Guzzi Airone Sport

[Don-Spada]

After many years of owning a few Guzzi Stornellos, I have recently bought myself a 1954 Airone Sport in England.  It is running, but quite poorly, it doesn't seem to want to rev, it is missing quite badly when riding it.  

So far I have checked the ignition timing, it was firing almost at TDC so have adjusted it to 21mm before TDC by adjusting the points gap.  That improved things slightly.  I was told by the previous owner that the mag has been overhauled, it certainly gives a good spark. 

I haven't checked the valve timing yet, that is next on my list to do.  From what I have read, firstly you remove the cap nut and set the valve clearance to 0.2mm.  Is this checked somewhere under the cap nut or between the rocker arms and the valve stem heads?  To check the valve timing, the inlet valve should start to open 55mm before TDC on the intermediate stroke.  Reset the clearances to 0.05mm inlet and 0.10mm exhaust.  

In an attempt to get it running properly, today I fitted a Jikov carb as I have read about several people have had great results with these.  Mine was 10 times worst.  It will start okay, but it won't rev.  It has no power, it coughs and splutters, backfires in the exhaust and occasionally spits flames out the carb!  The carb is the 26mm option, with remote float bowl.  I can't see any numbers on the jets.  Has anyone on here got an Airone running well on one of these carbs?  What settings have you used?  The slide on the original SS25 is very worn at the front.  

https://flic.kr/p/2rwxFoK  

https://flic.kr/p/2rwxFoK   

Many thanks  

Don West.  

[John O Regan]

Hi Don,

First off change to a known good sparkplug, next is the petrol fresh? (or even possibly from a bad batch?) so drain and refresh fuel

Remove the points cover and observe the points as the engine is running, lots of arcing indicates a failed condenser

Changing the points gap a large amount will disturb the internal  magnetic timing .

A wide open throttle compression test would be next on the list

A quick and easy way to check the valve timing is watch the exhaust valve close and inlet open as the piston rocks over TDC, on the alternate stroke from firing

John

--
You received this message because you are subscribed to the Google Groups "Guzzi Singles" group.
To unsubscribe from this group and stop receiving emails from it, send an email to guzzi-single...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/guzzi-singles/68bea10d-4413-4f8d-ae8e-ba8efa3f6e0en%40googlegroups.com.

[Andrew Nahum]

V good advice from Don. I would do all that he suggests and check all the clearances as suggested  Airones are not demanding and generally run sweetly. 

 

I’d also first change the plug cap making sure it’s a non resistor type and also the HT cable making sure it’s old style copper cored. The end connections get eaten away by corrosion and the screw thread in the connectors also cuts into the copper strands over the years. 

Condenser failure is always  a possibity. British magneto guys will probably say they can’t get Marelli condensers. My magneto guy, sadly retired fitted an external standard Brit ignition condenser by drilling through the body.  I’ll post a photo  but try all the other changes first. The arcing test is a good clue btw. to condenser trouble but not in bright daylight. !!

The worn slide on your original carb would not give the symptoms you describe.  Most likely to affect starting and idling - it should not stop it revving out.  

Personally I think you are more likely to get success with the original carb (let’s hope it is original) having done all the things discussed than with ann  unknown Jikov.  They may be good but that trade patern  of carb needs correct pilot jet, main jet, slide cutaway, needle profile (taper).  A study in itself on a good engine unless, as you say have the data. 

My instinct is that if you do everything discussed here systematically you should get a nicely running engine even on the old carb. 

Good luck, A

On 30 Sep 2025, at 20:48, John O Regan <chate...@gmail.com> wrote:



To view this discussion visit https://groups.google.com/d/msgid/guzzi-singles/CAGLq%2BgkwiyFuzvcqrcCCZj60e%2BZ5M5GXzLZgZgRx5bQQg-QzXg%40mail.gmail.com.

[Andrew Nahum]

Here’s an improved!! magneto.  It just needs a hole drilled through the body to take an insulated wire and 

another tapped for a screw to anchor and earth the condenser.  

If you do need to take the magneto off I’ll send you Mike Peavey’s excellent note to me a few years back on how to do it while preserving the timing and not ending up with a pile of gears on the floor!!  But suggest you leave that till you’ve done everything else suggested and cleaned the carb and jets right through. Spitting back through the intake is a symptom of leanness.  

PS

After checking and eyeballing all the jets, don’t neglect the passage connecting the float chamber to the main carb body. People tend to assume it’s naturally ok but it can fill up with some kind of chalky oxide when petrol goes bad. You can get a clue when the carb disassembled and is on the bench if you fill the float chamber with some environmentally approved fluid with the viscosity of gasoline and see if it passes freely to the main body main jet area.  

