carb rebuilt, valves adjusted, decent battery, new plugs ... hard to start

[avow]

Hi,

I was going through the top 10 newbie mistakes, so far I have...

1) Replaced petcock
2) Replaced battery
3) Sealed airbox and attached snorkel
4) Replaced intake boot orings and rebuilt carb with new orings (cycleorings)
5) Replaced plugs, gapped to 0.70mm
6) Adjusted valves, all are in spec except #2 intake at 0.02mm (ordering a shim tomorrow).

battery starts at 12.7, drops to 12.15 after running lights for 10 seconds (AGM Yuasa, spent a few days on an battery tender jr.)

Once it starts running, I don't seem to have any problems, but its a crap shoot as to whether or not it will start.

Electrical "appears clean" at a quick overview, but I haven't really drilled down into that yet. The plug wires are in pretty bad shape, but don't seem to arc. (They are also going to be replaced).

I get spark on all 4 plugs, not sure if its a weak spark, but its there.

I have checked compression on 1&2 and its around 120 psi on both, haven't checked 3 & 4 yet.

Any ideas of what is messed up? Its basically spark, air/fuel mix and compression I need and it should run?


Thanks

 

[Joe Garfield]

You can check the plug wires and caps with an ohm meter. The numbers are posted in several threads, but roughly 15 kohm for the wires/coils and 35 kohm for the assembly (please search for the proper numbers, these are approximate guesses).

Are you having issues getting the starter to run long enough before the battery dies, or is it the kind of thing where you just crank a lot and it eventually starts?

 

[Steve]

TECHNIQUE is just as important as maintenance. :-k

Please either give us a move-by-move description of your starting technique or a video of it. We might find something there, too.

.

 

[5t341th]

hows the voltage at the coils? do the coil relay mod. very nice mod and can only help you

 

[avow]

5t341th: The voltages look bad at the coils, less than 10V (I was distracted, but I think it was 9.15 volts). The coil relay mod makes a lot of sense. I was thinking the same thing myself.

Joe Garfield: I measured the wires (2 of them) and I was getting about 9k per complete assembly (cap and length of wire). I am going to measure the other 2 tonight, and get an order into z1 today.

Steve: As far as technique, I am not sure I have a starting the bike technique. 1/4 to 1/2 choke, crank it about 4 or 5 revolutions, wait a minute, pray or curse add throtle to 1/2 choke and hit it again...

So, I guess I have done a lot of the mechanical work, time to go over the electrical. Chapter 2!

Thanks everyone, I will update the thread when I have some more information.

 

[JTGS850GL]

No throttle input should be needed during cold starts. You simply pull the choke all the way and crank the engine. Once it starts you simply back the choke in to around 2k rpms while putting your helmet and gloves on. Push the choke all the way in and ride away. These bikes are not normally cold blooded unless there are carb or ignition problems.

 

[geol]

With 10VDC at the coils, you have a problem with poor spark. When starting, suggest you keep hand off throttle when choke (enrichener) is actuated as this defeats the enrichener circuit and will flood the carbs. When cleaning the carbs, did you replace the pilot jets and ensure that the wells that hold the enriichener circuit check valve are clear? How about the brass tubes that pick up fuel for the circuit? Many times, the check valve and/or the tubes will be plugged. It doesn't help to just replace orings if the pilot jets or enrichener circuits are not clear as starting the bike from cold requires a rich fuel environment. And if spark is poor, that compounds the starting problem and your plugs will foul pretty easily.

 

[avow]

geol: I was pretty OCD cleaning the carbs, I put a "special tool" down each orifice and checked for obstructions with light and ... even adjusted the float height with a micrometer. Did _NOT_ bench sync, so they will be coming off and getting bench synched.

Anyway I did the coil relay mod, and continued to have problems. Then I checked the resistance of the secondary on one coil, and it measures open. How could I have got a spark? This isn't clear to me. Tried rapping it with a screwdriver and metering but for the life of me it appears open.

