Weirdest mechanical failure or problem

I was racing a SORCS hare scramble in Resaca, GA. I had told myself I would fo a top end after this race. I knew it was over due. I could hear it rattle a bit. When I went to kick start my CR250R at the dead engine start the kick starter would not move. I rocked my bike backwards a little and kicked it again and it fired up. I finished the race in the top 5 of my class. Tore my bike down the next week and found this.

In 03 right when the CRF150 was released, i happened to get one of the first ones.
Ran great around the yard when my dad brought it home and before our first trip out on it, it wouldn't start.

Pull the spark plug, flip it upside down after pulling it and all is fine and shows spark.
Put it back in and nothing.
After a few hours, we take it back to the dealer.
A couple hours later we find out the issue.

The porcelain around the spark plug would slide down when in the installed orientation and not allow spark...$5 fix and a $200 bill later we were good to go.

My brother had an 09 CRF 450 that grenaded going up the collar bone hill at Millville. Rod shot through the cases and that's all she wrote. A few months down the road and a couple grand later, it was ready to go. Back to Millville for pro nats and we went to ride a track down the road the day before amateur practice to get the bike broke in. He pulls onto the track and second corner in, the brand new chain he had put on snapped and busted the drive side case. Needless to say he felt pretty defeated after that.

On the line in the late 90s on a '97 CR125. Guy runs down the gate to check everyone before he drops it. I click the bike into gear and rev up, easing the clutch so its right on the edge of engagement and instead of creeping forwards I creep backwards. Obviously that causes a panic so I dump the clutch and the bike crawls half out of my starting rut. Find neutral, put it in gear again and it's rolling the right direction now, so I roll in and barely make the gate drop.

Isn't it cool when one minute you're thinking, "Damn, this thing feels super fast, WOW!"

and then it blows up

Oh, ever start a two stroke, click it into gear and it goes backwards?

Somehow the engine fires up backwards...that's weird

Used to have a friend who raced flat track and short track. He told the story of a fellow racer that lined beside him at a race, fired up his Bultaco and when the rubber band released he went backwards. The two stroke motor was running backwards. Of course the story was embellished by saying that the guy was already shifting up a gear before he could get his brain around what was happening and hit the brakes .

Bent some bars on an old Honda 85, brought it in and my dad replaced the bars while me n my brother were out in the pits, I was into this girl n my dad couldn't keep me focused on the race and would come find us. Well that day the distraction was on him, next Moto wide open threw sand rollers my entire bars attached to the triple clamps slipped off and I pretty much fell off the back of the bike with my bars still in my hand long enough to realize it was time to let go. I think that was my only Moto I lost that weekend in the 85 class because mike was riding big bikes and supermini classes.

GNCC race in FL on an older CR. Make it through the first lap without any issue. No crashes and it’s a great day. Stop to get my number scanned (before transponders) and try to go. Twist the throttle and nothing. Bikes still idling and happy. Keep twisting and still nothing. Push it back to the trailer and take the top off the carb. Cable is there but nothing else. Wtf? Pull the slide out and finally realize that the piece that holds the cable end to it is still attached to the cable.

Eh I don't have that good of a story but I have a 2018 YZ250f that I maintain really well and it runs flawlessly as it should. Well last year I was on the gate for a race and so as guys are crossing the finish I kick my bike over. The card guy starts walking out and my bike just bogs out and dies. Immediately I yell WHAT THE FUCK, and Im thinking "of course this would happen to me right now" and I'm kicking and trying to start it in neutral, in gear, with the throttle cracked. After 15 or so kicks it comes back on as the guy drops the card. It was probably a 20 second ordeal but felt like an eternity. Never had that issue before or since, it was so bizarre.

I’ve had a lot of weird mechanicals over the years.

Had the flywheel break off the crank on a KTM 200 twice

During the start of a desert race I got hit with some roost and it shattered the in-line fuel filter on my KTM 200. Had to bite off my camel back hose and use that as the fuel line. Little did I know that the water line had some kind of plastic liner inside of it that didn’t react well to gas. Has to ride most of the race with my hand on the fuel line keeping it from kinking.

Hit a concrete water culvert going under the 15 freeway so hard that it pulled my rear wheel so far back that the chain was too tight to move.

