1100et running on 3.

[Spelli]

After a very slow recommissioning of my old 1980 1100et I  managed to get the old girl running quite nicely…until. 
 

About 4 weeks ago I took her out for a short run ( 10 miles ish ) and she was running great. Locked her up in the garage, all was good. 

2 weeks later I brought her out again and she struggled to start, she was running really ruff. Sounded like it was only running on 2.  

Began to check the electrics and found the electrical connections from the stator to the rectifier had overheated.

I replaced the connectors and checked the  output of the stator as per …https://gsarchive.bwringer.com/storagecliff/images/stator_check.pdf

Surprisingly, all seemed good but still running ruff. The no 4 exhaust header was cooler than the rest so I pulled the plug cap off the no 4 cylinder and it made no difference to the running, nothing from no 4. 

There was a spark and fuel in the float bowl and a decent compression (170 psi ) so I decided to clean out the carbs  yet again.

Complete strip and 40 minutes in the ultrasonic cleaner. Everything blown out with compressed air and reassembled. 

Still only running on 3 cylinders. No 4 is not firing . Swopped the plugs round. Still nothing on no 4. 

What am I missing ? Why did the electrical connections overheat and is there a link to the misfire I have got now ?

I am running out of ideas 

Any suggestions would be really appreciated.

[TLRS]

You say it sparked, can you remember the colour of the spark?

[Spelli]

The spark seemed to be the usual blue sort of colour I think.  All 4 seemed to be the same colour. 
 

Edited October 19 by Spelli

[imago]

In my experience with these it's always been an issue with the carb on the problem cyl. I've had ones where they've needed three or four goes through a heated ultrasonic before you get progress.

From what you describe you've eliminated ignition issues as if it was electrical swapping stuff around then you'd have moved the fault. NGK plugs are dog shit, even the genuine ones, but again it looks lie you've eliminated that. 

[Spelli]

Imago ,

Thanks very much for the input, it is really appreciated.

I think you may well be right. The plug when it is removed isn’t wet and doesn’t smell of fuel and I would have expected it to do so if it wasn’t running. 
 

This would be the 4th clean in the ultrasonic in total since starting the recommissioning  but only the 1st one since this particular problem has come up.
 

Is there any better way of positively identifying a lack of fuel as the cause?

Edited Monday at 08:16 AM by Spelli

[Gixer1460]

Other than using a known set of carbs that were taken off a running engine the same day - no, not really. Or a brand new set that have never been used!

Sometimes even the 'mighty fix all ultrasonics' struggle to clear the tiniest of jet drillings due to the build up of rock hard crud, so part replacement is the answer!

[imago]

1 hour ago, Spelli said:

Imago ,

Thanks very much for the input, it is really appreciated.

I think you may well be right. The plug when it is removed isn’t wet and doesn’t smell of fuel and I would have expected it to do so if it wasn’t running. 
 

This would be the 4th clean in the ultrasonic in total since starting the recommissioning  but only the 1st one since this particular problem has come up.
 

Is there any better way of positively identifying a lack of fuel as the cause?

As  @Gixer1460says there isn't really beyond the time honoured tradition of using a process of elimination and trusting the results. If you're certain you have spark and compression (sounds like it to me) and the timing is where it needs to be for cam and ignition (sounds like it's running fine on the other three) then the only thing missing is fuel.

The only outside possibility other than a carb issue is that the inlet valve isn't opening so the fuel isn't getting in but you'd still have compression. However, my money's sill on a blockage in the carb, they're bastards for it.

[Spelli]

Is there something I could pre soak the carbs it to soften any deposits before putting them beck in the ultrasonic cleaner ?

[imago]

You hear about all sorts of chemicals and home brew stuff, but the main thing that helps is heat.

Personally I use a heated ultrasonic bath filled with de-ionised water and screwfix no nonsense degreaser. The de-ionised water makes a difference because there are far fewer impurities in it so the cavitation is only/mainly where you want it which is on the carb surfaces.

If your cleaner's not heated then you can warm the carbs in the oven and heat the water before you fill the tank. Make sure that when the carbs go it you rotate them fully to try and move as many air bubbles as you can. For that reason I always break the bank down into single carbs so that they can be turned in all directions.

Two 20 minute cycles back to back, take the carbs out and blow them through, then warm them again and then spray aerosol carb cleaner into the drillings. Once that's evaporated and the carbs are cool and bone dry blow them through again with high pressure.

Just dumping carbs in a cold tank of filthy cleaner seems to be the norm, but there's a process to it like anything else and if you skip bits then it reduces the cleaning particularly of the difficult access blind drillings and small holes.

 

[TonyGee]

I use a tin of carb cleaner with a straw on the button, when you spray into the pilot circuit you can see where the fluid comes out on all 4 carbs, if one isn't flowing the same as the rest then you know where the blockage is.  works for me. 

[Spelli]

4 hours ago, imago said:

.The de-ionised water makes a difference because there are far fewer impurities in it so the cavitation is only/mainly where you want it which is on the carb surfaces.

Make sure that when the carbs go it you rotate them fully to try and move as many air bubbles as you can.

