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Classic Bike Trackdays

Eastern European's Infiltrate
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emzedder



Joined: 15 Dec 2006
Posts: 324
Location: E.Anglia

PostPosted: Fri Sep 08, 2017 6:56 pm    Post subject: Reply with quote

I need to get photo sharing sorted following the Bucket debacle.
Haven't posted here fro some time, thought it worth mentioning that I still view the forum and its good to see it is still active in face of the FB onslaught that appears to have killed off most forums.

So ... the MZ has been thrashed to death for over 10 years now through road and track days and pleased to say other than a mid term top end inspection she has not yet been rebuilt. I'm likely to do a partial strip and inspection and any remedial this winter but don't envisage anything urgent. I'm trying to track down a low 5th gear modification so anyone with any info much appreciated. Seems the recent batch for the MZ series boys has been sold.

I'm planning to build an alloy frame project based on the Herrero Ossa machine maybe with a thermo syphon based liquid cooled barrel based around a 250 MZ unit. I'll post some conceptual drawings on here in due course .... a sort of pre-retirement project. Why am I bothering .... because I can!
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emzedder



Joined: 15 Dec 2006
Posts: 324
Location: E.Anglia

PostPosted: Sun Oct 01, 2017 9:55 am    Post subject: Reply with quote

I'm thinning out in order to begin a new project. Plan is to construct a light alloy monocoque chassis housing a two stroke single close to the design of the Ossa campaigned by Santiago Herrero in the 70's. I'll use a heavily modified MZ 250 unit because I know what I'm doing with those and spares and tuning readily available. I have preliminary plan and due to start the mock-up in light alloy sheet this winter.

I have a couple of fabrication options, one is riveted sheet, I have test box sections and strength and resistance to stress fracture would meet the requirement if designed correctly. My son worked in aviation restoration on Superrmarine Spitfire wing sections also have friends in the aviation field which is handy. Alternatively the there is welded alloy fabrication but I prefer the former.

I'll post some pice and articles as it progresses.

Shed Built FB Group ... hmmm, I'd rather invite conversation through this forum .....
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DSBBadmin
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Joined: 13 Nov 2006
Posts: 717

PostPosted: Mon Oct 02, 2017 9:07 am    Post subject: Reply with quote

emzedder wrote:
Shed Built FB Group ... hmmm, I'd rather invite conversation through this forum .....

Good ! Looking forward to seeing it progress. Thumbs Up
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emzedder



Joined: 15 Dec 2006
Posts: 324
Location: E.Anglia

PostPosted: Fri Mar 30, 2018 7:37 pm    Post subject: Reply with quote

Well after considering the options of full frame fabrication and the implications for registering / forthcoming DVLA status / more stringent MOT's I decided to abandon and enhance the bike with purpose built alloy tank, seat and other fabrications. This will cut weight and retain an Eastern European aesthetic (flat, angular construction) with a honey-hole storage compartment in the seat unit.

Once I've sorted pic sharing I'll post original drawings and 3D mock-ups for anyone that's interested. I'll be on it at Cadwell Classic Trackday it'll all be together in a month ... it won't be substantially quicker (!) but it's all my own work!
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emzedder



Joined: 15 Dec 2006
Posts: 324
Location: E.Anglia

PostPosted: Thu Nov 28, 2019 7:51 pm    Post subject: Reply with quote

haven't entered anything on this subject recently.

Blew the old girl up at Cadwell in June ... all of the big end rollers had effectively gone ... but fortunately reassembly in progress with new race prep crank etc. Job will be a good's by end December. Amazingly bore hone after 14 years since last rebuild and piston ... cab't complain about that.

In meantime acquired an MZ that was campaigned heavily in Northern England until c2005. Heavily modified with 300cc Kawasaki JetSki piston set and gearbox mounted Yam YZ250 clutch (moved from clutch end as standard). Currently rebuilding the spare engine that came with it, that has radical porting arrangement and other mods. I'll slip it into the road bike for shakedown and refinement before its run out at Classic track day early as poss 2020!
Spare engine really needed a new liner so that's going away for fitting this week.
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James P



Joined: 31 Mar 2013
Posts: 184
Location: Sydney, Australia

PostPosted: Fri Nov 29, 2019 10:15 am    Post subject: Reply with quote

emzedder wrote:
...and gearbox mounted Yam YZ250 clutch (moved from clutch end as standard).


