJ02gBsSQBtJ9w-kgFYwf9DTANejjQtTlxHmeZjrXMlkPs3yX27eWaZ5IdR-Z1cYaAJ8oRcYJXY_RCT8Dyn6zsydKEpRdRrobSxkUohrOfBj-o8WAGzDIvUQpVNkBdB=w1547-h870-s-no

The seals are retained in the screw-on collar. two seals per collar then a felt washer on top to act as a dust seal. Similar setups on other bikes and they seem to work way better than the Japanese style. This bike has shrouded forks so junk doesn't tend to get on the stanchions in the first place. I'll need to paint the fork shrouds too. The seals are 1mm thinner than a standard size linear seal, there's enough room to fit that if I compress the felt washer some more.

https://lh3.googleusercontent.com/pw/ADCreHdBCdYrGiGqUiVJjVb6rflzHNJ02gBsSQBtJ9w-kgFYwf9DTANejjQtTlxHmeZjrXMlkPs3yX27eWaZ5IdR-Z1cYaAJ8oRcYJXY_RCT8Dyn6zsydKEpRdRrobSxkUohrOfBj-o8WAGzDIvUQpVNkBdB=w1547-h870-s-no
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.