Sunday, June 30, 2013

Loctite 5910, 598 and Permatex Ultra Black: KTM 350 EXC-F

Valve Cover Gasket Sealants

On my KTM, the corners of the “half circle” parts of the valve cover rubber gasket are supposed to have a little bit of “Loctite 5910” put on them before installation. However, it appears Loctite 5910 is only available in Europe. My web searches seemed to indicate that the closest thing to this in the USA is “Loctite 598”. That can be easily ordered online, but is still not at any of my local stores... they all carry Permatex products instead. It seems “Permatex Ultra Black” gasket maker is the closest Permatex product I could find. I looked at all the tech data sheets, and while I’m not a chemical engineer, these three products did seem very similar to me.

Loctite 5910 (Europe only?)

Loctite 598 (Professional distribution only?)

Permatex Ultra Black (Found at my local auto parts store)

All three of these ar Oxime Silicone, thixotropic paste. All are RTV (room temperature vulcanizing). All are oil resistant. And the properties once cured all seem similar to me.

If anyone knows of a substantial difference between these three products, please let me know!

Wednesday, June 5, 2013

Supersprox vs Dirt Tricks Ironman Sprocket Weight

Being a lightweight myself I like to keep my bikes light. The rear sprocket on a motorcycle is often a heavy steel part. You can get aluminum sprockets, but they often wear out very quickly. So the sprocket manufacturers have been coming up with cool ideas like making sprockets with aluminum centers and steel teeth or making sprockets of super strong spider webbed steel. I was curious which approach might be lighter.
So I weighed one of each! These are both 48 tooth sprockets for a KTM.

Supersprox 48T: 25.1 oz

Dirt Tricks Ironman 48T: 19.6 oz

Supposedly the Dirt Tricks Ironman sprocket approaches the weight of an aluminum one... but I don't have one handy to weigh.

While I was at it I weighed a pair of front sprockets. I had a OEM KTM sprocket and a Dirt Tricks one. Both are 13 tooth.

KTM 13T: 4.5 oz

Dirt Tricks Ironman 13T: 4.3 oz

I put the Ironman products on my bike.

I also heard rumors that it was a good idea to grease the splines where the front sprocket mounts. Supposedly the hammering away of the drive train wears down the splines and proper grease can help prevent this. Google around and you will find lots of threads on that. At any rate, normal grease won't do, you want high a high pressure moly grease. Apparently most people use Honda Moly 60 Paste. It's cheap enough. Another recommended fix is the dirt sticks washer on the front sprocket. Its harder and and supposedly holds the sprocket in place better.
Here you can see I've applied the Moly 60 paste to the sprocket. I was careful to use as little as possible. I also put it on the sprocket, not the shaft, hoping that any excess would be pushed to the outside of the sprocket where it could easily be wiped off.

Here's a shot of the installed sprocket. I cleaned the threads with a tap and used new loctite. Note I have marked it so I can see if it ever decides to come loose.

I should also note that I have seen the WASHER turn , while the bolt remains tight. I called dirt tricks, and they said that happens sometimes... I'm not sure what to think of that. But as long as the bolt stays tight I figure things are good.

You have to remove the chain to make it easy to put the new sprockets on, so now's a good time to upgrade the chain guide. I went with TM Designworks RCG-KT3 in black. Its a nice heavy duty piece. Note mounting it requires you throw away the top chain guide. E-Ticket also installed a trick metal plate to protect the mounts:
That's probably a good idea but as my riding isn't too rocky, and this guide does provide a little protection on it's own I decided to pass on that. Here's mine: