Tm250 main bearing LHS wear

[Sorelegs11]

My tm250 has quickly worn the lhs crank bearing.
It has had the oil system removed and as the outo feed passage seems to be directed to this bearing I am wondering is there a trick like drilling a hole in this oil passage so some of the oil being flung around may actually run down and supply a little more oil to said bearing.
Is this a common thing for this bearing to wear quickly without the oil system fitted.?

[djr]

I am not sure, but don't you have to split the cases on these engines and remove the bearing shield/slinger part when you take off the oil pump on these . and also drill a hole for oil to get to the bearing.
also I thought the RHS bearing was lubed by gearbox oil ?
(I am probably wrong, its been a few years since I worked on one of these)
the one I worked on had a worn out bearing probably caused by the low oil level in the gearbox
the bearing behind the flywheel side gets lubed by oil pump (or premix) if I remember correctly

[Sorelegs11]

Sorry LHS DOH!
Oil pump was gone when I bought this bike, the bloke I bought it from only raced it for a coupe of seasons and not a heap of races.
Its set up for dirt track and the rest of the engine is great, the bearing is skf so I guess its been running on a lean mix.

[pokey]

Not unheard of to have the left go if not looked after.
I always scratch my head when someone asks me about removing the pump on a suzuki.. WHY?

That side bearing has the most stresses so it pays to look after the bearing with plenty of good quality oil that it was designed to run on. pity we all wernt lucky enough to own these bikes from new and have to rely on others to look after them before they are handed on to us.

i do kind of like the idea of oil being fed direct to the bearing and being kept there for awhile to do the most good. if ever there was a reason to retrofit the pump and slinger i think we have it.

[Tomas]

Is the skf bearing c3? Could try c4 bearing for more clearance. Also make sure the bearing is installed right so there is no side load. C3,C4 bearing may apear to be worn/loose when cold since they have more radial clearance.

[sleepy]

You need to drill a hole about 4mm diameter down from the tranfer passage of the case to the outside of the bearing to allow the pre-mix to lube the bearing. I've done a few over the years and it seems help the bearing last. Just be carefull not to drill ito someware on the outside. C4 bearings will not help in this case it is a lack of oil that is the problem.

[OverTheHill]

Not loose on the shaft?, was just a passing thought [while passing] without reading it all. Had heaps of that over the years but only on smaller yamaha's through bad manufacturing tolerances [V50 scooters for one] Even had occasional owner come into work saying my mate put new crank bearings in & it's still making this noise. Grab the mag flywheel & up n down. Maybe not in this case--but just saying.  Thinking back though my RM125S was like that & i bronzed & machined the shaft up & made it tight, Next thing, flying through the air all good then motor stopped [in the air], didn't lock but stopped sparking. Had me head scratching, no spark. End had broken off the shaft flush with the bearing & magnets had grabbed the rotor [or rotor magnets had hooked to the stator lol], was sitting there all pretty but not turning. Sorry--getting off subject.

[Sorelegs11]

Crankshaft has some movement, you can wiggle it , not a great deal but its definately moving.
F$%#^&g thing keeps leaning right out and nipping up, I have sealed all other areas, new crank seal last time and my 15yr old daughter done 6 laps of nepean before it went again.
From my experience with the yammys, had to do 4 bottom ends last summer, I am sure its the movement in the bearing thats the problem.
I will drill the hole and hopefully that wil do the trick.
Thanks everyone for the tips.

[80-85 husky]

check the head bolts are not bottoming out or tightening prematurely. had that happen with a husky years ago, seized three times before found the culprit was a too long bolt bottoming out and allowing the head to lift at high temps

[Lozza]

Crankshaft has some movement, you can wiggle it , not a great deal but its definately moving.
F$%#^&g thing keeps leaning right out and nipping up, I have sealed all other areas, new crank seal last time and my 15yr old daughter done 6 laps of nepean before it went again.
From my experience with the yammys, had to do 4 bottom ends last summer, I am sure its the movement in the bearing thats the problem.
I will drill the hole and hopefully that wil do the trick.
Thanks everyone for the tips.

Have you completed a leak down test? I removed the oil slinger from the crank but did not drill the passage to the outside of the bearing in my TS. The hole will help, but the movement could be from the clearence in the bearing especialy when cold

[Suzukal]

You can remove the oil slinger, but you should replace it with a smaller diameter washer of the same thickness.
That’s just to keep everything in the same place it belongs.
You can also remove the oil slingers mating part from the bearing. It’s not needed if there’s no slinger.

[Lozza]

You can remove the oil slinger, but you should replace it with a smaller diameter washer of the same thickness.
That’s just to keep everything in the same place it belongs.
You can also remove the oil slingers mating part from the bearing. It’s not needed if there’s no slinger.

cutting the slinger down with tin snips is easier than finding that thrust washer