Bike won't start when it's cold - too rich?

[almarconi]

As mentioned, 2 of the spark plugs were wet with gas. #1 and #4. I don't think that giving it *more* gas is going to fix the problem. Now that I'm starting to suspect the ignition system, it would sound like I could be having a problem with one of the coils, no?

My plugs were also wet after I cranked the engine. The bike would catch for about 2 seconds and then would not start. I thought the coils were causing the problem. I replaced the stock coils with accel super coils, new wires and plugs. Bike still will not start when cold.

Try blowing into the breather hose. I know it sounds strange but just give it a try.

[themess]

With a cold engine in warm weather, my GS650G needed full choke to start. It only took a couple of minutes to be able to pull the choke off entirely, but it needed full choke. So I would suspect that you are running rich.

[sultan]

What this does, is to pressurize the float bowl and send some extra gas up through the jets into the throats. Essentially, it is like an accelerator pump, it puts some extra raw gas in the air flow. Awkward to use, but it is effective.
.

Assuming I had the correct hose, this did nothing.
Which one is the breather hose?

Battery voltage at battery, with key off:12V
Battery voltage while cranking: 11V

Voltage at coil (if I'm reading it at the right place)
while key is off: 11V
Voltage at coil while cranking: 10V

Other notes.
When I put the bike up on the stand, gas came out of the vent line coming from the airbox (the big plastic box between the air filter and the carb air intake.) Probably a couple tablespoons worth.

I must have the wrong place where I'm trying to test things. According to the manual, I should have relatively low resistance between the signal generator wires and ground. I do not. It's essentially infinite.

The manual also says that on the other side of this connector, I can test the ingitors/coils by either using a battery, or the ohmmeter. I tried both and don't get a spark on either #3 or #4 plug. I put everything back together, and cranked the bike with #3 and #4 grounded, and got spark on both plugs.

Another interesting note is that with #3 and #4 plugs out of the bike, it started and idled. I put them back in, and couldn't get it to start.

If anyone has any advice as to what I'm doing wrong (I'm following the manual, and it seems I'm in the right place...the color of the wires match) please let me know. If this information helps pinpoint the problem, let me know what I should be doing to fix it.

It's a warmish day here, and the bike wants to start anyway, so all of this is very frustrating. Thank you.

[sultan]

With a cold engine in warm weather, my GS650G needed full choke to start. It only took a couple of minutes to be able to pull the choke off entirely, but it needed full choke. So I would suspect that you are running rich.

I suspect the same thing. Is the fuel screw the only way to adjust the mixture? I understand there's the idle, and the mechanical butterfly valve adjust, and the choke. It doesn't idle high when it's warm, so the idle isn't making it run rich. The mechanical adjustment is just to balance the carbs, and the choke is full seating when the lever is pulled back. What else can I do to lean out the mix?

Thanks.

[derwood]

try boosting it with a good car battery as a test, you may have a poor battery consequently low cranking speed and low voltage to the coil while cranking

[Mysuzyq]

Did you set or check the carb float heights to spec after the carb work? I am having some similar issues, and the floats are a tad too high, (my carbs are off a '94 Suzuki). Bike started without choke, or with very little choke in warm weather, and runs great, but cold weather starts are no fun.
Tony.

[sultan]

try boosting it with a good car battery as a test, you may have a poor battery consequently low cranking speed and low voltage to the coil while cranking

It's an almost brand new battery, and even after a full charge on a charger, it does the same thing. However, I had the same idea, and the bike still won't start, even while hooked up to a car battery.

[sultan]

Did you set or check the carb float heights to spec after the carb work? I am having some similar issues, and the floats are a tad too high, (my carbs are off a '94 Suzuki). Bike started without choke, or with very little choke in warm weather, and runs great, but cold weather starts are no fun.
Tony.

I did check the float height while rebuilding the carbs. Had to post to the forums to figure out where to take the measurements from, but according to the manual, everything should be in spec now.

[almarconi]

Assuming I had the correct hose, this did nothing.
Which one is the breather hose?

Battery voltage at battery, with key off:12V
Battery voltage while cranking: 11V

Voltage at coil (if I'm reading it at the right place)
while key is off: 11V
Voltage at coil while cranking: 10V

The hose you want is attached to the carb, there are two of them one on either side of the bike.

IMHO your battery voltage is too low. A fully charged battery should be reading about 12v, I would expect to see 12.6-12.8v. Your voltage at the coils should be the same as at the battery. More than likely you don't have enought voltage at the coils to get a good spark. I would start by doing the coil mod to ensure full voltage to the coils.

Did you check to see if your RR and stator are working properly?
It is also important to make sure your ground connectors are clean and tight. I would remove the headlight and check all the wires in the headlight bucket to make sure you don't have any burned connectors. Also look at the wires leaving the RR and make sure these are clean and tight.

[82Shafty]

I meant your spark plug boots

http://www.z1enterprises.com/detail.aspx?ID=425

They unscrew off of your plug wires.

[twistedwankel]

'83 GS650, 23K miles. All summer the thing has been running great! With the choke half-on, I'd just have to tap the starter once and it would fire right up. Compression is 175 (or better) on all 4 cylinders.

