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I have a 2005 SM with only about 7000 miles on it. It seized solid when on a run about a month ago. It was running perfectly up to that point. The oil level was good.

I bought it with less than 5000 miles on it and I changed the oil and filters (& cleaned the gauze thing) after about 500 miles. I Used fully synthetic 10/50 (Q8 SBK Racing). There was no sign of any metal in the oil & filter I took out.

A new crank has arrived but the mechanic cannot find any other problem with the engine, i.e. no cause for the big end bearings to weld themselves solidly to the crank. We had expected the oil pumps (he tells me there are 2 of them)or the drives to it to be knackered - but they both look fine. There no sign of any blockages in the lines. There is no sign of anything else not getting enough oil.

I just wandered has anyone else ever heard of the big end seizing on a 950 SM. Is there anything else we should check before we put her back together?
 

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I wouldnt put it back till you find the cause of the seizure , start off at the oil pump and look at the drillings through the cases , push pipe cleaners through all drillings and use compressed air through any other smaller drillings , have seen blobs of silicone sealer stuck down drillings before .

Is the crank on plain shell type bearings ? does the crank have a drilling through it from the mains to the big ends , on the strip down had the shells spun over and blocked the oil supply off that comes through the hole in the half shell .
Had the conrods turned blue at the ends ?
 

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oil pressure valve stuck open?
 

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Thanks for the reply, Lee.
Jeff had already checked all the oilways as you suggested. They were all clear.

Yes, the bearings are plain shell bearings. As you can see in the photo the conrods have turned blue with the heat and yes, the tabs broke off and allowed them to spin.

Seized-Crank---small-file.jpg
 

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Does the oil get from the mains to the big ends through a cross drilling in the crank ........ i would say it does as i can see the drilling end blanks , the mains look perfect is there any wear on the main shells at all
 

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I have a 2005 SM with only about 7000 miles on it. It seized solid when on a run about a month ago. It was running perfectly up to that point. The oil level was good.

I bought it with less than 5000 miles on it and I changed the oil and filters (& cleaned the gauze thing) after about 500 miles. I Used fully synthetic 10/50 (Q8 SBK Racing). There was no sign of any metal in the oil & filter I took out.

A new crank has arrived but the mechanic cannot find any other problem with the engine, i.e. no cause for the big end bearings to weld themselves solidly to the crank. We had expected the oil pumps (he tells me there are 2 of them)or the drives to it to be knackered - but they both look fine. There no sign of any blockages in the lines. There is no sign of anything else not getting enough oil.

I just wandered has anyone else ever heard of the big end seizing on a 950 SM. Is there anything else we should check before we put her back together?
Crikey - bad luck!

If it's not lubricant at fault, could it be the coolant?
 

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I would be very nervous about reassembly without finding the cause the motors are generally very tough 7k is no mileage maybe pm kev in yorks the ktm oracle
 

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Discussion Starter #11
No, coolant is fine. Anyway, I think the back cylinder would have seized long before the crank if it was a coolant problem.

But, thanks for the suggestion!
 

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Thanks, KTMZOOM

I will mention this to Jeff in the morning. Is this something you have come across before?
not on a ktm but seen it before, pressure relief valve opens and closes to maintain a static pressure at high and low rpm. If it sticks open at high rpm you wont get enough pressure at mid-low rpm which could cause the bearings to pick up.

can I just say the tabs on the bearings are an alignment aid and wont stop them from spinning, there should be an amount of bearing crush to stop them spinning, but if the rod end heats up and expands you loose the crush and they then become "under size" and spin.
 

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Discussion Starter #16
Hi Kernow - It had only been about 3 weeks since I changed the oil, but during that time I had been away with the lads for long weekend in the Scottish Highlands so had done about 1,400 miles.
 

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The only other thing I could think of would be the water pump seals failing, especially on an early 950 engine. When that happens, the water gets into the oil very quickly and then the oil filter absorbs a lot of it, collapsing due to incoming oil pressure soon afterwards. When the oil filter collapses, you could get oil starvation to the rest of the engine. On my 950SM there was a lot of top end noise and the oil light came on, but thankfully I had only just set off when the filter gave up. It needed the modified pump parts changing out and a full oil and filter change. An early sign is that the main paper oil filter is much heavier than you expect when you change it. That, and coolant level dropping over a period of time of course.

cheers, Bob
 
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