Yesterday I drove by a motorcycle in a parking lot driveway, and saw the man was beside it with his tools already out.
I went back to see if any help was needed and he gave me a problem I could not solve.
This was a 1970 Triumph 650, twin, with kick-start only.
The problem was that he had gone for an hour ride for enjoyment and on his way home the bike began losing power and cutting out.
The power loss grew in frequency and duration until he had to stop and park the bike where I found him.
Once stopped, the bike would show signs of starting, but would do so for only seconds before cutting out.
A change happened since the bike was parked: after tickling the carb he tried to start it and it failed, but there was backfiring.
The backfiring happened also when start effort was stopped while ignition was ON
There seemed to be some movement in the positive terminal on the battery, but it showed 13.2 volts, so it was still working , and connections were tight and clean, however the power monitor light in the gauge cluster was dim/weak, suggesting low voltage at that point and likely poor connection in the harness .
The bike was a barn find for him and he had rebuilt the engine entirely by himself.
He was certain that the coils were good....they were both new and he had the bike running on one coil two days before.....but the symptom of slightly erratic running under no load was close to what had just happened.
Plugs were clean and dry, no fuel fouling, and spark plug/coil wire connection was good.
All gaskets were new, and compression seemed good to him as the bike has only kick-start and he could detect no change in effort.
Carb had fuel and fuel filter and lines to/from carb were checked. All was clean. Carbs seemed tight to the engine, but we had no means of checking air leak so that cannot be ruled out.
Bike has electronic ignition, and the timing had already been checked while he was there. (remove the cover, remove the timing check bolt at the back of the engine and rotate the engine until it reaches the detent. )
It seemed there was some spark as the bike would still start/run for three to four seconds before halting. (possible intermittent connection or ignitor problem?)
He had already called CAA (same as AAA) and was waiting for their truck to collect the bike and transport it home. (I could not help with that as it will NOT fit into the trunk of a Mustang.)
Ideas?
I went back to see if any help was needed and he gave me a problem I could not solve.
This was a 1970 Triumph 650, twin, with kick-start only.
The problem was that he had gone for an hour ride for enjoyment and on his way home the bike began losing power and cutting out.
The power loss grew in frequency and duration until he had to stop and park the bike where I found him.
Once stopped, the bike would show signs of starting, but would do so for only seconds before cutting out.
A change happened since the bike was parked: after tickling the carb he tried to start it and it failed, but there was backfiring.
The backfiring happened also when start effort was stopped while ignition was ON
There seemed to be some movement in the positive terminal on the battery, but it showed 13.2 volts, so it was still working , and connections were tight and clean, however the power monitor light in the gauge cluster was dim/weak, suggesting low voltage at that point and likely poor connection in the harness .
The bike was a barn find for him and he had rebuilt the engine entirely by himself.
He was certain that the coils were good....they were both new and he had the bike running on one coil two days before.....but the symptom of slightly erratic running under no load was close to what had just happened.
Plugs were clean and dry, no fuel fouling, and spark plug/coil wire connection was good.
All gaskets were new, and compression seemed good to him as the bike has only kick-start and he could detect no change in effort.
Carb had fuel and fuel filter and lines to/from carb were checked. All was clean. Carbs seemed tight to the engine, but we had no means of checking air leak so that cannot be ruled out.
Bike has electronic ignition, and the timing had already been checked while he was there. (remove the cover, remove the timing check bolt at the back of the engine and rotate the engine until it reaches the detent. )
It seemed there was some spark as the bike would still start/run for three to four seconds before halting. (possible intermittent connection or ignitor problem?)
He had already called CAA (same as AAA) and was waiting for their truck to collect the bike and transport it home. (I could not help with that as it will NOT fit into the trunk of a Mustang.)
Ideas?
