Two Stroke Motocross
Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: keeptwostrokesalive on December 28, 2010, 10:05:28 AM
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This guy on vitalmx is selling his 450 and 250f because his bike shutt off at the face of a triple. The good thing is that he is going to buy a yz250. sometimes people have to figure out things the hard way dont they.
http://www.vitalmx.com/forums/MotoRelated,20/2009CRF450R,1160758 (http://www.vitalmx.com/forums/MotoRelated,20/2009CRF450R,1160758)
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I agree, when Stewarts 450 blew up in the air at Southwick it threw him into a nasty endo. On the tv replay you could see the spokes in the back wheel stop were it just locked.
Atleast a 2 stroke will usually bogg. Either way is still bad news on the face of a jump
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Its a shame people have to learn like that, atleast he has come to his senses and is switching over. I cant tell you how many times I have seen or heard of 4 strokes cutting out or even worse blowing up right before jumps. So not only are 4 strokes expensive for the rider, its expensive for insurance companies after they wreck!!!
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Free revving a thumper is bad news. The gasses in the cylinder provide a bit of a cushion each time the piston moves to TDC. When these idiots are blasting off the rev limiter, there is no cushion. You just get mega torsional loads trying to stretch the rod into two pieces. This is what happened to Bubba on that downhill. Rod snapped, engine locked. IT's like no one realizes that people used to free rev their two strokes at the gate just to make sure the plug was clean, not to show off.
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Yeah, I always have a chuckle on the start line, when the fourstroke riders "clean out " their engines before the start.
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Let's not get retarted. 2 strokes sieze up on the face of jumps too, remember fro on his YZ250 in 2000? He broke both of his wrists. It ended his career.
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Yesterday, at the private track of fellow Yamaha rider Stephane Roncada in Riverside County, California, Emig came up short on a triple jump, reportedly snapping both forearms above the wrist.
Have any proof his bike seized? I do remember Doug Henry's 4 stroke bike seizing. I also know there is a difference of a 2 stroke seizing, which means loss of power, and a 4 stroke, just stopping dead locked up.
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Yeah but a clunker seizing on the face of a jump is much more dangerous than a smoker doing it due to the fact that a smoker is not as likely to nose dive. Four strokes just love to endo.
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If I remember correctly Emigs bike didn't sieze in 2000, the throttle stuck wide open. Had a friend with a 2000 yz 250 had the same thing happen and he lost his splene (sp). They had a problem with those carbs that year.
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Ok, maybe it didn't sieze on him, I thought I remember reading it did though.
True that 2 strokes are not as prone to just locking up. I have had 2 125s seize on me, and both times they obviously lost a bunch of power before just dieing.
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Free revving a thumper is bad news.
I dont see how they keep valves in Barcia's bike.
Yeah, I always have a chuckle on the start line, when the fourstroke riders "clean out " their engines before the start.
I agree on a 4 stroke it seems pointless. I think revving on the line is more about getting yourself ready to race, like pumping yourself up.
Yeah but a clunker seizing on the face of a jump is much more dangerous than a smoker doing it due to the fact that a smoker is not as likely to nose dive. Four strokes just love to endo.
Agreed. But an unexpected loss of drive on the face of a jump will endo anything.
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Yeah, every 125 I've popped open had scoring on the piston. Early signs. Always on the exhaust side. I just picked up a 125SX and I'll be runnin Amsoil interceptor at 40:1 and see what happens after luggin my 200 lbs around the track..
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I have had both 2 and 4t bikes die on the faces of jumps.... When the 4-stroke died i broke my back, leg and nose, when the 125 locked up i broke 12 bones and got knocked out......... so you cant really say one is worse than the other. The 4 stroke died on a HUUUUUUGE jump and endo'd. The 125 locked up solid on the face of a triple end endo'd. 6 in one 1/2 dozen in the other when it comes to a bike quitin on you.
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i will third the above. we wish it was the 4t that is the danger but its just physics..... 2 or 4 any sudden loss of momentum on a jump face combined with the compression and say hello to your front fender......... but what we do have going for us is the simple fact 2t are not ticking time bombs and with simple maintnace of our 2t we can avoid this all together.
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I'd say there is a huge difference in the numbers of each that have had this particler thing happen. First, when my bikes ever blew up, it had full power, until I let off, and then, it went, wa wa waaaa. But even at that, I'm hearing much more percentage of riders experiencing motors locking up at bad times on 4 strokes. So yes, I agree, it probably does happen here or there on 2 strokes. But I'd bet my dollar that it is like 1:99 ratio. Most 2 strokes blew up, because wrong jetting, or didn't let their bike warm up enough. Mine blew up from the crank going, but, after my first and only, I always would take the cover off every season and feel the movement. If there was any at all, it was crank time. I can guarantee that my hours on a crank are atleast twice as much as on a same cc 4 stroke before they let go. We can pretty much protect ourselves from any problems on a 2 stroke. If you build it right, jet it right and keep maintence, not too many issues. On a 4 stroke, you have a good chance even if you do things right. It's called much more moving parts. If a 4 stroke had equal parts, let's say, I'd say they would have equal chance. But given the have so many more, it increases that many areas they can fail. JMHO ;D
And let's not forget the higher RPMs they are running on a 4 stroke.
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Yeah. My Cr80 blew up twice in one month (my dad said something about the mechanic not changing to oil after the rebuild) and both times it had full power till it died.
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Ive blown up four 2 strokes and all of them bogged out while pretty much wide open.
My kx125 blew up while I was flying down the road. It bogged out like the plug fouled then locked up. (top end)
My yz125 blew up 2nd gear pinned in a set of whoops. (top end)
My rm250 blew up while I was going up a straight. (top end)
While riding a friends cr250 it blew up climbing a hill. (crank)
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I have never had an engine failure till my piston went at the dunes, and it didn't lockup either.
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That's why I won't ride the dunes, if you're not air tight gonna be sucking in some sand.
I never had a bike blow up, bikes usually become noticably hard to start when they need a new top end.
The only bike that ever blew up of mine but I wasn't riding it was a 1970 Honda SL125S (4 Stroke). I wouldn't really count that though because that bike sat in the woods for years before I got it and we tried to get it running. It was never running right and when my dad thought he finally had the points adjusted right (which were actually ones we had laying around from an ATC 90), it locked up in 3rd gear. Never took it apart though or did anything with it. So being that it was sitting out in the woods for years before it was given to me I can't count that as an honest bike blow up, was amazing the bike was running at all.
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I have had one 4t stop on the face of a jump and numerous 2 strokes. all in my 125 days. The 450 just died going up the face of a 4th gear pinned double and i just bailed. The 125's mostly died in "safe areas" but I had several let go in the whoops and twice on the face of a jump. The last time it locked up solid and thats when I broke all the bones it was like someone put a stick thru my spokes........ As stated before, both are equally as dangerous. If one dies on teh face of a jump it doesnt matter what stroke it is, your going for an unwanted ride!