The whole bike sounds interesting and I'm looking forward to seeing the pictures! Is the MZ clutch normally fixed to the end of the crankshaft? If so, I'm especially interested to see what work was involved in moving it to the gearbox input shaft. Waiting with bated breath for the photos... Very Happy .

Regards,
James
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Dave B



Joined: 24 Oct 2019
Posts: 15
Location: Staffs Moorlands

PostPosted: Fri Nov 29, 2019 10:27 am    Post subject: Reply with quote

It's a shame you gave up on the ally monocoque. I have a friend who lives Bedford way who made several LCR copies for 80cc race bikes when that class was running. Just like the Louis Christian frames used for the Krauser 80cc GP bikes, they were glued and rivetted, and, in the final version, good handlers. The first one got named "the Plough" by its new owner, on the grounds that it spent a lot of time in fields.
I'm sure you will have researched grades of aluminium, but if not, your son into aircraft restoration will know how to source the right sort for structures.
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emzedder



Joined: 15 Dec 2006
Posts: 324
Location: E.Anglia

PostPosted: Fri Nov 29, 2019 8:32 pm    Post subject: Reply with quote

I'll find a pic sharing solution and share here. The clutch was crank mounted and ran at crank speed on the 250 right through to the last models. Weight and flywheel effect made the engine torquey but limited rev capability. The clutch has been moved to the mainshaft using the large gear previously meshing with the crank end clutch.
Consequently the modified engine revs completely differently and has massive inlet duration mated with a large reed valve to compensate. potentially revs 30% higher revs than standard.

I haven't given up on the alloy frame, itime is so limited ... it will happen but maybe next year.
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emzedder



Joined: 15 Dec 2006
Posts: 324
Location: E.Anglia

PostPosted: Tue Sep 08, 2020 7:30 pm    Post subject: Reply with quote

Haven't posted for ages however I have been active despite the C Word. Currently have an additional MZ originally built in early 2000's and competed regularly in northern area circuits. I'm currently rebuilding the 300cc engine which I've fitted a new thicker liner with radical porting and a Kawasaki Jetski piston from US. It has the clutch relocated from end of the rank as standard to the gearbox mainshaft. Needs some re-engineering including a clutch mounting fabrication machines. It has a Mikuni pump jet carb from a TZ350. Initially I will fit it into my road bike for shake down and tuning/testing but them hope to run at Clssic track days ... was targeting the Cadwell session in July but of course that was abandoned.

I'll have to get some pice here of the motor while it is stripped, might be interesting for members.

Meanwhile the trusty 250 (seen in this thread) destroyed its big end and broke piston skirt at Cadwell last year. She's all rebuilt and running again. Given she was first built in 2006 and done countless thousands of miles and many track days over 13 years can't really complain! Good old MZ engineering for you.
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Dave B



Joined: 24 Oct 2019
Posts: 15
Location: Staffs Moorlands

PostPosted: Fri Sep 11, 2020 8:36 am    Post subject: Definitely Diffrent! Reply with quote

Not mine, or belonging to anyone I know, but this MZ special is certainly different.

[url] https://www.ebay.co.uk/itm/1972-MZ-Lowrider-Bobber-ETS250-ETZ301-Hardtail-Springers-May-P-ex-WHY/164346017480?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Dd6f57fce7f904c99a8e44e1f553a9379%26pid%3D100675%26rk%3D1%26rkt%3D15%26mehot%3Dpp%26sd%3D164346017480%26itm%3D164346017480%26pmt%3D0%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3A100c83fc-f409-11ea-b581-74dbd1802374%7Cparentrq%3A7c49a38a1740ad4d89974d0effffedd6%7Ciid%3A1 [/url]
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emzedder



Joined: 15 Dec 2006
Posts: 324
Location: E.Anglia

PostPosted: Fri Sep 11, 2020 9:32 pm    Post subject: Reply with quote

I saw that special on FB Group, it is quite nicely done but its on its original chassis and V5 details which is well dodgy. It should be Q plate I would think, as a lowrider quite well thought out!
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