Went to Australia to race the Australian 4 Day Enduro in 2018 and rented a brand new KTM 450 EXC from a dealer. The piston rings broke half way through day 3.

2019 ISDE on a 2019 350XCF, at the first fuel stop of day 5, rode in, got gas, got a bit of food and went to get back on the bike to roll into the next time check and special test. Hit the starter and nothing, battery had shorted or dropped a cell or something Half houred out trying to figure it out. Put a new battery in and restarted day 6 for the final moto. Good news is I was able to win my final moto.

1979 YZ125,
I had rebuilt the bottom end and ran it in on a flat track, next week every time I landed from a jump it bogged badly, after many laps it just died altogether.
Week's later I eventually found one of the wires in the ignition coil was rubbing and shorting on the stator.
Ruined two race weekends.

Problem? I know of a rider here in SA, he is a mate of mine now and I wont name drop...he is well known. And has been ripped to pieces by the followi g deak.

He was on the start line at a national when he realised he never had his goggles. He's oldman was his mechanic and they both assumed all was good.

The oldman got permission for the rider to hurry back to the van to get his googles.

He never returned, the gate dropped on the premier class and nothing...he never returned.

The oldman apon returning to the pit found the bike laying against the van and the rider screaming from the darkness of the rear.

When he jumped in the back to get goggles the wind blew the door shut and he was trapped inside. No one could hear his calls for helo.

The van was a homefitted deal and had no inside alternative to open it.

I had the carb slide on my '01 YZ426 work loose and close while in the air over a jump during a night practice in Highlands Texas. Bike died, I kissed the front fender when I landed, then managed to roll to a stop without crashing. I kicked that bastard on the side of the track for 5 minutes or so, pushed it to the pits, replaced the spark plug, then kicked it some more. Had to load up and go home.

The next day I did some more diagnosis, saw I had spark so decided to remove the carb. When removing the carb I could hear the screws that hold the slide rattling. Fortunately nothing got sucked into the cylinder. I was able to loctite the screws back in and no other issues after that.

It was totally my fault. I had taken the carb and slide apart for something and just didnt do a good enough job reattaching it.

Poor bastard,
That a regular dream of mine, I'm on the starting line and I have forgotten gloves, boots or goggles.

So at a race, a guy next to me has a bike that wouldn't run , rode it back after the first race, didn't fire up for the second, I didn't get involved as I had my own stuff going on, but it became obvious that he was struggling and his mate with him was clueless.

So after hearing this 610 Husky , pop and backfire, I figure it sheared the woodruff key. I ask him if he has checked the ignition, and he looks at me blank. So I grab my T Bar, pull the cover off. and the rotor is loose. I pull the nut off, and the rotor, and the key is sheared. He has like 3 mins, before he has to be down to the holding area, so I told him, to get his kit on, as I needed to get something out of my toolbox.. he gets kitted up and just as I finish sticking the cover on he is ready, jumps on and kicks it, and it goes second prod, he shoots off and does his race.

Our paths didn't cross for another hour or so, and when we both got to talk again, he said ' its so lucky that you had a spare key'.. I laughed , and said ' I didn't, I went to get the magic marker to mark the slot position' ..

He didn't believe me, and I had to take the rotor off again to prove it.

I used to have a 2006 YZ450 and one morning before a ride, I pulled it out of the shed, checked it over, kicked her in the guts and warmed her up a little.
I loaded her onto the ute and headed off but do you think I could start it when we got to the track, we checked the usuals, we pushed it, towed it, checked everything and nothing so I packed up and headed home.
It wasn't until I had run out of things to check that I pulled the rocker cover off and found that the timing had moved a tooth or two on both cams.
My initial though was this is a disaster as being a mechanic, i was expecting the valves to be bent and potential piston damage but after pulling the head off, the valves had just barely made a small mark on the carbon on top of the piston and after checking the valve seat, stems, chain tensioner and everything else that goes with it, i pieced it back together and rode it for another few years with out an issue again.

Hi Mate

I had the same thing a few years ago when working on a friends bike in the shed over a few sherbets.
The bike would break down at high RPM under no load so we checked a few things, changed the plug, checked for carb issues and the usual.
It wasn't until his father come down and said when it would start breaking down, the TV reception in the granny flat next to the shed would go all pear shaped, I put 2 and 2 together and found the coil grounding wire loose!

