Mad Potter 2 109 Posted June 11, 2015 All that is needed is to ban rider's & tuner's from fitting none standard engine parts. They can only use part's supplied by the engine manufactures. Share this post Link to post Share on other sites
The White Knight 9,039 Posted June 11, 2015 Liked what I saw of the rides by Bomber, must say though it seemed to lack quite a bit in straight line speed. That could have been down to the gearing and not the engine though. It was good off the start and if Bomber can get it to go from the tapes, then it must be good. I really can't see how it can be leagle. You could have said the same about the GM's when they started to replace the Jawa's. But noone knows for sure, unless they have seen one in pieces, what is actually going on inside the engine. All I have ever seen are pictures of the outside of the engine, there are no scematics of it. Come to think of it neither are there any for the Jawa's and GM's come to think about it. What made them come up with the very chuncky looking barrel, it just looks like an unfinished block of aluminium but it works very well for all that. But on the inside it is no more that a crank and a piston. With a bore of 500cc like all the others. Would love to know, what they have done to make the big difference to the other engines. This is an interesting Thread. I have a query, as I am not very technical. Can anyone explain how you can find out if a Rider is on a 'big' Engine these days? 1 Share this post Link to post Share on other sites
Bream 29 Posted June 11, 2015 Waiting to see pics inside GTR engine. Head looks wide so it must be DOHC. Problem with older DOHC engines was roller chain that wasnt very durable. Just a little streching on it messed the optimum performance that was possible to get out of the double cam engineering. I bet that under that valve cover there is tooth chain like in modern double cam motocross engine that can go for hours and hours with the same chain. Second thing to get more hours out of speedway engine would be an oil injection nozzle built in the engine case pointing upwards to oil the cylinder every time piston is in the TDC. Same type of nozzle would be nice to oil valve train components at the top. Share this post Link to post Share on other sites
ruffdiamond 6,115 Posted June 11, 2015 This is an interesting Thread. I have a query, as I am not very technical. Can anyone explain how you can find out if a Rider is on a 'big' Engine these days? Make sure piston is 'bottom dead centre', take the spark plug out, get a jug of water and fill the hole,,, tip the bike upside down and collect the water into an 'empty' measuring jug, and see what the volume is,,, if it's more than it should be, you've got em ;-) 1 Share this post Link to post Share on other sites
weatherwatcher 664 Posted June 11, 2015 Do we still have many riders that are over boring engines these days, would have thought with all the titanium bits and bobs and other costly add on's that those days where long gone. In this modern era, of electronics, I can't see why the riders still have to remove the cover to advance or retard the points. Is it just that the powers above can't get around to the fact, that things have gone a very long way from the days when riders where using JAP rudge and various other past museum pieces. I really think they could make life within the speedway world so much simpler. Share this post Link to post Share on other sites
SCB 0 Posted June 11, 2015 Do we still have many riders that are over boring engines these days, would have thought with all the titanium bits and bobs and other costly add on's that those days where long gone. In this modern era, of electronics, I can't see why the riders still have to remove the cover to advance or retard the points. Is it just that the powers above can't get around to the fact, that things have gone a very long way from the days when riders where using JAP rudge and various other past museum pieces. I really think they could make life within the speedway world so much simpler. Isn't the easier way to get a bigger engine to use long and short stroke bits interchangeably? Share this post Link to post Share on other sites
Grand Central 2,654 Posted June 11, 2015 I'm more surprised that after all those years spent so close to Speedway riders of several generations, right up to date. Philip Rising doesn't seem to understand their mindset on an issue like this even one iota. 2 Share this post Link to post Share on other sites
speedibee 3,091 Posted June 11, 2015 Make sure piston is 'bottom dead centre', take the spark plug out, get a jug of water and fill the hole,,, tip the bike upside down and collect the water into an 'empty' measuring jug, and see what the volume is,,, if it's more than it should be, you've got em ;-) Nope . no you havent . because the volume of the cylinder head has nothing to do with actual swept volume ,, the on ly way to check is to remove the head and measure the bore and stroke .. Share this post Link to post Share on other sites
Arson fire 4,785 Posted June 11, 2015 How slow is it down the straights lol 1 Share this post Link to post Share on other sites
