jse Posted October 1, 2010 Report Share Posted October 1, 2010 Folks, Apologies if this has been dealt with before but I'm new to trials. My 10 year old son and 14yr old nephew are riding beta's in junior divisions at the moment. We've had a few instances of bikes getting stuck on full revs ( for a number of reasons, (dropping,caught cables etc.)On a few occasions the engine kill button doesn't work ( I presume because the engine is so hot at that stage. Can anybody tell me what is the best method of stopping the engine when this happens ? Some suggestions we've heard are "turn the bike upside down", "Rip the carb off asap" or "block the exhaust with your hand and choke the engine" Any help would be appreciated, Thanks Don't apologize, we all have/will run into this problem. The best way I've found is to block the exhaust with a gloved hand and when the rev's drop the ignition kill switch will then work, so use the combination of the two techniques. The porting arrangement and fairly high compression of a Trials engine will tend to lead to auto-ignition under no-load/open carb slide conditions. As an aside, I like to mount my kill switch in the center of the bars so that if the bar end (with the killswitch) gets buried in rocks or brush the switch in the center of the bars can always reached easily. Jon Quote Link to comment Share on other sites More sharing options...
buchanan84 Posted October 1, 2010 Report Share Posted October 1, 2010 Does anyone use a lanyard kill switch? was looking at a mates racing quad and thought it would be quite usefull on the trials bike, would maybe even stop it getting to this point of running on Quote Link to comment Share on other sites More sharing options...
nzralphy Posted October 1, 2010 Report Share Posted October 1, 2010 Remove a glove. Press it over the tail pipe to block the gasses. It WILL work..... but it WILL be hot! Never failed for me. Quote Link to comment Share on other sites More sharing options...
zippy Posted October 1, 2010 Report Share Posted October 1, 2010 As an aside, I like to mount my kill switch in the center of the bars so that if the bar end (with the killswitch) gets buried in rocks or brush the switch in the center of the bars can always reached easily. Jon I have my killswitch mounted in exactly the same place for just that reason. Don't forget about bar ends being buried in mud. Quote Link to comment Share on other sites More sharing options...
exobyte Posted February 3, 2011 Report Share Posted February 3, 2011 (edited) Blocking the exhaust can work or flick the plug cap off, if it's still going pull the fuel hose off rather than go for the carb. I pulled the plug lead off a Go-Kart I once had because it was stuck at full revs and can honestly say that it's not advisable, you can imagine the plug sparks once for every stroke of the piston and at full revs will be doing several thousand RPM, I was zapped god knows how many times in just a few seconds, luckily I was ok and would hate to imagine what it could have done if I'd had a dodgy heart or had been a child. personally I would try stalling the engine by either covering the exhaust with something other than a bare hand or applying the rear brake if it's in gear. Edited February 3, 2011 by Exobyte Quote Link to comment Share on other sites More sharing options...
lumpylion Posted February 11, 2011 Report Share Posted February 11, 2011 I started my bike after cleaning the carb to find that the throttle cable had gotten bunched up. Being a 2010 Sherco, It had no petcock and the fuel pump and tank baffles keep it running upside down for a while. I ripped the plug cap off and got shocked so hard I almost lost the clutch with the other hand. The muffler blocking technique did not work either. We eventually got the throttle cable fixed but next time if I can't fix the cable I'll just rip out the carb. Starving the bike of fuel is not an ideal method seeing as the fuel is also the lubricant in a two stroke. Quote Link to comment Share on other sites More sharing options...
copemech Posted February 11, 2011 Report Share Posted February 11, 2011 (edited) I started my bike after cleaning the carb to find that the throttle cable had gotten bunched up. Being a 2010 Sherco, It had no petcock and the fuel pump and tank baffles keep it running upside down for a while. I ripped the plug cap off and got shocked so hard I almost lost the clutch with the other hand. The muffler blocking technique did not work either. We eventually got the throttle cable fixed but next time if I can't fix the cable I'll just rip out the carb. Starving the bike of fuel is not an ideal method seeing as the fuel is also the lubricant in a two stroke. A good shared experience there! As you always want to hear the little "click" of slide hitting bottom after working on things prior to starting the bike! Otherwise, you have only about 0.2 seconds before the kill button no longer functions! You would be lucky if it did not sieze the piston off cold!!!! . You actually gotta pull the cable to rip the top off the throttle housing on the bars!!!!! Then it will return as long as the slide itself is not stuck. Edited February 11, 2011 by copemech Quote Link to comment Share on other sites More sharing options...
