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Now I have a new problem. I know everyones tired of hearing from me about this '81' GL1100 but I sure do want to get it going.

For those that are farmilar with the work I've been doing (GL1100-Got compression and fuel, no spark?) I've got good compression and spark but fuel is not getting to the top of the piston. This morning I cleaned the carbs for the fourth time (did not split), reinstalled them an still nothing. So in talking to JackJohn I performed a test, by removing the plugs and adding a couple of drops of fuel, replaced the plugs and turned the engine over. It accually tried to start:)!
The question is how does the fuel get from the bowl to the top of the piston:baffled:? Is it sucked in by the downward movement of the pistonor is it pushed in by the movement of the throttle and fuel pump?Or What. I think if I can answer this question I'll know what to clean, repair, or replace!
 

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Hi my thoughts on your situation I would start at the fuel tap this supplies the fuel pump via an in line filter is the fuel getting to the pump? if it is, is the pump working ok it should feed the carbs. I would take the pipe off the out side of the pump and check but be careful as it will squirt a lot of petrol if it is working ok. From the pump it goes into the carbs and passes to each float chamber via pipes under pressure to the float needles. If you have cleaned the carbs when you turned them upside down did fuel spill out of the tops of the carbs as the fuel drained out. Asure indication the carbs are getting fuel.Now if the carbs are empty then the needles must be stuck!when the float chambers are emptythe needles drop and fuel flows in , the floats lift the needle on to its seat cutting off the fuel at a set point. When you turn the engine the fuel is sucked through the jets into the main chamber of the carb into the cylinder through the inlet valve. the flow increases as you open the throttle and the piston in the main body of the carb is lifted due to the suction from the engine allowing more fuel through. You have compression therefor you must have suction. If the carbs are full of fuel and the engine is sucking it should start. have you checked the Plugs are they damp, is there a good spark. I am not a trained mechanic but this is my understanding of the situation. I am sure the Guru's on this site will also try to help also I have just had my carbs in bits so know the pain in removing them.

Rich
 

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Thanks rich,

I am getting fuel to the bowl. The fuel pump is pumping fuel to the bowls. To check this I took the carbs off, removed the bowls and suspended the carbs between to fixed points, turn the engine over and fuel flowed out of each needle seat. I also lifeded each float to 'turn off' the fuel flow and it did!

I figured it the fuel was sucked in then I must have a proper seat at the carbs and head via the manifold boot, so at both points I applied a fix-a-gasket seal. That helped as it now will backfire through the carb air intake.
 

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Fuel is sucked in on the intake stroke of the piston. Since you have normal compression it's pretty certain that the valve timing must be pretty close and the piston rings sealing. The valves themselves aren't leaking since the compression proves that.

The best check of the carb is to remove the drain screws on the carbs while they are set up normally on the engine. Checking the float operation with the bowls off as you describe really doesn't prove much. If you crank the enginewith the carbs installed ready to run and then remove the drain screws each carb should drain fuel out of the drain. That tells you that fuel is getting to the bowls in NORMAL CONFIGURATION. If there's fuel there the only thing standing between the combustion chamber and the carb bowls are the carb jets. They would all have to be blocked to have your problem and that seems very unlikely.

One more test you could try would be to squirt a very small amount of gas or starting fluid down the air intake as you crank the engine, if it tries to start it will verify the fact that your engine can suck air through the carbs and into the cylinders. It would indict your carbs as the problem.

You haven't mentioned what effect if any using full choke has on attempting to start.

In their most basic, a carb has float bowl that is designed to keep gasoline at the same depth in the bowl at all times, allowing more in as it's drawn out by the engine, and slowing or stopping the feed of fuel in when the engine demand reduces or stops. The fuel is suctioned from the bowl by vacuum which is developed when air flows through the carb. The vacuum comes from the air being accelerated through the carburetor throat where it's pinched off a bit. Since fast moving air has less pressure than slower moving air (Bernoulli principle) it creates a vacuum and sucks fuel through one of the jets. Which jet provides the fuel is determined by the amount of vacuum and the position of the throttle plate among other inputs. The choke operates by closing off part of the intake increasing the vacuum to the point where more fuel is pulled in to help ignition and combustion in a cold cylinder.

The point of all this is that if the carburetor is assembled properly and the jets are installed right, and the floats are set properly so the fuel level is at least reasonable correct, the engine can't help but run if there's spark and compression. In my opinion you really don't know if the floats are allowing fuel into the carbs. That's got to be determined with a check while the carbs are in normal operating condition, not removed from the bike. If fuel comes out of each bowl drain then it's most likely there's a major error in jet positioning or carb assembly.
 
