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Discussion Starter #1
Hey Yalls,

SYMPTOMS:
I am trying to get my bike running again after sitting for a few months (almost a year)
I cannot get my bike to start and maintain a proper idle. If I crank it with no choke, it will sometimes will catch combustion but not enough to idle. Sometimes it will start without choke but very rarely. (temp is around 60deg F +- 5deg) If i use choke it will start after a few seconds of cranking but will have either very high rpm (3000) or low rpm (1000). It is random and is inconsistent. Sometimes it won't start with choke but mostly does. I have not been able to have it run for a solid minute until it cuts of by slowly having the rpm drop off or randomly cut off quickly. When it is running, I would flip the throttle and it would react, sometimes like there is no issue, other times it will shut off the bike as if too much air went in. If I move the throttle very slowly it would not cut off even though sometimes I can feel that it wants to. But again there are times that I would move the throttle and it is fine but this is rare.

When the bike was running almost a year ago, I was riding and then it died mid ride out of no where. I would try cranking it up but then it would have a hard time starting but would sometimes start back up. When it did start back up it would die randomly within a few minutes and then I lost power from the battery because I was cranking it too much. Haven't been able to get it started properly since then.


WHAT I DID:
  • I did a crab clean like 4 times, not exaggeration.
  • The one time I had it running at 2500 rpm consistently with no fluctuation, I sprayed carb fluid all around the outside of the carb to test for vacuum leak. No change in rpm.
  • I had a buddy blow smoke when it was idling like crap to see if it got sucked in somewhere but nothing happened.
  • I checked all vacuum likes, visually and made sure they were routed correctly as per the manual (I have the 49 state/Canada Version).
  • Had the same buddy blow smoke through all the vacuum lines and didn't see it come out of any weird places like cracks or whatever.
  • I am seeing fuel in the intake of the engine when I remove the carbs after cranking
  • I am getting spark on all 4 plugs.
  • I checked the regulator rectifier, the stator, the ignition pulse generator, and the ignition control module as per the manual. 100% good with the regulator rectifier and the stator.
  • With the ignition pulse generator. and the ignition control module, I need a peak voltage tester but I was using a regular multimeter. This test is not conclusive because I was reading rms voltage and converting it to peak from a calculator on google. It is also not conclusive because I don't know if it should be AC rms or DC rms. I never heard of DC rms but the manual said VDC. Anyways the readings for the ignition pulse generator were above spec when I tested it with AC rms. There was no readings when I was testing the ignition control module with the meter set to AC or DC. But keep in mind there is spark on all 4 plugs. I think this test is inconclusive.
WHAT I THINK IT IS:
  • The symptoms of the bike all point to an improper air/fuel mixture. I think it is caused because of an air leak somewhere throwing the air/fuel mixture off. I think this because it is hard to start and dies when I turn the throttle fast. Now If it was a bad enough air leak to make it hard to start, I think I would have found it with the smoke and carb spray.
  • I may have cleaned the carb wrong even though it is not my first time doing it
  • I may have the idle mixture screw adjustment off even though I have adjusted them as per the manual every time I cleaned the carb.
  • I feel like even though I am getting spark, when I test the plug by grounding it to the engine, I may have the ignition system only working intermittently and that is why it cuts off. I am not too sure about this but I don't want to rule anything out until I am sure.
Thanks for reading and please offer any advise, something you suggest can help me out a lot. Thank you!
 

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Discussion Starter #2
This is link to video 1:
This is link to video 2:
This is link to video 3:
This is link to video 4:

1) This is when I was able to start it with full choke. Throughout the whole video I never messed with the choke and had it on the whole time. Notice the lag with my throttle movement. Also you can hear it start to slowly drop even though I don't adjust anything. Then towards the end when I use the throttle a bit it just dies. (The way it dies at the end seemed to me like an ignition issue)
2) At first I tried to start it with no choke. you can hear it catch combustion a few times. Then I try with the choke on in various positions and you can still hear it catch combustion but no real difference without it on.
3) I have the choke fully on and you can see when I blip the throttle it wanted to cut out once but also would lag.
4) Choke is not on in this video at all. It does Idle high but that might be because I had the idle screw high so it would die out. Notice how the first time it started it was idle around 2500 and then when I started it up again it idled at a different rpm (around 1000). Also notice towards the end when I crank it there is no combustion catching.

Im happy to provide more information just let me know
 

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Discussion Starter #3
  • I made sure the bike is running on 93 fuel.
  • I checked and cleaned the pilot screw again. It was clean but I still hit it with some carb cleaner. I also sprayed carb cleaner in the port of the pilot screw and made sure it came out
  • I made sure there were no vacuum leaks again incase I missed a spot before
  • I checked to see if the diaphragm on the carbs were operating properly. all 4 were even though I think they don't work on idle.
  • I checked the valve seat and valve for the float for wear and they were good.
  • I checked to see if the float moves freely and it does
  • I checked the float level and they were all in spec
  • I re-adjusted the pilot screw 3 and 1/8 turns out as per the manual, I also replaced all 4 o-rings for them
  • I took apart the choke valve (its called "Starting Enrichment" or "SE" valve in the manual) and they were all good
  • When looking through the manual I found in the fuel section something called an "air cutoff valve" and I took it apart to to verify its operation as per the manual. It works as it said it should but when I took it off I saw that the o-ring was pinched. I was pretty hype because I thought this was it. I don't really know what this valve does but it is on the carb so I thought this was the culprit. I replaced the o-ring but still acts the same.
I have a picture of the manual and the carb disassembled to see what else there is to check and I think there isn't anything else left lol

