Bernies Bike Shed

PUCH 175 SVS engine strip

If you have seen the other pictures of the Puch that(i hope) i will be restoring you would have noticed the state of the engine .So before the restoration starts i thought i would strip down the original engine to see what state its in.Also if anybody wants to take their 175 apart the picture’s and captions should be helpful.The little Puch engine  is well engineered and does need some specialist tools to strip it down! fortunately when i restored my first 175 i had a friend who made me the tools i needed !do not try to do the job without out these tools.

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components of clutch, a 175 with 9 steel disc and 8 friction plates also the tools needed top centre is for withdrawing the armature from the crank next to that engine sprocket fits on a taper shaft and needs  the tool to the left which screws onto the boss end of the sprocket and a tool i made for undoing the  six clutch screws.NOTE.. THE FIRST STEEL PLATE INTO THE CLUTCH BASKET  IS 2 THOU THICK AND THE LAST PLATE HAS TABS THAT POINT INWARDS.

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to split the casings, you need to undo 13  8 mm screws,note one is longer than all the others,it fits closest to the black cap on top  of engine then knock out the 2 steel locating dowels.front one shown and one at the rear.

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Crankshaft sprocket needs the withdrawal tool as used on the chain sprocket to remove it.

Next pictures show the splitting of the crankcase halves, starting with the right hand side first using a tool (which is used for splitting NSU engine crankcases) being adapted for use on the Puch.

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The alloy plate is secured to the crankcase by 2 screws and 4 , 6mm studs hold the withdrawal tool to the plate

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Crankcase off !no problem ‘Not a pretty site’ the crankshaft dosen’t look to different from a well done beef burger!! no wonder it didn’t want to turn!

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The right hand crankcase still attached to the plate

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By contrast to the crank,the gearbox in good condition note the small needle bearings cage! most gearboxes have a plain bushe for that end of a shaft.

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Gearshaft and layshaft and the caged needle bearings

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Left hand side crankcase with crankshaft after a bit of a clean already to be pushed through the double bearing.But after applying a lot of pressure it hasn’t moved. So a trip to a friend with a 20 ton hydraulic press is next. some thing will give i hope its not the alloy case!!

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The crank finally has to give up it’s rusty grip on the bearings under the hydraulic press

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The other side of the’Beef burger, a exchange crank/bigend is available from RBO the Austrian Puch specialist.

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Left hand crankcase!  oil ,steel,alloy and water leave a strange deposit after 30 years !!!

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The above crankcase after a good cleanup! showing the tell tale marks of debris (probably some piston skirt) being ground into the bearing area.The gulley top left carries two/stroke mixture to the back of the bearing.

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Another view of debris damaged,small hole at top carries mixture to front bearing.

My detective work on the probably cause of why the engine was without a barrel was correct! 100% sure it was a piston problem because when cleaning the crankshaft and bigend( which you can see  2 pictures up) a large lump of piston shirt came out on the work bench.The above article has satisfied my curiosity about the history of the engine failure, but what will happen to it, is uncertain ! maybe if i find a barrel and head and carbs !!! who knows!!

The next couple of photo’s are from stripping down my substitute engine

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The engine showing the configuration of the pistons in the Puch split single.The front piston with blacking around the crown and down the sides shows the internal gases are escapeing so new rings or a rebore with a new piston maybe in store??

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The piston on the left called the slave piston is connected to the bigend by a wrist pin also note the good condition of the crank webs.

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The crankshaft from my substitute engine,looking the opposite to my original crankshaft,the front piston(lower in picture) will need new piston rings.

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