I cased a big outdoor triple on my 98 YZ125 when I was young. It landed so hard it ripped the linkage off the frame, flt out split the tube down the middle, and bent the shock shaft.. I didnt crash, and even raced in pain the next day, then Monday found out I cracked 3 vertibrae. To be young again.....I cant even put socks on without pain nowdays, let alone ride w cracks in vertibae. Hmm, maybe thats why i cnat out on socks....
I kept the broken linkage as a fun prize.

1983 RM125 swing arm pivot bolt broke and started coming out. I would kick it back in over the jumps. Fixed the problem by taping the bolt on the nut end and installing an grade 8 Allen bolt.

This is just your ordinary "fouled plug" episode BUT.... I have, in my entire riding career, fouled literally ONE plug. Maybe there were others, but It's so rare that I can't remember them. That one plug was a BR8EIX in my '04 KX125 and occurred at start-up after arriving at the track. I'm telling you that to tell you this.

My son and I both put Lectron carbs on our KTM 150's. Mine is a XC-W with a RK Tech insert. His is stock SX. We rode them around the ranch, tested them, fine. He had a little trouble starting his bike but had been having some trouble for a month or so. We'd put a new top end in and then things seemed okay, although rich down low.

Okay, so, fast forward to our first enduro with the Lectrons. We'd ridden down the road, warmed up, our neighbor with Lectron experience had ridden both bikes. All's good. We're sitting on the line, engines off, and 2 minutes to go so we fire up. His bike won't start. I said "change the plug, now!!!" A friend of ours at the line SLOWLY gets the plugs out and everything moves at the speed of "crawl". I kick my bike over. Chug...chug...chug... it sputters to life and promptly dies. In 50 h with this bike, I have NEVER had that happen. E-start doesn't bring it to life. Nothing. So, I grab the plugs, rip mine out, toss a used (but clean) one in and boom... starts up. I take off, some 7 minutes late now while my son is trying to push start his bike. He eventually went to our truck (parked right across the road!) and dropped a new plug in. Starts right up and off he goes, 15 minutes late. In spite of starting 15 minutes late, he still won the test (by 1 minute) and won the overall C class.

Later, we're talking about it and figured out that his starting problems started when we switched to BR8EIX plugs. We both had new EIX plugs on that day and guess what the KX had in it when it fouled? BR8EIX. We also suspected our oil/ratio as a contributing factor since we'd switched to Klotz R-50 which has a very high flash point, as I later found out, and the fact that we were trying 60:1 instead of our normal 40:1. With this, we have a lot of fuel (not burning it all) mixed with a very high flash point oil (not burning it either)

My suspicion is that the EIX is sensitive to initial flooding... the Lectrons run richer on start-up, then add the richer mixture of 60:1 and you've got much richer start-up... and the plugs were just flooding out. Spray them with contact cleaner, and they'd run again. After this mess, we switched to Motorex, went back to 40:1... I've got a stock plug in mine, he's got a BR8EG, 20+ hours later, no more issues... instant start-up for both of us.

BUT... for us to BOTH foul plugs on the starting line of the first enduro of the year, after all that testing and warming up and preparation... that was exciting!!! And I have video!!!!

https://www.youtube.com/watch?v=lGBsalprhzA

I was running in a comfortable 2nd in a SA national with a lap to go when the bike started reving higher and higher, the throttle was actually becoming unresponsive....the bike was screaming and I was working that clutch....and then she died with a few corners to go.

My oldman fined turned the carb before the moto and had changed the needle...he admitted that he could not recall tightening the carb slide cover down...the whole damn slide was out.

I owned him on that trip home....

Me and my buddy where riding in Austria. Guy next to us couldn’t start his bike. First we let him mess around but soon we start feeling sorry for him and we start helping him. Bike sounded like it was flooded. He had no spark plug with him but we had. So we changed the plug and it was completely whet. New plug in, still nothing. We ask him if he changed the airfilter? Yes he had. Did you put in a rag en did you take it out before you put in the new filter??? His face lighted up and he knew he had forgotten to take the paper rag out. We took the filter out and there was the rag. We pulled it out and putt the filter back in. Few kicks later the back ran and the guy was super happy!

