Weirdest mechanical failure or problem

moto804
Posts
218
Joined
3/14/2014
Location
Schaumburg, IL US
5/11/2020 7:03pm
Sorry, kinda long winded...
2005 broke my leg real bad, and had already caught the Supermoto bug pretty bad. That same year we supported a kid out of my dads shop on a KTM525 in the AMA SM series and he did really good.

The next year we managed to talk the Husaberg distributor to support a team featuring him out of our shop and get a "demo" bike for me. He was a top 5 guy, I made 7 out of 10 mains in the Unlimited class in 06.

Fast forward to 07, I had spent too much money chasing my dream of being a "PRO" the previous year, so just focused on the local series in WI. Final round of the series at the Road America kart track, I need to finish ahead of a friendly rival in both heats to tie for the championship. I beat him by a couple bike lengths the first heat. The 2nd heat, as I crossed the finish line I looked down under my right arm to see his orange fender almost touching my armpit! It was an awesome end to a really fun season (he won the championship on tie breakers for more wins).

When we coasted back toward the podium for post race interviews my Berg stalled which doesn't seem significant, but it always idled perfectly. After the interview it was time for the dash for cash, bike wouldn't restart no matter what. Just decided: End of the season, let's have a beer!

Tore the bike down a couple weeks later and:


One of the many quirky designs on the Bergs was that the air filter is on the backbone of the frame. The crankcase breather also vents to the frame. When this piston cracked, the cc pressure went thru the roof and blew a bunch of oil into the carb causing it to stall at idle. The crack goes all the way across the crown and is almost to the pin, not sure how many more laps I had under power before it would have come apart completely...

Mid way through 06 I had put in a hi-comp piston that my team-mate had laying around. You can really see a difference in structure between the stock and hi-comp units.


2
DirtRoadmx47
Posts
168
Joined
6/18/2012
Location
Campbell Hall, NY US
Fantasy
1640th
5/11/2020 7:12pm
1983 250AM on the gate realize my axle nut is gone, shrug my shoulders and say to myself " well it didn't cause a problem in practice" gate goes down and I pull the holeshot, I'm running a solid 2nd and with 1 lap to go my chain derails. DNF,, come back 2 years later in the open class, Win the first moto only to realize my kick start lever is gone, my friends jump start my bike and I'm running 5th and can see 1st place up front , I think to myself I can pass these guys and next thing a rock kicks up and hits my rear chain guide and knocks it off and it lodges into the countershaft sprocket and kills my bike..... A 1st and a DNF ??? would have been my first trophy
FlickitFlat
Posts
3018
Joined
8/15/2006
Location
,, WV US
Fantasy
644th
5/11/2020 7:40pm
Weirdest? I had a buddy miss a moto during a mud race because his bike wouldn't start. It took a little bit to figure it out but turns out that it was mud stuck in the gas tank vent hose. The clogged hose wouldn't allow fuel to the carb. So simple but cost him a race.
RonSkj
Posts
2812
Joined
6/20/2008
Location
Radiator Springs, CA US
Fantasy
129th
5/11/2020 7:53pm Edited Date/Time 5/11/2020 7:54pm
Riding a grand prix years ago and I get my front end taken out in one of the first few turns, resulting in a tip over that snaps off my front brake lever. Get going again, riding with no front brake. I come into this section where they had put a bunch of tires in the track that were 1/2 buried into the ground. With guys zig zagging around them, I figure I can just kinda blast my way straight thru and power over the tires that got in the way, as these tires were just smaller size car tires. All went as planned and I made short work of those tires. From there we head down a straight away that came into a 90 degree turn. As I go to slow down for the turn, I can't find my rear brake. Why? because going over one of those tires, I remember a momentary hangup that I figured was just due to hitting this tire. I was wrong! It was the rear brake peddle catching on the buried tire and breaking off. I made Brandon proud in that turn.
1

