Crankshaft bearing blew to bits :(

Questions regarding the DR800

Crankshaft bearing blew to bits :(

Postby Monodoggie » Mon May 14, 2018 8:28 pm

I finally finished working on my Big last friday and got it up and running.
I replaced the balancer chain, cam chain and guides + the camchain tensioner. I also got the head and valves cleaned and machined at the local shop. All was fine and the weather was perfect. Shame that I only got to ride it for 2 days before the magneto side crankshaft bearing blew into bits today :tdown:

Now I have to take it all apart again and hope that there is not any significant damage done to the engine. Atleast the stator and magneto + cam and balancer chains seem to have survived without any noticeable damage when I took the magneto cover of to have a look. There were big chunks of metal from the bearing stuck to the magneto, couldn't see the balls from the bearing anywhere so I guess they are still in place.

I didn't notice any strange noise prior to the bearing breaking other than a occasional rumble when idling that would only last for a short time and go away. My last Big also made the same noise from time to time so I tought its normal. Seems it was the bearing on its way out, I wish I would have realised that and saved myself alot of trouble. When I was replacing the chains I checked if there is any play in the bearings but couldn't feel any so I was convinced they are fine :crazy:

Not a great start for the summer but hopefully I'll get her up and running soon enough, wish me luck :D
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Re: Crankshaft bearing blew to bits :(

Postby nug » Mon May 14, 2018 11:04 pm

Very strange that it failed so dramatically. Bearing don't always show play in the early stages of failure. The races could have started to break down causing the rumble which then led to rapid failure. Very bad luck.
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Re: Crankshaft bearing blew to bits :(

Postby BigBob » Tue May 15, 2018 8:16 am

One of the main bearings on the original 1988 DR750 was not up to the job and consequently it used to make a noise after a few thousand miles.
Often this was a pronounced knock which would drive owners mad as it sounded like the engine was about to explode, but the bearing never seemed to fail like your one has.
In 1989 Suzuki uprated the bearing and no more problems were encountered.
I lived with my 1988 750 making this noise for nearly 175,000 miles and then it was a camchain tensioner failure that eventually killed it by bending all the valves :tdown:
I`ve never heard of a SR43 crank bearing failure before except when someone has had the clutch cover off and damaged the crank end seal in the cover which means a dramatic loss of oil pressure.
If you have removed the clutch cover then I would check to see if the seal is OK.
There is a small plate underneath the engine held on by 4 bolts. If you remove this you will probably find lots of bits of bearing
Good luck with the rebuild
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Re: Crankshaft bearing blew to bits :(

Postby Monodoggie » Tue May 15, 2018 9:46 am

I didn't touch the clutch side when I was working on the engine. However when I bought the bike the last owner told me he had done some work on the clutch, so this might explain things if he managed to screw something up while fidling with the clutch :prob:
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Re: Crankshaft bearing blew to bits :(

Postby Monodoggie » Mon Aug 27, 2018 5:29 am

Summer has kept me busy with all kinds of stuff but I finally had some time to work on the bike. When I removed the cylinder head it became obvious that the valves have hit the piston. There are 2 deep cuffs on the piston :c The valves look OK but I haven't taken them out of the head for further inspection yet. Timing was still on point when I disassembled the engine so maybe there was enough play in the crank for the valves to hit the piston after the bearing failed?


Here is a image of the piston:

151


Going to take the crank out later this week and get it looked at to see if its still good to go. Any tips on where to look for a new piston?
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Re: Crankshaft bearing blew to bits :(

Postby O.R. » Mon Aug 27, 2018 3:48 pm

Too bad !

Finding the OEM piston won't be that hard. 105,00 and 105,50 can be orded new @ CMS. But you will need more than only a piston.
I'm afraid you must replace two valves and maybe even the complete base engine (since you don't know where the bearing balls have gone...)
Like BigBob, I've never heard of failing SR43 crank bearing, so take a closer look.
First remove the cylinder, then you know the condition of your connecting rod and the "clearence" of your big end. And check your oil strainer.
BTW, are parts well available in Finland?
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Re: Crankshaft bearing blew to bits :(

Postby Monodoggie » Mon Aug 27, 2018 5:09 pm

There is one retailer in Finland that seems to have almost every oem suzuki part for the DR800 you can possibly image, so availability is not the problem. The prices on some parts are pretty high though so I'm always looking for alternatives :)

I allready stripped down the rest of the engine and I'm almost ready to split the casings apart. Only problem at the moment is the ring nut on the magneto side. Gotta try and find something that I can open it with.

The conrod seems straight and there is no noticeable up/down right play in it.
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Re: Crankshaft bearing blew to bits :(

Postby Monodoggie » Sat Sep 01, 2018 6:05 pm

The ring nut just doesn't want to come off. I've tried creating my own tool for it from some pipe and large sockets with a power grinder but they didn't turn out so good. Tried borrowing the tool from local suzuki dealers but none had it unfortunately. I'll try to borrow a MIG welder from someone and try welding something to get the nut off. What have you guys used to get this dammn thing off? It seems to be hella tight aswell, didn't even budge when I hammered it with rubber mallet and a large screwdriver.
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Re: Crankshaft bearing blew to bits :(

Postby BigBob » Sat Sep 01, 2018 9:06 pm

If it is no 17, then it`s a l/h thread which is why you can`t get it off.
If it`s 15 then it`s an absolute bastard to get off, and if I remember correctly, I basically destroyed it while removing it and had to buy a new one @20 euros.
suzuki-dr800su-1994-r-germany-e22-crankshaft_bigsue0077fig-5_b0dc.gif
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