'79 GS550--battery shot?

[tbrand69]

Hey guys, quick question:

What are the volts required to actually start the bike?

I ask because the bike started and ran about 3-4 weeks ago while I was getting it put back together. However, now it won't start at all. I left the battery on a charger for a couple days, then came out, primed the carbs for about a minute, turned on full choke, switched the petcock to ON, and teh bike just sits there and turns and turns without starting.

The starter is going, all of the lights are nice and bright, and the carbs have been FULLY rebuilt and serviced. Battery read:

13.11 volts while off
12.56v with ignition on
9.56v while the starter is cranking

For the sake of thoroughness I pulled the plugs and found that they are completely dry. No residue at all. So it's either a battery issue or a fuel issue. I'm just trying to narrow things down here.

[tom203]

"while I was getting it put back together"

What had you been doing to it?
"FULLY" serviced carbs (?) might need more priming
If the starter keeps cranking, your battery is doing its part. Dry plugs mean no fuel, so start there.

[ChicagoBob]

Might be flooded. A CV-carb 550 can be difficult to start cold if you touch the throttle. I'd suggest checking for spark and fuel flow,and check all the settings, such as plug gap, timing, etc. Then set the petcock to prime for 10-20 seconds, set the choke, and crank it with no throttle. If your starter is turning, your battery is good. Good luck!

[tbrand69]

"while I was getting it put back together"

What had you been doing to it?
"FULLY" serviced carbs (?) might need more priming
If the starter keeps cranking, your battery is doing its part. Dry plugs mean no fuel, so start there.

I was updating all of the worn out bits on it. Just finished the front brake rebuild when I started the bike a few weeks ago without issue. I did the usual stuff: new rubber stuff front to rear, dipped and rebuilt carbs, new intake o-rings, rebuilt both brakes, new TS relay, new spark plugs, etc. Just the usual stuff.

What would cause no fuel getting to the cylinders?

Might be flooded. A CV-carb 550 can be difficult to start cold if you touch the throttle. I'd suggest checking for spark and fuel flow,and check all the settings, such as plug gap, timing, etc. Then set the petcock to prime for 10-20 seconds, set the choke, and crank it with no throttle. If your starter is turning, your battery is good. Good luck!

I'm using the VM carbs, prime, choke, pertcock on, and start. The plugs are getting spark; I held them against the head to test. I will double check the gaps, though. I already set the points gaps and the timing according to the manual, and I can see them arcing little blue arcs while the starter is cranking. The valves were also checked and found to be within specs. The petcock also flows fuel when set to prime.

[koolaid_kid]

If you are getting a blue spark and the timing is correct, assuming it is getting air, the only thing left is fuel. The plugs should not be dry, so I would check the carbs to see why no fuel is getting into the cylinders. Possibly the float levels?

[Toasty]

Did you verify that fuel is actually getting to the carbs? You can try starting it in prime, just don't forget to turn back to run after or you'll flood the bike and ruin the oil.

[koolaid_kid]

Are there drain plugs on these carbs? If so, you can use those to see if fuel is getting to the carbs.

[tbrand69]

Did you verify that fuel is actually getting to the carbs? You can try starting it in prime, just don't forget to turn back to run after or you'll flood the bike and ruin the oil.

Are there drain plugs on these carbs? If so, you can use those to see if fuel is getting to the carbs.

Yes gentlemen, the carbs are getting fuel. I checked #1 by opening its drain screw slightly and fuel started seeping out. However, I did not check #2-4. I will do that tonight.

I have tried to start it in PRIME as well. Seems to have no effect. I really don't want to take these damn things off again, as it is an incredible pain in the ass to put them back on. Actually, if you have any tips on how to get them back in easily that would be awesome.

[tbrand69]

If you are getting a blue spark and the timing is correct, assuming it is getting air, the only thing left is fuel. The plugs should not be dry, so I would check the carbs to see why no fuel is getting into the cylinders. Possibly the float levels?

I sure hope the timing is correct. I did the little light bulb check when setting it and followed the manual and the GSR's guides, so all should be well. It is also getting air because I can feel a draft on my hand when I put in front of the air box opening and start the bike.

[koolaid_kid]

I sure hope the timing is correct. I did the little light bulb check when setting it and followed the manual and the GSR's guides, so all should be well. It is also getting air because I can feel a draft on my hand when I put in front of the air box opening and start the bike.

You should be fine with your timing. Pulling and installing carbs is a PITA, to be sure. There is no easy way, just be glad you don't have an 1100E.

[Toasty]

It's odd that the plugs would be dry if the carbs are getting fuel... Even if they were super clogged there should be something.

[barnbiketom]

I do NOT think 9.56 volts is good enough when cranking. I've had many a GS series that will not start with that low of a voltage.. the spark plug INSTALLED will blow out under pressure.. simply holding the plug against the head is not a good enough check. Check again with a better charge on it or jump it.. jumping it correctly will NOT hurt anything . just make sure + to + and - to -....

VOLTS IS VOLTS.. and the components on the bike will only draw so many amps.. it does not matter what battery is used to jump.
let the flame war begin

if that does nothing then it may be fuel.. assuming nothing else was done???



I know I'm gonna get flamed again hahha here BUT a couple 'small' shots of starting fluid into the airbox inlet will tell the tale.

I know , a bike should not need starting fluid to start and run but maybe the floats are stuck from being dry? On a fresh rebuild sometimes they don't seem to want to fill up.

[tkent02]

Depends on your ignition, a points type system will make sparks enough to run at maybe 7 or 8 volts to the coil while cranking, sometimes less, while the electronic variants all need something over 10 or so volts.

[barnbiketom]

this is true. I'm just saying I'd do the jump thing first, then shoot starting fluid second.

In five minutes I'd know if either was the issue......

[tkent02]

You should be fine with your timing. Pulling and installing carbs is a PITA, to be sure. There is no easy way, just be glad you don't have an 1100E.

The 550 and 650 air boxes are every bit as challenging to remove and replace as the 1100E, actually harder I think. Never had to remove the fender to gain access on an 1100E.