The Shop

cable
Posts
1184
Joined
6/11/2008
Location
Rockford, MI US
5/11/2020 8:51pm
2004 ktm 450. leading my moto and the bike seems sluggish on last lap. i win and people tell me i was leaving a smokescreen. I pull the top end off and the rings fall into peices everywhere. it was a stock bike, the KTM sals rep let me race for awhile. I had a 2001 cr250 that broke a crank pin. bike had maybe 10 hrs on it. Honda warrantied it. apparently cases were cracking and causing it? i never felt a vibration, it just let go in practice, and i was lucky not on a jump.
rk337
Posts
31
Joined
9/5/2017
Location
Orange, CA US
5/11/2020 9:39pm

I raced NHHA so 40 mile loops in the southern desert

-broke the bolt that holds the top of the subframe in, also sheared off and lost a bolt holding the lower subframe in, all without crashing. silencer and airboot held it all on as the seat bounced up into me continuously for about 7 miles. Got to the pits and grabbed another top bolt from my van and screwed it in as much as possible, and added the duct tape. Raced it for another 40 miles before finishing and finally being able to figure out what went wrong.

Another race, 1/2 mile in, Brabec passed me off trail going side hill and slightly hit my front wheel. Everything was good until we went down a hill and I had no front brake. Somehow the front brake banjo bolt got hit. loosened up from the contact, and drained all the fluid. Fun times for 40 miles with no front brake and quite a few high speed fire roads! Refilled the line, bled the brake real quick, and back onto the race

Have also lost 4 pins for my stabilizer without the stabilizer coming off while riding, neither myself nor Scotts has been able to figure that one out..
1
Muzzle
Posts
166
Joined
6/20/2013
Location
Vernal, UT US
5/11/2020 9:51pm
I was racing a Utah hare scramble and somewhere on the first loop the bolt securing my shift lever backed out and the lever fell off. I was able to find the lever but not the bolt! Luckily I had some pliars in my camelbak so I tried to ride the rest of the loop Dungey style reaching down to shift with the pliars. Needless to say I was not as smooth as the Dunge and would just about fall over each time I tried it, lol. Eventually I had to stop for each shift before I hurt myself. Made for a long loop, haha!

Good times!
Cokeham23
Posts
547
Joined
3/4/2010
Location
TX US
5/11/2020 9:54pm
Weirdest? I had a buddy miss a moto during a mud race because his bike wouldn't start. It took a little bit to figure it out...
Weirdest? I had a buddy miss a moto during a mud race because his bike wouldn't start. It took a little bit to figure it out but turns out that it was mud stuck in the gas tank vent hose. The clogged hose wouldn't allow fuel to the carb. So simple but cost him a race.
Had this happen to me and it drove me nuts for weeks. My bike would run great for 15 minutes or so (about a motos length for me), any longer and it would bog down and die then wouldn’t restart for a couple minutes. Checked everything over, and over. Carb, electrical, whatever I could. Finally a buddy rode it, it died and he put the bike on its side to see if fuel came out the overflow, none did so he pulled the vent hose and bam fuel came out the overflow. I was so pissed it was something so dumb and simple, but glad that it was solved. I was about to burn the bike Laughing
Boomslang
Posts
6932
Joined
12/22/2018
Location
Cape Town ZA
Fantasy
725th
5/11/2020 10:33pm Edited Date/Time 5/11/2020 11:13pm
I worked at a Kawasaki dealership in the early 1990's, one of the mechanics got his job card, it was to completely reduild a 1983 KX500's motor, stripdown, assessment and a estimate was presented to the client.

Fast forward, job complete and the bike was started and ran like a dream. The mechanic warmed the bike up good and put it in first gear, he let the clutch out and promptly went over the bars and hit the ground in front of us.

The motor ran in reverse. First and only time I've seen it happen.
3
mattyhamz2
Posts
10879
Joined
7/6/2015
Location
So Cal, CA US
Fantasy
846th
5/11/2020 10:46pm
moto804 wrote:
Sorry, kinda long winded... 2005 broke my leg real bad, and had already caught the Supermoto bug pretty bad. That same year we supported a kid...
Sorry, kinda long winded...
2005 broke my leg real bad, and had already caught the Supermoto bug pretty bad. That same year we supported a kid out of my dads shop on a KTM525 in the AMA SM series and he did really good.

The next year we managed to talk the Husaberg distributor to support a team featuring him out of our shop and get a "demo" bike for me. He was a top 5 guy, I made 7 out of 10 mains in the Unlimited class in 06.

Fast forward to 07, I had spent too much money chasing my dream of being a "PRO" the previous year, so just focused on the local series in WI. Final round of the series at the Road America kart track, I need to finish ahead of a friendly rival in both heats to tie for the championship. I beat him by a couple bike lengths the first heat. The 2nd heat, as I crossed the finish line I looked down under my right arm to see his orange fender almost touching my armpit! It was an awesome end to a really fun season (he won the championship on tie breakers for more wins).

When we coasted back toward the podium for post race interviews my Berg stalled which doesn't seem significant, but it always idled perfectly. After the interview it was time for the dash for cash, bike wouldn't restart no matter what. Just decided: End of the season, let's have a beer!

Tore the bike down a couple weeks later and:


One of the many quirky designs on the Bergs was that the air filter is on the backbone of the frame. The crankcase breather also vents to the frame. When this piston cracked, the cc pressure went thru the roof and blew a bunch of oil into the carb causing it to stall at idle. The crack goes all the way across the crown and is almost to the pin, not sure how many more laps I had under power before it would have come apart completely...

Mid way through 06 I had put in a hi-comp piston that my team-mate had laying around. You can really see a difference in structure between the stock and hi-comp units.


My dads 17 RMZ450 cracked a piston just like that. Thankfully his shut off before he reached the face of the jump in front of him. Bike had around 20 hours
Husky Cat
Posts
5
Joined
1/29/2020
Location
Shawnee Mission, KS US
5/12/2020 3:34am
This past Saturday I took a minor off trail excursion right into a dead fall. Instant steam bath. Got back to my truck and I found this. Branch went between my skid plate, exhaust and down tube to knock my coolant line off.

sandman768
Posts
6095
Joined
3/21/2014
Location
Saratoga Springs, NY US
5/12/2020 6:03am
2006 YZ450. 1. Shock spring snapped in 1/2 on a very small double, destroyed the complete shock
2. Transmission exploded in section of whoops...complete transmission was destroyed
3. Engine started making a loud growling noise...removed head...piston wrist pin was broke in 2 .. still ran.
2008 YZ250 2T
1. Wicked air leak..could not find it.. soon as you touched the throttle the rpms just hit the ceiling.
Leak down test, showed the main bearing pocket behind stator was cracked completely around the
Main bearing. The bike did have around 100-150hrs on it.
Went back to Honda’s......
sandman768
Posts
6095
Joined
3/21/2014
Location
Saratoga Springs, NY US
5/12/2020 6:07am
Not really a mechanical but.. in 1987 I was on an 87RM 250... first turn pile up.. I get back on my bike, I”m covered in gas... someone’s handlebars went right through my gas tank... nothing like spending 300.00 on a part that does nothing for the performance of your bike...as usual the dealer felt bad for me and gave me zero discount on the part👍
Robgvx
Posts
3687
Joined
4/1/2008
Location
GB
5/12/2020 8:59am
Was running in tenth in a GP, heading for my first-ever points. Then the front tyre bead came partly off the rim, for just about 6 inches. The still-inflated inner tube bulged out of the side of the tyre like a balloon and jammed up against the fork leg.

WTF?

The Inside Line book
mxtech1
Posts
1957
Joined
7/21/2011
Location
Galesburg, IL US
5/12/2020 9:35am
I've heard various stories of the cut off ends of twisted safety wire getting into odd places and causing damage. Learned lesson...always account for where the trimmed off end goes (in your hand and into the trash)

Roost/objects hitting the petcock lever and shutting it off happens more than we think. This is why some OEMs use to mount the petcock with the lever facing inwards.

