weatherwatcher 664 Posted June 11, 2014 Never having worked on a speedway bikes engines, can anyone tell me what the parameters of these engines will allow tuning wise. Is it possible to overbore the engine, to give you a larger bore size, what tolarance allownces have you got for skimming the head to give you a higher compretion ratio, and what sort of work can you do to the valve setups. The toop riders in the world who have that extra spare cash to be able to afford some of the worlds best engine tuners, seem to be able to get at least an extra 10 or 20 mph out of thier bikes and I am sure this is not just down to carbs and nozzles in the carb jets. What is the most work that can be done to an engine that still makes it legal. If not legal then in some way that noone can tell without taking the whole bike apart. Share this post Link to post Share on other sites
Vince 9,458 Posted June 11, 2014 The skill of the tuner is being able to match an engine to a rider in such a way that he can make best use of it, outright power is not generally what they are looking for. Can't imagine anybody trying to get away with an oversize engine on Speedway these days. If any rider ever does 10mph more it's because of his skills not the engine, more realistically they are looking for fractions of a second per lap. Share this post Link to post Share on other sites
weatherwatcher 664 Posted June 11, 2014 Some of the bikes are a lot faster than other you only have to see this when they are riding side by side on the straights. When a bike pulls so far ahead of the others in cases like this this is not down to the riders, or the gearing setup. Share this post Link to post Share on other sites
Jonny the spud 2,281 Posted June 12, 2014 Start off with two standard bikes and two riders of equal ability, set them up the same and then forbid one rider to touch his. The other can change the gearing to suit the changing track conditions, alter his timing, change jet in the carb , lengthen / shorten the wheelbase by moving the rear wheel, adjust the trye pressure etc etc. by the end if the meeting one will be much quicker than the other. It's not all just about tuning. 2 Share this post Link to post Share on other sites
speedibee 3,091 Posted June 12, 2014 Been thinking about this - Is this REALLY true?? - even as a generalisation?? On an upright you would have the benefit of gravity as the piston went down. I would have thought it was more to do with bore and stroke etc. If speed and revs are a problem on modern bikes - what about enforcing a smaller diameter carb?? centre of gravity is lower in a laydown . but with modern crank balancing techniques accurate to 5 grams + or - there is no gravitational pull from the moving crank and piston , Never having worked on a speedway bikes engines, can anyone tell me what the parameters of these engines will allow tuning wise. Is it possible to overbore the engine, to give you a larger bore size, what tolarance allownces have you got for skimming the head to give you a higher compretion ratio, and what sort of work can you do to the valve setups. The toop riders in the world who have that extra spare cash to be able to afford some of the worlds best engine tuners, seem to be able to get at least an extra 10 or 20 mph out of thier bikes and I am sure this is not just down to carbs and nozzles in the carb jets. What is the most work that can be done to an engine that still makes it legal. If not legal then in some way that noone can tell without taking the whole bike apart. Top riders dont need the extra money , engine tuners have always given them ther best bits and the best service free, create the illusion that your engines are faster because you are a better tuner , and hey presto riders queueing up to pay ridiculous prices , Share this post Link to post Share on other sites
Bruiser McHuge 589 Posted June 12, 2014 Start off with two standard bikes and two riders of equal ability, set them up the same and then forbid one rider to touch his. The other can change the gearing to suit the changing track conditions, alter his timing, change jet in the carb , lengthen / shorten the wheelbase by moving the rear wheel, adjust the trye pressure etc etc. by the end if the meeting one will be much quicker than the other. It's not all just about tuning. That is very true...when my brother in law rode you wouldn't believe the amount of changes and fiddling about we did between races..changing the jets and all the other little adjustments....it was hectic and it's no surprise some riders don't know the score of the meeting they are racing in ! It's certainly not all about getting a fine tuned engine , turning up and riding it Share this post Link to post Share on other sites
Vince 9,458 Posted June 12, 2014 Some of the bikes are a lot faster than other you only have to see this when they are riding side by side on the straights. When a bike pulls so far ahead of the others in cases like this this is not down to the riders, or the gearing setup. I'm afraid it is, all depends how much speed they carried off the corner, the difference in potential straight line speed of bikes is minimal. Share this post Link to post Share on other sites
FAST GATER 853 Posted June 13, 2014 That is very true...when my brother in law rode you wouldn't believe the amount of changes and fiddling about we did between races..changing the jets and all the other little adjustments....it was hectic and it's no surprise some riders don't know the score of the meeting they are racing in ! It's certainly not all about getting a fine tuned engine , turning up and riding it Well this is the problem in the 70's( i know I'm old out of touch memory selective and all that ) the average rider between races changed tyres ,wheelbase ,gearing and adjusted or changed clutch plates and managed to put on races I was happy to watch that much I do remember, Share this post Link to post Share on other sites
spinkox 37 Posted June 16, 2014 centre of gravity is lower in a laydown . but with modern crank balancing techniques accurate to 5 grams + or - there is no gravitational pull from the moving crank and piston , Im a bit out of my depth here - but surely there will always be a gravity pull - you cant avoid it on this planet. Whether it makes any difference to the engine - I dont know. Share this post Link to post Share on other sites
Phlipphlopp 3,913 Posted June 16, 2014 Well this is the problem in the 70's( i know I'm old out of touch memory selective and all that ) the average rider between races changed tyres ,wheelbase ,gearing and adjusted or changed clutch plates and managed to put on races I was happy to watch that much I do remember, Talking about gearing , Mauger famously for a while had false stickers on his gearing cogs so as to outfox the opposition who might have fancied changing theirs at the same time as he did......... Share this post Link to post Share on other sites
SCB 0 Posted June 16, 2014 Im a bit out of my depth here - but surely there will always be a gravity pull - you cant avoid it on this planet. Whether it makes any difference to the engine - I dont know. It will but if you piston is moving horizontal it'll be pushing down on the barrel very slightly due to gravity. Eventually this will cause slight wear. If the engine is only going up and down, the gravity of not being exerted on any parts you need to keep in shape, just the piston itself that doesn't ever actually hit anything. In addition to the wear on the barrel, it will obviously cause a small amount of friction, probably an irrelevant amount. I would imagine the only real saving is the fact the centre of gravity is lower. But it's certainly not bad thing in other respected. Share this post Link to post Share on other sites
Vince 9,458 Posted June 17, 2014 Won't the inertia of the piston easily overcome the force of gravity and make it behave the same no matter what angle it's at? As far as I know the service limit on the old radial aero engines was the same for all barrels and they point every which way. Share this post Link to post Share on other sites
The White Knight 9,039 Posted June 17, 2014 Won't the inertia of the piston easily overcome the force of gravity and make it behave the same no matter what angle it's at? As far as I know the service limit on the old radial aero engines was the same for all barrels and they point every which way. As in the Gnome Le Rhone "Monosoupape" (single valve) B2 9 cylinder rotary engine of WW1. Share this post Link to post Share on other sites
weatherwatcher 664 Posted June 23, 2014 Found this nice clip on you tube of some old uprights. Some very nice bikes on here. Hope you enjoy. https://www.youtube.com/watch?v=esQixdiNJyU Share this post Link to post Share on other sites