107513
 

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Discussion Starter #4
I found this in the manual and though this was a good checklist.
Everything I have in green is things I checked and am fairly confident that it is good. Although it is not 100%

For "2." I am not sure what insulator they are talking about but there is no leaking fuel from the carb

107514
 

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Hi what size jets are you using, were they the original fitted,after you refitted the carbs did you do a Synchronise and if so did you replace the vacuum pipes to their dummies, the Insulator #2 is the rubber interface between the Carbs and the engine Inlet
 

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Hi what size jets are you using, were they the original fitted,after you refitted the carbs did you do a Synchronise and if so did you replace the vacuum pipes to their dummies, the Insulator #2 is the rubber interface between the Carbs and the engine Inlet
I am using factory jets (Im assuming that. I never replaced the jets and the jets don't look new/aftermarket. However they don't look scored or damage in anyway).
When I cleaned the 4 carbs, I never separated them from one another so I didnt sync them.
I didnt replace any vacuum hoses but I installed all of them to the correct spots including the dummies.
Based on what you said about insulator number 2, They are all good. I frequently spray carb cleaner around there to see a change in rpm and saw nothing. Plus the visual inspection passed.

Additional note, I don't have a muffler (it is straight pipe) on the bike because it fell off in the highway but it was running the same when that happened almost a year ago. I know that will affect the air/fuel mixture but would it give me the symptoms that are seen in the video? Or is it an issue but not enough to cause a no start/rough idle.
 

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No ,having no exhaust at present wont stop it from running, although you have symptoms of very lean running, but I think thats just a set-up of the carbs,I know its a PITA, but the carbs have to be scrupulously clean , I've had carbs on and off bikes countless times, and I think they will have to come off again, did you do check float height's (although your's are not adjustable) try a bench set-up before you put them back on, what do the spark plugs look like colour wise (black or white)
 

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Discussion Starter #8
You absolutely right that they are finicky! I checked my float heights yesterday and they were all in spec as per the manual. I check the float valve and the float valve seat and they were all good. While I was there I checked the pilot screw and that had no issue but I still cleaned it anyway. There is no debris in any of the ports, I can see clear light when I hold them up. I checked the diaphragm operation even though I don't think they operate at idle and they were all good too.
 

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It's got to that stage with me that I ain't going to do another carbed bike, just make sure that when you put them on they are pushed home all the way and the bands are tight, how were the plugs?
 

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Discussion Starter #10
Yea I feel that! This is the 3rd and last carb bike I will ever own lol. They are definitely pushed in all the way and the spark plugs are all a yearish old, they probably have a few hundred miles on them nothing more than 1000 miles really. They all look good when I pulled them out around a week ago. Are you thinking its a fuel or spark issue based on the videos? I think that would help me narrow my search down. What do you think when the bike cuts off around 3000rpm? My opinion is that it has enough engine momentum to overcome any small inconsistent fuel are mixture. Thats why I am entertaining a spark issue. Or am I wrong to assume that cutoff at high rpm wouldn't be fuel/air related?
 

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are you running it with the tank on or off? there is a chance that when you put the tank on you pinch a breather pipe from the carbs - long shot but happen to me on a 900 - ran fine with the tank raised and then every time we refitted it the bike we got running issued! just a thought...........
 

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Discussion Starter #13
Tank is on but the breather hose is not pinched. All coils are plugged into the right spot since the wire lengths would only allow me to plug them in correctly. No suggestion is silly so keep them coming!
 

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Yea I feel that! This is the 3rd and last carb bike I will ever own lol. They are definitely pushed in all the way and the spark plugs are all a yearish old, they probably have a few hundred miles on them nothing more than 1000 miles really. They all look good when I pulled them out around a week ago. Are you thinking its a fuel or spark issue based on the videos? I think that would help me narrow my search down. What do you think when the bike cuts off around 3000rpm? My opinion is that it has enough engine momentum to overcome any small inconsistent fuel are mixture. Thats why I am entertaining a spark issue. Or am I wrong to assume that cutoff at high rpm wouldn't be fuel/air related?
Well basically we have ,Spark Fuel and Air , so now we're down to quantities of each so
Do we have a good spark
Have we got Air
What quantities of fuel do we have entering the cylinder
Right at the very start you said that when you took the carbs off fuel was pooling in the cylinder, could be that float needles aren't seating and letting fuel by , also try taking the pilot screws into 2 turns out, (are the points damaged on the pilot screws), and can you clean out the Float needle seats to shiny (cotton bud will help), undo the connector to fuel pump and turn over engine continuously for 10 seconds, just to clear out anything in the cylinders and start again with pump connected, maybe do this last one first
 

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Man, all this CARB BASHING makes me want to jump in front of BUS! :p I was thinking I would stay away from this one, but alas, here I am.

