GS550 - Get it started!

[Anonymous]

I have a 1978 GS550E which I have done a fair bit of work to. The engine has been rebuilt from the pistons up, bringing compression back to an acceptable 150 (before it was 106). The carburettors have been rebuilt except for the central needles (as they did not come in the kits), so I took the crap off them, polished them and adjusted accordingly.

I have taken the bike in to be tuned by SUZUKI mechanics and it runs great up to about 3/4 throttle. I do not thrash the bike so I am not worried about this (guess its related to not replacing those needles!).

The problem I do have is in starting the bike when it has been sitting for a couple of days or when the weather is cold. Usually takes me about 5 - 10 mins to get it going, but when its going it runs fine. I normally give it a few kicks then press the electric start.

Not sure what the problem is, plenty of spark and I usually switch it to prime for a minute beforehand.

Anyone have any suggestions? This is driving me crazy as otherwise the bike runs nice!

Cheers,
Paul

[denouden]

I dunno but my 80 550 was exactly the same....

I just made sure the battery was always topped up and I'd eventually get 'er going.

What a pain to start after a winter storage though....hope you find the cause...I know it drove me a bit nuts but it never left me stranded either which was good.

[satchmo]

Why doesn't it run great after 3/4 throttle?

The reason I ask is because it might be a carb issue. I used to have the same problem on my 77GS550 and I think my problem was a broken idle intake jet on the carb body.

Sometimes if the carbs aren't clean, or not setup right, it may hinder one of your cylinders from starting properly which will hinder your bike from starting, even if the battery's good, and the coils are firing properly.

What work did the mechanic do?

[Anonymous]

It doesn't run great after 3/4 throttle because the jet needles are pretty old. I just cleaned them up, I didn't replace them (because I didn't get any new ones in my carb kits).

As for the mechanic, he pulled the carbs back out and made the final adjustments to the needles and float levels. He also 'bored' something out in each carb to aid the fuel flow specifically to help with the cold starting problem - however, it hasn't done the job.

[jimcor]

I've found a little of that hard starting after sitting is just the nature of the beast. If I haven't run the bike for a few days, especially if it's been raining, it will tke a bit of cranking to get her to fire up. Been this way since I bought her many years ago. Double check your plug gap as a long shot.

[satchmo]

Well, there are a number of things it could be.

One thing I would check are the voltages coming from the coils (thank Earl for that tip, because I still remember it).

Sometimes if a coil is on it's way out, it won't send the full voltage down to the sparkplug.

I can't remember the exact specs, but they're pretty easy to check with a voltmeter.

Wait ... I found it.... copied from Earl (all credit goes to him).

OK now, it appears (from the voltages you quote) that the wiring is OK.
the next thing I want to check is coil primary and secondary outputs/values. Disconnect the positive and negative leads from both coils. Set your multimeter to the ohms scale on the lowest scale...that should be 200 (not K....just 200) On the left coill, put the meter test leads on the + and - terminals. You should get a reading between 2 and 5 ohms. Anything between 2 and 5 is satisfactory. Do the same for the right coil. These are the secondary readings.

To check primary values......

for the left coil, remove spark plug caps from the spark plugs on cylinders 1 and 4. (you will have the spark plug wires complete with the end caps in your hand. Set the multimeter to the 200K (yes, the 200K) ohm scale. Place one of the meter probes into the #1 cylinder spark plug cap touching the metal ring that normally connects to the top of the spark plug, place the meter's other probe into the #4 cap touching the metal ring inside it.
Any value between 30K and 40K ohms is good.

If either of your coils are outside the range of 2 to 5 ohms on the secondary or 30K to 40K ohms on the primary, you will need to replace them.

This will ensure that your coils are providing the optimal voltage to the sparkplugs which will help ensure it starts decently.

I see that you've checked the spark now. So who knows if the above will be of help, but it might.

Good luck.

[xifer]

The output side resistance on both my coils is 25 K a little lower
than it should be - spark looks weak on all plugs. Primary
resistance is 4.1 ohms on each coil.

Are my coils gassed? Because my other problem affects
only one coil: I have a 3 or 4 volt drop on one of the coil inputs.
When the split wires for each coil emerge from the loom one has
lost power. Should I rewire from the headlight connector where
the voltage is good or strip into the loom to find the problem?

BTW Thanks to Earl for coil testing procedure!

[jhibs]

I am also having mysterious starting issues with my 1981 550L. It has never been a good starter -- requiring a huge fistful of throttle and lots of positive thinking -- but recently it began refusing to start after the first attempt. If I tried starting it shortly after shutting the engine off or stalling on my initial try: no luck, just lots of cranking. If i did get it running on the first attempt it ran beautifully (or at least as well as it ever did), but I would have to wait at least an hour after riding or stalling on the first try to get it going again.

I just got back from a 2 week trip, and now it is giving just the slightest hint of wanting to start up when I first crank it, but it won't get going.

My spark plugs don't appear to be fouled, and there didn't seem to be any sign of a fuel supply problem when I did have it running.

I don't want to steal Paul's thunder (it is his thread after all), but does anyone have any ideas?

Thanks much