BY STEVE COOPER ORIENTAL ANGELS
It is, so I have discovered, perfectly possible to drive yourself batshit crazy maintaining old motorcycles. Yes, I fully appreciate that Japanese motorcycles don’t, traditionally, leak oil but decades after their creation they probably have a right to do so. Of course, two-strokes have even less excuse to do so, but I know several that do. There’s a small Yamaha twin of mine that has the tiniest of weeps from the rear of its oil pump and it has done this reliably for the last 18 or so years. “Get it fixed and replace the seal,” you say, and I have – several times – but to no avail. In fact, I have almost fed the thing seals (Part No 93101-10090-00 as you’re asking), yet the leak remains. I can see no evidence of grooving or wear to the pump shaft, I can’t convince myself said component is worn or out of true, yet the fact remains it still suffers from the same level of oleaginous incontinence whether it’s standing parked up or running. The very fact that, despite my best efforts, I have failed to seize the engine or blow it up suggests that the leak isn’t critical and, after a recent top end overhaul, I can confidently state that there’s plenty of oil getting to the crank, thank you. I just give the weep hole behind the pump cover an occasional wipe as I simply cannot come up with a viable Plan B.
And on that very subject of oil seals, have you noticed how the Japanese have a persistently annoying habit of using said devices that are of odd sizes? There are three basic dimensions to oil seals in case you didn’t know: internal diameter, depth and external diameter. Generally, our Oriental friends will opt for two standard dimensions and then throw in an oddball one either for ‘considered best engineering practices’ or simply because they can. Historically this has caused real issues when it came to replacement time. This inevitably leads to angst, raised blood pressure and profanities over the cause of a strip and rebuild when you find the seals you need are either NLA (No Longer Available) or are hideously expensive – another reason to lose your mind, etc.
Although I still prefer to use OEM crank seals on strokers, I recently discovered that a lot of the seals I need are out there and available from alternative sources if you go about the task the right way. Reliably, if not regularly, the internet and that well-known online auction site can dig you out of holes. A bike in the stable required a new pushrod seal back in the winter and, yes predictably, was an oddball size, NLA, and eBay didn’t have any NOS ones on offer either. However, upon investigation, one of the parts books squirrelled away for said machine actually gave the sizes of the seal. (Yes, I know normally they are embossed on the face but not in this instance.) Typing the sizes in a search engine revealed three sources and one in the UK. Acquired and fitted, it turns out the dimensions given were the metric equivalents of an old imperial seal. Who knew, etc.
And just to add spice to keeping things oil tight, there’s a bike in the stable that has an early Suzuki GT750 front end nailed to it. In need of fork seals I found numerous OEM and aftermarket examples for sale, but all were expensive to my mind. Entering in the seal size and selecting Honda and not Suzuki divvied up numerous seals at significantly lower costs. It would appear that Honda F2N seals are less ‘valuable’ than Suzuki GT750 versions. Once again – who knew?
Of course, there’s always the belligerence factor. The same forks also required sealing O-rings for the fork top nuts and no one had them except Suzuki. Nothing else I found or tried would work. The nearest Imperial equivalent was 7/64ths but it wasn’t quite right. Two O-rings later and £11 poorer the job was done. Sometimes you just have to splash the cash I guess, but at least it’s still possible to repair these old bikes!