When you removed and cleaned the carbs you said you separated them from each other and DID NOT sync them after? That will surely need to be done, and could be the root of your issue. HOW did you clean them? Ultrasonic bath? Just spraying carb cleaner through the orifices? Removed all the jets (mains, slows, mixture screws) and emulsion tubes? Did you take take note of the numbers on them? What position was the clip on the jet needle?

The second point I'll offer is have you done a compression check? Yes, fuel, air, and spark are all needed to make a combustion engine run, but if it's not compressing the mixture, it will barely catch and/or just fart. So check the compression on each cylinder, plugs out, and WFO throttle.

Is there any chance you took pictures of the carbs while they were out?? Can you post some of what they look like now? Maybe use a drop tank/remote tank/soda bottle tank and test without using the actual fuel tank?

Get the compression numbers and any pics you can offer and report back. (y)
 

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Man, all this CARB BASHING makes me want to jump in front of BUS! :p I was thinking I would stay away from this one, but alas, here I am.

When you removed and cleaned the carbs you said you separated them from each other and DID NOT sync them after? That will surely need to be done, and could be the root of your issue. HOW did you clean them? Ultrasonic bath? Just spraying carb cleaner through the orifices? Removed all the jets (mains, slows, mixture screws) and emulsion tubes? Did you take take note of the numbers on them? What position was the clip on the jet needle?

The second point I'll offer is have you done a compression check? Yes, fuel, air, and spark are all needed to make a combustion engine run, but if it's not compressing the mixture, it will barely catch and/or just fart. So check the compression on each cylinder, plugs out, and WFO throttle.

Is there any chance you took pictures of the carbs while they were out?? Can you post some of what they look like now? Maybe use a drop tank/remote tank/soda bottle tank and test without using the actual fuel tank?

Get the compression numbers and any pics you can offer and report back. (y)
Hey glad you joined in! lol I need all the help I can get
When I clean the carbs I did not separate them so that is why I didnt sync them. I didnt use a bath I just sprayed carb clean through every possible hole that exists. I want to point out that when I sprayed fluid through a hole I always made sure it came out from somewhere. What do you mean when you said "What position was the clip on the jet needle?"

I will do a compression test tomorrow and take picture of the plugs.

Here is the link to a video of me just going over what I cleaned on the carb.

Let me know if there is something I missed or something you want me to go over. The condition was good when I took it apart because this is like the 6th time so I didnt find anything out of the ordinary. I did however think of 3 things to do.
  • I think I am going to do the pressure test on the float needle to make sure it is really holding fuel and not leaking
  • Going to test the air cutoff valve on the other 3 carb bowls because I only checked one. I am very reluctant to do this because I will have to separate the carbs for that
  • I am going to do a little research on if the diaphragm should be wet or not because I saw it a little moist but I am not sure if that was because I was turning around and such
As always thanks for your help and let me know if I missed something in the carb cleaning video
 

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When I clean the carbs I did not separate them so that is why I didnt sync them.
Ahhhhhhh ok, I must have read that wrong. Sync them anyway.

What do you mean when you said "What position was the clip on the jet needle?"
In the center of the slide there is that threaded tube. Take one of the screws from the vacuum topper (top of the carb) and thread it in there. Then grab it with needle nose pliers and pull it out. You will then be able to remove the silver needle itself. I was curious to know if the needle was adjustable (it would have slots for an e-clip) and would suggest it has a jet kit in it.
 

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Hey guys quick update. I took out the plugs to do a compression test but when I unscrewed one of the plugs, a helicoil was stuck to it and now the plug wont screw back in. So my guess was that the person before me put a helicoil in after he messed up one of the threads and it got loose because I remember when I replaced the plugs a year ago I had no issues. Im not too happy about this but I think there might be a bright side to this. The plug that had the messed up helicoil has slight burn marks on it passed where the threads are. This makes me think that there was not good compression because there was a leak passed the plug. If that is the case then the bike might have been running funny and giving me the issues because of a bad cylinder compression. I hope this solves the problem with the idle and that the issues are related.

So I will be taking out the head and rethreading it and inserting another helicoil. While Im there I will also clean the cylinders/valves and check the valve clearances. I just checked timing today and its good.

There wont be any updates from me for a few days since I have to search wait for parts but I will be active if there are any comments.

107570
 

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Ahhhhhhh ok, I must have read that wrong. Sync them anyway.



In the center of the slide there is that threaded tube. Take one of the screws from the vacuum topper (top of the carb) and thread it in there. Then grab it with needle nose pliers and pull it out. You will then be able to remove the silver needle itself. I was curious to know if the needle was adjustable (it would have slots for an e-clip) and would suggest it has a jet kit in it.

I checked yesterday and it does not have an adjustable needle so I think it is factory or has no kit
 

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Man, that doesn't even look like a heli-coil. :oops: Why is there an o-ring on that plug?

Good find, but I don't think that would kill the bike. Hopefully when you get it repaired it will be better though.
 
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