Went for world record time main bearing swap in an 06 yz125. Got it all back together same night that we started and the bike would not shift into 6th!

So the next day it came back apart, much slower this time, stared at the transmission for a few hours and noticed one of the shift forks wasn't sliding.

Turns out a little bit of case glue got between the fork and its slidy shaft. Could have just warmed it up and shifted harder!!!

I rebuilt the bottom end on my Maico AW250 back in the day after the carb boot split at Ohio International in Ravenna and sucked the bottom end full of mud..

Took it to a Suzuki dealer to split the cases and install new main bearings and seals. Took the bottom end home and re-assembled it.

Fired her up, let out the clutch and she went in reverse!

After much fucking around wasting time setting and re-setting the timing, I pulled the rotor off and discovered that the shop beat the end of the crank with a hammer getting the crank out and slightly mushroomed the end of it so that when the rotor went on the tapered end of the crank it had a bit of a wobble on.

Filed her down, re-installed the rotor and stator/points assy and was good as gold.

Weird-ass feeling going in reverse, though!

Racing at Tomahawk, WV one time, I came over a blind jump and there was a guy and a KX450 laying in the middle of the track. I had to choose either hitting him or the bike- I chose the bike.
Once I got up and going again, I'm riding around and my rear brake isn't working. I look down and there is a green rear fender jammed between the brake pedal and the cases. I kick it out and keep going.

My buddy picked up a Suzuki LTZ400 quad for his girlfriend, ran great until one day he found it would only run for about 2 minutes and then die. Wait 10 minutes or so and it was good to go- for another minute. Go through the usual suspects- carb, check grounds, go through ignition system, vacuum operated petcock, etc. Nothing. He got irritated and stuffed it into the barn, only to pull it out every few months to dick with it some more. The quad languished for several years.

Last year I was helping another friend with his neighbor's Warrior quad. It didn't want to start, would run really poorly when it did start, etc. I eventually figured out the timing was off- the rotor had spun on the crank after breaking the woodruff key. It ran, but something was still off. I suggested that he throw a fresh plug in there, as the old one looked like it had seen better days. It fixed the issues and the Warrior was back to hauling beer around the campsites.

I mention to my friend with the Suzuki what I found, and he said "doubt it, plug looks perfect in the LTZ." However, he met a guy that said he had several Suzuki 400's, and that he could come over and swap parts until the problem made itself known. Upon arrival, my friend discovered that while the guy did indeed have several Suzuki 400's, they were DRZ dirtbikes, not LTZ quads. On a whim, my friend asked if the guy had a sparkplug handy. "Sure, but those never go bad on these bikes." Well- you already know the ending- the damn sparkplug had gone bad nearly 10 years prior and changing it resulted in a perfect running quad. To this day my friend will change a sparkplug anytime something even remotely odd goes wrong with one of his many quads, SxS, and dirtbikes.

Ah! Forgot about one until just now.

Buddy bought an 08 KTM450 from his brother in law(a good friend of ours). It had been sitting and the brother in law had the frame and stuff powder coated a while before. Well, he forgot the put the collars back on the swingarm(PDS setup). So I went through the carb and replaced the lower shock bearing and collars. Fired right up for me and ran great. Rode it around on my street once or twice just to make sure all was good. Ran great, so my buddy picked it up and took it out to the desert for a weekend camping trip.

He rode around camp for 2 minutes just to get used to riding again since he hadn't ridden in a little bit. All was good! So he rested and gassed up the bike to go for a 30 minutes cruise. He got a little ways from camp and the bike died. Fired it back up, ran for a few seconds then died again. This kept happening until the battery was finally drained. He pushed it about half a mile back to camp. He called me and we tried a few things, but nothing worked so he parked it for the weekend.

He brought it back to me on Monday. Took a quick look and noticed the fuel line was kinked! It was some cheap type of hose and kinked super easy. It was just a little too long and that is why it kinked in the first place. I cut a little bit off of the hose and no more kink. Fired it up, rode it around for a good ten minutes and no issue. Both of us were pretty bummed it was something so small and stupid. It was never something I even thought to check out before he grabbed it to go camping. Needless to say, I constantly check every bike I work on now.