250-500cc Video: This is how a bad rod big end bearing sounds like...

View: https://www.youtube.com/watch?v=t-6Fho763_4


Seems like hitting the +600hrs barrier on this bike is giving me some extra homework...

Two weeks after I noticed the fractured swingarm (>LINK<) the motor started to sound ugly in the last ride, it started progressively, first I thought that the piston is making too much noises today, but not much later the noise became pretty obvious and too loud. I was more or less expecting to see the con rod fail in the more or less near future. I opened the low end last year in August to change the transmission to the wide ratio, checked everything and the rod didn't have play in it so I remounted the crank as is, but with new crank bearings. Well It lasted a little over one year, should I have replaced the rod last year ? Well, maybe, but I got another year of abuse out of it, not that bad.

Last Saturday just after the ride I started to inspect the engine, removed the pipe and passed the finger around the exhaust port, looked like a black metallic paint, with copper colored metal flakes in it. I was now 99% sure that the big end bearing of the con rod did say good bye, so I proceeded with the tear down:



Engine on the bench, ready to start digging...


Cylinder removed.


View: https://www.youtube.com/watch?v=Qs0WIaj5ivU

Rod bearing failure confirmed.

I have some collateral damage because of the small metallic debris that the con rod bearing was throwing at the crankcase, everything is coated in a metallic finish, the piston took most of that abuse and it is clearly visible:


Intake.


Exhaust, you can even see small metal particles sticking to the skirt.

That piston does only have about a year of usage, I usually change them every two years and they come out pretty decent. That one however seem like it was there for a decade .


Ready to order some parts.

I will get a new Vertex probably in C size (that one will be the fourth piston on this engine/cylinder, The original one was an A and I mounted two B's after that. I think this will be the last piston for that nikasil.

For the con rod I am looking to get a Wössner, anyone tried them on the WR's ? I contacted Wössner asking about the correct reference to get, because on their most recent catalog they have a P2057 for the WR250's and a P2023 for the WR300's, the same rod as for the KTM engines. I doubt that this is correct as the OEM rod is the same on both 250 and 300 engines: 8A00 50632

I'll also get new main bearings, not sure about the transmissions bearings, the roller caged one of the secondary shaft is damn expensive, and they all look just fine.

Will keep you posted.

Cheers !

Wössner confirmed the right reference is P2057, already ordered, once received the crank goes to the specialists to install the new rod, unfortunately the shipping and work will take some time so probably 2-3 weeks no riding

Put new bearings in throughout then she'll be golden for years!

New Wössner P2057 rod received yesterday:








Crank is in the workshop for installation and truing. Should be ready tomorrow.
They did also measure the cylinder bore with a micrometer and it gave 72.01 mm, same measurement as last year. I think I will go with a C sized 71.96 mm Vertex piston this time (had two B's before), that would give me 0.05mm clearance (the book calls for 0.04-0.06 )

Crankshaft bearings are on their way and I'm right now ordering the piston and misc stuff like gaskets and such.

I plan to start assembly this WE.

Cheers !

Crank bearings came today:




The rest of gaskets and stuff should be here next week....

Any chance when you are finished you could please update the first post with all the part numbers you have used?

Crank is back from the specialist, old rod and pin was really bad, it's a mystery that the piston didn't punch the head:












New Wössner rod installed:



The rest of the parts came just in, assembly can start !

Cheers.

Hi Craig, here is the list:

Piston:
23457C Vertex reference. I got the 'C' size, sizes A,B,C available


Bearings:
2x 800042155 Crankshaft bearings: 6305 TN9/C4 SKF Explorer, got them directly from a SKF dealer for half the price as OEM reference.

