Engine Oil Seals | Yamaha XS650 Forum

There's been some oil seal talk recently, particularly about the cam shaft seals, and I realized I really didn't know too much about oil seals in general. So I decided to educate myself, which proved quite easy. One simple Google search turned up all the relevant info. Oil seals have a code number, usually stamped right on them, that gives the seal type and size. The 1st entry in the code is the seal type and consists of 1 to 3 letters. The numbers following are the size, in our case in MM (I.D. x O.D. x thickness). Determining the 650 seal types and sizes proved pretty easy because they are listed in the earlier factory parts manuals, so I made up a chart .....



Now let's talk a little about seal types. It was pretty easy to find well illustrated info on that. There are as many as 5 different types used on the 650 engine. Some types changed when seals were updated so you may not find all 5 on your particular machine. Most of the seals are the "SD" type, with a sprinkling of "SO" and "SDD" types thrown in. Here's cross sectional drawings of the various types .....



And here's a little tidbit of info about the "SD" type I found interesting, highlighted below .....



Looks like I'll be packing some grease into them before install from now on. Maybe it will help them seal better, and I certainly don't see it hurting anything. Seal sources have also been mentioned recently. MikesXS was mentioned as a good place for quality seals. Granted, they do have good ones, the same ARS brand as the originals, but their prices aren't very good at all, many times twice what you can get them from Yamaha for. Here's a comparison chart. Yamaha prices are the discounted ones from Partzilla. The only seal we're beholding to Mike's for is the starter motor shaft seal because it is N.L.A. from Yamaha. Thankfully, that seal doesn't go bad often .....



I thought I'd also talk about the cam seals a little. 2m posted a listing from the XS1-XS1B parts manual showing the 2 types. The early seal was 5mm thick, the replacement in mid '71 was 6mm thick. This "upgraded" seal was then used until the end of production. But now it seems Yamaha has reverted back to using the old 5mm thick seal again, and under that same old original part number.



2M also postulated that the "S" type was probably a single lip, and the "SD" type a double lip seal. That's somewhat correct. The "SD" type does have an extra lip but it's a dust or wiper lip, not another actual seal lip. I don't think the 7mm thick "improved" cam seal from Mike's is necessarily a bad seal, it's just wrong for this application. It's too thick. It can't be seated deep enough into the points/advance housing for the seal lip to get good purchase on the end of the cam shaft. There are quite a few reports of it not working at all or failing shortly after install. Yamaha originally used a 5mm thick seal here, then switched to a 6mm thick one, and now has gone back to using the 5mm thick one again. So, it appears thinner is better in this application. The seal lip is able to sit deeper onto the end of the camshaft and do it's job better. 5t
Yeah I went with the 40x25x5mm seal on this as the Mikes ones were 6mm and I did need the extra 1mm.
gggGary
I didnt do any photos of the install but they are really simple to install as they come with the installation outer sleeve to hammer the inner speedi sleeve on.
They key was to pre cut the rear raised lip for installing the speedi sleeve with a Dremel to the grooved line on the main sealing surface. i did it in 3 places. Then when installed carefully tear iit away with pointy plies without damaging the sealing surface to leave a nice new Stailess Steal resleeved shaft. You can leave the rear raise installation sleeve
Cost was $21AUD.
Check out SKF site with small video.
http://www.skf.com/au/products/seal...als/wear-sleeves/skf-speedi-sleeve/index.html
Cheers

I guess you might have had some unpleasant experiences with buying low-quality oil seals. Today, I'd like to share with you how to distinguish whether an oil seal is good or not.

Link to Dingtong

Distinguishing a good oil seal from a defective one involves inspecting several key aspects:

1. Visual Inspection: Check for any cracks, tears, or signs of wear and tear. A good oil seal should have a smooth, unblemished surface.

2. Material Integrity: Feel the material of the seal. It should be flexible, not brittle or overly hard. A good oil seal maintains its shape but adapts under pressure.

3. Dimensional Accuracy: Measure the seal to ensure it matches the specifications it's supposed to meet. A good seal should have accurate dimensions for a proper fit.

The company is the world’s best s type oil seal manufacturer supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

4. Surface Irregularities: Look for any uneven surfaces or manufacturing defects. A quality oil seal should have uniform thickness and surface.

5. Age and Storage Conditions: Check the manufacturing date if available. Oil seals can degrade over time, especially if stored in poor conditions (extreme temperatures, exposure to sunlight or chemicals).

6. Brand and Manufacturer Reputation: If the seal is from a reputable manufacturer, it's more likely to be of good quality.

7. Elasticity and Hardness Test: Gently press and bend the seal. It should return to its original shape without any deformations.

8. Compatibility with Fluids: Ensure the material of the seal is compatible with the type of fluid it will be exposed to. For instance, some materials are better for oil, while others are suited for more corrosive fluids.

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