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thank you exavid,

I just checked the fuel supply tocarb, its ok. I loosen the bowl drain plug and empty the bowl, I then retighten and turn the engine over a few times to fill the bowl, then loosen the bowl drain plug again and fuel flowed out as before. I also checked each spark plug for wet,dry, or damp. Its hard to tell, there's not a lot of fuel on each plug but it's between damp and wet, I guess? I also checked each plug for spark again. Each spark looks good, but I don't know a stronge spark from a weak spark. It is a WHITE spark not blue. I do have a meter and can check, just don't know how.

When I had the intake manifolds off (one at a time) I apllied smoke at the head and it suck the smoke right in. That''s good? Right? However, by aplying a small amount of fuel to the top of the valve and turning the engine over and stopping with the valve closed I notice small air bobbles at the lip of the valve. Is that ok?
 

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Teacher.. Exactly what have you got for good compression? Can you give us the psi? If the compression psi is on the money, then the valves and crank are mechanically timed properly.. Next, if the spark occurs at the correct moment, all that's left is fuel.

Exavid pretty much covered it all as far as in-depth engine requirements to run it. I understand you're getting fuel into the carb bowls, but what's not making sense is there is fuel, compression & spark (white is good), but the engine still does not run. What did you set the plug gaps at? Now we need numbers.

You mentioned "wet plugs". That tells me the engine is flooding.. When the carbs were apart, were the pilot screws set up correctly for the initial start?

Like Exavid said,,, If all the parameters are correct,,, the engine has no choice but to run... It was designed that way..

Keep the questions coming.. This is a real brain teaser....
 

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PSI is about 148-152 on each cylinder. I'm going to retest this morning. I set the air pilot on each at 1 turn out from closed. twisty explained how to test for spark at the right time, I'm just now sure how to use the timing light properly. I've never used one and the direction in the box are confusing. I've try spraying starter fluid in air intake as I turn the engine over and I get 1 or 2 backfire through the carbs. I've pulled and held the choke while turning the engine and I get alot of mist or backfire through the carbs.
This morning I'm going to try turn the air pilots out 1 more turn to create more vacuum, maybe? It could be to much fuel, but I'm not seeing any evidence on the top of the pistons. And it does not smell like it's flooded.
I know all of the Guru's are frustated with this situation as it appears to be imposible: Spark right, timing right, fuel right, compression right, this engine HAS to start! But it won't. I've tried everything twisty as suggested except the spark at the right time with the timing light.
 

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hey all,

I took the carb assembly out and apart yesterday. In 1/2 first, then each. On the #4 and #2 carbs the Air Cut Valve (located on each side of the carbs)diaphram was just eat up. I understand this controls the richness of the fuel? This could be the problem? I'm going over to the Honda Dealership in Texas City to order new ones this morning. Could this be the problem? Ifnot, I'm back to square one.
 

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Hi Teacher. I have just changed all 4 air valve diaphrgram's the engine ran ok before but the mixture would not adjust correctly. Now three of mine only had small pin holes in them butone was shot fullof holes rotted away with age. Iam not sure it will cure the starting problem but it sure will help. dont forget to check the other diaphgram under the 1st carb on right side works in conjunction with the choke I think?

Rich
 

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teacher wrote:
Now I have a new problem. I know everyones tired of hearing from me about this '81' GL1100 but I sure do want to get it going.

For those that are farmilar with the work I've been doing (GL1100-Got compression and fuel, no spark?) I've got good compression and spark but fuel is not getting to the top of the piston. This morning I cleaned the carbs for the fourth time (did not split), reinstalled them an still nothing. So in talking to JackJohn I performed a test, by removing the plugs and adding a couple of drops of fuel, replaced the plugs and turned the engine over. It accually tried to start:)!
The question is how does the fuel get from the bowl to the top of the piston:baffled:? Is it sucked in by the downward movement of the pistonor is it pushed in by the movement of the throttle and fuel pump?Or What. I think if I can answer this question I'll know what to clean, repair, or replace!
Teacher, if you have fuel in the carb float bowls I doubt you have a fuel delivery problem.. Try spraying a little gasoline or ether down the intake.. If it fires off & runs for a short second or two you probably do have a fuel delivery problem inside the carb. If it backfires or still won't fire off for a few hits you probably are not sparking at the correct time.. If you determine it might NOT be sparking at the correct time post back & we will try to explain (in a little more detail this time) how to verify you are getting spark on all 4 cylindersat the correct time.

