Cylinder/head studs on Suzi T20

[doug rooney]

Well jab, "assuming" I did this correctly (big assumption), getting some odd readings. Now, I had the Meter set on 20v, the red probe INSIDE the headlight at the hot wire (red) with switch on. All things hooked up.
1) Both points open (business card), got about 13v at the points BASE and zero at both black and whites and/or upper part of point. (Lower part is screwed to base so gets 13v).
2) Left point open. Once again had red probe inside headlight at red wire and went to the first connectors (orange, also in the headlight) with the black probe...Got 0.03V on those. At the second Orange connectors from the coils, got 0.08v. At the left points, got 12v on the BASE and 0.08v on the white connection. On the right side, got 12v at both the base and black connection wire. Again, red meter probe was inside the headlight at the red (hot) connection.
Bear with me....Prolly misunderstood something????

Edit: Again tested the rectifier as the book says and meter doesn't wiggle at all. Always infinite. If the book tests are to determine whether the current is flowing in the right direction, shouldn't the meter do SOMETHING?? Could a defective rectifier cause these problems?

[jabcb]

What do you get with the right point open & left closed?

[doug rooney]

Right open (all else same as above):
Red inside headlight case to ground: 12v
0.05v at first orange
0.12v at second orange
0.10v at right points and/or black wire....11.85v at base
11.80v at left points and white wire and/or base

[jabcb]

Putting your readings as I understand them on the diagrams I got these results:

voltages_2012-01-01_dr_bo.jpeg

voltages_2012-01-01_dr_lo.jpeg

voltages_2012-01-01_dr_ro.jpeg

You can ignore the negative signs. They are just there to be technically correct. (My diagram used battery negative as the reference & you used battery positive as the reference.)

All these readings look reasonable. Readings with the right points open are a little inconsistent due to dropping battery voltage.

Primary sides of both coils look ok. While the wiring doesn't look good, it doesn't look like there is a problem in the wiring.

That leaves problems with coil secondary sides & non-electrical problems.

Its also worth checking your connections. A connection could be loose, so that it looks good for these static tests but becomes a problem when the engine vibrates.

More ideas on electrical will have to wait. I'll leave non-electrical issue up to others.

[doug rooney]

That's a tad depressing. Was hoping something would give you a clue. Will go over each connection once again with a fine tooth comb and maybe even replace all wiring and connectors with spade connectors. Clymer book says coil primary should be 1-2 ohms. (I have 4 on all coils). Suzi book doesn't say. Could be all 3 sets of old coils are bad but doesn't seem likely. Tried testing condensors and none checked out as the Clymer book said. ie: Black wire to + battery terminal, Body of condensor (called it negative?) to (-) terminal of battery to charge. Disconnect and touch black wire to body for spark....nothing???
Rectifier would have nothing to do with any of this??? Thanks jab

[jabcb]

No need to overreact.

From what I've read the coil primary resistance for the early bikes like the T20 should be 1-2 ohms. Coil primary resistance is about 4 ohms for the later twins (T250, T350 & T500). Suzuki may have actually started using 4 ohm coils when the T20 was in production.

What is the secondary resistance for all 6 coils that you have? (You will need to adjust the meter to read 20,000 ohms.)

Reviewed the topic history. Looks like you started out with left running ok & problems with right side. Then later had the right side working ok & the left not working. Am I right? What's it now doing? And what changes did you make?

The wiring connectors that are on your bike are still available. No need to switch to spade connectors.

[doug rooney]

OK, Just ran it and still running on the right only, not left (can and does change as I've said).

Checked resistance on all the caps I have. Some (most)are infinite ?, and the 2 I have on there now have about 4.2k (Caps ONLY).
Snipped off about 1/2" of the plug wires from coils to make sure I had fresh connections.
Coil on bike secondary:
L is 9K without caps on and 14k with newer NGK's.
R is 8.75K without caps and 13K with

Coil I took off:
L is 8.6K and R is 9K W/O caps

Third set of coils ( one side at least) jumps from 9-18K so I think wire is shot (flimsy in a couple spots including where it enters the coil. Other coil there is about 9K.