I decided to not change all of the transmission bearings, they seem to be fine and I don't have the extraction tools to remove those blind bearings but I decided to change the big 6205 from behind the clutch because it is fairly cheap and easy to change:
800024952 BALL BEARING HUSQVARNA WR 250/300 09-14 6205/C3


Gaskets:
8A0063593 O-RING CYL. HEAD EXTERIOR HUSQVARNA WR 250 2005 2.62X112.6
8A0044117 O-RING CYL. HEAD INTERIOR HUSQVARNA WR 250 2005 1.78X75.7
800086868 GASKET LEFT SIDE CYL. HUSQVARNA CR 250 2004
800086865 GASKET RIGHT SIDE CYL. HUSQVARNA WR 250 2007
8B0086902 GASKET BASE CYL. 0.5 MM HUSQVARNA WR 250 2005
800072522 GASKET CENTER CASE HUSQVARNA WR 250 2006
800048216 GASKET CLUTCH SIDE HUSQVARNA CR 250 91-96
800089954 INTAKE REED GASKET (I would suggest using an additional btw. the reed and the OEM rubber intake manifold)
In my case I am using a VForce4 reed box from a GasGas and the above reference was not in stock so I ordered some GasGas gaskets instead:
ME25644005 GASGAS INTAKE GASKET (same as 800089954)
ME250644105 GASGAS INTAKE VFORCE (special for the VForce uncentered intake)


Seal Rings:
800092896 Crankshaft Right side Seal ring (ø20xø40x7 mm)
800059977 Crankshaft Left side Seal ring (ø32xø40x5mm)

The following were get directly from a bearing shop for a fraction of the OEM price, adding references just in case:
800059977 Transmission primary gear Seal ring (ø32xø40x5mm double sealed NBR)
800048209 Kick starter seal ring (ø20xØ28x6 mm double sealed NBR)

I did not change the tiny clutch lever one becuse I did a few month ago, but you should:
800048856 Seal ring (ø13xø20x4mm)


800036857 CLUTCH SAFETY WASHER HUSQVARNA SMR 400 2007 (change the old crushed washer)

Optional:
66N021211 PRIMARY DRIVE STOP RING HUSQVARNA TC 250/310/450/510 07-10 WR 250/300 09-14
800023110 O-RING PRIMARY DRIVE HUSQVARNA 28.68 X 1.72

I did also buy new bearings for the exhaust valve, the old ones were getting some play:
2x 6802 ZZ [ 61802-2Z ]

I broke the plastic connecting rod from the power valve once again (did the same few years ago):
800069750 EXHAUST VALVE ROD HUSQVARNA WR 250 05-14 WR 300 09-14



That's all for the moment, hopefully I didn't miss anything.

If you need to find out more references check out the italhusky webside:
https://shop.italhusky.com/en/products/2010/wr-250-300-4

Yesterday I had time to make some progress:

Checking ring end gap:




One of them were spot on but the other needed a little light touch with the high end diamond file:


Yes, it's a nail file, but it just works great, I'm making sure to do only from outside-in movements, to not strip the coating on the outside of the rings, and keeping it straight:


Power valve cleaned and ready for assembly:


New bearings (61802-2Z) and new Viton O Rings (14x1.78mm) installed:


Powervalve installed:


Crankcase is next...

To install the bearings I chill them down in the freezer and heat up the casings, I did the below video last year but opted this time to use the kitchen's heater and not the heat gun:


View: https://www.youtube.com/watch?v=3G-u8QSByKA


Bearings will just drop in their location just as in the video, no force is needed preserving the crankcase bearing surface:


The 'clutch bearing' was also changed, notice the still missing safety plate:


The ordered right side crankshaft seal is different from the previous and original one, I contacted the dealer and they confirmed that the part is correct and may be an upgrade from factory. The OEM had two lips and the new one has only one. I think they went out of the original Husqvarna stuff and are now shipping KTM parts, make sense ?


Left seal installed:


Right seals also in place, notice the blue NBR standard seals on the transmission and kick starter shaft:


Transmission and fork's in place, some patience is needed to align everything and not loosing the washer that goes at the end of the secondary shaft (part 21):




Crankcase closed. Next step is to install the crankshaft collar, gear, spring washer and nut. Also the gear pedal shaft assembly need to be installed before the clutch basket, don't forget the little collar detailed in this picture:


The primary drive nut was installed using a gear stopper like the one from motion.pro, it get's 51÷56,9 Nm of torque. Also notice the little washer that goes at the end of the shift shaft (part 20):




To tighten the clutch nut a special tool is recommended to grip the inner hub, but that nut 'only' get 29,4÷32,4 Nm so I opted to do something else, put the transmission in last (fifth) gear and using an old sprocket and piece of chain I jammed it against the kick starter shaft to keep it from turning over. I recognize that I'm stressing the gearbox with this but I only did so because of the relatively low torque needed, have done it in the past with no issues:


Clutch pressure plate installed:



That's all for the moment, hope I'm not boring you to death with this.

Cheers !

Next part is the water pump that get's a new bearing and seal.
The difficult part is to unscrew the pump impeller, I installed the casing temporally on the engine so that the pump gear engages the crankshaft so that it keeps from spinning, then I took some vice grips, wrapped some tape around the ends and fitted them so that it grabs on both sides of the impeller, then used another vice grip to turn it clockwise to loosen it. I also heated the impeller with the heat gun before trying that. it did came off easy without any damage.

Next I took the casing back off the engine and warmed it with the heat gun, then I pressed the bearing out with some sockets and a vice. I prefer to put a new bearing as I needed to press it out on their inner race, stressing the assembly. You may be able to get just the seal out with an blind bearing extractor for example.


Probably overkill but I frozen the bearing again and heated the casing to install the new bearing:


Next comes the shim:


And then the seal:


Bushing and gear+rod installed:


Note that under the bushing goes the little O-Ring (part 3):

Let's finish this up:

I installed the impeller with a little bit blue Loctite and put the pump housing back on:


Clutch cover back on, ready to install piston:


Needle bearings oiled and installed, I like to install the piston C clips with the opening to the bottom:


Seal rings installed, remember to put the one with the wider ring-end-gap to the bottom:


I compress the rings with my left hand fingers and carefully slide the cylinder over with the other hand:




Cylinder fully seated and base nuts tightened:




Cylinder head installed with new O-Rings:


New plastic linkage also installed, I already broke one a few years ago, seems like they get a little brittle over time and tend to crack during disassembly. Notice the error in the pic below ? You need to install the black rubber seal to the power valve actuator arm outlet first, I like to use some RTV to get a better seal. once that is in place you can install the plastic linkage:


Exhaust valve side covers installed:


I didn't take any pics of the ignition side, I installed the stator aligning the advance to the OEM marks and used some silicon gasket maker (RTV) on the cable rubber piece to ensure a good seal:


Engine is now ready for implantation. The next Saturday I proceed to mount everything back to the chassis, it took quite some more time than expected as I was also changing out a few other non related parts such as new sprockets, chain, sliders etc.:


Overall I was working until late in the garage as I wanted to ride the bike the next Sunday morning to do some break-in as I had an event happening the upcoming WE.




(Yes, I use my tires until that point if I have no special events ongoing, that picture was taken just before I installed something decent)

Break-in ride was successful, no strange noises or anything and the bike felt a lot different, like new with no odd vibrations, super smooth power.

That event I was telling happened last WE and was also a success, engine pulls stronger then before and I'm happy !

Cheers !

Great post up mate, enjoyed reading it & lots of pics was cool

This has been my favourite thread in the cafe. Thanks for your time and effort Hurky you legend! I’m glad your event went well.

Really enjoyed the play-by-play!

Wow! Thanks for taking the time to document and share all this information :-)

great thread

Great thread.

Ive just ordered a complete top and bottom end rebuild kit and they have only sent the main big bearings, do I have to source the rest? I can't find any online apart from.the main bearing.

Hi Jack, do you mean that you also need the transmission bearings ?

You can have a look at https://shop.italhusky.com/ in order to find / buy OEM part numbers, or you can find the bearing models and get them at a bearing shop.

Cheers.

Hey mate, I'm not mechanic but I was assuming the bottom end rebuild would include all the bearing. Thanks for your help, really appreciate it