help! won't start

[hansimusmaximus]

my 1980 gs850 will not start The carbs are nice and clean, new gas, good spark. the carbs are getting gas but the gas is not getting to the engine. as i said, the carbs are CLEAN. when i try to start it it won't even kick, not even a sputter. the airbox is well sealed as well. i can't figure it out. any help will be appreciated!!

 

[eddiev]

try a shot of starter spray. Also make sure the choke is on and working. It sounds like you recently cleaned, maybe rebuilt the carbs so maybe the choke mechanism isn't working right. The starter fluid should still kick it over. Don't over do it though. Hope it helps.
Eddie V

 

[Steve]

Well, the first question is going to be:
How did you clean the carbs? If you didn't take them completely apart, dip them and re-assemble with new o-rings, don't even bother to go any farther, just go back and do your carbs correctly.

Next question:
When were the valves last adjusted? If the valves are tight (which they tend to do), the engine will be very hard to start, especially when cold. DO NOT use any starting fluid to try to get it going, it will only make it worse.

Third question:
How are you trying to start it? Proper procedure (after priming the float bowls) is to apply full "choke", NO throttle, pull the clutch, press the starter button.

.

 

[Guest]

Are the spark plugs dry?
Did you prime the carbs?

 

[hansimusmaximus]

Are the spark plugs dry?
Did you prime the carbs?

yes to both. could it be a bad vacuum line?

 

[bonanzadave]

Are the spark plugs dry?
Did you prime the carbs?

Try it with the Petcock on PRI.

 

[hansimusmaximus]

Try it with the Petcock on PRI.

tried it, didn't work

 

[almarconi]

the carbs are getting gas but the gas is not getting to the engine. as i said, the carbs are CLEAN. when i try to start it it won't even kick, not even a sputter.

If after cranking several times and the plugs are dry you are not getting gas to the engine. When you cleaned the carbs did you take them completely apart?

Open up a drain screw and see if gas comes out the float bowl. Your fuel T could be clogged with dirt. If you've got gas in the float bowls your almost there. More than likely the carbs are still clogged. It's nothing personal but unless you've cleaned many many sets of carbs, it may take more than one cleaning to get everything working properly.

 

[49er]

If you have good spark and the spark plugs are dry, you either have poor vacuum through poorly seating valves, or no fuel in the carb bowls. Do as suggested above and remove the drain plugs from the outer carbs. If you find no fuel which is my bet, you will have a blocked/faulty petcock.

With the petcock on, remove the fuel line while holding a collector under the petcock. Now turn the valve to the prime position. If fuel doesn't gush forth, you have an empty tank or a seriously blocked filter/petcock assy.

Fuel, air and heat/fire is all you need!!

 

[Kcwiro]

my 1980 gs850 will not start The carbs are nice and clean, new gas, good spark. the carbs are getting gas but the gas is not getting to the engine. as i said, the carbs are CLEAN. when i try to start it it won't even kick, not even a sputter. the airbox is well sealed as well. i can't figure it out. any help will be appreciated!!

Have you verified with petcock on prime that it is getting out out the petcock (no fuel line attached?) maybe ... if your petcock is not letting fuel out even on prime then you probably need a new one. You can open your gas cap as if it is not letting air in there is another problem. Nice part about motorcycles is they need only 3 things fuel, air, and ignition..seems you have eliminated two of the 3 so have at it.

 

[Steve]

LOTS of guesses about the fuel situation, but still have not heard the answer to my question:

When were the valves last adjusted? If the valves are tight (which they tend to do), the engine will be very hard to start, especially when cold.

:-k

.

 

[49er]

LOTS of guesses about the fuel situation, but still have not heard the answer to my question:

:-k

.

I had an echo after my last response. I didn't want to do the same to you.

However, I don't think these symptoms are caused by tight valves. For the valves to be that out of adjustment, ALL of the valves would need to remain slightly open so that no cylinders produced the vacuum needed to draw fuel and air into them. This would need to be the case, as the owner has stated that he doesn't get a kick from any cylinder, even when he has confirmed good spark is present. For all valves to be partially open, their clearances would have needed to be set nearly identical, and the wear rate on the seats identical to achieve this highly unlikely result.

 

[hansimusmaximus]

i have no clue when the valves were last adjusted. I'm sure they're past due for an adjustment. i do have fuel in the float bowls, just put a new petcock on a few months ago. i think i'm going to get a full carb o-ring set and dip the carbs again just to rule it out. i really appreciate the replies! i'll keep ya posted as i get time to work on it. thanks!

