Nan And Back On The Big Cat

Discussion in 'Touring Northern Thailand - Trip Reports Forum' started by ianyonok, Jun 12, 2016.

  1. I had had a bit of an issue with the '71 Morgo Triumph 750 Tiger. The rear frame loop was cracked on one side for a few years and then finally broke right off.
    2015-12-31 16.47.14.
    I had in the past attempted welding the first broken side with external weld, but that does not work. The "oil-in-frame" Meriden Triumphs often had this frame failure at this location. The Reynolds frame is a good rigid frame for a it's day, but this is a known weak point. I believe it's due to the loop carrying the full weight of a passenger and the fact that the rear shock mounts are welded to the frame at the front of the loop. Many people with custom bikes or who only ride solo, just cut this loop off and ride it like that with a different seat. But I did want to keep a full length seat in order to strap a bag on the back.
    After online research and talking to engineers, the only real way to fix this failure is to weld plugs into the frame tubes. So, I turned some solid mild steel plugs on a lathe, to fit snugly inside the tubes. Heated and bent them to shape (a bit tricky trying to get 2 lengths bent identically). Before fitting the plugs I drilled the frame tubes about an inch away from the break, 2 opposed holes on each side of each break. Then with the plugs tapped into position and the mudguard fitted to ensure correct positioning, welded the plugs onto the tubes at the break and on the holes. This worked out well and all is now strong.
    2016-03-21 14.22.36.
    Some old mates were coming up from Pattaya to Nan, so thought I'd have a blast down there for dinner and test the repair. I had also re-wired the bike recently so needed to test all that.
    2016-06-10 08.15.13.
    The 1148 down to Nan seemed like an ideal route to test the a sporting bike.
    2016-06-10 11.19.48.
    For me, this is the best time of year to ride. Fresh, clean, clear air, minimal traffic and the scenery just looks beautiful with an overload of green. Cool mornings too, after overnight rain. Or just clouds keeping the temperature down.
    2016-06-10 11.45.05.
    Constant 80psi oil pressure at the big ends, thanks to the Morgo rotary oil pump which at least doubles the oil flow over the standard plunger pump...... great to have an oil pressure gauge too, to give you confidence.
    The bike was occasionally misfiring for the last hour of the ride into Nan. Initially, I thought water in the fuel, but draining the float bowl of the carb showed none. After arriving at the hotel, I check plugs and points and all seemed good. Still have the original Lucas mechanical contact breaker on this bike and it works fine, haven't adjusted it for years. Then luckily noticed the spade terminal of the low tension wire on the drive side coil was loose. Squeezed the female connector tighter and fault fixed.
    2016-06-10 11.45.18.
    I stayed at the Bahn Nan, a good upmarket Nan city hotel, rooms 1200 Baht which I thought a bit high considering no swimming pool. But it is a nice place.
    2016-06-11 08.32.42.
    On the way south to Nan I followed the 1148 into Ta Wang Pa but the last part of the road is horrible with those long long straights. Then the busy 101 south down into Nan, which is all road widening and mud at present.
    On the way back I went the preferable route, up to Santisuk, then Pua and onto Chiang Klang. Then take the lovely 1097 past Tadman waterfall to Songkwae and back to the 1148. A much better route at present due to the roadworks.
    2016-06-11 08.35.55.
    The 1097 down into Songkwae is wonderful with superb views. It used to be a tough road years ago, but now it's been resurfaced it's great.
    2016-06-11 08.37.13.
    2016-06-11 08.44.52.
    2016-06-11 10.11.11.
    ......"I can see for miles and miles and miles and......."
    2016-06-11 10.13.32.
    Is this the most "taken" photograph on this forum...... hahaha....
    2016-06-11 11.20.18.
    2 days, about 400 miles. Pure joy, on a wonderful old machine, in a fantastic country.
    • Like Like x 6
  2. Lovely bike you have there. I'd go for electronic ignition. I had Boyer unit on my Norton. That and the Japanese carbs made all the difference.
  3. I fitted a Boyer on my '59 Thunderbird about 17 years ago. It has worked fine since but I have heard of them failing. I did fit a Tri-Spark ignition for about 2 years but then it died. Shame as that is a nice set-up, with no black box. Electronics and pickup plate built together. But I guess it means the electronics get repeatedly too hot until they fail. So the old Boyer went back on.
    Decided to keep the points on the TR6 and they have been fine. I need to replace the oil seal behind the auto-advance unit, it does leak through a little.
    I recently fitted a new Amal Premier Concentric carb. These are now better made than the old Concentrics and cast in a new die, so no apparent "crack" in the body casting. Looks a finer material they are made of too. It has an anodised slide and adjustable height float.
    It works well, so don't need to fit jap carbs.
    What really transformed this bike was the larger valves in the head and the Morgo 750cc conversion. Small increase in BHP but the increase in torque in the low and mid range is very noticeable. The bike pulls like a train on just a whiff of throttle. Most satisfying....

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