As the temperature has dropped though, it's become harder and harder to start. Today, for the second time this fall, I cranked (and paused) and cranked (and paused) until the battery went dead. (Interestingly, it did the exact same thing with the same symptoms *last* fall when the temperature dropped, which prompted all the work in the spring. In a pinch a couple of times I used starting fluid in the air filter, and doing that caused the bike to fire right up.)

Ideally, I'd like to ride the bike until the roads get bad, but I can't do that if it won't start. Any advice is appreciated.

Thank you.

I feel for you (I once thought of having an ether tube installed). I'm on my 2nd GS now and they both were/are really cold blooded below 70F. I finally left them on the battery tender anytime when I wasn't using them daily. If they sat for more than three days I would turn on "prime" before starting as some gas apparently was evaporating from the bowls (not leaking-I checked). I virtually always had/have to use full choke on the first daily start and let the thing run for 10+ minutes to get any heat into the engine and be able to turn the choke fully off.

My present original stock 81-750E starts the same as my old original stock 82-450L. Everything electrical/fuel/valves was gone over on both. One thing that did help alot was to run a direct ground from the Rectifier to the Negative battery terminal - site suggested. It raised the volts (I have a meter installed) from 12.3V to 13.8V at idle now with lights on. That is a big deal for these little batteries and original weak coils (but you changed yours-I didn't.). If you can't turn off your headlight the relay starting headlight (Steve) mod on this site is a great idea.

I still have to use full choke (first start of the day only) but it pops right off hitting on 2 cyl (sounds like it anyhow) and within a few seconds will rev normally and can back off choke to 2k. On an 80F day I can crack the throttle a 1/4 turn with no choke and hold it until the bike will rev by itself and idle (about one minute).

I was able to start the '81 with a dying battery showing only 8.2V while cranking and it actually fired when slightly warm. I have occassionally push started these bikes with a slight roll in 1st gear when the battery is weak rather than killing it entirely (no juice for coils).

For some reason once they get flooded by gas a little shot of ether into the airbox will fire it off immediately (volatility diesel issue?). You do what you have to do when you have to go in the snow!!

I suppose you could keep the bike in a heated garage or invent a block heater like in Canada?? They are cold blooded!! I now live in FL and even when 90F my bike cools so fast that within 15 minutes of sitting off the idle is dropped down upon restart and takes 10 minutes to get back up to operating temperature. So much for worrying about overheating these aircooled motors.

Once I got a slug of fines/rust into the carb bowls which I flushed out by draining the bowls repeatedly,replace rusted bolts and installed a gravity prefilter - no more rich running.

You will develop a cold starting system that works eventually. Like all cold blooded creatures they like to hibernate in winter. That's why I retired in the South and ride year round now Good luck.

[82Shafty]

After the relay mod and new plug boots, my bike pops and fires on the first revolution even on a 38 degree morning after it has sat for a week.

The great thing is I dialed the A/F ratio in when it was 80 degrees out and have not had to compensate for the cold weather.

[sultan]

I meant your spark plug boots

http://www.z1enterprises.com/detail.aspx?ID=425

They unscrew off of your plug wires.

I also replaced the spark plug boots with NGKs this past spring. ; )

[derwood]

here is a long shot that happened on the 1150.....one of the bolts in the linkage that lifts the enrichment rods was loose so when i put the choke on only one enrichment rod was being lifted, I think you are too lean....confirm all of the enrichment rods are being fully lifted and don't touch the throttle when starting cold.

[sultan]

Fixed?

I'm not yet sure this is fixed, but thought I'd follow up with an update.

Ran into a problem last weekend due to stripped oil filter cover studs...messy. Had to wait for parts. It's all back together now and running.

Last weekend and this past weekend I:
-changed the oil
-put the battery on a charger overnight
-reseated all 4 carb fuel needle valve/screws, and took them out 2 turns

I rode the bike on Sunday, and it was about 45 degrees. The bike sat for about 6 hours and started right away (second try) and I was able to make it home. I've been going out to start the bike the past few mornings just to see if it will continue to start, and there's been noticeable improvement. Yesterday morning (~40 F) the bike started with 2 tries. Last night (12 hrs later, ~40F) it started on the first try. This morning (a brisk 35F) it also started right up on the first try.

Also, after doing these things the lagging/bogging at lower RPMs seems to have fixed itself. I'm getting good pickup at lower RPMs in addition to above 6K.

Honestly, I think it was the fuel screws. I *know* I set them to 2 turns out when I cleaned and rebuilt the carbs. And, it's not like they're loose enough to turn on their own with engine vibration.

I know some will say that it's the battery charge that fixed it, but if that's the case, why wouldn't it start previously when I hooked a car battery up to it? And, changing the oil shouldn't make any difference, right? Maybe it's slightly easier to turn, but not enough to effect starting the bike.

So, that's where I am. I'm hoping for a good, cold, 10 degree day soon so that I can be sure that this is actually fixed. Thought I'd give an update to see if anyone has any feedback and in case this might help someone else in the future.

Thanks!