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Does this Cycleworld comment raise an eyebrow with anyone?"An unexpected and fairly radical technical modification separating the V7/V9 V-twin engine from all previous editions, and from the V85 TT, is that the crankshaft here is of the press-fit type, with one-piece con-rods turning on plain bearings, rather than a forged one-piece unit. This follows the same engineering approach used on all Piaggio four-stroke scooter singles. Reducing production cost is the ultimate reason for the change. The more powerful, higher-revving V85 TT retains its solid forged crankshaft and cap-type rod."
Harley has been using press together cranks form its beginnings to this day (on the big twins).
The biggest benefit of the industry moving away from roller bearing bottom ends in the 70s and before was the elimination of pressed together crankshafts. Itís an archaic concept that only survived as long as it did due to concerns about reliable oiling of plain bearings that themselves should should have been put aside in the 1940s or before. Just because Piaggio has equipment to make built up crankshafts for scooters and apparently cuts cost of production using them does not make pressed together multi-piece crankshafts a good thing for the owner of a Guzzi.
And thats a recommendation?Ciao
^ No they were not ! Press fit cranks on Harleys didn't start until the Twin cam model ( FWIW) . The Laverda triples had press fitcranks and were fairly durable . Not to forget most 2 strokes were also pressed together cranks !
I thought all Harleys had press fit cranks. Isn't that how they installed those "knife and fork" rods?
Wait, I always thought that pressed cranks were quite bit more labor intensive and expensive to build. This is the first time I've ever read the opposite. I don't know why two piece rods could be revved at higher RPMs and more stress than one piece rods; if there is a difference, I'd think would be the other way around. OK, since I'm the least mechanically inclined person on the Board, someone please educate me.Thanks.
I always thought that pressed cranks were quite a bit more labor intensive and expensive to build. This is the first time I've ever read the opposite. I don't know why two piece rods could be revved at higher RPMs and more stress than one piece rods; if there is a difference, I'd think would be the other way around. OK, since I'm the least mechanically inclined person on the Board, someone please educate me.
Itís just a cost saving thing, squeezing pennies out of something in exchange for reducing its practical lifespan. Fine for the first buyer who likely never knows, fine for Piaggio because there wonít be as many multi-resale used bikes for them to compete with in selling new bikes. Not so good for anybody who thinks long life is a measure of quality.
Like older British bikes some were a tapered pin with a nut to hold in place from memory.The side by side rods on a common pin like a Ducati has is the best option unless crank width/length is an issue. Articulated rods in all there forms whether a "master rod" situation or a forked arrangement like a Merlin engine uses are less desirable and generally for low rpm applications only.Ciao
Crazy panic time!Thinking of all the older sports and racing cars with built-up cranks. Not to mention my Laverda triple.Like Chuck I have never worn out an engine. I suspect this will be a big savings for Piaggio. To help with the angst, I should point out that you can't buy main bearing inserts for Vespa engines-they are sold as part of the case.
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