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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: danpalooza on May 22, 2016, 02:13:26 AM
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I just bought a '92 K75 RT today and was so excited to take her out on her first little ride. I pulled out of my place, gaining speed with a smile on my face, when suddenly my elation was halted after I shifted into second gear. An alarming CLUNK sound, followed by the rear wheel locking up, sent me in a panic. I squeezed the clutch in to stop the skidding and to try preventing from highsiding. Luckily I wasn't going very fast. I coasted into a nearby parking lot confused and frustrated. I test rode the bike earlier that day and it shifted smooth 1-5, no problems at all. The guy I bought the bike from was a mechanic and apparently he maintained it regularly (I'm not putting it past me that he could be lying). Anyway, only getting 500ft from my house wasn't a good way to start the relationship with my bike. Although I'm thankful I wasn't on the freeway when it happened. I will be taking her apart soon and let you know what I find. But in the meantime, anyone have ideas on what could have caused the transmission to fail like that?
-Danner
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Welcome. Your experience is very much unlike a K-bike. These beasts are usually robust and bulletproof.
In the absence of any evidence, it's hard to say what went wrong, whether it is a failure of the transmission or the driveshaft or final drive, or something else. My first guess is probably the U-joint on the driveshaft may have failed. If the transmission or final drive had locked up for some reason, you would not have been able to coast. It's known to have driveshaft U-joint failures, and to have the grub screw on the shift lever inside the transmission loosen and fall out. But, this would be a first for me to hear of the transmission locking up.
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My 1st vote would also lean towards a u-joint failure.
Though I have heard more of them happening with the paralever(2-joints) than the monolever(1-joint)
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You mention pulling the clutch to be able to coast. That would indicate a problem with the engine.
Can you move the bike with the clutch out and the transmission in gear? That would put the problem downstream of the clutch. Probably in the drive shaft. Most likely the universal joint as mentioned by others.
Is the wheel locked up or free turning?
Does it free wheel when in gear and the clutch pulled in?
Does the engine run? Does it stall when the clutch is let out in gear when the bike is up on the center stand? That would make me think the problem is in the transmission or final drive.
Can you shift gears with the engine running? If you can, I would think the transmission is probably ok.
Do you hear any noises from the drive shaft when you turn the rear wheel? That would point to the universal joint.
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Gryphon,
I cannot move the bike with the clutch out and transmission in gear.
The wheel frees when in gear and the clutch is pulled in.
The engine won't start.
I can shift gears with the engine off.
No noises from the drive shaft when I turn the rear wheel.
I'm beginning to suspect the problem is in the engine now. I wondering if it has seized up and that is the reason why it won't turn over now.
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UPDATE:
I couldn't see this from last night when it happened but just inspecting the bike again this morning I saw it is leaking oil badly from the oil sump. Definitely an engine problem not transmission. I'll be tearing it down this week...
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The engine won't start.
Thanks to Gryph for providing a well-considered check list, and to danpalooza for a timely followup with it.
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The engine won't start.
Thanks to Gryph for providing a well-considered check list, and to danpalooza for a timely followup with it.
Yes, thank you Gryph. Very much appreciated.
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Wow, it's hardly ever the engine! How many miles?
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Mystic,
55k, not that much for those engines. The previous owner must of really not taken care of it. What a shame.
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:popcorm
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Mystic,
55k, not that much for those engines. The previous owner must of really not taken care of it. What a shame.
No shit, he must have been a hell of a mechanic. 55K is about when mine needed a slight valve adjustment.
Be interested to see what the problem turns out to be. If it turns out to need a rebuild, I'd call him up and ask him what he ran for oil. Used, unstrained chainsaw oil?
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I'll keep you guys posted.
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Does the oil light come on when you turn on the ignition? If not, is the wire connected to the sensor on the front of the engine? I am suspecting an oil pressure problem leading to a thrown rod. OUCH!!! If the wire is disconnected, the seller might have known there was a problem and figured he could hide it long enough to sell the bike. Have you contacted him yet? I would consider small claims court if he doesn't offer some sorrt of compensation.
