synchronizing carbs


Technical information and Q&A applicable to all years and models of Goldwings
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winguyjo
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synchronizing carbs

Post by winguyjo »



seems like every how-to that i have read or watched says to have a fan (not the bikes own fan) blowing on the engine during the synchronizing procedure so as to keep the bikes fan from kicking in.

why does this matter ? i don't see how engine temperature affects vacuum, but then again, i can barely spell thermodynamics ... so there's that. even if it did, it should affect all cylinders equally, yes ?

so ... why the fan during carb synch ?


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Overdog
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Re: synchronizing carbs

Post by Overdog »

I never heard the part about the fan. I thought it was referring to air cooled engines so they don't overheat.
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winguyjo
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Re: synchronizing carbs

Post by winguyjo »

thanks for the reply, overdog. you had me questioning my already questionable memory, but yes, in our very own how-to section it mentions using a fan so as not to change vacuum readings. it makes sense to not overheat the engine and to keep it at operating temperature, but a healthy goldwing cooling system will do that, no problem.
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Re: synchronizing carbs

Post by WingAdmin »

When the bike's fan comes on, it adds electrical load, which will slow down the engine, which will affect the vacuum readings that you're trying to match. So you use an external fan to blow through the radiator to keep the bike cool, and prevent it from turning on its own fan.
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Re: synchronizing carbs

Post by winguyjo »

hi, wingadmin, and i appreciate you joining in on this. i understand that there is a possibility of changing vacuum readings, but my thinking is that it will affect all 4 equally. perhaps this precaution was introduced at some point just in case someone were synching using only a single vacuum gauge, i which case, a person would indeed be chasing their tail as they moved the gauge from cylinder to cylinder with the fan kicking on/off.
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biguns
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Re: synchronizing carbs

Post by biguns »

Water cooled or not I have always used one especially with the Goldwing finicky carbs as soon as you balance all 4 you then balance left to right then it upsets the balance of the 4 all over, As well the idle adjustment can do the same.
It takes time and having a fan move air while standing over a hot engine is nice, not having the radiator fan load down the motor makes sense too, could you do it with the fan off and on, perhaps but I would rather it be off just incase.
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Re: synchronizing carbs

Post by Solo So Long »

WingAdmin wrote: Tue Jun 28, 2022 6:12 pm When the bike's fan comes on, it adds electrical load, which will slow down the engine, which will affect the vacuum readings that you're trying to match.
OR wait for it to warm long enough for the fans to kick in.

All you're really looking for is a CONSISTENT, steady RPM that can be used when going back and forth between carbs.

If using a multiple-carb synch unit, the job can be done in a minute or so anyhow.
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Re: synchronizing carbs

Post by newday777 »

Solo So Long wrote: Mon Jul 04, 2022 5:14 pm
WingAdmin wrote: Tue Jun 28, 2022 6:12 pm When the bike's fan comes on, it adds electrical load, which will slow down the engine, which will affect the vacuum readings that you're trying to match.
OR wait for it to warm long enough for the fans to kick in.

All you're really looking for is a CONSISTENT, steady RPM that can be used when going back and forth between carbs.

If using a multiple-carb synch unit, the job can be done in a minute or so anyhow.
Yah right. Not.
It's not that simple... .
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newday777
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Re: synchronizing carbs

Post by newday777 »

winguyjo wrote: Tue Jun 28, 2022 6:41 pm hi, wingadmin, and i appreciate you joining in on this. i understand that there is a possibility of changing vacuum readings, but my thinking is that it will affect all 4 equally. perhaps this precaution was introduced at some point just in case someone were synching using only a single vacuum gauge, i which case, a person would indeed be chasing their tail as they moved the gauge from cylinder to cylinder with the fan kicking on/off.
Only the unlearnered shade tree wannabes use a single guage to dial in these very precise carbs.
Just put a fan on it and don't try to be analytical on why to add a fan to keep the bike's temperature down.
Even these water cooled bikes still require airflow to cool them properly. That is why there are multitudes of posts by new wing owners(from gl1000 to the present day gl1800 models!) that ask 'why is my temp guage showing overheating when in traffic or slow riding in the mountains?' The bike has to have fast air movement to cool it properly, especiallyin the synchronization process. And yes, it takes time to properly sync these carbs, especially for newbies. You've been in a learning stage on this gl1100. Take the pill with a grain of salt from those you've read from.
Do you have the right tools to do the job....... the fan is necessary in a shop environment to give you the airflow to mimic the riding airflow.
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winguyjo
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Re: synchronizing carbs

