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'73 Tiger trouble

1070 Views 9 Replies 8 Participants Last post by  Desert Rat
A few weeks ago I found a sweet 1973 Tiger 750 in the local Nickel. The price was right and it did well on the two short test drives. I brought it home, did some minor work on the carb and some electrical fixes but the more I ride it the more unreliable it seems. Ill be cruising along, holding speed, the bike sounds good then out of no where it sputters and dies. At first I figure no gas, but tickle the carb and gas flows and it would start right up again. This is after only maybe 20 min of riding. Then the other day it dies and wont start again. Gas is there in the carb but no turn over. I trucked it home and checked the points and they're good so now Im thinking the coils are bad? Could I loose spark mid ride? Thanks ahead for the tips...
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check the vent hole in the gas cap,if its plugged it can cause the fuel flow to stop when the tank vacuum locks, then after a moment it releases the vacuum and fuel flows again.
I agree with Tony BUT then again Mr. Lucas is riding bitch
You might also want to take the float bowl (s) off, turn the gas on and make sure there's good fuel flow all the way through the carb. The filters on the petcocks (inside the tank) may be plugged, the petcocks may be plugged, lines, filters where the lines meet the carbs, etc.
Coils are a possibility, but unlikely that both would go at the same time, ditto for the condensers, though you should probably replace the condensers.
To check if a plugged cap vent is the problem, you can try riding with the cap only partially screwed on.
Could I loose spark mid ride?
Of course,you could.Kill-switches are famous for getting corroded and killing the ignition.Same with the wiring plugs that lead to the kill switch.Old ignition switches can cut out any time.
Have you got any spark?

It doesn't sound like you have a fuel problem.If you take out the float bowl drain plug and turn on the fuel,you should get at least 300 ml/minute fuel flow.
check the gas cap vent first before you start taking it apart - drill a new hole if you need to
Got an inline fuel filter? If so it could be clogged, or could be a car filter that restricts flow.
Otherwise, my first suspect would be gunge in the fuel system through the petcocks to carb jets. Common on old bikes that have sat long.

And it is always worth trying a new set of sparkplugs in an old bike out of storage.
And the plug leads on those old Triumphs go bad with age, they were carbon leads, best replaced with wire core leads.
Since it is dead now and the problem is no longer intermittent determine if you have spark. You are already pretty sure you have gas but I don't see anything in your post that said I checked for spark and there was none. Confirming no spark will head you in the right direction and you can hunt from there. Unlikely both coils would go bad at once.

like Pete says, if you still have the handle bar kill switch they go bad all the time. open up the headlight bucket, find the white and white/yellow wire going up to the handle bars and disconnect the plug and patch them together.
Not the gas cap, have new plug wires, have fuel at float bowls. Next in line for trouble shoot are the kill switch tip, pull the plugs and kick it to make sure I have spark. Thanks for the specs on the kill switch wire color, Tony, thinking that might be it... Love this board
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