Spiriling out of control - woe is me!

I seem to have well and truly got myself in a pickle! I stupidly changed the points for electronic ignition at the same time as refurbishing the carbs and now can’t tell which (or both) is giving my bike such grief!

If it runs at all it soon stops when warm after 5 mins up the road. I noticed petrol leaking out of the K&N filters so have reset the floats and now it does not leak, but the bike now runs even worse - backfiring to the point I even get a flame thrower effect!

Perhaps the timing sensor securing bolts have slipped and I need to recheck the timing, but it was spot on and started beautifully at first so I assumed the problems were fuel delivery - I cleaned out the carbs and changed all gaskets - I expected to have to fiddle with the idle and mixture screws but nothing I do seems to make it run any better. To the point now where I can’t get it to run long enough to get out of the garage.

I took the heads off and changed the cylinder gaskets - the barrels were smooth but the valves did need a little regrinding - although the compression has stayed the same (70-80psi). It’s possible the compression is higher but I haven’t checked it since fixing the carb float issue that was pouring excess petrol into barrels and probably washing the oil off the rings.

Any suggestions on how best I should stand back from this and plan a logical new approach? It was all working fine before I decided to fit the electronic ignition and service the PHBH’s. I am thinking I should give up the amateur mechanics and get a proper garage to take it and sort it out - anyone know a Guzzi expert mechanic in Oxfordshire?
:angry:

The backfire could be due to the timing being out, what type of electronic ignition did you fit? Was it new or second hand? If second hand it could be faulty if not check the ignition timing.

Where in the world are you?

Best of luck

I would look at timing as well. It is easy to get mixed up with the various timing marks. You don’t mention what model the bike is. I’m guessing it might be a V50 Mk3?
These don’t have a full advance mark for strobe setting, I would suggest putting a degree wheel on the crank and marking full advance at 34 degrees? (Check that) and then time it with a strobe to full advance. The engines are to rough and lumpy to strobe on the static marker.

Thanks Guys - it was a new Dyna S for Moto Guzzi - the bike is a Monza.

I did have a hard job understanding the timing marks and spent a lot of time slowly turning the back wheel and counting each cog! I made a drawing of the marks showing at TDC of each piston on the compression strokes and the marks before that. Using a strobe I also saw that the mechanical advance unit was working when I revved the bike. At first the tick over and throttle revving was great and I thought I had cracked it!

Surely if I’d made a major mistake on the timing it would not have run so well on first start up?

Then the petrol overflow became apparent on both carbs and the engine as it warmed up started to die. It was after I fixed the float heights and stopped petrol leaking out of the air filters that the misfiring really kicked off.

My plan therefore (in a couple of weeks when I can be free to start) is to recheck the timing and hope it is something silly like the sensors were not tightened down enough and have come loose and moved, recheck the tappet clearances since running the bike after its top end rebuild, and then take both carbs off again and go through all the sections there.

I live near Oxford - I have seen there is a local branch but not yet managed to make a night free to go along and introduce myself (once again I am out the day of the net meeting on the 14th of July but will make the 11th of August I hope!).

Guzzis are quite forgiving of inaccurate timing and will run (all be it roughly) with timing wildly out of the correct spot. Dyna ignition can be fussy about the type of coils fitted, a few have mentioned coils failing shortly after fitting Dyna systems. They do recommend fitting their own coils. My Cali runs fine on standard lucas coils, but it did blow one not long after I bought the bike.

So just to recap, you refurbed the carbs - and that has since meant that you have had to fool with the float heights. I’ve never ever (ever) had to set a float height on any carb. Why did they need to be changed, as in what did you do to them in the refurb?

Sounds like the overall changes we have to consider here are - ignition swapped out, carbs serviced, heads removed and valves lapped, K&N filters fitted.

. When you were previously on points had you successfully timed with those and using the marks?
. Was it previously running OK on the KNs?

Thanks again for the interesting replies - no I had never set the timing using the old points. The bike did rev well and ran well up and down the road with the new electronic system until the engine warmed up and the petrol flooding became a problem. Now it has gone so astray with the backfiring the comment about the coils failing could be significant - I fitted new coils to a Honda Superdream once and it backfired like crazy in the same way - turned out Rex’s Speedshop had sent me the wrong kit for that bike and when they changed it all went perfectly thereafter.

I had checked the resistances of the coils beforehand and all was within spec but will recheck in a weeks time when I can be at the bike without interruption - I will keep you posted on developments!

errr… yes it was a mistake to ‘fix’ what wasn’t broken - I checked the floats as per manual and they seemed to be out of measurement so I adjusted them to what was quoted… obviously buggered that! And yes, previously it ran well on the K&Ns that were on it when I got it. Some of the jets were a bit crusted up inside so the clean out was well worth it.

Well good news - after refining the float heights and stopping the fuel pouring out of the K&Ns, I rechecked the electronic ignition - I found that the RH coil was being intermittently triggered and that the switched earth lead from the sensor was not making proper contact through the in-line bullet connector to the coil wiring, which terminates on a spade connector on the earth side of the coil.

That fixed I checked the static timing and it was bob on.

I rechecked the tappets and they were now a little tighter than when I set them after I’d put the heads back together so I loosened them a gnat’s.

Just before I turned the key to start her up I noticed my garage wall bike calendar was still on June so I flipped it to July and low and behold the bike of the month was a Monza!!! I took this as a sign ha ha and was well pleased when she roared to life. A quick ride up the road and back and she defiantly has much more poke than she did before I started my buggering about!

Now I have a 20 mile round trip to get the bike MOTd on Monday and if she gets me there and back I may have confidence to take her to the IOM 23rd-26th August :smiley:

Well done, it is always a head scratcher if there is more than one problem, enjoy the bike!

Great news and good luck for Monday

Thanks - happy to report MOT passed - bike ran great and compression when tested on my return was 150psi on both sides. Electronic points running great and carbs behaving themselves - so I am happy now to take her to the IoM next month!

Just for the record:
I was having the devil’s own job setting up my old T3 Cali until Pietro Marino told me to go back to basics and set the float height first in each carb. They were different and not what the proper Guzzi workshop manual quoted (although near enough to the values given in the Haynes manual).
I altered them and it transformed the tuning of the bike.