One particular KFX 90 (kids quad) I worked on kept filling the crankcase with fuel as it sat overnight. I bet I had that carb on/off and completely disassembled a dozen times and tried 3 different carb rebuild kits. I could find nothing wrong with the carb it looked perfect inside and out and was basically a new machine. I quickly grew to resent that little machine. We eventually requested a new OEM carb from Kawasaki under warranty and the replacement carb solved the issue.
Shaggin589
Posts
223
Joined
4/30/2019
Location
Gallatin, TN US
5/12/2020 9:54am
Had a 2006 YZ450F with around 100+ hours on it. Came up a hair short(no big deal) on a table top style
Triple, noticed a weird feeling in the rear end and pulled off. The rear axle snapped dead in half inside the rear hub, no wear marks or anything to lead to the reason why.

Threw a new axle in it and got to almost 250+ hours on a stock piston with just valve adjustments till she finally dropped a valve and grenaded at the local sand track Loved that bike. Got my money’s worth
PFitzG38
Posts
1637
Joined
11/6/2009
Location
Newport Beach, CA US
5/12/2020 10:26am
First time I go to Bean Cyn. years ago, a few miles into our ride one of us loses his countershaft sprocket circlip. He mulls the sitch over and says oh well I guess I'll head back and look for it. Yeah right I think - we'll see ya back at the truck when we get back in a few hrs. A couple hrs later we are resting and hear a 2stoke in the distance when the guy pulls up and said yup, he found it about halfway back. - That was one in a million
4
mattyhamz2
Posts
10879
Joined
7/6/2015
Location
So Cal, CA US
Fantasy
846th
5/12/2020 11:05am
PFitzG38 wrote:
First time I go to Bean Cyn. years ago, a few miles into our ride one of us loses his countershaft sprocket circlip. He mulls the...
First time I go to Bean Cyn. years ago, a few miles into our ride one of us loses his countershaft sprocket circlip. He mulls the sitch over and says oh well I guess I'll head back and look for it. Yeah right I think - we'll see ya back at the truck when we get back in a few hrs. A couple hrs later we are resting and hear a 2stoke in the distance when the guy pulls up and said yup, he found it about halfway back. - That was one in a million
Haha that's actually impressive! Especially up there
1
Evansguy
Posts
4
Joined
5/6/2020
Location
Wilmington, DE US
5/12/2020 11:31am
I came off the track after practice (roadracing at Summit Point on a Honda Ascot) and was scratching my head because it was breaking up at higher RPM. A guy walks by and says "I heard it breaking up, you should check the ground to the coil" and keeps going. He was right, the coil was loose and the vibration would cause it to stop grounding momentarily.
BobbyM
Posts
21449
Joined
8/15/2006
Location
AZ US
5/12/2020 12:33pm
Joel Spoor wrote:
Hey guys! So just a simple one to help pass some time,. Tell me a story of your weirdest problem that led to a failure or...
Hey guys! So just a simple one to help pass some time,.
Tell me a story of your weirdest problem that led to a failure or stoppage..

I’ll kick things off.
I was competing in a desert race. About 3 days in a stick flew up and perfectly bumped the fuel tap to the off position.
The bike ran long enough for me to forget the stick hitting my leg and the bike stopped:.

