Intermittent loss of power

[CatatonicBug]

Didn't read all the input C.Bug, but think you got a broken one or two pick-up coli wires........under the wire insulation.

Nope, double, and triple checked them all. Nothing wrong with the wires there.

[dbeardslee]

So far the only thing that's still unexplained and out of spec is the zero voltage on the TCI black/white wire. I double checked the Yamaha manual just to make sure the testing voltages are the same for all TCI's, and they should all show the same readings across all years. Have you checked your PM's?

[CatatonicBug]

PM's?

[dbeardslee]

PM's?

Private Messages - I sent you one yesterday that might interest you.

[CatatonicBug]

Oh, yes! Already following up/negotiating.

[dbeardslee]

Oh, yes! Already following up/negotiating.

Atta boy! The motorcycle gods may be smiling on you.

[CatatonicBug]

Just curious, where are you getting the voltage specs for the connections at the TCI? I don't see any '81-specific TCI information in the manuals.

[dbeardslee]

Just curious, where are you getting the voltage specs for the connections at the TCI? I don't see any '81-specific TCI information in the manuals.

The way the FSM's work is that there are supplements for each model year. They only list the changes from year to year, and anything that's not listed is the same as the earlier model. I checked for the LH and for the SH and it has nada on the TCI tests. Which makes sense since the main difference between the 4R0 and the 2H7 is that the 4R0 has the electrical advance while the 2H7 uses a mechanical advance. But the voltages should evidently look the same when tested.

You could always pull the cover off your TCI and see if anything is obviously fried. Course you'll only be looking at one side of the circuit board and you have to unsolder the big connectors to get at the other side.

Maybe somebody else that's got an H model with the 4R0 would be willing to run the tests on their TCI just to double check the voltages. JAT

Also - you need to clean out your mailbox. I was trying to send you another PM, but your box is full and won't accept any more PM's.

[CatatonicBug]

Yeah, it sent me an email that you tried to send a PM, but my box was full. 150 messages is all I get?!?! I deleted some less-important ones, so I can receive messages again.

I just found the voltage readings you mentioned. I figured with the differences in the advance system, there would be some mention about it in the supplements.

[dbeardslee]

The manual does mention the electronic advance in the SH supplement, but there's no mention of a change in the testing procedures. It also has details on the corresponding changes to the pickup coil assembly.

Again, why not start a thread and ask if anyone with a 4R0 TCI is willing to run the power-on test on theirs to see if they get 6V on the black/white, or zero like yours is showing?

[dbeardslee]

Another thread got me thinking about the 11.2V measured at the TCI. You might want to load test your battery. Use alligator clips to attach your dmm leads to the battery terminals and get a voltage reading - should be about 12.6V. Then turn the ignition on - voltage should drop, but it should still be above 12V. Then, with the gas shut off and the carbs run dry, hit the starter and let it crank for ten seconds or so. Voltage should drop to 11V or so, and immediately return to above 12V at the battery when you let off the starter.

Here's what I'm thinking - the TCI requires a minimum of 10.5 volts to work properly, and you've only got 11.2V there to start with. The battery will not charge below 2500 rpms, and if you're running at low rpms you're running off the battery. If the voltages start approaching 10.5 volts at the TCI it's going to get squirrelly. JAT

[ViperRon]

Just a thought on something that is kinda like a got you thing. To get good voltage you have to also have a good ground. In measuring voltage you usually use a frame etc for ground. Where you put the ground lead should not make a difference in the reading. So if you measure from a bare spot on the frame reading should be the same as from the top of the battery. If not you could have a bad ground from motor or frame to battery, This would also cause the problems talked about by dbeardslee in previous post. A bad ground can show good with a resistance check because there is no load however when you start a bike the load of the starter with a bad ground or you are running down the road with lights on it can show up.

[bikerphil]

Marshall, you did check that mid way connector in the PU coil harness for corrosion/looseness right?

[TopCatGr58]

Hey Bug,

Get those POS graphite resistance wires out of there!! As Steve and I think also CZ has stated, as temps rise, so do resistances...so as the engine heats up, the wires heat up and can develop even more resistance! The Bikes TCI is not RFI sensitive, nobody uses AM radio anymore , and so any RFI that the coils/wires/plugs will create is negligable. Put some SOLID CORE wires on those hot coils to get the most spark energy to the plugs.

I may be able to do your TCI test tomorrow....just have to take the seat off of my 81 SH that I just got back from XSSE rally, and it ran just fine!

WHICH 2 cylinders are you loosing...I didn't re-read the whole thread?
Remember, if 1-2 or 3-4 it's fuel, if 1-4 or 2-3 then it's electrical.

T.C.

[dbeardslee]

Hey Bug,

Get those POS graphite resistance wires out of there!! As Steve and I think also CZ has stated, as temps rise, so do resistances...so as the engine heats up, the wires heat up and can develop even more resistance! The Bikes TCI is not RFI sensitive, nobody uses AM radio anymore , and so any RFI that the coils/wires/plugs will create is negligable. Put some SOLID CORE wires on those hot coils to get the most spark energy to the plugs.

I may be able to do your TCI test tomorrow....just have to take the seat off of my 81 SH that I just got back from XSSE rally, and it ran just fine!

WHICH 2 cylinders are you loosing...I didn't re-read the whole thread?
Remember, if 1-2 or 3-4 it's fuel, if 1-4 or 2-3 then it's electrical.

T.C.

He said it was dropping 2&3.