t3 running badly 3/4k revs

[newlyncountychoppers]

hi, i bought my first guzzi last week to join my xs650's.i'd always wanted one .its a 1976 t3 in very good original conditio with 22k miles.it was serviced and worked on last year by corsa italiana in london and was said to be in fine fettle! i rode it home 300 miles and seemed good ,but if i try and hold it at 3/4k revs in lower gears it doesn't want to run right. same if its revved in neutral. its ok if rev straight through to 5k and change gear. it doesn't like ngk bp6es plugs atall and runs a bit better on iridium equivelant. the bikes got rita ignition and no air box but k@n type air filters. any advice would be appreciated. also can anyone advise me on which air filters to get (no airbox at all).

 

[Chris R]

It is difficult to diagnose such a thing half way around the planet; you will have to do some investigation of your own.

1. Check the timing and quality of spark- I am not fond of the Rita box- or any sealed black box for that matter - but the Rita box is IMO worse than the Dyna as it forces you to use 6V coils. Check the volts going into the Rita unit which can cause all sorts of bizarre behaviour. Getting rid of the advance mechanism to me is not a really positive aspect of the RITA - the RITA's curve is not adjustable and is a crude one size fits all deal.

A guzzi should have no trouble with BP6's which may point to a weak spark. I would be tempted to return to points at least for diagnostic purposes (I have a Dyna on my bikes and never had a problem FWIW but am not overly enthusiastic - I am not a fan of the points either as they are a bugger to set up and impossible to set accurately but they are good enough for a steam engine like the guzzi). & check the coils of course as they are likely ancient and oil filled. As a matter of course I would change the HT leads for new solid wire ones and fit some NGK plugs ( the original metal shielded Bosch ones are a short waiting to happen).

2. If it has sat around then as a matter of course remove the carbs,clean the filters, note all the jets and needles used and check the float level. Return to the forum with the info and lots of folks will give you their recommendations. I suspect that given that the bad running happens when it should be well onto the main jet it is more likely ignition but you never know.

3. If none of the above yields results, do a leak down test and check valve timing. You will find that the guzzi is a breeze to work on.

Ta,

ChrisR

 

[Chris R]

Oh ... and if you fit NGK caps either pick ones with resistors (6k is fine) and non-resistor plugs or vice versa. Resistor caps + resistor plugs will lead to trouble.

Air filters are really a surface area game - lower efficiency is made up for by increased size. The T3 airbox is a nightmare and it is a real pig to change the filter. THe pods speced by K&N are a bit small - they are round. There is an oval version spec'd for a ducati that fits fine. Some people insist that K&Ns don't filter welll enough - I think that they are a not bad compromise and if you live in england the good thing is they don't rot.

The single biggest improvement you can do is fit nikasils.

 

[newlyncountychoppers]

how many parts would be needed to change back to points from rita ignition ? i've been told that when installing rita ign a lot of mechanical parts are discarded ! rita ignition is also no longer available and current t3 compatible electronic ignition systems require some of the discarded parts. it also looks like a lot of parts would be needed to convert the bike back to its original air box, filter system.it seems that when bikes are taken away from standard with aftermarket ignitions ,air filters ,exhausts etc it becomes very difficult to diagnose running problems when they occur with no standardbase level to work from . think i'll have to listen to some loud music and have a few beers and hope my t3 gets her act together by herself. maybe she's sulking over being sold by her previous owner!

 

[Chris R]

Don't fret. The Guzzi replies to logic unlike many old british iron I have dealt with.
I really wouldn't bother refitting the airbox and just keep the pods as is. Removal of the airbox will not change the carb tuning significantly if at all. I suspect that it can't be all that wrong as it must have worked OK for the previous owner at some point and Guzzi's are not that hard to sort out.

You don't need many parts - the dist plate, condensor and cam and two 12V coils - the ubiquitous and cheap as chips bosch blue cans are fine. Likely the easiest route is just to find an old distributor from a wrecker and fit it in one go. But before we bad mouth the RITA check the input voltage and coils. It is not a bad idea to ground one plug against the bike crankcase and see what sort of spark you are getting. If it is a feeble yellow then there is the problem.

In my experience a lot of time is spent blaming carburetion for 'going out of tune' when the ignition is at fault.

 

[Rafael]

Hey Chopper

What do you mean by 'doesn't want to run right' ? I have the Rita ignition on my T-3, installed it in '87 or so and haven't had any problem with it; runs great -hate points. I've had to change the coils once; used PVLs. Have you taken a reading of your plugs?

After following ChrisR's recommendations, I recommend you warm up the engine, put in fresh PB6ESs run it at 3.5k rpm for a 1/4 mile, cut the engine while riding and pull the plugs. You should get some indication as to what is going on. Post a picture. Make sure carbs are clean, it'll be easier to diagnose them once they are.

The Rita will or won't work; no in between. To go to the Dyna III system you will need the point plate, points, springs, condensers, and weights. But there is a German system out there that eliminates the distributer all together.

As fas as air filters are concerned I use one UNI sock 1 3/4" x 8", cut one end and fit to both stacks. It's easier to oil than K&N, stays oiled longer, and is easier to clean. Less expensive to replace too. The T-3 filter box was integral with the crank breather box so I installed the 850-T box. Augostini used to make one as well.

The T-3 is a great bike, once you have it sorted you'll have lots of fun and reliability.

Rafael
'

 

[newlyncountychoppers]

hi,
thanks for all the help and advice ,once we've done oil ,filters, valves, stripped and cleaned carbs etc i'll take your advice and post an update .i'll even give the rita and after market filters benefit of the doubt :?: apart from these niggles the t3 really is a beautiful ,comfortable machine which i can't wait to go touring on, nick

 

[guzzibob]

OK, I've had a '78 T3 since new in 1978 with 162,000 miles & counting, so I'll put my 2 cents in.

1)I would never go back to points, too big a pain to fiddle with every few thou miles for no reason. I have a Dyna which I am very happy with, but since you already have a Rita & it would be a pain to retrofit stuff, no reason not to try to make it work.

2)Agreed the stock air box is a pain, no need for it. I have used the big oval K&N's with complete satisfaction for decades. I don't think they ever dry out or lose their oil-I just clean & re-oil when they get to gukked up with crud. They NEVER need to be replaced unless physically damaged. Personally, I just think the UNI socks look very, very tacky. Just my opinion. Also, although I have the big ovals, I've seen lots of LM I's out there with the smaller pods that run just fine, & that bigger valve engine sure needs more air than the small valve T3.

3)I have used Bosch 4219 plugs with satisfaction for some time. Most recent NGK usage was BPR6ES, no complaints there either. I doubt the plugs are the problem anyway. For sure check coils, plug wires & caps, carb jets, valve adj.

4)For sure it came with chrome bore. If still in there, if not peeling yet will eventually so replace now with Gilardoni's (the common favorite) or iron sleeves (in mine as it happens), before the chrome bits cause all sorts of damage.

5)For better performance than stock, by far biggest bang for the buck is replacing the woefully restrictive at anything over 4500 RPM or so VHB 30 carbs with PHF 36's (which most do) or PHF 32's (I happen to have & love-but they are rarer & harder to fit). Changing the carbs (once the jetting is sorted out) will greatly increase performance from 4500 RPM on up to 7000 or so with little to no cost below that number. At least that is what it did on my T3, which runs better now than when new.