Monday, March 21, 2011

Near misses...

These are some motorcycles I almost bought, partly because I wanted to get one and turn it into my idea of a scrambler and partly because I think OIF BSAs are underrated. They are great "little" bikes that can truly do it all. If you don't have a bike and are thinking of going British vintage, give one of these some serious thought.
Anyway, probably for the better, I never bought any of these and concentrated on the chopp instead.

Sunday, March 13, 2011

Stay strong Japan!

first look: the front end

I got the front end out of storage and started giving it a bit of a clean, mostly to see if everything looked ok and complete. What I see so far is good. There are no cracks or pitting or rust. Ok, there is some slight scoring on one of the stanchions but at least at first glance it doesn't appear to be something worth worrying about. One of the things to look out for on this type of fork are the alloy "caps" that clamp under the wheel spindle; they are retained by an arrangement of four studs and nuts per side and they can often be improperly tightened. Excessive and uneven stress can result in cracks, leaving often no choice other than replacing the damaged parts. In this case they appear to be in good shape and all the threads are very good. The brake plate anchor is also intact and complete with its thick washer/spacer.

Upon closer inspection I noticed something. You will see that there is a thin rib that runs the length of each slider. This was originally polished at the factory as a nice detailing touch. At the bottom end of this rib you'll find a small screw that plugs the oil draining point. On the left hand side, it looks like this point might have come in contact with something abrasive at moderate speed... It's hard to say what or how, I doubt it was dropped because there aren't any other marks anywhere else and there would be other protruding points that would come in contact with the tarmac before that. Anyway, it's not very noticeable and there isn't any real damage. I'll probably replace the screws though (and the washers, of course).

Sunday, March 6, 2011

Wednesday, March 2, 2011

Steering head bearings

Now, this is an interesting "little" detail: the steering head on the wonderfully made David Bird frame is an exact replica of the ones Triumph made from 1954 to 1970. Actually, "an exact replica" could sound a little bit pejorative, and since this is no knock-off perhaps it would be more precise to say that it is accurately CNC-machined to the exact specifications of a 1954-1970 Triumph one. Yeah, that's better.

This arrangement allows you to use the older style of forks used by Triumph and BSA (the latter with some modification to the bearings) and they are handsome, elegant forks that work well when set-up properly. However, having opted for OIF cycle parts I'm now faced with a small obstacle, in that the OIF steering stem is of a considerably smaller diameter than the pre-OIF one.
There is an excellent write-up that illustrates precisely this scenario here.
I prefer the tapered roller bearings to the original ball & race type. There are conversion kits to fit tapered rollers to the pre-OIF Triumphs and BSAs, a sensible upgrade for any motorcycle in my opinion. In this particular case though, I could do two things:
1) choose one of those conversion kits and machine some inner spacers to slide on the OIF stem, thereby increasing the diameter of the stem to that of a 1970 stem; or
2) machine a "cup" type spacer to fit in the steering head and accept the original OIF bearings. As explained in the Chopcult article, this is not advisable and there are some practical reasons why this is so.

SRM, make a bearing kit for this very purpose but it won't fit the Triumph neck. Again, great for a BSA though!

In the end I found a tapered roller bearing conversion kit for Triumphs up to 1970 from Supreme Motorcycles and will machine a set of spacers to adapt it onto the OIF stem. I think that's the most straightforward thing to do.

Finally, here's a very useful how to by Lowbrow: