Haha - thanks, Don - you are the second person in the last few hours to suggest Guy! A good sign 
If I continue to struggle I may well give him a call.
Cheers,
Steve
I sympathise. After several years trying to make my old PHMs work, with rebuild kits etc, I gave up and bought new ones and they worked straight away. Actually, well worth the money.
Just out of interest, when you swapped carbs, did you swap the whole carb including the slide and top, or just the carb bodies ?
I think my old dellāOrtos had the slides worn enough that a non-negligible amount of air was leaking around the sides and so not contributing to drawing up the fuel. Similarly, any cracks in the rubbers can cause air leaks and mean that no matter how carefully you set them up with gauges etc, you get inconsistent results in use.
Just some thoughts for what theyāre worth.
A T3 uses rigid mounted carbs so there are no mounting rubbers to split like those on a Le-Mans or similar. Also there werenāt any studs used, the manifolds are usually mounted with allen head bolts into the head.
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Thanks for the input, Andy. I swapped the whole carb over. Been out today and did about 100 miles, checking plugs and adjusting on the way round.
Given that I replaced all gaskets, seals, cleaned the jets, etc., I have still had to lean-out the r/h carb (to just under 1 turn out, I think) and enrich the l/h carb, just to get reasonable colouration on the plugs. Iām inclined to agree with Andy that I am trying to compensate for some worn component.
As an aside, I noticed a could of dark smoke from the r/h exhaust when revved hard. Not consistently, just the once. Not sure if itās related ā¦.
Hi, me again. Still got the rough running/sooty r/h plug problem.
It occurred to me that it could be the coil, as I had a similar(-ish) issue years ago. Iām getting some funny (high) secondary readings on the r/h side and canāt get a primary at all!
Am considering replacing them both for peace of mind. Can someone point me towards the correct part please?
The bike came with electronic ignition fitted. See photos for reference.
Thanks in advance.
Steve
I had to replace the coils on my California and just used a pair of standard Lucas coils. Do you know electronic ignition system that you have fitted?
All the info I have on it is in the photo, Don - it says āMagneti Marelliā.
I take it I am looking at 12v (as opposed to 6v) - I am a complete numpty with electrics!
P.S. The coils are in the most inaccessible place around the headstock!
That is the standard cover for the distributor. There could be anything inside that, maybe the original points or an electronic ignition pick up.
I donāt see any condensors on the outside so suspect that it has been converted to electronic. Is there a control box anywhere under the side panels or attached to one of the top frame rails?
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If you took the distributer cover off and posted a photo of what is inside we would be able to tell what system you have in there.
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Hi,
Just thought Iād contribute to this discussion, as I too have had carburation problems on my 1975 T3. I was having puffs of black smoke from the RH exhaust, and when I inspected the spark plugs found the RH side to be running rich compared to the LH which seemed spot on. In the end after a lot of faffing around trying to tune the carbs, switching back to the recommended basic settings for idle adjustment as per the manual (i.e. 1.5 turns out on the screw) I seem to have got my bike pretty close to as good as it gets. However, I am going to double check the points gaps and the advance/retard position of points opening.
I am also now considering electronic ignition, but I note that if you do it is recommended to also change the coils to a lower (4-5 Ohm) resistance type coil, otherwise there is the potential to burn out the standard coils if you leave the ignition on for too long without starting the engine. That may perhaps be the cause of your problem with one of the coils?
I hope this helps.
Best Wishes,
Jim
Thanks for all the replies. Here are some photos of the system. Iām afraid there appear to be no identifying marks on the black control box.
If anyone can help me to identify the system I will source the appropriate coils.
Regards,
Steve
It is electronic ignition not points, but it is not the same as my system, so I will let someone with better knowledge of this answer your question.
I reckon that is a Dyna system. The box probably looks like this if you could see the top of it.
These systems either work fine or not at all. A failing coil is a possibility. They are not too difficult to swap over to see if the problem swaps sides.
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After scouring the web, I agree that it looks a Dynatek system. Itās difficult to photograph the control box but, on inspection, the control box has no visible markings.
I have ordered up a couple of replacement coils. As working on them is so fiddly, Iām just going to fit them and see what happens.
Testing the resistance with a multimeter was less than successful. The photo shows the readings for r/h and l/h and primary readings taken through the ht leads @ 20k ohms, with secondaries at 200 ohms. The results meant nothing to me!
Will keep posting until I resolve this,
Cheers,
Steve
Installed new coils, cleaned out tank (filthy!) and petrol tap filters, new HT leads. Runs quite nicely but still got the r/h āsootyā plug.
Did compression test - left 125/ right 100 - I think there is something wrong there.
I am uncertain if this is indicative of worn rings, valve guides or something else. Any diagnosis ideas would be gratefully received.
Cheers,
Steve
1st stop is oil down the plugāole followed by compression test. This lets you know whether its the rings or valves leakingā¦
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Compression should be higher than that and within 10% of each other!
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Hello everybody Iām a new club member.
I bought my first Guzzi a couple of months ago. A T3, with G5 engine fitted and am experiencing the same carburation problems. I now have my bike running reasonably well. It runs well at slow speeds in town and cruises nicely at single carriageway speeds. Much smoother on the motorway. However, I still have sooty plugs but at least the plugs are not fouling and causing misfires, backfires and occasional conking out.
My fault finding has not been done in very logical manner. But here are the main points in the order I carried them out. Each step gave a significant improvement but didnāt singularly fix the problem. Itās a work in progress kind of thing. Here it is:-
Stripped carbs, found LH accelerator pump assembly was fitted upside down - main jets were over sized, replaced with standard, New standard needles fitted and standard atomiser jets - Stopped using octane booster additive in the fuel, now using E5 99 octane without any shots of booster or ethehnal treatment - Fitted one step hotter spark plugs - Checked out RITA electronic ignition, found rotor gap to be way too big - advanced the ignition a tad, not timed with strobe yet - replaced the two 6v ignition coils and wired in series in accordance with the RITA instructions - replaced HT leads with wire type, HT caps 5 ohm resister type.
Just ordered the Dellorto VHBT tuning manual from Eurocarbs to try and fine tune a bit more.
I hope the above is helpful to owners experiencing similar problems. From my experience I would say try not to throw too much money at the problem. It may be cheaper to buy replacement carbs. Set about the fault finding in a logical way. For example start with the ignition. Bear in mind modern fuels burn cooler.
Iām not there yet but will update you if I can get my engine to run any leaner.
I assume you are still on the square body carbs.
One easy thing to check is the cold satart (choke) plungers. Make sure there is a little bit of slack in each cable when normal running. Or if you have levers, make sure they are the right length. Then inspect the rubber seals at the bottom of the plungers. They can go hard over time and let fuel through when they should be stopping it.
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