On 30 Sep 2025, at 21:52, Andrew Nahum <andrew...@gmail.com> wrote:

V good advice from Don. I would do all that he suggests and check all the clearances as suggested  Airones are not demanding and generally run sweetly. 

[Alan Comfort]

Spitting through the carburetor can also be a sign of worn cam followers. Worn followers have an ill effect on the valve timing. It is an easy fix. Turn the engine over until both valves are fully closed and remove the timing cover. When the timing cover begins to ease away from the engine case, slip a thin blade into the opening to hold the cam in place. This will save a lot of fiddling with valve and mag timing if the cam decides to join the outer case in the separation. If the rollers  on the cam followers show any sigfns of wear, replace both of them.. Cam followers are coinsiderd to be a wear item and should be replaced whenever a major service is performed on the engine.

Alan in Roberts Creek

To view this discussion visit https://groups.google.com/d/msgid/guzzi-singles/D2EAA764-B461-414D-AC65-FE7B2AABA398%40gmail.com.

[RogerRowland]

Hi Don I have some info reference carb and mag based Uk if you can give me a shout regards Roger my E mail is 

Jamesro...@btinternet.com 

Sent from my iPhone

On 1 Oct 2025, at 02:09, Alan Comfort <alan.c...@gmail.com> wrote:



Spitting through the carburetor can also be a sign of worn cam followers. Worn followers have an ill effect on the valve timing. It is an easy fix. Turn the engine over until both valves are fully closed and remove the timing cover. When the timing cover begins to ease away from the engine case, slip a thin blade into the opening to hold the cam in place. This will save a lot of fiddling with valve and mag timing if the cam decides to join the outer case in the separation. If the rollers  on the cam followers show any sigfns of wear, replace both of them.. Cam followers are coinsiderd to be a wear item and should be replaced whenever a major service is performed on the engine.

Alan in Roberts Creek

On Tue, Sep 30, 2025 at 3:59 PM Andrew Nahum <andrew...@gmail.com> wrote:

Here’s an improved!! magneto.  It just needs a hole drilled through the body to take an insulated wire and 

another tapped for a screw to anchor and earth the condenser.  

If you do need to take the magneto off I’ll send you Mike Peavey’s excellent note to me a few years back on how to do it while preserving the timing and not ending up with a pile of gears on the floor!!  But suggest you leave that till you’ve done everything else suggested and cleaned the carb and jets right through. Spitting back through the intake is a symptom of leanness.  

PS

After checking and eyeballing all the jets, don’t neglect the passage connecting the float chamber to the main carb body. People tend to assume it’s naturally ok but it can fill up with some kind of chalky oxide when petrol goes bad. You can get a clue when the carb disassembled and is on the bench if you fill the float chamber with some environmentally approved fluid with the viscosity of gasoline and see if it passes freely to the main body main jet area.  

<image0.jpeg>

<image1.jpeg>

To view this discussion visit https://groups.google.com/d/msgid/guzzi-singles/CAC8DhY2P7hpi6ZJxb-4%3Dq324Su%2Bz3cCA%2BsQE4XNpr%3DMq60%3Dm%2BQ%40mail.gmail.com.

[Patrick Hayes]

On 9/30/25 12:07, 'Don-Spada' via Guzzi Singles wrote:
> I was told by the previous owner that the mag has been overhauled, it
> certainly gives a good spark.

That seems like a lot of adjustment via points gap.

If the mag was overhauled then it was removed from the bike. How
confident that it was returned and timed accurately? Some mag shafts
have a keyway and the mag gear has a matching keyway. Some do not and
are more finitely adjustable. I think you should remove the timing
cover to verify valve timing and to inspect/verify mag timing.

As to the valve rocker gap: Very difficult to get a feeler gauge in
there. Study the valve adjusting screw. It should have a very standard
6mm X 1mm thread pitch. If so, one full turn of the screw will yield
1mm variation in the rocker gap. Turn it in by fingers until it bottoms
at zero and then extrapolate as you come back out.



--
Patrick Hayes
Fremont CA
Falcone-NT and SuperAlce
www.motohayes.com

[Patrick Hayes]

On 9/30/25 12:07, 'Don-Spada' via Guzzi Singles wrote:

> Many thanks
> Don West.

Don, in future postings please indicate where you are located. Perhaps
a knowledgeable resource is close nearby.