Frantically tracing spark, fuel and electrical possibilities
The tap wasn’t marked so wasn’t clear which was off / on so it took me a good 2/3 minutes to figure it out while bikes were flying past me! lol
I lost a rear wheel in the 2nd moto after I forgot to tighten up my rear axel nut after adjusting the chain. Was leading the 2nd moto when my rear wheel came off. It was the 1st race doing my own maintenance after my dad said it was time to maintain my own scooter, after many years of him always taking care of it.
Crash course (no pun intended) of learning on the job training in the worst way. 😳😁👏
5/12/2020 1:07pm
Can remember being out on my 1985 Maico on a wet cold winters day Grabbed the front brake at the bottom of a steep hill and got a electric shock off of the lever Thought at first it was a severe case of pins and needles in my hand with been freezing wet but no the lever had a electric current going through it
2
TxT0RKiT
Posts
246
Joined
5/19/2015
Location
Garland, TX US
Fantasy
4387th
5/12/2020 2:10pm
Had that high rpm CR250R bog. Sounded something like... rang a dang danga ding bog bog dang. Dumb silencer packing clogged. I noticed it while unloading the bike out of my truck when the light above the garage door hit just right.
1
edge60
Posts
45
Joined
5/11/2020
Location
MC
5/12/2020 3:34pm
Had another strange thing last year with my 2007 YZ 250. During a practice session i began to hear some weird noise. It was the end of the day so i pulled off the track, shifted to neutral and twisted the throttle one last time. Dont know why, but i do it often. Inmediately it looked if it was kicked in a gear. I was standing beside the bike and it allmost flew out of my hands. The gearbox was locked after that. Strange because it was in neutral. There was a gearwheel that is supposed to run free over a bushing when its not shifted. But it allmost looked like they where welded. Gearwheel was stuck. So the bike was in 2 gears at the same time. The mechanic at my dealer asked me if i noticed if the rear wheel was rotating fast when the bike was running on the stand in neutral. And indeed a week earlier i noticed that. He said it is a common problem with YZ's.
wildbill
Posts
4358
Joined
8/15/2006
Location
Christmas Valley, OR US
5/12/2020 5:45pm
Saw an air cooled ATC250R at a garage sale in 89. He only wanted $250 for it, so I asked what's wrong, he said he didn't know. It had good compassion so I offered him $75, which he took. Got it home and found the slide sitting crooked, and the pin pushed out, allowing this to happen. Peened it back in and fired it up and railed on it with a smile.
AngryBear
Posts
765
Joined
4/1/2008
Location
Asheville, NC US
5/12/2020 6:17pm
TWO brand new '95 RM 125's. BOTH, at the same time, month two of ownership, fuel tanks started splitting apart as if you had filled them full with water and frozen them. nothing wrong with gas caps. never anything in them but pump gas

suzuki made good on it.
AngryBear
Posts
765
Joined
4/1/2008
Location
Asheville, NC US
5/12/2020 6:19pm
few month old '97 RM 125. jumped small table, bike falls to ground/skid plate on ground. linkage / frame joint broke. very beginner level riding, very little jumping.
Rob YZF250
Posts
118
Joined
4/7/2019
Location
Essex GB
5/12/2020 6:19pm
When I was a schoolboy on my 2000 CR80 at Mildenhall, came round a right bend onto a straight and as I started going wide open down the straight the bike just started sliding like a locked up feeling to a complete stop.. I got off and see my rear wheel cast hub was mostly gone and a shit load of spokes missing too from it. The chain had let go. Laughing
5/12/2020 8:15pm
Non moto, but in speedway I was leading the last race of the year and I heard a massive racket coming from the engine.. there was only a couple laps left so I left my foot planted. I lost power but not that much and continued as flames came at me through the firewall.

Came over the finish line in first and pulled straight over. the engine had spat a con-rod out the side of the block and there was a football sized hole looking straight into the crank/sump area 😝
1
9bro9
Posts
295
Joined
2/9/2019
Location
Salt Lake City, UT US
5/12/2020 9:06pm
Big 6 Havasu round 2017 30C - Nabbed the holeshot and led the first lap, I tangled with someone in another class ahead of me coming out of the right hand sand corner where the canal jump is and tipped over. Throttle stuck and would only open up about 1/3 of the way, somehow finished the race in 3rd. Pulled it apart and it was lodged with sand even with a brand new throttle tube, grips and bars.
1
mh226
Posts
185
Joined
3/18/2015
Location
CA
5/12/2020 9:58pm
Redbud National Weekend - Amateur Sunday

Riding a stock 12 ktm 250f and the ruts were so deep that they managed to dislodge the stock oil cap. Somehow I was unable to determine that hot oil was covering my pants / boots, nor clue in to the fact that my dad was questioning the smoke coming from the bike as I went by. Finished the moto. Luckily the thing didn't grenade, just fried the clutch.
1

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