If there is a bright side to this, it might be that a decent short block can be had fairly reasonably as these engines seem to usually outlive the rest of the bike, and there are a fair number of them out there.
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i have never heard of a motobricker with a donkey avatar throw a rod on a 750 motobrick...
coincidence... i dont believe in coincidence...
j o
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S
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Before we leave this as an engine tear-down................Could you have had a sloppy shift which jumped higher, loading the engine, causing the stall? Do you have a strong battery? I would test the electrics, starter,etc. to be sure there is a good starter system. Does the transmission give you 1-N-2-3-4-5? The oil could be an unrelated issue. Check the battery and starter relay before dropping the engine.
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Should be able to remove the crank cover from the right side for inspection without too much difficulty. (other than draining some coolant and removing the coolant hose)
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i have never heard of a motobricker with a donkey avatar throw a rod on a 750 motobrick...
I believe scripture indicates the donkey avatar motobrickers wring driveshafts into scrap metal using the 1100 motobrick.
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Mystic,
55k, not that much for those engines. The previous owner must of really not taken care of it. What a shame.
The least reliable part of my brick was the odometer- speedo actually...I'm on my third,two gone under warranties.I have to add 50,000 km to my third which stopped at 175,000 odd' bout 30 k ago...
Gryphon
I'm beginning to suspect the problem is in the engine now. I wondering if it has seized up and that is the reason why it won't turn over now.
Yep ,but it will be because of something stupid,I'll bet.2nd gear....you were lucky,but...
I bought a T150.in the seventies,cheap..completely rebuilt with Norman Hyde big bore and crank.No oil pressure.....He told me he'd run it about five miles and then laid it up.He said it was ok when he did.I didn't run it ,just took it apart.The "mechanic"left the oil plugs on the brand new crank out...
Blue big end journals,effed con rods.reground 10thou under,new rods.Made the mechanic pay for it ,on threatening his reputation.kept it ten years,50kmiles,two top end rebuilds.
I'm over it ....now.
'Hope yours works out OK....
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Had a long day at work and finally had a chance to get a better look at the damage. I got the fairings off and my heart dropped when I saw this. Here's a couple of pics of the crank case cover.
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The pictures got turned upside down for some reason.
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Sorry, looks like something has let go. Should be able to pick up a short engine at a reasonable price with a bit of luck.
Best of luck Martin.
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There are a couple of engines on ebay for around 200 bucks. These motors aren't worth much because they rarely blow up. Sorry for your experience, very disheartening I'm sure.
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Yeh,new motor,for nix....well worth it...but what the Fifi?...oil light???loose oil filter?conrod cap bolt?
These bricks are bullet proof...so, please post pics of inside.
All,the best.
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I'm going to tear it apart when I get some free time, I'll post what I find. And seeing how available and inexpensive the engines are made me not freak out as much as I was. :yow
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I just bought a '92 K75 RT today and was so excited to take her out on her first little ride. I pulled out of my place, gaining speed with a smile on my face, when suddenly my elation was halted after I shifted into second gear. An alarming CLUNK sound, followed by the rear wheel locking up, sent me in a panic. I squeezed the clutch in to stop the skidding and to try preventing from highsiding. Luckily I wasn't going very fast. I coasted into a nearby parking lot confused and frustrated. I test rode the bike earlier that day and it shifted smooth 1-5, no problems at all. The guy I bought the bike from was a mechanic and apparently he maintained it regularly (I'm not putting it past me that he could be lying). Anyway, only getting 500ft from my house wasn't a good way to start the relationship with my bike. Although I'm thankful I wasn't on the freeway when it happened. I will be taking her apart soon and let you know what I find. But in the meantime, anyone have ideas on what could have caused the transmission to fail like that?
