*Parts Compatibility - TBS 1998

[sikatri]

I think an important observation has been made, it’s helpful if a thread has a specific goal and issues are checked and verified. It does get confusing when new issues are introduced or old ones not addressed. I may be wrong but the coil issue has been discussed numerous times with suggestions and advice given. They should have been tested and verified by now. Personally I would have changed them out as I’ve understood they are old and apparently an issue with this model as a few noted. It does seem like some issues are going in circles. Grounds and electrical connections should be checked before any other issues can be resolved. Being systematic is critical as noted earlier.

 

[atomsplitter]

I hope Biiim reports back and we can start another thread (on why the carbs don't work) if the engine not turning over is now complete and he has spark at the plugs.

 

[JCooper]

There is no evidence yet presented that the carbs do not work.

I'm still betting there's some burnt up ground wires or collateral damage causing all the odd issues.

First thing I'd concentrate on is getting back to square 1 by making sure all the problems introduced by cranking without the ground connected have been rectified.

 

[atomsplitter]

There is no evidence yet presented that the carbs do not work.

I'm still betting there's some burnt up ground wires or collateral damage causing all the odd issues.

Go back to Biiim's post on the throttles not opening in this thread (about 9 posts back, complete with picture of the carb throat and slide). incidentally he has no idea how the carbs work. His big complaint about 5 posts before that was the bike would not turn over on the starter, that's no longer the case.

 

[JCooper]

Go back to Biiim's post on the throttles not opening in this thread

She is referring to the slides not lifting. I told her to lift the slides and look at the throttle plates, but there has been no response.

 

[atomsplitter]

OK if Biiim is 'she' it still follows she has no idea about how CV carbs work because the slides did not lift with the throttle cable. No disrespect intended with my input, I see this is an opportunity to assist a rider and provide a little education. Your comment earlier got me to thinking I ought to try my T-120 start with, kickstand up, in neutral, clutch out and see if it starts. I'll test that today.

 

[JCooper]

I see this is an opportunity to assist a rider and provide a little education.

I agree, except, at this point we should help her focus on correcting the known problems first.

I make no claims as to how a T120 works. The last time I rode a T120 you had to have the trans in neutral and the clutch lever out or the kicker wouldn't be connected to the engine. (And twisting the throttle did lift the slides...)

 

[atomsplitter]

OK, result. With T-120 kickstand up, in neutral, clutch out and starter switch ON, nada. The neutral light didn't even go out. Pulled the clutch in and the starter engaged bike was running. Nefarious these bike enginerds, just nefarious.

 

[sikatri]

Perhaps a summary of what has been tested and what works at this point would be constructive. Biiim could you give us a brief summary. It would be helpful if we were all on the same page.

 

[JCooper]

The logic of "disengage clutch to start" is a lot simpler to implement. You need it regardless to restart when you stall in the middle of a busy intersection. Adding the "start in neutral" function is really unnecessary.

Neither one should make the neutral light go out. Only shifting out of neutral should do that. Which brings us back to the damaged ground wiring.

 

[sikatri]

Yes, if you’re at speed and stalls pulling the clutch in turning the key should be all that’s needed. I shouldn’t need to put it in neutral. But whatever works. This is a bit of a sidetrack. Is the OP running into this issue?

 

[Biiim]

Those are CV (Constant Velocity) carbs and the slides (that thing blocking the intake throat) is operated by vacuum. First thing to do is test the slide diaphrams (whats under the cap on top) by pushing the slide up with your finger as far up as it will go and then release it. It should snap back down to the position in nthe picture. Do that a couple times to make sure is free to move, push the slide to the top then using the index finger on your other hand cover the large slot at the top and press tight to seal the slot with your finger. Release the slide and now it should very sloooowly lower back to the position you see in the picture. If it falls down like before (under spring pressure) the diaphragms need replaced. Test all three to make sure they are all the same. Get that test done and tell me the results. BTW the throttle cable opens butterflys that are past the slides in the front of the carb. If that tests then the carbs can be synchronized, if not then they can't until the diaphrams are replaced.

They are not snappy. It takes a whole second to go back to position.

 

[Biiim]

The logic of "disengage clutch to start" is a lot simpler to implement. You need it regardless to restart when you stall in the middle of a busy intersection. Adding the "start in neutral" function is really unnecessary.

