Backfiring

[hillsy]

Hey 00Vs1400GLP - whilst old mate is having a hissy fit here I went back and re-read your original post.

How high is your idle set? If it is overly high you can get a pop or backfire when you shut the bike down - which is "normal" in the sense that the engine is just cycling past another compression stroke.

[Designer]

Good that you have stopped posting your Destructive Attitude,...sad that you feel you must continue to post more of your Baseless Assumption with your Personal Attack.

Just to add, when looking over the Tech Board, a Higher Idle speed ( between 1100 and perhaps 1500 RPM) alone has not been shown the cause of a backfire upon shut down. It has been accompanied by either a Lean Idle Screw Setting (that Herb has mentioned) , or some other Carb Condition making for an abnormal Fuel/Air Mixture or amount thereof.

[hillsy]

Just to add, when looking over the Tech Board, a Higher Idle speed ( between 1100 and perhaps 1500 RPM) alone has not been shown the cause of a backfire upon shut down.

I wasnt looking at this tech board - I was referring to my own personal experience with my LC.

[Designer]

Just to add, when looking over the Tech Board, a Higher Idle speed ( between 1100 and perhaps 1500 RPM) alone has not been shown the cause of a backfire upon shut down.

I wasnt looking at this tech board - I was referring to my own personal experience with my LC.

Gee,....I must have missed you posting that information in your last message of Advice.

At least 00Vs1400 GLP was helped out with Advice From A More Broader Based Set Of Experience, ....which is why we are all here, eh?

[navigator]

the wheels on the bus
go round and round

round and round
round and round

the wheels on the bus
go round and round

round and round
round and round

[00Vs1400GLP]

Hey 00Vs1400GLP - whilst old mate is having a hissy fit here I went back and re-read your original post.

How high is your idle set? If it is overly high you can get a pop or backfire when you shut the bike down - which is "normal" in the sense that the engine is just cycling past another compression stroke.

I don’t have a tach so I’m not 100% sure about the idle speed. Went for a ride for about an hour yesterday though and I think I have a vacuum leak somewhere. While at a stop light, the idle speed would vary slightly. I now suspect this may also cause the lean condition that brought on the backfiring.

[Designer]

How high is your idle set? If it is overly high you can get a pop or backfire when you shut the bike down - which is "normal" in the sense that the engine is just cycling past another compression stroke.

I don’t have a tach so I’m not 100% sure about the idle speed. Went for a ride for about an hour yesterday though and I think I have a vacuum leak somewhere. While at a stop light, the idle speed would vary slightly. I now suspect this may also cause the lean condition that brought on the backfiring.

Your Diagnoses seems a good likelihood. Is this variation like you report something new? I went back and read your OP and didn't see that symptom. If it is relatively new, has the Backfire after shutdown changed any?

To sleuth this possible leak, I'd start with looking for a leaking Vacuum Hose. Next would be the Seal around the Carb Mounting Boots. Less likely but still possible is the Boot-to-Head connection.

You have a good mechanical approach. Let Us All know what you find with this.

And,...any Updates on getting your Idle mixture Screw operational again?

[hillsy]

Sounds like your carbs are coming off so let us know how you go with getting the mixture screws out.

[navigator]

While searching for a possible vacuum leak, look closely at the hard rubber intake manifolds between the head and carb.
After 22 years they could be cracked. They are pretty thick, so smearing them with RTV could seal any possible cracks.

[hillsy]

While searching for a possible vacuum leak, look closely at the hard rubber intake manifolds between the head and carb.
After 22 years they could be cracked. They are pretty thick, so smearing them with RTV could seal any possible cracks.

They also have o-rings between the manifold and head and these are worth inspecting as they are likely to have perished.

[00Vs1400GLP]

While searching for a possible vacuum leak, look closely at the hard rubber intake manifolds between the head and carb.
After 22 years they could be cracked. They are pretty thick, so smearing them with RTV could seal any possible cracks.

There appears to be a little dry rot on those. Probably won’t have time to dig into for a couple of weeks. We’ll see.

[Designer]

While searching for a possible vacuum leak, look closely at the hard rubber intake manifolds between the head and carb. After 22 years they could be cracked. They are pretty thick, so smearing them with RTV could seal any possible cracks.

There appears to be a little dry rot on those. Probably won’t have time to dig into for a couple of weeks. We’ll see.

Does this mean you are working on the Removed Carbs?

Inquiring Minds Wanna Know. ( that's a modified line from the Enquirer)

[00Vs1400GLP]

Not working on the carbs yet. Real job and work around the house is getting in the way.

[Designer]

Not working on the carbs yet. Real job and work around the house is getting in the way.

I hear you on that. Priorities being what they are, my "toys' have to sometimes get Back Burnered.

At least your Bad Boy seems Rideable,...yes? You'd need a Break from those nagging "need-to-dos"

[00Vs1400GLP]

Not working on the carbs yet. Real job and work around the house is getting in the way.

I hear you on that. Porites being what they are, my "toys' have to sometimes get Back Burnered.

At least your Bad Boy seems Rideable,...yes? You'd need a Break from those nagging "need-to-dos"

Rideable, yes. Just could be running/looking a bit better.

[Designer]

Not working on the carbs yet. Real job and work around the house is getting in the way.

I hear you on that. Porites being what they are, my "toys' have to sometimes get Back Burnered. At least your Bad Boy seems Rideable,...yes? You'd need a Break from those nagging "need-to-dos"

Rideable, yes. Just could be running/looking a bit better.

Dang,...If we were closer, I'd help you get your Bad Boy running like a fine watch.

As to the .."looking better"...what if you Shaved and Showered before you Ride it?


( I'm pulling your leg again )

[Lechy]

Check that the header bolts are not loose, could also be that the header crush gasket has disintegrated.

[navigator]

Check that the header bolts are not loose, could also be that the header crush gasket has disintegrated.

+1, an air leak there will certainly backfire.

[hillsy]

Check that the header bolts are not loose, could also be that the header crush gasket has disintegrated.

+1, an air leak there will certainly backfire.

True - but you will also usually hear a ticking noise when there is a leak at the exhaust gaskets so it's fairly easy to diagnose.

[Designer]

Check that the header bolts are not loose, could also be that the header crush gasket has disintegrated.

+1, an air leak there will certainly backfire.

Yes, I found that out when talking to A guy on the Purple Board after he installed my 1500 Clutch Springs.

True - but you will also usually hear a ticking noise when there is a leak at the exhaust gaskets so it's fairly easy to diagnose.

You might. Depends on how loud your Pipes are. Standing three feet away, you might not hear it.

To check if I had a leak, I used a the Carboard "tube" from the Roll of Paper Towels and put it right up close so as to "focus in" my listening, and tune out the Exhaust Note. REALLY made a difference!