-Danner
Not that it will come to it, but in-case you have to take the trans apart- no fear! its quite easy to do.
Edit: saw the pictures. Thats a total downer. I would like to know what caused this? Broken timing chain? Interested to see what the engine looks like with the crank-case cover off.
Best of luck! :2thumbup:
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Not that it will come to it, but in-case you have to take the trans apart- no fear! its quite easy to do.
I took apart watches when I was a boy. I had a box full of parts. That was easy, too. I had to buy one with my allowance when I wanted one that worked.
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Yes it's easy to take something apart and not be able to put it together again... I did this when I was very young too. Telephones, really old computers etc.
As far as the trans goes the most difficult part is only if you forget where the shims go.
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Looks like I may have been right about the thrown rod. Did you look to see if the oil pressure sender was didsconnected? Have you contacted the seller yet to see if he will give some compensation?
With the price of used engines what they are,the good news is that you should be able to part out your old one for a good chunk of what the replacement will cost. Or have a nice supply of spares for cheap. Too bad this had to happen at the start of the riding season.
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The oil pressure sensor was connected. But I took the crankshaft cover off today. Turns out the connecting rod snapped. Any ideas how this could have happened? it did some damage.
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I forget but somebody on here had me check my rods if they were bent. Hydrolock?
Wiki:
Hydrolock (a shorthand notation for hydrostatic lock) is an abnormal condition of any device which is designed to compress a gas by mechanically restraining it; most commonly the reciprocating internal combustion engine, the case this article refers to unless otherwise noted. Hydrolock occurs when a volume of liquid greater than the volume of the cylinder at its minimum (end of the piston's stroke) enters the cylinder. Since liquids are nearly in-compressible the piston cannot complete its travel; either the engine must stop rotating or a mechanical failure must occur.
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Looks like I may have been right about the thrown rod. Did you look to see if the oil pressure sender was didsconnected? Have you contacted the seller yet to see if he will give some compensation?
With the price of used engines what they are,the good news is that you should be able to part out your old one for a good chunk of what the replacement will cost. Or have a nice supply of spares for cheap. Too bad this had to happen at the start of the riding season.
Good call Gryph, you called it.
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I forget but somebody on here had me check my rods if they were bent. Hydrolock?
Wiki:
Hydrolock (a shorthand notation for hydrostatic lock) is an abnormal condition of any device which is designed to compress a gas by mechanically restraining it; most commonly the reciprocating internal combustion engine, the case this article refers to unless otherwise noted. Hydrolock occurs when a volume of liquid greater than the volume of the cylinder at its minimum (end of the piston's stroke) enters the cylinder. Since liquids are nearly in-compressible the piston cannot complete its travel; either the engine must stop rotating or a mechanical failure must occur.
Not sure how water could get in the engine. I live in AZ, it hardly ever rains here.
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Fuel... idk foreign material in the chamber
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Thanks for showing us the insides.
Is the big end seized?The rod is twisted and broke.
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Bummer.
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It's also possible that there could be a broken valve at the head end that could have caused it.
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Wow. That's discouraging. Where will you plan to go from here? Bummer,indeed........sorry for your trouble.
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Dude, not sure what you mean by the big end. The crank doesn't move at all if that's what you mean.
Scott, I'm planning on doing a tear down to investigate further.
Ace, it was a day ruiner for sure. My plans from here is to source a new motor and make a project out it. I was thinking about turning her into a scrambler since I'll have her completely torn apart.
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Yeh,terminology is terminally misunderstood."Big end"is the larger con(necting) rod bearing and runs on the crank shaft.If it is seized up it may indicate that a lubrication failure caused the con rod to snap.
This is the most likely cause,imho.
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There you,go, Danpalooza, sure it's a kick in the teeth, but after you coast for a bit, jump back on that mule and make it your bitch! :clap:
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Dude, I'll take a look when I get the engine completely torn apart
Ace, no way I'm giving up yet!
This where I got this weekend. Hopefully next weekend I'll get the engine more torn down.
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Oh, Man, I think I just figured out what caused your problem...................sibling rivalry with a certain shiny silver Honda.
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Dude, I'll take a look when I get the engine completely torn apart
Ace, no way I'm giving up yet!
This where I got this weekend. Hopefully next weekend I'll get the engine more torn down.
The motor is toast.Best concentrate on finding a next one and get back on that ride...the dead motor isn't worth mending,just curiosity as to why?I guess.
You mentioned the crank shaft was seized.Can you rotate the bolted cap of the broken con rod on the crank?Take the cap off,even?Inspect what you reveal.
All the best.
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Ace, I wasn't planning on mending it. I just wanted to see what caused the failure (as I'm sure you and other curious motobrickers do too on this thread).
I'll try to rotate the rod on the crank to see if it can even turn.
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Oh, Man, I think I just figured out what caused your problem...................sibling rivalry with a certain shiny silver Honda.
Ha! That's actually my dad's bike, he was helping me out with the tear down. That new goldwing is pretty sweet though.
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True ACE? " There you,go, Danpalooza, sure it's a kick in the teeth, but after you coast for a bit, jump back on that mule and make it your bitch! :clap:"
This is a donkey mecca
tom :hehehe
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Well, I say "Donkey-Wonkey"..........my people's & me always been more partial to mules, sort of runs in the family, if ya know what ah mean....
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In the first picture that was posted I see mud on the cover and a distinct dirty line near the intake snorkel. I wonder if the bike was submerged and hydro locked?
That could have damaged the rod and it broke later.
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As in flood damage? Where was this bike located?
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As in flood damage? Where was this bike located?
The danpalooza is from Phoenix. There was a flash flood in the Phoenix area in September last year.
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In the first picture that was posted I see mud on the cover and a distinct dirty line near the intake snorkel. I wonder if the bike was submerged and hydro locked?
That could have damaged the rod and it broke later.
Interesting but....danpalooza, could you please take out the rear cylinder spark plug and let us know if there is any water in there?
Thanks.
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In the first picture that was posted I see mud on the cover and a distinct dirty line near the intake snorkel. I wonder if the bike was submerged and hydro locked?
That could have damaged the rod and it broke later.
Pretty sure that was just dust caked on there. It gets pretty dusty 'round theez partz of Arizona.
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In the first picture that was posted I see mud on the cover and a distinct dirty line near the intake snorkel. I wonder if the bike was submerged and hydro locked?
That could have damaged the rod and it broke later.
Interesting but....danpalooza, could you please take out the rear cylinder spark plug and let us know if there is any water in there?
Thanks.
I'll take a look and let you know what I find.
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The danpalooza is from Phoenix. There was a flash flood in the Phoenix area in September last year.
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Along the Ridley in Vermont.
carfax???? did I stutter?? insurance paid off? lol
tom
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Interesting but....danpalooza, could you please take out the rear cylinder plug
I'll take a look and let you know what I find.
So ......have you found any reason why the motor did the 1 in million thing?
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So ......have you found any reason why the motor did the 1 in million thing?
Apologies, work has been a little crazy and I had to take a trip out to LA for a conference. I don't have access to my bike at the moment but when I pulled the rear plug out it was pretty black and looked like it was running pretty rich. Not great evidence for me to why it snapped a rod, but that was the only spark plug that had a ton of carbon build up. I tried taking the head off to get to the valves and see what the piston looks like but I snapped two T-50 bits trying to get the cylinder bolts off. So now I have to order a better bit and get creative with getting those bolts off. Engine does not turn over at all. Wouldn't even budge when trying to turn the crank to TDC. Every thing else on the top end looked completely fine. Transmission is in working order as well.
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Hey,thanks for the communication ,no apologies needed!let us know in your own good time.
"motobrick curious"
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UPDATE
So after snapping two different torx bits, I ordered a snap on heavy duty removal bit and me and the old man finally got the head off. A lot of carbon build up but to me it looks look all the cylinders were running rich; especially #3. #3 also had some knicks from the intake valve (probably from when the rod snapped. But any opinions from looking at this what could of caused the rod to give way?
Pics are ordered Cylinder 3-2-1 for the pistons and valves. Second to last pic is the close up of where the valve hit the piston, last one is the gasket that had a hole in it.
Happy Father's Day!
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Thanks for posting.No clues that I can see why the rear rod broke from the top end images.
You say that the crank won't turn at all.Big end bearing seizure (oil supply failure)is the most likely cause IMHO.
If you can reach it then,undo the broken connecting rod cap to confirm.
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Still looks usable to me hah
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Took the crank and Pistons out. Bearings didn't look too bad. Definite signs of wear, but nothing pointing to bearing failure. I found some matching etchings on the side of the rod caps and connecting rods. It doesn't look factory. So to me, it seems that someone had this bike apart before and just didn't put it back correctly. Also the previous owner told me the engine only has 50k on it. The west of the engine seems like a lot more than that.
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Doesn't look usable to me...😂
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Bearing looks serviceable bore doesn't look that bad. I suspect hydraulic lock, drain and measure the contents of the oil pan.
Regards Martin.
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Bearing looks serviceable bore doesn't look that bad. I suspect hydraulic lock, drain and measure the contents of the oil pan.
Regards Martin.
I already got rid of the oil. Do you think that hole in the head gasket could have leaked some coolant into the cylinder? The block is completely shot. You can see in the photo that the connecting rod that snapped went through wall of the bore.
Also the cylinder #3 had the most wear on the bearing and the dirtiest valves and spark plug. Not sure if that's an indicator of anything.
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What was the condition of the oil, can you remember the level in the container that you drained it into. The damage on the head gasket looks like it was done on removal. Can you see signs of leaking on the gasket, head or block. The only time I have seen con rods with that amount of damage was on vehicles that had been submerged in water while the engine was going. Big end lube failure causes different damage not evident in your pictures. Have you contacted the previous owner.
Regards Martin.
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Oil was a little dirty. Not terrible though. Didn't notice any leaking on the head or block. And I definitely wasn't near any water lol. I haven't contacted the previous owner. I feel like he's just going to give me the run around.
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Can you take pictures of the head gasket both sides of the offending cylinder. While it is unusual for a leaking head gasket to cause a hydrostatic lock it is possible.
Regards Martin.
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I can only see the first and last images.The first image shows the con rod(big end) shell significantly worn.I guess that journal isn't blue,is it?The main bearing shells are not.Not definitive proof of cause though.Bummer!I would contact the previous owner and.......
ALL THE BEST.
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Could just be a bad batch of steel that the rod was made out of... I suspect that if the cause it's not evident, then it will remain a mystery
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Just got back from picking up my two gold crash bar bolts from the local BMW wrecker, who has been working on K's & R's for 30 years +. I asked if he had heard of one bending and breaking a con rod, his answer was never. He has seen a couple do big ends from lack of oil, but even then they have never thrown a rod. I asked about if a blown head gasket could have done it, his answer highly unlikely. He said it might have been apart and assembled with damaged parts, but I can't see how. He did say that given the Bricks reputation you were highly unlucky, if that is any consolation.
Regards a perplexed Martin.
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We may never know what the actual cause is. I'm going with my gut and thinking the previous owner tore it apart and did a hack job with re-assembly. Those etchings on the pistons point to that. Nothing else to do but move on and buy a new motor for the bike. Shame it happened but it was a good chance to get to know the bike inside and out. Appreciate all the help from everyone. Hopefully in a few months I will be posting build progress photos of the bike coming back together. Thanks again! :bmwsmile
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Take the motor apart and sell it's parts. Given enough time you'll likely make 2x back what you paid for new/used
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