Strange bore size

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nightcruiser
Beiträge: 2
Registriert: So 13. Jan 2008, 19:09

Strange bore size

Beitrag von nightcruiser »

Hi everyone, I'm new to this forum and wondered if anyone can help me please?
I have a German RD350LC 4LO, 1980 model and can across a wierd discovery.
The bore sizes on my bike measure 63.5mm and not 64mm as all the manuals state.
Can someone shed some light on this, also the German registration document also states the engine size is 345cc and not 347 UK spec.
Am i right in assuming the DE engine were different?
Thx Dave.
pepsi12128
Beiträge: 717
Registriert: Do 31. Jul 2003, 01:00
Wohnort: Heilbronn (BW)

Beitrag von pepsi12128 »

Hi Dave and welcome to this forum,

sorry no, you're wrong, the german engine is exactly the same as the British one. There's only a difference in the performance of the 1980 cylinders in comparison to the 1981-82, but not in the bore sizes. I've never heard of a 63.5mm bore, neither in any construction year nor in any country-specific model of the 4L0.
No kidding - is it possible you had an error in measuring or an imprecise caliper?
I would suggest to measure the cylinders at the bottom and the top again and for safety the pistons too. If the size you mentioned above still remains, you have very rare cylinders - maybe they're made-to-measure, and it will be hard to get fitting pistons.
Normally there is a mark at the bottom on the outer side of the cylinders with the cubic capacity "347ccm" - what is on yours?

best regards
Martin
Moped: 4L0 Bj 81 (Zustand: passt)
4L1 Bj 80 (Zustand: passt)
Fahrer: Bj 58 (Zustand: oje!)
nightcruiser
Beiträge: 2
Registriert: So 13. Jan 2008, 19:09

Beitrag von nightcruiser »

Hi Martin and thanks for your reply.
I've measured the bore top & bottom of the bores and both measure the same/ under size, my friend who is an engineer measured to confirm.
I am also amazed to discover this, there must be a reason behind it.
The barrels have 347 stampted on them, but the German paperwork states 345cc?
The reason this cropped up was because i need to replace the pistons.
It now means i have to have .50mm removed to fit some new standard size pistons.
All sounds strange to me.
Thx Dave in England UK.
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Charles
Beiträge: 306
Registriert: Do 7. Aug 2003, 01:00
Wohnort: Geldern

Beitrag von Charles »

Hi Dave, can the previous owner perhaps shed a light on this strange story?
Cheers, Charles
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MatthiasD
Beiträge: 866
Registriert: Mi 16. Mai 2007, 14:15
Wohnort: Niederlande
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Beitrag von MatthiasD »

Could it had new sleeves fitted that where made too small? Strange though as I can't imagine where to get pistons that size.
..und wahrscheinlich ist ihnen das nicht mal peinlich, es fehlt ihnen jede Einsicht
Und wieder mal zeigt sich: Sie sind kleinlich, unvermeidlich fremdenfeindlich
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