[Phil Macdonald]

Don

I have fitted a Jikov carb and it worked 'out of the box' with some minor pilot jet adjustment. I suspect that the cam/mag timing has been incorrectly set up whent the mag has been removed. You will need to remove the timing cover to get at the gears. As someone else has stated the cam wants to stay with the cover (in a plain bush/oil suction) as you remove it, I use a 6 inch steel rule to seperate it from the cover. I suspect this is what happened when the mag was removed. There may be marks on the gears to indicate the correct timing points (there wasn't on mine - not sure why) but you can set it up from scratch (inlet valve just startimg to open at 55mm btdc). This is quite tricky to determine in practice and I have more than once (don't ask) managed to set it up one tooth out. Having said that it would run and rev like this. Not sure what that means for your bike, I guess it might be a combination of things that are causing the issues decribed but if the cam timing is out that is a good/essential place to start ?

Where in the country are you. I'm in Coventry and would be happy to help if you're close by.

Phil

[RogerRowland]

With timing set up etc I put a timing disc on  the flywheel, simply cut a hole n fitted with blue tack. Using a strobe could see the advance in action surprisingly the advance was more than 30degrees ie 2x15perhaps play in mechanism. 

Regards Roger Gloucester 🏴󠁧󠁢󠁥󠁮󠁧󠁿

Sent from my iPhone

On 1 Oct 2025, at 10:55, Phil Macdonald <philmac.c...@gmail.com> wrote:



--

You received this message because you are subscribed to the Google Groups "Guzzi Singles" group.
To unsubscribe from this group and stop receiving emails from it, send an email to guzzi-single...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/guzzi-singles/794ceb8e-bca2-4bac-930c-39883ab30d51n%40googlegroups.com.

[Don West]

I have had another play with it this afternoon and ascertained that the valve timing seems to be correct. I tried experimenting with a few different plugs and it made a slight improvement, then rembered the suggestion to try running it with the mag cover off and sure enough, it lights up like a christmas tree so a new condensor and points have been ordered from Nik's Euro parts.  Once I receive them I will try again.  

Many thanks for all the suggestions.  

Don West  

Market Harborough, England.  

https://groups.google.com/d/msgid/guzzi-singles/D2EAA764-B461-414D-AC65-FE7B2AABA398%40gmail.com

.

[John O Regan]

Hi Don,

50+ years mucking with old yokes, some things have sunk into the grey matter.

Apprentice wages started at £5 a week so the possibility of owning a new bike back then was a pipe dream!

Seems i stuck with the oldies???

John

To view this discussion visit https://groups.google.com/d/msgid/guzzi-singles/724825386.4981161.1759339376191%40mail.yahoo.com.

[RogerRowland]

Hi Don have a look at HMB Germany and his opinion of Italian condensers I fitted his type to my T3. Perhaps one channel on this type , also I think there is a company that makes an electronic trigger that fits.

Regards Roger 

Sent from my iPhone

On 1 Oct 2025, at 21:03, John O Regan <chate...@gmail.com> wrote:



Hi Don,

50+ years mucking with old yokes, some things have sunk into the grey matter.

Apprentice wages started at £5 a week so the possibility of owning a new bike back then was a pipe dream!

Seems i stuck with the oldies???

John

On Wed 1 Oct 2025, 20:29 'Don West' via Guzzi Singles, <guzzi-...@googlegroups.com> wrote:

I have had another play with it this afternoon and ascertained that the valve timing seems to be correct. I tried experimenting with a few different plugs and it made a slight improvement, then rembered the suggestion to try running it with the mag cover off and sure enough, it lights up like a christmas tree so a new condensor and points have been ordered from Nik's Euro parts.  Once I receive them I will try again.  

Many thanks for all the suggestions.  

Don West  

Market Harborough, England.  

On Tuesday, 30 September 2025 at 23:59:03 BST, Andrew Nahum <andrew...@gmail.com> wrote:

Here’s an improved!! magneto.  It just needs a hole drilled through the body to take an insulated wire and 

another tapped for a screw to anchor and earth the condenser.  

If you do need to take the magneto off I’ll send you Mike Peavey’s excellent note to me a few years back on how to do it while preserving the timing and not ending up with a pile of gears on the floor!!  But suggest you leave that till you’ve done everything else suggested and cleaned the carb and jets right through. Spitting back through the intake is a symptom of leanness.  

PS

After checking and eyeballing all the jets, don’t neglect the passage connecting the float chamber to the main carb body. People tend to assume it’s naturally ok but it can fill up with some kind of chalky oxide when petrol goes bad. You can get a clue when the carb disassembled and is on the bench if you fill the float chamber with some environmentally approved fluid with the viscosity of gasoline and see if it passes freely to the main body main jet area.  

<image0.jpeg>

<image1.jpeg>

To view this discussion visit https://groups.google.com/d/msgid/guzzi-singles/CAGLq%2Bgm43XjTS7mi2Jpw2X-BcW2BbqcFtNQUQ6rqgWRseKmxJw%40mail.gmail.com.

<image1.jpeg>

<image0.jpeg>