Post by winguyjo »

thought i would add a little closure to this thread, having finally got around to using my fancy new vacuum synchronizing kit on this bike. i had previously been using a mercury manometer and i had trouble with it which i won't go into in this thread.

as i suspected, there is absolutely no need to have an external fan blowing on the engine during this procedure. the vacuum does change somewhat as the bikes fan kicks on and off but the vacuum rises and falls equally on all 4 cylinders so it's absolutely not an issue. likewise, a healthy water-cooled engine will happily idle in the driveway all day and all night without the help of an external fan.

in summary, the notion of needing an external fan during the carb syncing procedure on these water-cooled bikes is incorrect; must be a carry-over from air-cooled engines.
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Re: synchronizing carbs

Post by newday777 »

Actually you don't have all the factors included in your assessment.
You've left out the fuel atomization factor of the heat. High heat can boil the gas in the carbs and the tank. That changes the running aspect of the bike from what happens of proper air flow.
Not a good conclusion on your part.
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Re: synchronizing carbs

Post by joecoolsuncle »

newday777 wrote: Tue Jul 05, 2022 5:15 am
winguyjo wrote: Tue Jun 28, 2022 6:41 pm hi, wingadmin, and i appreciate you joining in on this. i understand that there is a possibility of changing vacuum readings, but my thinking is that it will affect all 4 equally. perhaps this precaution was introduced at some point just in case someone were synching using only a single vacuum gauge, i which case, a person would indeed be chasing their tail as they moved the gauge from cylinder to cylinder with the fan kicking on/off.
Only the unlearnered shade tree wannabes use a single guage to dial in these very precise carbs.
Just put a fan on it and don't try to be analytical on why to add a fan to keep the bike's temperature down.
Even these water cooled bikes still require airflow to cool them properly. That is why there are multitudes of posts by new wing owners(from gl1000 to the present day gl1800 models!) that ask 'why is my temp guage showing overheating when in traffic or slow riding in the mountains?' The bike has to have fast air movement to cool it properly, especiallyin the synchronization process. And yes, it takes time to properly sync these carbs, especially for newbies. You've been in a learning stage on this gl1100. Take the pill with a grain of salt from those you've read from.
Do you have the right tools to do the job....... the fan is necessary in a shop environment to give you the airflow to mimic the riding airflow.
carb sync is most effective at idle and lower rpm range, which is when there is very little to zero air movement. it only takes a few seconds to do the sync, so just disconnect the fan..............it will take many minutes to heat to the point of worry.
how in the world did we even tune air cooled multi cylinder bikes? geeesh.
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winguyjo
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Re: synchronizing carbs

Post by winguyjo »

"Actually you don't have all the factors included in your assessment.
You've left out the fuel atomization factor of the heat. High heat can boil the gas in the carbs and the tank. That changes the running aspect of the bike from what happens of proper air flow.
Not a good conclusion on your part."

as already stated, with a healthy cooling system, a water-cooled engine can run all day ... with no boiling of gas in the float bowls. you seem intent on arguing that black is white. all i am doing here is reporting a successful syncing of my carbs without the use of an external fan. it worked, i am happy, and others are free to try this method or stay with what worked for grampa.
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Re: synchronizing carbs

Post by Noclue »

I have an 83 gl1100 aspencade I just did rebuild on carbs today and it's running worse that before and I'm pretty sure I over seated pilot screws
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Re: synchronizing carbs

Post by winguyjo »

Noclue wrote: Fri Jul 22, 2022 2:39 am I have an 83 gl1100 aspencade I just did rebuild on carbs today and it's running worse that before and I'm pretty sure I over seated pilot screws
welcome ... you might be best to start a separate thread where people can more easily follow where you have been and where you are at now. 2 threads in one can be confusing.
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Re: synchronizing carbs

Post by Noclue »

Ok I understand thank you lol


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