ATV crank pin to web weld

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Pressed crank apart and replaced rod, bearing, and pin. Trued up then welded. This is to keep web clocked. Some customers will tip in a little pop, or spray. This can create enough cyl pressure to rotate web if its not welded.DC, 3/32 red, .035 309 rod. Peter Attached Images
Reply:It's fine that you welded the pin, but its not needed or recommended on an engine with only one cylinder. Welded cranks are usually only found on dragbikes with dragsliks. The problem they had is when the wide tire hooked up at the starting line, the load had a tendency to twist the crank out of true (usually 4 cylinder engines). This problem was fixed by welding the crank pins. Welding the pins on a crank that small just makes it harder to replace the rod next time. Why do you think they don't weld it from the factory? Twisted cranks on a single cylinder engine are unheard of.
Reply:Originally Posted by BrianstickIt's fine that you welded the pin, but its not needed or recommended on an engine with only one cylinder. Welded cranks are usually only found on dragbikes with dragsliks. The problem they had is when the wide tire hooked up at the starting line, the load had a tendency to twist the crank out of true (usually 4 cylinder engines). This problem was fixed by welding the crank pins. Welding the pins on a crank that small just makes it harder to replace the rod next time. Why do you think they don't weld it from the factory? Twisted cranks on a single cylinder engine are unheard of.
Reply:I always wondered how a crank was pressed apart then aligned back perfectly. I know that some engines use pressed cranks and have also ran across  two cranks in outboard motors that have been "twisted" out of alignment.I have always had to ship  my cranks to be repaired,and was just wondering if this is something that a "backyard" mechanic could do. thanks
Reply:Originally Posted by busymanI always wondered how a crank was pressed apart then aligned back perfectly. I know that some engines use pressed cranks and have also ran across  two cranks in outboard motors that have been "twisted" out of alignment.I have always had to ship  my cranks to be repaired,and was just wondering if this is something that a "backyard" mechanic could do. thanks
Reply:Originally Posted by castweldThanks for your opinion. But engines I work on are being seriously abused, I have customers running methanol mixed with nitro and prop. Trying to turn two Rippers (agressive paddle tires) will  unclock a single. Other customers have gone with nitrous, spraying as much as 60 hp in some singles.Yes I know that stockers are not welded, and I have rebuilt some cranks (welded) more than once. This is not problem for me.Call Crankworks or Falicon and ask for a performance single, it will come welded.And I agree if you work on stock stuff then you need not weld it.Peter
Reply:Originally Posted by castweldv-blocks, dial indicator, copper hammerI check in v's remove and set on wood or alum plate, hammer on webs untill true. Can be tough to align to specs.You will need press and plates to press apart/togetherI am in Eunice where are you?Peter
Reply:Being a long time engine hotrodder and especially motorcycle engines. The reason that they are welding the pin in high performance single cylinder  cranks is not to stop the twisting of the crank halfs but to keep the oil passages from the clutch end and up throught the rod journal to oil the bearings in the big end of the connecting rod. I do it myself because I had a 250 mojave spin the pin and starve it of oil and I bet you can guess what happened next.
Reply:I forget if it's Sulzer or Man B&W that uses built-up (pressed together) crankshafts on 12-14 cylinder engines approaching 120,000 horsepower.  There is actually a misalignment tolerance published by the manufacturer.  Slipping only happens if you run aground or something.