Ned Posted June 3, 2012 Share Posted June 3, 2012 Fucking love it! Quote Link to comment Share on other sites More sharing options...
mark105 Posted June 4, 2012 Author Share Posted June 4, 2012 made a throttle today and took bike to the drome, ended in fail as 20 year old cam belt liked to stretch and although tests down the road may have gone well it just kept kicking the belt off. so have added cambelt idler like so and this is keegan having a burn after i rode it round the block. cant see shit but you get the idea, just look for sweet head lamp haha. prob wont get another change at the drome till next weekend now. Quote Link to comment Share on other sites More sharing options...
rot808 Posted June 4, 2012 Share Posted June 4, 2012 nice, very nice Quote Link to comment Share on other sites More sharing options...
japawagons Posted June 4, 2012 Share Posted June 4, 2012 Fucking roughtastic to ride. Wish I was riding it right now actually. Damn you sun and neighbors. Quote Link to comment Share on other sites More sharing options...
Yowzer Posted June 4, 2012 Share Posted June 4, 2012 Quote Link to comment Share on other sites More sharing options...
peteretep Posted June 4, 2012 Share Posted June 4, 2012 good job mark, is this direct drive or did i miss something? if it is, how do you get on with starting? Quote Link to comment Share on other sites More sharing options...
Yowzer Posted June 4, 2012 Share Posted June 4, 2012 Yup, direct drive. Run/push start has worked well so far Quote Link to comment Share on other sites More sharing options...
peteretep Posted June 4, 2012 Share Posted June 4, 2012 why not tensioner on vee belt section? so easy, then you can rev the engine obnoxiously, which incidentally is half the purpose of velo bikes Quote Link to comment Share on other sites More sharing options...
Ned Posted June 4, 2012 Share Posted June 4, 2012 Looks good fellas! Quote Link to comment Share on other sites More sharing options...
peteretep Posted June 4, 2012 Share Posted June 4, 2012 i wonder how much power a cambelt can transmit? Quote Link to comment Share on other sites More sharing options...
mark105 Posted June 5, 2012 Author Share Posted June 5, 2012 well its on the end of a crank shaft in a fiat twin cam that makes 180hp normally, doesnt have a huge amount of load on it but id say its capable of handling a fair bit. 300cc takes a bit to push start but its generally sweet. we just chuck it up on a wooden tool box to rev it obnoxiously/warm it up cause it push starts easier warm. no reason why i could pinch an idea or 2 from you pete and make a v belt tensioner though. maybe once i got the initial bugs ironed out and manage a few laps round the drome will look at further improvements. really want to get fly wheel on the lathe and lighten it heaps. weighs a tonne and im sure would allow for more rev's if it was lighter. Quote Link to comment Share on other sites More sharing options...
japawagons Posted June 5, 2012 Share Posted June 5, 2012 My 180HP figure was more in reference to cambelts in general on a modern twin cam fuel injected engine, a standard Fiat Twincam was in no way anywhere near 180HP but in saying that the Lancia Intergrale 16V Turbo is the same engine and exactly the same cambelt arrangement and I would say 180 is a realistic figure for that engine. Just cause I felt like a rant. Quote Link to comment Share on other sites More sharing options...
mark105 Posted June 5, 2012 Author Share Posted June 5, 2012 yeh something like that, will be sweet for most small stationary engines anyways. gets a fair bit of a hiding being push started before we put the tensioner on it, jumping teeth and shit all over the place. got some grub screws to hold crank pulley on as im using just some old screws from super cheap at the moment and have lost 2 or 3 of them already from 2 rides round the block hah. Quote Link to comment Share on other sites More sharing options...
Seedy Al Posted June 5, 2012 Share Posted June 5, 2012 fuck yeah dude good job Quote Link to comment Share on other sites More sharing options...
Steelies Posted June 5, 2012 Share Posted June 5, 2012 wicked man! badass seat/bar/motor locations. Quote Link to comment Share on other sites More sharing options...
KIRK Posted June 5, 2012 Share Posted June 5, 2012 really want to get fly wheel on the lathe and lighten it heaps. weighs a tonne and im sure would allow for more rev's if it was lighter. is it cast iron? there probably an alloy flywheel out there to fit this engine/vertical shaft version of it. Will be harder to roll start tho Quote Link to comment Share on other sites More sharing options...
Ned Posted June 5, 2012 Share Posted June 5, 2012 Cam belt only transfers whatever power is needed to turn the cams and open some valves. Does not matter how much power the engine makes, it still requires just as little power to turn the cam and open some valves right? Not saying a cambelt can't handle a bit of power, but pretty sure engine power has noting to do with cam belt strength Quote Link to comment Share on other sites More sharing options...
alfalfa Posted June 5, 2012 Share Posted June 5, 2012 Cambelt strength would be way more related to max engine RPM and valve spring rate/rocker ratios etc Quote Link to comment Share on other sites More sharing options...
Rookie Posted June 5, 2012 Share Posted June 5, 2012 ^ This, mostly valve spring rate I would guess. Ned have tried turning a cam over by hand? It's quite hard. Also, propellers, Ned. Quote Link to comment Share on other sites More sharing options...
Llama Posted June 5, 2012 Share Posted June 5, 2012 For a normal (or V) belt the maximum power is: Power = (P1 - P2)*w*® Where P1 is the tension in the tight side, P2 is the tension in the slack side. w and r is the angular speed (rad/s) and radius of a pulley (both measurements taken of the same pulley). Tensions are related by P1/P2 = exp(u*theta/sin(a)) where u is the coefficient of friction, theta is the contact angle of the smaller pulley, and alpha is the semi-angle of the wedge (if you are using a V belt). Looks like I learn something useful at uni afterall... I would imagine toothed belts get a lot more fucktardly complicated with deflection of the teeth and yadayada. They'd probably just snap before anything. Quote Link to comment Share on other sites More sharing options...
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