In thinking back on the history of when this started, perhaps that will help. It's been so long ago, I had to ponder it this morning. Also will have to admit to doing something dumb.
OK, nearly 2 years ago, I had it running fine after fussing with a lot of little things but NOT electrical. At that time, I did not know there was a hole all the way through the case from top to bottom under the carbs. Was running and noticed a pool of gas dripping on the floor. Since I hadn't seen that particular problem before, I thought I had somehow cracked the case....Nope! AND...Yup: carb float on left side (or needle valve) was causing carb to overflow. Didn't see it. Duh! Tore it ALL down and checked high and low for crack and nothing. Somehow (don't recall how), I realized what the real cause was and put it all back together. Since then, I've had THIS issue. I could be wrong again but am once more thinking stator. Have 2 of them and tried both. Same deal. Just before you got involved (I think), I split both stators and the copper wiring (single twisty strand running around the stator inside)insulation on both was very brittle or bare. Taped them up as best I could but maybe not good enough?? Taking it apart as many times as I have likely caused the damage to the brittle wiring insulation. That's where I am this morning jab. Thanks for the help and if you're tired of it, I certainly understand. Frustrating....

Edit: Yes, you are correct. Started out running fine on left, then switched. Have changed out caps, condensors, and coils.

[jabcb]

Coil secondary resistance (without cap resistance) of around 9K is ok.

The caps with infinite resistance are not usable. You might want to keep them because there are some posts about replacing the cap resistor. Don't know if the resistors in your caps are replaceable.

There are some posts about replacing the HT lead in the Suzuki coils. You might want to keep the coil with the bad HT lead too.

You should use non-resistor plugs since both the old caps and the newer NGK cap have resistors.

Do you have a manual or vacuum petcock?
If manual, does it leak in the off position? If vacuum, does it leak with the engine off? (Pull off a fuel hose to check.)
You'll need to fix the petcock if its leaking.

You mentioned throwing gas on the left side. Did you mean gas coming out of the exhaust pipe?
If that's the case, you may have to drain the gas out of the left cylinder crankcase.

My GT250 had a leaking petcock & I couldn't get it to run right until the petcock was fixed. Had gas coming out of the exhaust too.

The GT250 has bolts for draining the gas out of the crankcase. Don't know if your T20 has those bolts or not.

Perhaps someone else can provide advice on draining the gas and carb/petcock issues?

Some of the forum members are great at restoring wiring. Your wiring has seen better days -- fixing up the wiring is definitely worth doing after you've got the bike running ok.

[doug rooney]

Non resistor plugs?? Hmmm? Not sure what I have. I am in the boonies bigtime up here and my only parts store is Napa 20 miles away or the net. I wonder if They would have "non-resistor" plugs? Didn't know there was such a thing.
Petcock is manual and does not leak a bit.
This is the TC250 Scrambler version X6. Therefore, the pipes when on the bike form a "trap" as they bend down, then back upward. the same type of trap as under any sink. Sooo, there are no pipes on and the gas is blowing out the exhaust port of the engine. Had this same trouble with the pipes on, and the non-firing side would load up the "trap" with raw fuel mix.

edit: no bolts to drain fuel on this one and yes, I have seen the posts on replacing the HT of a bad coil.

[jabcb]

Per Clymer's, the correct plug for your bike is an NGK B-77HC.
It discontinued but still available on eBay. Box of 10 is $20:
http://www.ebay.com/itm/NGK-Spark-Plug- ... 0755848430

The currently available plug is an NGK B7HS.

The NGK B-77HC & B7HS do not have resistors.

Once you have the bike running ok, might be worth considering more expensive high performance plugs.

NGK sells non-resistor caps. You can use them with resistor plugs if you want.

Might be a good idea to start a new topic and ask about your fuel problems. Am no expert, but I suspect you will need to empty out the left cylinder crankcase. Carbs might need some work too.

[doug rooney]

Thanks for the plug info. After you told me that, I did some searching on how to tell the difference and a couple forums said the plug description would have an "R" in it if it were resistant. In the house now and bike is waaaaay down in the shop but quite sure I'm using one of the numbered plugs you mention (non-resistant).
I've appreciated your input and time very much jab and have learned a lot from you. Thanks so much! I'll get er! I keep thinking it HAS to be something simple that I've overlooked?? I'll get that wiring in better shape and proceed from there. GRACIAS! Doug

[zk0ot]

hmmm... i know i didnt put them back on the exact same... i may have them stacked. something to try.

[Suzukidave]