Know Thy Beast

Know Thy Beast

UP FRONT

My title this month comes from the definitive work on the Vincent Twin. It's borrowed without permission but with a strict sense of justice, both because the subject is a Big Twin and the lesson concerns how one copes with problems.

In a sense this is the punchline delivered before the story.

Acting in accordance with an avalanche of reader mail I counted at least six letters but there may have been as many as seven next month we will present pictures and details of the Harley XR750 I've been working on for what seems like, and was, years, In our previous installment I had the bike running but not well. What it did do well, was start. Easily. So one day I got a call from another XR750 owner, Buzz Walneck, and he said he's swapped his magneto for coil and battery because he could never get his engine to start.

I couldn't resist. Mine, I gloated, fires in seconds, hot or cold.

No points to those who giggle something like, Jinxed it, dincha?

First, it balked when hot. Then it wouldn't go, hot or cold, without wearing out two kickers and all the pushers not lucky enough to hide.

This came at the worst possible time. The Champion 200 weekend at Laguna Seca has become the bike event on the west coast. Two days of speed plus all sort of related events. In my case there was the Vetter Economy Run and the VROOM vintage show'. I planned to take the XR and Red Rooster, my CB350R. My oldest son is stationed at Ford Ord, so he could co-ride. We'd be 'the only guys in both the economy run and the vintage parade and I'd be the wealthy sponsor complete with hotshoe rider. Wow.

Whoa. Or maybe I mean woe. The XR wouldn't start for rehearsal the night before the run, so I scrubbed it and rode the 350. ( Details in Roundup.)

We got to the track as timed practice ended. We got to the vintage paddock as the others were getting ready to go out for the parade. We got the bikes off the truck, I kicked and kicked, then wore out two teams of pushers and kicked some more. When it finally lit we revved and cajoled our way to the track entrance . . . just as the other crocks came in.

My hearing is exceptionally acute. Odd, considering my exposure to all sorts of unmullled exhaust since I was 14, but there it is. While kicking and bumping I heard one spectator mutter “That’s why I sold mine."

After the show we were driving out of the display area and I heard didn't see but 1 think it was the same man somebody say “I wonder if they ever got that thing running."

Hold that thought while I switch to something that reads like a bestremembered-character story in the Reader’s Digest.

During all these frustrating times I have had the benefit of lots of advice. As mentioned elsewhere in this issue we, the staff, have heaps of experience, in years and brands and types. Plus I know other enthusiasts who know about engines. No names, because none of this was their fault, but I was told the jetting was too rich and too lean. The spark was too advanced and too retarded.

Magnetos throw sparks an inch long, and they throw' good sparks that are invisible.

Meanwhile, a year or so ago I was talking with the editor of another magazine. He had with him a friend, who mentioned that he and his brother run a shop specializing in Sportsters, a de-stroked example of which my engine is. He gave me a card, which I saved for the same reason I save frayed throttle cables, that is, you never know.

Wade Roberts has an XLCR. He has an S&S carb on it. He bought a K&N filter and needed to change jets. The local dealership and parts stores didn't have any. I thought of the friend of the friend.

This shop is two blocks from our office. I managed, well, Wade pushed and I clutched, to get the XR running. We went to the shop. No sign. Seems these guys don't deal with the public. They don't want customers in off' the street. They don't work on motorcycles. Potential customers apply and have an in-depth interview. They sign a written estimate and deliver the parts, then the brothers work their magic in secret. The customer knocks on the door and is handed his wonder engine and told to go away.

I am not making this up. I listened and figured it was all hype. Wade picked up the jets and we went outside. Where my XR refused to start.

We tried bumping and all we got was that terrible pf-pf-pf-pop-pop-pf-bangpf-pf as I groped at all possible settings of spark and throttle and choke while poor Wade pushed.

Roll it around back, said the brother. We did. He took out the plugs, which were soot black but dry. He cleaned them with solvent and put them back in. May I kick? he asked. Sure, I said, having had all the fun I could stand.

He kicked. Wait a minute, he said, something is wrong. It shouldn't kick like that. There’s nothing there. Radical cams, I said. Radical cams my sainted mother, he said. And he leaped to the tool chest, got two big screwdrivers and snapped off the pushrod covers.

The front exhaust valve wasn't closing. No clearance. The back exhaust valve w'asn't closing. No clearance. He slacked off the tappets, we put the covers back. He kicked. He kicked again.

Perhaps, he said, it would help if I turned on the ignition.

Kick, brooOOOM! We shut it off and again, it ran. XR and I went dancing homeward, skimming over the road. A great weight had been lifted from my soul.

Now that I am calm enough to think about it, sure, I should have checked.

But while I've known valve clearance to increase during break-in, I never suspected valve trains could tighten up.

Further, I doubt that we home modifiers appreciate how closely the factory guys make the various parts work together. When we put a pipe on our YZ250, a filter on our GS750, we know' what we've changed and we’ve learned what changes we need to make. So we muddle through.

But this particular XR750 has most of its components from something else, as in ignition, heads, pipes, carb, cams, all supposed to go with other components. And none of us had previously owned or worked on an XR, so we were blind men who couldn’t even find the elephant, much less describe it wrong.

What it took, and it happened as quickly as I recount it here, was a man who knew the beast.

Back to Laguna Seca.

What I had nearly told the man in the crowd was that no, we didn't get it running, not so’s you'd notice. But because the racing was so good, and the vintage show 68 bikes! went over so well, and a record crowd enjoyed the perfect weekend I'd have to say that despite my personal disappointment, I'd had a wonderful time.

And so I did.

But it’s more fun when you know your beast and the beast runs. B3

ALLAN GIRDLER