On your--
The question is how does the fuel get from the bowl to the top of the piston
With the exhaust valve closed & the intake valve open & with the piston moving DOWN in the cylinder, that creates a low pressure (consider it a vacuum) in the cylinder right above the piston.. With that low pressure in the cylinder (below atmospheric pressure) it allows the outside atmospheric pressure at your (elevation above sea level) to try & fill that void by rushing in through the carb to fill that cylinder.. When the air rushes in through the carb it flows through the carb's built in restriction & picks up fuel from the exposed jets orifices when it does. (In a nut shell the piston moving down the cylinder pulls the fuel/air into the cylinder.

Twisty
 

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Thanks twisty,

Your advise is always right on, and I always check as you advise. Sometimes I am unable to do some of the test you sugest as I don't have all the equipment orknowledgenecessary to follow through. I now have a meter and a timing light but that knowledge thing keeps getting in the way.

twisty said:

I guess your next move should be to bring each cylinder up on compression (use your finger in the plug hole) thenuse a very soft wire in through the spark plug hole & find close to exact TDC on each cylinder (one at a time),, then when TDC per cylinder is found mark the camgear to cyl head, or center cam gear to block, or wherever you can match 2 moving parts..

Then installa timing light on each cylinder, crank it & see if you are getting a spark as that cylinders marks are close to lining up.. If ALL cylinders are sparking at ornear TDC on COMPRESSION then you either have a weak spark, bad spark plugs, or a fuel delivery, mixture, or volatility problem..
Can I check for spark at the right time to the right cylinders without the carbs as they are off the wing? An email from forum member "JackJohn" ask me if I had the pulse generator off when I had the engine out. I told him yes! He also told me that it was possible that I switched the order so that now #1&2 is now #3&4, etc.. Don't totally understand this. But it is possible I might have switch them, not knowing. I also ask him if I could correct this without taking the engine out again. I have not hear from him yet: I expect and answer today, I hope.

Thank you so much for your help. As long as I have suggestions coming I have hope!
 

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teacher wrote:
I guess your next move should be to bring each cylinder up on compression (use your finger in the plug hole) thenuse a very soft wire in through the spark plug hole & find close to exact TDC on each cylinder (one at a time),, then when TDC per cylinder is found mark the camgear to cyl head, or center cam gear to block, or wherever you can match 2 moving parts..

Then installa timing light on each cylinder, crank it & see if you are getting a spark as that cylinders marks are close to lining up.. If ALL cylinders are sparking at ornear TDC on COMPRESSION then you either have a weak spark, bad spark plugs, or a fuel delivery, mixture, or volatility problem..
Can I check for spark at the right time to the right cylinders without the carbs as they are off the wing? An email from forum member "JackJohn" ask me if I had the pulse generator off when I had the engine out. I told him yes! He also told me that it was possible that I switched the order so that now #1&2 is now #3&4, etc.. Don't totally understand this. But it is possible I might have switch them, not knowing. I also ask him if I could correct this without taking the engine out again. I have not hear from him yet: I expect and answer today, I hope.

Thank you so much for your help. As long as I have suggestions coming I have hope!
Teacher you ask...

Can I check for spark at the right time to the right cylinders without the carbs as they are off the wing?
--- Yes, as long as the engine can be spun with the starter & the fuel supply is blocked off so it doesn’t squirt fuel everywhere..



An email from forum member "JackJohn" ask me if I had the pulse generator off when I had the engine out. I told him yes! He also told me that it was possible that I switched the order so that now #1&2 is now #3&4, etc.. Don't totally understand this. But it is possible I might have switch them, not knowing
— That is very possible & could easily be your problem..




I also asked him if I could correct this without taking the engine out again. I have not hear from him yet: I expect and answer today, I hope.
[/quote]--As long as the correct pulse generator goes to the correct coil & they both work they shouldn’t have to come back out. If they are wrong now probably just a simple wire swap at either the ign box or coil trigger wire will allow it to then be correct..





You can go through a lot of set-up for verifying the correct spark timing to each cylinder but with the possibility of the pulse generators being reversed you might try a quick test & if that proves out you won’t have to do a lot of timing verification tests with that dreaded timing light... TO DO THAT_- if you have long enough spark plug wires just simply swap the front spark plug wires to the rear spark plugs & swap the rear spark plug wires to the 2 front plugs,, if it starts & runs then you probably have the pulse generators reversed.. OR, if the plug wires are too short to do the above just swap the coil primary trigger wires where they attach to thecoil (those are the small wires going to the coil that are not powered with the ign switch turned on.. If it starts & runs then you could probably just leave it like that, or swap the pulse generator leads going into the ign box..



Try the above to see if that will get it going.. If it still won’t start, post back & we will try to explain how to use that timing light & marks on the crank pulley to verify if you are getting a correctly timed spark as each cylinder comes up on compression..



Twisty

 

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thanks twisty,

I have the carbs off and am waiting for air cutoff diaphrams to arrive on Friday. Forum Member "Bobby W" suggested JC Whitney over Honda Dealership and man what a difference in price. I will install the carbs on Friday and Post the results of coil swap.

Im thinking I'll have this wing flying by the weekend.
 

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I think I may have the same problem. I have an 82 interstate GL1100. I got my bike back fro the shop after getting the stator replaced and i drove it a block and it started popping and backfiring and then stopped. The mechanic took it back to the shop and found that the spark pugs were dry, no fuel said that was not his problem (even though it ran fine for several weeks after my carb rebuild up until i took it in to him). I went home and took the carbs apart again since i rebuilt them the first time. i found that fuel is flowing from the pump to the number 3 carb and filling the bowls of all four carbs. however the ony carb getting fuel into the throttle body is the number three carb. all the others are dry. therefor the fuel is not leaving the bowl and flowing through the needle jet to the throttle body. i checked the jets and they are all clear. so the problem must lie with the suction you were talking about. so if anyone knows, how exactly does that work? what makes the piston at the top of the carb rise to bring the needle jet up to open the gas flow from the bowl to the throttle body.
 

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Buffalo Wing wrote:
I think I may have the same problem. I have an 82 interstate GL1100. I got my bike back fro the shop after getting the stator replaced and i drove it a block and it started popping and backfiring and then stopped. The mechanic took it back to the shop and found that the spark pugs were dry, no fuel said that was not his problem (even though it ran fine for several weeks after my carb rebuild up until i took it in to him). I went home and took the carbs apart again since i rebuilt them the first time. i found that fuel is flowing from the pump to the number 3 carb and filling the bowls of all four carbs. however the ony carb getting fuel into the throttle body is the number three carb. all the others are dry. therefor the fuel is not leaving the bowl and flowing through the needle jet to the throttle body. i checked the jets and they are all clear. so the problem must lie with the suction you were talking about. so if anyone knows, how exactly does that work? what makes the piston at the top of the carb rise to bring the needle jet up to open the gas flow from the bowl to the throttle body.
Buffalo Wing, you ask..
therefor the fuel is not leaving the bowl and flowing through the needle jet to the throttle body. i checked the jets and they are all clear. so the problem must lie with the suction you were talking about. so if anyone knows, how exactly does that work? what makes the piston at the top of the carb rise to bring the needle jet up to open the gas flow from the bowl to the throttle body.
First off that needle jet &needle position only controls the fuel well above idle so if it won't even idle that isn't your problem.. Even in the lower mid throttle ranges the fuel is metered by the large diameter of the needle shank in the needle jet before the vacuum piston lifts up.. The lifting of the vacuum piston is by engine vacuum in the carb venturi area as the air flow through the carb increases with both throttle opening & air speed through the carb.. Those vacuum pistons will stay all the way down until you rev the engine up to part throttle or above. Most of the low speed fuel is controlled by pilot jet & that fuel/air curcuit,, most fuel above 3/4 throttle (at high RPM) is controlled by the main jet.. If those vacuum piston(s) aren't lifting it shouldn't effect the low speed or idle operation.. If they are stuck open it can effect all ranges except wide open at high RPM's..

Twisty
 

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Thanks twisty,

I am not the most knowledgable (obviously). so then I still can't figure out why the fuel will not leave the bowl and continue on its course to my spark.I did check the air cut vavles as suggested above and found that they were sticky and gummy I am assuming that is because some of the carb cleaning solution i used got through the pri and secondary air jets and broke down the rubber diaphram of the valve. I am hoping that this might be my problem. I am deploying to the middle east with my military unit soon and I would really like to get in some riding before I go.
 

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Buffalo Wing wrote:
Thanks twisty,

I am not the most knowledgable (obviously). so then I still can't figure out why the fuel will not leave the bowl and continue on its course to my spark.I did check the air cut vavles as suggested above and found that they were sticky and gummy I am assuming that is because some of the carb cleaning solution i used got through the pri and secondary air jets and broke down the rubber diaphram of the valve. I am hoping that this might be my problem. I am deploying to the middle east with my military unit soon and I would really like to get in some riding before I go.
BW, Usually failed cut-off valves causes an over rich condition not a lean condition.. Those cut-off valves control the air into the pilot jet circuits so if they are open (or leaking) they allow normal operation of the pilot jet circuits,, if they are closed they cut off the air to the pilot jet circuits & cause the pilot jet circuits to then go rich (supply the fuel without any air mixed with it)..

I’m not sure why your crabs are not supplying fuel to the cylinders but at least one of the carb circuits should be working if there is fuel in the float bowls.. Have you done a cranking compression test on the engine? If not, start there.. If the engine doesn’t have any compression it can’t suck any fuel/air mixture from the carb.. If the bike has been sitting a long time make sure the exhaust system isn’t plugged with mouse or squirrel nests.. If the air can’t get out the exhaust it won’t allow any new to be sucked in through the carbs..

If you have good engine compression & the exhaust & intake are open, then you probably do have plugged carburetor internal jets & jet passages or other problems..

The more detailed the information on your problem & when it was first noticed the more we will be able to help you.. The only part of your problem we see is what you write here so the more we know the better we can help you..

Have you actually verified you are NOT getting fuel to the cylinders or are you just relying on that mechanics weak explanation? Maybe you have other problems & telling you that your weren’t getting fuel into the engine was an easy cop-out for the guy that did the work. Have you tried spraying fuel or starting fluid into the intake to see if it will even try to fire up? If not try that just to see if you are barking at the correct tree..



Twisty
 

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thanks again,

You guys are the best. The quick responses are much appreciated. Well I can start with the whole long story if you like.

I got the bike from a guy that had it sitting in his garage for 5 years (his friend died in an accident and he wouldnt ride anymore) so i took it to my place and immediately drained all the gas, flushed the tank and did all the routin maint. to it like oild change fluch the rad, new plugs all that stuff and last but not least rebuilt the carbs. once the carbs were rebuilt I put everything back together and hooked up a brand new battery and turned her over. she fired off relatively quickly and was running. I rode the bike about a mile and then back. I did this a few days in a row trying to build confidence in the bike (making sure it wouldn't leave me stranded) and then i noticed the battery was dead. I recharged the batt and rode again, the battery would not stay charged. I checked the stator and found it was bad so I bought a new one however with a full time job my own business the navy reserves and three teenage kids my time is at a premium so I took it to westside cycle accesssories who told me they had a wing guru. I gave him the stator and the bike and told them to replace the stator and do a tune up on the bike. 1400 bucks later i had a new stator and he had redone all the work that I had done including another new battery. He did not however mess with the carbs at all. when I arrived to pick the bike up the mechanic said he had run it the day before for a while and then he started it up for me it ran for about a minute and i said later and jumped on I left the parking lot and gotabout one block before the bike started to sputter and backfire and then die. I walked back to the shop and told the mechanic he went and pushed my bike back and could not get it to run either. he told me he would look at the bike again and to call him the next day and he would let me know what he had found. when i called him he said the plugs are dry no fuel and since he didnt mess with the carbs it was not his problem. I told him they seemed fine before and he just said sorry they dont work now but if i wanted to pay him another 600 bucks he would rebuild them for me (needless to say he will never see me or this bike again, unless i can prove he screwed it up and has to fix it for free). when i got the bike home i quickly checked the status of the carbs and he was correct, all four bowls were full but when turned over, the fuel only goes into number three carb (first inline off the fuel pump, the other three carbs are bone dry. i took the carbs apart and checked the jets again and looked for anything obvious and found nothing. then i posted here to try to get some help, which you have been very good with. I will check the compression as soon as i can and let ya know whats up with that. I figured maybe after that mechanics tune up he should know if i had any compression or not but i guess not.

thanks again for all your help
 

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It's not the jets or the floats, it's the fuel line between the carbs, something is plugging the passage way from #3 to the rest of the carbs.
 

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all 4 bowls are filling though. so the fuel is flowing from carb to carb just not going up through the jet into the venturi or throttle body (whichever they call it on these carbs).
 
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