barncooseboy 237 Posted June 11, 2015 Gerhard engine has a very comprehensive oiling system which helps out with its longevity Share this post Link to post Share on other sites
The White Knight 9,039 Posted June 11, 2015 Make sure piston is 'bottom dead centre', take the spark plug out, get a jug of water and fill the hole,,, tip the bike upside down and collect the water into an 'empty' measuring jug, and see what the volume is,,, if it's more than it should be, you've got em ;-) Thank you RD. Share this post Link to post Share on other sites
Arson fire 4,785 Posted June 11, 2015 Harris would have been better on Ivor the engine tonight!! 3 Share this post Link to post Share on other sites
speedibee 3,091 Posted June 11, 2015 Thank you RD. What are you saying thanks for ?, he just quoted you a complete load of nonsense . no one would be daft enough to fill an engine with water for a start , and even if they did , it would give completely innacurate measurement .. there is only 1 way to accurately measure an engines capacity , and that is to remove the head and measure the bore and stroke . If you believe someone is using an oversize engine , you have to pay £150 protest fee to have it checked . the engine will then be sealed by the machine examiners and the rider has a limited time to present it fortesting , it will have the head removed and bore and stroke measured , also occasionally a random engine will be chosen for measurement . same thing seals are applied and the engine taken for testing , not filled up with water and tipped upside down to empty it !!!!! , taken apart and measured . if the engine is not oversize the rider is compensated £80 to cover the cost of a rebuild .. no water is used whatsoever during this measuring process , and only someone with virtually no mechanical knowledge ,but who think they have,, would suggest it Isn't the easier way to get a bigger engine to use long and short stroke bits interchangeably? something like that , long stroke conrod short stroke piston , but you nee extra gaskets to make the extra length up or the piston hits the head , so effectively you have created an overbored long stroke Share this post Link to post Share on other sites
ruffdiamond 6,115 Posted June 12, 2015 What are you saying thanks for ?, he just quoted you a complete load of nonsense . no one would be daft enough to fill an engine with water for a start , and even if they did , it would give completely innacurate measurement .. there is only 1 way to accurately measure an engines capacity , and that is to remove the head and measure the bore and stroke . If you believe someone is using an oversize engine , you have to pay £150 protest fee to have it checked . the engine will then be sealed by the machine examiners and the rider has a limited time to present it fortesting , it will have the head removed and bore and stroke measured , also occasionally a random engine will be chosen for measurement . same thing seals are applied and the engine taken for testing , not filled up with water and tipped upside down to empty it !!!!! , taken apart and measured . if the engine is not oversize the rider is compensated £80 to cover the cost of a rebuild .. no water is used whatsoever during this measuring process , and only someone with virtually no mechanical knowledge ,but who think they have,, would suggest it something like that , long stroke conrod short stroke piston , but you nee extra gaskets to make the extra length up or the piston hits the head , so effectively you have created an overbored long stroke He didn't ask how to do it acurrately, he asked how to find out ;-) If you don't wanna use water, another things you could do is,,, get an old spark plug, bore it out, just like coring an apple ;-),,, fit a balloon to it and, with the engine in the same position BDC (bottom dead centre),,, fit the spark plug and do 1 revolution of the engine,,, the balloon will take the air from the barrel,,, size your balloon against a factory set balloon, and there ye go,,, no need for expensive engine rebuilds :-) Share this post Link to post Share on other sites
speedibee 3,091 Posted June 12, 2015 He didn't ask how to do it acurrately, he asked how to find out ;-) If you don't wanna use water, another things you could do is,,, get an old spark plug, bore it out, just like coring an apple ;-),,, fit a balloon to it and, with the engine in the same position BDC (bottom dead centre),,, fit the spark plug and do 1 revolution of the engine,,, the balloon will take the air from the barrel,,, size your balloon against a factory set balloon, and there ye go,,, no need for expensive engine rebuilds :-) To find out what ? if the engine might be somewhere within 25 CC of the allowed 500 .? I have heard of a much simpler method and equally as accurate as your suggestions , simply get a factory measured ant that Is 1 cc then remove the plug . count out 501 ants and if they all manage to walk in through the spark plug hole ,hey presto " you got em" oversize engine . just put a damp sugar lump on the top fin and they will all walk out again no damage to the engine and no expensive rebuilds . just the cost of an official Briggo sugar lump 2 Share this post Link to post Share on other sites