On the coil that is open, I measured 12.1V on both of the terminals on the primary with reference to ground (on battery post). I don't get that really.

I'm gonna try and go down to my local motorcycle salvage and see if I can get some coils.

 

[Steve]

Steve: As far as technique, I am not sure I have a starting the bike technique. 1/4 to 1/2 choke, crank it about 4 or 5 revolutions, wait a minute, pray or curse add throtle to 1/2 choke and hit it again ...

As you have seen by now, adding ANY throttle while using the "choke" is counter-productive. NEVER add ANY throttle while using the "choke".

Although you might still have some electrical issues, let's concentrate for a moment on the carbs.
What is the setting on your mixture screws? How many turns out from "lightly seated"?
Three full turns should be your starting point. After the bike warms up enough to not need "choke", you can slowly turn each screw in, listening for a drop in engine speed, then back the screw back out about 1/4 turn. They might end up in the 2 1/4 to 2 1/2 turn range, but start at 3 turns for easy starting.

.

 

[avow]

Replaced the coil with one that measured about 12k, bike didn't start. Checked for spark 1&4 were dead, checked coil, secondary coil open (instead of the 12k it was an hour before). So it looks like I am blowing coils. I am gonna start searching and try and find the cause for this.

Incidentally the primary is 2.6 ohms, where the service manual recommends 3-5 ohms. The secondary is 12k while the service manual recommends 30-40k. ( Tek ZCT006-TR12V is what was shoehorned in by some previous mechanic ). Glad I didn't by a pair of $200 Dyna and pay for overnight express.

I'd rather be riding my bike than working on it, but I would rather be working on my bike than the lawnmower. Hopefully I can get on the road for the weekend.

Could anyone please offer why my coils are blowing?

 

[avow]

I think I solved the hard to start problem. The ground to my igniter (Black/White) was not connected to ground. I fixed that and fought with getting the (new) 7mm dyna suppression wires onto the little spike in the (not factory) coils and it started right up.

Pretty sure my R/R is toast too, at least it fails the tests in the Suzuki manual with measurements that should be 6-8 ohms coming in around 3 megohms. The connections that are supposed to not exist are about 30 megohms, I suppose that's close enough to infinity at 12v. I'll have an run down to the salvage and see if I can find a R/R.

There is continuity on all 3 sections of coil in my stator (0.8 ohms) but I haven't done the no load AC readings yet.

Thanks y'all for the great resources. I know a lot more about my bike than I used to.

 

[dantodd]

Everyone is going to start chiming in to recommend getting a series R"R rather than an OEM shunt style. The shunt type always runs your stator at full output and dumps energy back into the stator when it doesn't need the full output. A series R/R will "shut down" the stator when it doesn't need full output. This will increase stator life and reduce heat in the case. Compufire and Polaris (SH775) seem to be the most popular.

 

[Steve]

Pretty sure my R/R is toast too, at least it fails the tests in the Suzuki manual with measurements that should be 6-8 ohms coming in around 3 megohms. The connections that are supposed to not exist are about 30 megohms, ...

I don't know of any measurements on the R/R that are supposed to be 6-8 ohms. The only thing that you can measure OUT OF CIRCUIT would be the forward bias of the rectifier diodes. There will be 12 measurements in all, if any ONE of them is bad, the entire device is bad. The readings that you get will depend on whether you have a "diode function" on your meter, but you should see conduction in one direction and non-conduction when the meter leads are reversed.

I'll have an run down to the salvage and see if I can find a R/R.

If you are going to go look for a replacement R/R, do yourself and your bike a favor. Do NOT look for one from a Suzuki. Look for one from a Polaris Razr ATV. I think it has to be about 2011 or newer, but what you are looking for will be much larger than what you have now, and will have "SH775" on the fin away from the connectors.

.

