Main crankshafts bearing alternative [Stella 4-stroke]

[martinvh]

Hi all,

I split the cases on my Stella 150 4-stroke manual to rebuild the cush gear. But now I'm all the way in the engine I would like to replace the crankshaft main bearings as well.

The current bearings have 5000mi on them and especially the left one has some axial play. Is there a replacement alternative for the Indian 'quality' bearings? If I search online for the part number on the bearing, nothing shows up.[/b]

[dasscooter]

If you bring the bearings to a local bearing supplier, they will usually be happy to measure them and source you some USA made replacements.

[az_slynch]

It's the same bearing used in the pre-LEADER Vespa ET4, the Italjet Dragster and the Gilera Runner engines. Similar ID and width to a 2T bearing, but markedly bigger OD.

Part number is NTN SC05831CS37. Dimension is 25mmx68mmx12mm.

I got two sets, one for my 4T and one for a friend's 4T. Had to source them from SIP in Germany. Still need to pop the crank apart and find a decent big end bearing replacement option.

[Neurotic-Hapi-Snak]

It's the same bearing used in the pre-LEADER Vespa ET4, the Italjet Dragster and the Gilera Runner engines. Similar ID and width to a 2T bearing, but markedly bigger OD.

Part number is NTN SC05831CS37. Dimension is 25mm�68mmx12mm.

I got two sets, one for my 4T and one for a friend's 4T. Had to source them from SIP in Germany. Still need to pop the crank apart and find a decent big end bearing replacement option.

That's good to know. I have a suspicion that the "bad cranks" that kill 4T engines, are actually bad bearings. Do you have a list of the other bearings? Like the camshaft bearings? Are the transmission bearings same as the 2T?

[az_slynch]

That's good to know. I have a suspicion that the "bad cranks" that kill 4T engines, are actually bad bearings. Do you have a list of the other bearings? Like the camshaft bearings? Are the transmission bearings same as the 2T?

Camshaft uses a 6202 on the driven end and a 6002 on the far end. The needle bearing for the cam gear is an HK1412.

The trans bearings are spelled out in my transmission thread. The caged needle bearing for the intemediate shaft is an HK1616 and the roller bearing is a 6302. Bearings for the final shaft are the same as a PX Lusso.

[dr3wbize]

Did anyone find a replacement for the big end bushings of the connecting rod?

Stella 4t resulted in hard seize; after taking the motor apart, found that my crank bearing were still ok but connecting rod is hard to rotate. All else looks nice.

Photo is just for fun, it's the way the spacers go on.

[az_slynch]

Still working on this. The dimensions for the rod/bearing are close to a Honda CRF150. Waiting for parts to be sure. Will post when I have the answer.

[az_slynch]

Long overdue follow-up on this. Didn't have dimensions handy and couldn't measure the dismantled unit. Losing one's crankshaft in the shop will do that.

Big end bearing has the following dimensions: 28mm bore diameter, 36mm roller outer diameter, 13.8mm height.

NTN lists this bearing under the following part #: PK28X36X13.8X4 . I'm back to looking for a vendor to purchase this part, but it doesn't appear to be commonly stocked.

Another good reference is that it's the same big-end bearing as a Honda SH125/150 or the PCX125/150. Rod kits with new bearings are available and if you're truly mental, there are offset crankpin kits to make it a +5mm stroker, which can be found on eBay, particularly out of Thailand.