Neither one should make the neutral light go out. Only shifting out of neutral should do that. Which brings us back to the damaged ground wiring.

I’d like to clarify it doesn’t go out it dims. Like I worded that incorrectly

 

[Biiim]

You're all over the place. Coils, throttle, kill switch, neutral switch, CB500...

We've covered the throttles in two places now. A good reason to stick to one thread. Did you lift one of the slides and look at the throttle plate?

The bike will start without pulling the clutch, but it has to be in neutral. Otherwise it would lurch forward. I'm sure the CB500 is the same. (Also discussed elsewhere.)

The kill switch is simple to test. If you have 12 volts at the coil + terminals it's on and working.

You said the starter was turning the engine over, then you said it wasn't. Which is it?

The neutral light going out could be a ground problem, related to trying to start the bike with the engine ground not connected. (It should not go out when you press the starter button or when you pull the clutch in, only if you shift the transmission into gear.) Have you verified a good ground between the battery and frame? I assume you've reestablished the engine ground. Fix them first. If your grounds are flaky you'll have all sort of mysterious, confusing problems.

Coils are easy to test. Don't add new parts to the mix unless you know replacing them will be an improvement.

If you decide you need to replace the coils, search the internet for the coil-on-plug modification. Saves money and works better.

Successful troubleshooting, especially successful electrical troubleshooting, requires a logical. methodical, step by step process. Focus on one issue at a time, and don't change things until you understand what is going on.

Heard! The neutral light only dims when engaging the starter button. With the clutch pulled in I can turn over the engine. No successful start. Where to go from here? My guess is to check the coils? Already cleaned the spark plugs. Could replace them? How does one check the coils I’m assuming w a multi meter ?

 

[sikatri]

This should give you an idea.
https://bigbikereviews.com/test-motorcycle-ignition-coil/I think you mentioned they are old. I would simply replace them. It’s typically an item that eventually wears out. Nology makes good coils.

 

[atomsplitter]

"How does one check the coils I’m assuming w a multi meter ?"

You can use a multimeter, but if you want a quick and dirty to see if the coils are working there's an easier method. Pull the right side (#3) spark plug out and reconnect it to the plug lead. Then rest the plug against the engine so it's metal to metal contact. Then try to start the engine and watch for sparking at the electrode. If you are getting a blue spark at the electrode the coil for that plug is working. You can test the other plugs the same way since there is a coil for each plug. That will confirm the coils and the igniter are working.

 

[sikatri]

"How does one check the coils I’m assuming w a multi meter ?"

You can use a multimeter, but if you want a quick and dirty to see if the coils are working there's an easier method. Pull the right side (#3) spark plug out and reconnect it to the plug lead. Then rest the plug against the engine so it's metal to metal contact. Then try to start the engine and watch for sparking at the electrode. If you are getting a blue spark at the electrode the coil for that plug is working. You can test the other plugs the same way since there is a coil for each plug. That will confirm the coils and the igniter are working.

This is the quick and dirty alright. Used it on old cars in the past. Keep your battery charged up before and after testing. You don’t want your battery drained.

Oh on a side note, when your motorcycle is all fueled up and you have checked everything else works before you turn the key put the fuel petcock valve in the on position. I had this “duh” moment once when I went to start mine and forgot. I thought something had broken when it didn’t start. Went through my start procedure again and realized I hadn’t turned the fuel on. LoL. Things happen and don’t when we forget.

 

[atomsplitter]

They are not snappy. It takes a whole second to go back to position.

OK cover that slot at the top with your finger again and try to push the slide UP and you should feel some air pressure against your finger and the slide should resist going all the way up.


View: https://youtu.be/9zCBSBINtys

 

[JCooper]

Don't mess with the carbs until you confirm you have spark. Laying a plug on the engine is a simple but effective test.

The dimming neutral light may be normal. Make sure your battery is fully charged. Pull the fuse for the headlight to reduce the load on the battery when starting, until you get farther along. The igniter won't spark if the voltage is much below 10 volts.

Testing the coils is simple if you have an Ohm meter. Test between the two tabs and expect about 0.6 Ohms (IIRC) then test between the negative terminal (actually, either one will work) and the connector for the plug lead. Expect about 10K (10,000) Ohms.

Don't change any parts until you have verified they are bad. It just adds more variables to the equation.

 

[sikatri]

How’s the project going? Any updates?