 

[Guest]

The problem described was similar to the problem I just got through with my gs1100es project.
I went through all the check lists of newbie mistakes like you did (and more including SH775 and coil relay mod).
The engine started, but idled and ran very poorly. It turned out that #1 and #2 is not idling at all (#1 and #2 exhaust pipes were warm but not hot).
As I was reading your tread few weeks ago (to resolve my problem), I saw geol's post regarding replacing pilot jets.
During carb rebuild, I remember seeing one of the pilot jet was slightly scoured (but not plugged) at the tip.
I replaced all four pilot jets (along with rubber plugs for pilot jet opening), and now the bike runs very well at all throttle openings.
I like to thank GSResources and a very special thanks to geol for the timely advice.

 

[avow]

I was trying to follow the test procedure from this part of the manual:


Not sure exactly how meters work, but maybe if there is not enough voltage on the ohmmeter mode to forward bias the recitifiers it would measure open? I think its 0.7v or something for silicon if I remember from when I was a child. My meter does have a diode tester but I didn't try that.

I have a 32800-34210 so possibly original R/R. Good call on the upgrade. The salvage only has bins full of parts, not that much is labelled I was going to try and find a Shindengen but I will try and find a part number or picture of the one you suggested and maybe I will get lucky. I feel very privileged to have a salvage shop that I can go to, otherwise its a lot of waiting on ebay and stuff.

 

[Steve]

The diode test function would be better. Yes, you remember rather correctly about the .7 volt drop. In the diodes used in the R/R, it's typically in the .55-.60 range, but they should all be pretty close to the same reading.

Step 1: Put the red meter lead on the red wire from R/R. Touch black lead to the three input terminals (wires). You should have open (OL) readings.
Step 2: Switch meter leads, put the black lead on the red wire from the R/R. Touch the red lead to the three input terminals. You should get a reading. All three should be pretty close to another.
Step 3: Put the black meter lead on the black wire from the R/R. Touch the red lead to the three input terminals. You should have open readings.
Step 4: Put the red meter lead on the black wire from the R/R. Touch the black lead to the three input terminals. You should get the same readings that you got in Step 2.

If ANY of those 12 readings is not right, you have a bad R/R.

Note that this only tests the rectifying diodes. The only way to test the voltage regulation part is to plug everything back in and fire up the engine, but it's good to know if the diodes are good before testing the regulator.

.

 

[avow]

I ran the test you gave me Steve, and it turns out I have a blown diode. So I know the R/R is toast. I got expected measurements ~0.55V except one makes sense because I would see a voltage increase with throttle, but nothing up in the 13.5V range, more like 12.7 or something.

The stator has 0.8 ohms on each coil, but I couldn't get the bike to start to do the AC readings.
I realize the R/R has nothing to do with my no start problem, but its a problem nonetheless. I think I am just gonna order a new SH775 instead of bothering with the salvage.

This bike has certainly had some problems, probably the battery lighting the seat on fire didn't help much, nor running it with the ignitor not grounded...

 

[avow]

So since the R/R was toast, I tested the stator 43/41/6 VAC at 5000 RPM. Bought 2.5 lbs of wire for $20 rewound it and installed it. (Wired up Delta).

Next up, formerly starting bike wouldn't start so I ran more tests until I concluded the igniter was toast. Drove 200 miles out of tenacity/OCD to pick one up I bought on ebay. Installed it and bike fired up immediately. Getting about 12VAC from each leg at idle with my stator rewind. Tonight I wire it into the new SH-775 R/R I got with the Furukawa connectors I got from Eastern Beaver, assuming i get 80VAC out of my stator at 5k RPM.

Hopefully back on the road ...

New petcock, valve adjust, carb rebuild with new o-rings, new intake o-rings, airbox sealed, new battery, rewound stator, new R/R, new igniter...

Incidentally I cut out the starter cover gasket and pickup coil gasket by tracing the used ones with pencil and cutting it out with scissors and x-acto knife, that went real smooth.

 

[avow]

Uhh, turns out I am looking for Wye not Delta wiring. I'll reconnect it tonight hopefully and get more like 80VAC than the 60VAC or so I was getting. Took it out for a spin last night and today and its great to be back on the road!