Enginehead
Member
Designing an engine generally is extremely difficult at times. Making it roadworthy can be even worse depending on the country.
Also, I can fully understand that I lost you on that part, Especially since it all doesn't sound too believable......Kinda lost everyone with 1500CC's of single cylinder within a Honda frame. Send photos of your machine shop with engineering staff.
Thanks for that heads up there, it's really appreciated.Hi Engine head, Keep posting please, many of us I reckon will be interested in the obstacles you meet and overcome in this project. I learn from most who are ambitious and do things like you are attempting. It is through the experience and sharing that we all learn. So don't be put off by Longboy with his doubting Thomas attitude. None of us individuals represent the whole readership. We all choose to read the posts that interest us, and ignore that do not hold our interest.
So, "My query": Plain bearings are not sympathetic to crank flexure. I experienced the large degree of crank flex under dynamic conditions when I wiped-out alternators on various regular motorcycle engines, while trying to fit better generators for better lighting.... The 1960s engines needed 0.004in clearance between the rotor and stator - outboard of he main crank bearing. Later alternator parts (to mid-1970s) that were "interchangeable" and had higher outputs had 0.003, 0.0025 and 0.0015in clearances. On a Triumph 650 cc. twin (1962) I could just get away with 0.0025in clearance, but on a 1964 500cc Single I could only get away with 0.003in clearance. The main bearings on both engines were ball races, as plain bearings with suitable close clearances could not survive the crank-flex and consequential dynamic axial mis-alignment of the crank main-shafts. Car engines (e.g. 4-cyl 2 litre) with similar bore and stroke have a much larger main bearing size and consequential crank stiffness.
So how are you designing the crank for the plain main bearings to are planning? Is it very stiff? Check main bearing sizes for a 9 litre 6-cylinder diesel truck engine and compare to yours? I am curious...
K2
His name is Allen Millyard. He has been adding cylinders to bikes long before youtube was a thing. I am a subscriber to his page.
https://www.youtube.com/c/AllenMillyard
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