toofasttim Posted February 11, 2011 Report Share Posted February 11, 2011 As you always want to hear the little "click" of slide hitting bottom after working on things prior to starting the bike! Before starting the bike I always just touch the carb so I can feel the slide returning to "home". Thank goodness somebody has mentioned that starving a 2T of fuel is not a good idea. Choke yes, top gear and rear brake on yes, boot/glove on exhaust yes. Remove spark plug cap? If the kill switch doesn't work why would removing the spark plug cap? Also you are likely to get a helluva belt. <why doesn't the kill switch work in these situations? Well read up about the Honda EXP-2 bike and find out> Quote Link to comment Share on other sites More sharing options...
mattylad Posted February 11, 2011 Report Share Posted February 11, 2011 All the above advise is good but the rear wheel is whizzing round right next to the exhaust. I have seen a magnet activated kill button attached to Fabio lenzis Future team bike. As soon as you let go of left handlebar the magnet was pulled off by the attachment to your glove. Even works at high rpm so would be good for kids. Possibly made by acerbis or domino Quote Link to comment Share on other sites More sharing options...
zippy Posted February 11, 2011 Report Share Posted February 11, 2011 All the above advise is good but the rear wheel is whizzing round right next to the exhaust. I have seen a magnet activated kill button attached to Fabio lenzis Future team bike. As soon as you let go of left handlebar the magnet was pulled off by the attachment to your glove. Even works at high rpm so would be good for kids. Possibly made by acerbis or domino When I was a youngen my dad made a kill switch similar to that out of a set of points for when we did parades. The points were held apart by some non-conductive material and that was attached to our wrists by a string. All pretty low tech but very effective. Not sure how well it would work at high RPM's. Quote Link to comment Share on other sites More sharing options...
toofasttim Posted February 11, 2011 Report Share Posted February 11, 2011 Not sure how well it would work at high RPM's. I doubt it. When 2Ts are on full throttle the mixture in the barrel self combusts. It's similar to dieselling. Quote Link to comment Share on other sites More sharing options...
jse Posted February 12, 2011 Report Share Posted February 12, 2011 (edited) I doubt it. When 2Ts are on full throttle the mixture in the barrel self combusts. It's similar to dieselling. That's been my experience also as the fairly high compression and porting arrangement of Trials engines lead to autocombustion fairly quickly. Usually I've found that to avoid damage to the engine something has to be done quick and moving the bike can be time consuming and/or dangerous. Since I'm right handed, I'll quickly take off my left glove, wad it in my right gloved hand and cap the exhaust, which usually drops the RPM's down to the point the kill switch then works and I avoid burns to my hand. Jon Edited February 12, 2011 by JSE Quote Link to comment Share on other sites More sharing options...
toofasttim Posted February 12, 2011 Report Share Posted February 12, 2011 (edited) Honda took the phenomenon, controlled it and built a bike around the principle (told you I admired Hondas engineering). From: Honda EXP-2 "Honda has tamed pre-ignition; on the EXP-2 this auto-ignition is computer controlled to enhance performance and most importantly virtually eliminate pollution. Usually thought of as a bastion of four-stroke technology, Honda's new two-stroke design promises less pollution, better fuel economy and most important, no loss in power. Pre-ignition will destroy a normal two stroke. It is caused when the temperature and pressure in a cylinder builds to a critical point and the air/fuel mixture ignites prematurely in a violent explosion rather than in a controlled burn. The premature explosions are ignited either by red-hot engine parts or highly ionized reactive molecules left from the last exhaust cycle. Using premature combustion to more thoroughly burn the mixture is not a new idea -- diesels don't have spark plugs either. But it's the first time that auto-ignition has been successfully applied to a gasoline two-stroke. Above idle, and below 40 percent throttle, the spark plug is not used. The exhaust power valve automatically regulates combustion pressure, guaranteeing that pre-ignition will start and end at the correct time. Once the critical pressure is reached, the reactive molecules act like millions of tiny spark plugs, firing the mixture much more evenly than any single plug could." Edited February 12, 2011 by TooFastTim Quote Link to comment Share on other sites More sharing options...
buchanan84 Posted February 14, 2011 Report Share Posted February 14, 2011 I doubt it. When 2Ts are on full throttle the mixture in the barrel self combusts. It's similar to dieselling. I reckon it would have a much better chance than a normal kill switch as it would be activated much quicker as you've usually fallen off the bike before it starts auto ignition i think i'm going to fit 1 this summer, will definately prevent a few nervious moments when mucking about doing wheelies, stepping off and the bike carrying on without me usually heading towards someones car Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted February 14, 2011 Report Share Posted February 14, 2011 I reckon it would have a much better chance than a normal kill switch as it would be activated much quicker as you've usually fallen off the bike before it starts auto ignition i think i'm going to fit 1 this summer, will definately prevent a few nervious moments when mucking about doing wheelies, stepping off and the bike carrying on without me usually heading towards someones car Strewth where do you ride? I want to avoid it. Quote Link to comment Share on other sites More sharing options...
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