 

[Big T]

Here's how you confirm your problem

1. Take out all 4 spark plugs
2. Using a small hose or syringe, put up to an ounce of gas in each cylinder
4. Reinstall plugs
5. Try to start

If it pops or tries to start, your carbs are still plugged up.

 

[Kitten Tooth]

Ignition unit or signal Generator may be bad..

 

[Steve]

i have no clue when the valves were last adjusted. I'm sure they're past due for an adjustment. i do have fuel in the float bowls, just put a new petcock on a few months ago. i think i'm going to get a full carb o-ring set and dip the carbs again just to rule it out. i really appreciate the replies! i'll keep ya posted as i get time to work on it. thanks!

Thanks for the reply and confirmation of my guess.

While you are waiting for the carbs in the dip, why not adjust the valves, too?

Of course, that would mean that you changed two items, so you won't know which one of them actually cured your problem, but they both need to be done, so it doesn't really matter.

.

 

[hansimusmaximus]

Here's how you confirm your problem

1. Take out all 4 spark plugs
2. Using a small hose or syringe, put up to an ounce of gas in each cylinder
4. Reinstall plugs
5. Try to start

If it pops or tries to start, your carbs are still plugged up.

i just tried this. it popped and ran for a second then died. so the carbs are still the culprit?

 

[Guest]

Check compression also but all signs point to carbs being clogged
http://www.thegsresources.com/_forum/showthread.php?t=148764

 

[Steve]

Come to think of it, my first question has not been answered either.

Well, the first question is going to be:
How did you clean the carbs?

But, then, neither has this one:

Third question:
How are you trying to start it? Proper procedure (after priming the float bowls) is to apply full "choke", NO throttle, pull the clutch, press the starter button.

Next issue:

... I don't think these symptoms are caused by tight valves. For the valves to be that out of adjustment, ALL of the valves would need to remain slightly open so that no cylinders produced the vacuum needed to draw fuel and air into them. ...

Not necessarily. The intake valves close after the piston is already on the upward stroke. Usually, there is enough inertia in the incoming air to pack a little more air in by the time the valve closes. If the valves are just a little tight (still some clearance, not none), they will close later in the piston's travel. Maybe late enough that the piston actually pushes some of the mix back through the carb. Air moving across the carb jets will pick up fuel. Since it has already been by there before, it will richen up the mixture a bit more. Next time the valve opens, air will be drawn over the jets a THIRD time, making it even richer. By now, it's too rich to burn and not enough has stayed in the cylinder to get the engine to run.

Some that are desparate to get the engine to run will have sprayed some starting fluid in there by now, and some of that might have stayed in the cylinder and, because it is so volatile, would have managed to start the engine. The profound discovery now is that "this engine is so cold-blooded, it needs starting fluid to get it going", so that is what is now used.

As the engine warms up, the actual clearance at the valve will change, due to the expansion of the aluminum in the head. This change in clearance delays the valve timing enough that warm starts are made with no problem, mentally reinforcing the conception that the bike is, indeed, cold-blooded.

All of this frustration in spite of the fact that a simple valve adjustment will fix it all. Clean carbs will then ensure that the right amount of fuel will be metered into the airflow. Proper starting technique will help even more.

.

 

[Guest]

+1 on all this very good, classic advice.

Come to think of it, my first question has not been answered either.

But, then, neither has this one:



Next issue:

Not necessarily. The intake valves close after the piston is already on the upward stroke. Usually, there is enough inertia in the incoming air to pack a little more air in by the time the valve closes. If the valves are just a little tight (still some clearance, not none), they will close later in the piston's travel. Maybe late enough that the piston actually pushes some of the mix back through the carb. Air moving across the carb jets will pick up fuel. Since it has already been by there before, it will richen up the mixture a bit more. Next time the valve opens, air will be drawn over the jets a THIRD time, making it even richer. By now, it's too rich to burn and not enough has stayed in the cylinder to get the engine to run.

Some that are desparate to get the engine to run will have sprayed some starting fluid in there by now, and some of that might have stayed in the cylinder and, because it is so volatile, would have managed to start the engine. The profound discovery now is that "this engine is so cold-blooded, it needs starting fluid to get it going", so that is what is now used.

As the engine warms up, the actual clearance at the valve will change, due to the expansion of the aluminum in the head. This change in clearance delays the valve timing enough that warm starts are made with no problem, mentally reinforcing the conception that the bike is, indeed, cold-blooded.

All of this frustration in spite of the fact that a simple valve adjustment will fix it all. Clean carbs will then ensure that the right amount of fuel will be metered into the airflow. Proper starting technique will help even more.

.