Twin

[dixie]

Well i managed to end up with both

Tried both out and feel the 500 is hardest to ride so hence i am keeping the 500.(Westcountry boy see , strong in the body and thick in the head)

So i have the 350 for sale on the classifieds page.

[cvgmmartin]

I ride a 500 Triumph twin in Canadian vintage trials but since nobody else around here rides one I have had to fumble through design mods and improvements myself which in turn has usually meant doing it myself at next to no cost. Also since our trials have fairly tight sections, the engine has to have really good low speed running performance. As far as the engine is concerned, I have found that using standard cams (E3134 inlet) and rotating the inlet cam gear relative to the idler gear such that the valve opens around 30 deg BTDC (I think it was 2 teeth, but easy to check), the low speed running and pick up was better and it was less prone to stalling. I left the exhaust valve timing as standard. Quick response from idle comes from an old Keihin carb with accelerator pump, it no longer coughs and stalls when quickly opening the throttle after a long descent. My electronic ignition system using an ignition box from a Yamaha twin and a pick up coil that I have made to fit where the contact breakers are normally mounted. I use just a 12v battery without charging system since our trials are multiple laps and long distance rides are not an issue and this has left space for an external flywheel to be put on the end of the crankshaft where the alternator normally is. This gives a marginal improvement in bottom end power and seems to give more grip in the mud. I made the frame myself and found that handling was very sensitive to the fork angle and trail. I probably cut the steering head off atleast 5 times before getting it right. A little front axle lead of 3/4 inch (i.e. axle infront of fork centreline helped keep the steering light but too much caused the wheel to turn in on itself on down hill turns.

The wheel base is 51 1/2 inches similar to modern bikes so it turns as well as a TY 250. Wheels, forks, and shocks come from old Honda/Yamaha trail bikes which keep costs down (sometimes even free). Instead of buying expensive rear shocks I have found that for slow sections over rocks and trees it rides well with no damping, the weight of the bike probably provides sufficient damping effect. Worn out shocks are not collector's items so you should be able to get them fairly cheap. It probably wouldn't be so good for a flat out in third hill climb over rough ground but then unfortunately we don't have any sections like that.

Although it wouldn't qualify as a pre 65 bike, I don't feel guilty since I have to ride it against Yamahas, Bultacos, Shercos, Fantics, and Hondas.

Over the years I have probably only spent about 1000 dollars on it (500 pounds). I am shocked at the high prices of some of the bikes and parts in the UK and I would hate to think of the cost if I had to buy parts from the UK and shipped them over here. I did once try to buy some 3TA cams once from a well known southern UK dealer (not Sammy) and I was mailed a pair of cams that must have been sitting on a wet metal shelf and were badly corroded and obviously useless, so I get nervous ordering parts from overseas and prefer to do/make things myself.

[peterb]

Hi PaulB,

That 500 Triumph of yours is one of the best looking Triumphs I have seen. I had a road going Tiger 100SS for 5 years when in Yorkshire in the 70's, such a lovely motor I thought it would have made a great trials bike save for the weight. Good to see such fine efforts going on.

Bye, PeterB.