Two 20 minute cycles back to back, take the carbs out and blow them through, then warm them again and then spray aerosol carb cleaner into the drillings. Once that's evaporated and the carbs are cool and bone dry blow them through again with high pressure.

 there's a process to it like anything else and if you skip bits then it reduces the cleaning particularly of the difficult access blind drillings and small holes.

 

Imago

Thanks again for the input. I would never have thought to use de- ionised water. I will give that one a go. 
 I will also try turning the carbs and the carb cleaner  

I think you are on the right track, I just need to keep cleaning until it is clear. 

[Spelli]

3 hours ago, TonyGee said:

I use a tin of carb cleaner with a straw on the button, when you spray into the pilot circuit you can see where the fluid comes out on all 4 carbs, if one isn't flowing the same as the rest then you know where the blockage is.  

Thanks again Tony, 

your input is always appreciated.

Could I ask you what brand of carb cleaner would you recommend?

I bought some from Halfords called Prime Shine motorcycle carb cleaner.

I used it on something else and it seems a bit aggressive. The can says it is not to be used on rubber or painted surfaces.  it seems to soften plastic in no time.  
 

I haven’t removed the butterfly shaft seals as I was a little worried about removing the peened over grub screws on the  butterfly’s so I am a little worried about what  this cleaner would do to the rubber seals.

 

[Gixer1460]

Considering most carbs use plastic floats, I'm not sure use of this stuff on bike carbs can be recommended LOL!

Edited Tuesday at 08:10 AM by Gixer1460

[Spelli]

I always strip the carbs as far as I can and that includes the floats. 

can you recommend a safe carb cleaner ?

Edited Monday at 07:36 PM by Spelli

[TonyGee]

1 hour ago, Spelli said:

Could I ask you what brand of carb cleaner would you recommend?

its just the normal stuff from Halfords,  but i do strip the carbs down as much as possible. 

[Dezza]

I've found a mixture of acetone and cellulose thinners is good for removing carb cack. Remove all plastic and rubber bits and then soak in an airtight container overnight or longer. As with all carb cleaning, you'll get best results when the bank is completely stripped. Obviously, remove the floats before exposure to a solvent that damages plastic. If you have painted carbs then they won't be after using this mixture. Sometimes repeated cleaning is necessary. The last carb problem I had took 4 ultrasonic cleans and a blow through with an airline to rectify the problem on what were really clean carbs to begin with - problem caused by fuel in carbs and bike not being used during a four week heatwave.

[gsxwill]

The last time I had this on my ez after a lot of cleaning and checking it turned out the diaphragm had perished, OK on the blow test but no good in working conditions 

Just a thought 

[Spelli]

3 hours ago, gsxwill said:

The last time I had this on my ez after a lot of cleaning and checking it turned out the diaphragm had perished, OK on the blow test but no good in working conditions 

Just a thought 

Thanks very much for the input.
The diagrams look ok to the eye. And appear to hold pressure if lifted and then released with the rear air intake blocked.

All 4 return to their seats about at the same rate.  
 

How did you discover yours were perished ? Was the damage visible?

[Spelli]

On 10/22/2024 at 3:55 AM, Dezza said:

The last carb problem I had took 4 ultrasonic cleans and a blow through with an airline to rectify the problem on what were really clean carbs to begin with - problem caused by fuel in carbs and bike not being used during a four week heatwave.

Just shows how bad ethanol based fuel is. Not like the days when I was running on good old 3 star. 
if anyone else remembers that perticular brew ?

Edited Wednesday at 08:00 PM by Spelli

[TonyGee]

11 minutes ago, Spelli said:

Just shows how bad ethanol based fuel is. Not like the days when I was running on good old 3 star. 
if anyone else remembers that perticular brew ?

don't you mean 4 star ?  i remember that stuff. 

[Spelli]

1 hour ago, TonyGee said:

don't you mean 4 star ?  i remember that stuff. 

No, I actually mean 3 star. 

Back in the day when my old et was king the fuel stations had the choice of 2, 3 and 4 star. 
 

I found mine happiest on 3 star. 

Edited Wednesday at 09:23 PM by Spelli

[Gixer1460]

And a bit before that when 5* was available for Jags and Aston's that needed 100+ octane.

[Spelli]

6 minutes ago, Gixer1460 said:

And a bit before that when 5* was available for Jags and Aston's that needed 100+ octane.

I had forgotten about the 5 star. 
I could not afford a Jag !

[Enjoythesilence]

Yep good old 2 and 3 star,filling them old gt185`s and super sixes with 50p of fuel,i feel old

[gsxwill]

19 hours ago, Spelli said:

Thanks very much for the input.
The diagrams look ok to the eye. And appear to hold pressure if lifted and then released with the rear air intake blocked.

All 4 return to their seats about at the same rate.  
 

How did you discover yours were perished ? Was the damage visible?

Two ways I checked with carbs off gently blow in the vacuum hole, slides should raise up the other way is cover vacum hole with thumb and gently life slide you should get resistance, and stop, don't force it!! 

But the light test on the diaphragm is how I found it holding diaphragm up to a strong light could see perishing that was not visable to the naked eye