V50 II

I have just bought a very tidy 1979 V50 II which I collected yesterday, just in time to beat the lockdown.
Before I loaded the bike the seller started it and it fired up first press on the button.
When I got it home and in the garage I tried to start it to show it off to my wife and no way would it start, but instead just back fired VERY loudly !!!
Now, I am very confident that the seller was genuine and that I have just been very unlucky that something appears to have occured within the ignition system.
I previously owned a Monza quite a few years ago so I am familiar with the small block engine but I am also aware that the V50 II has an electronic ignition system which I believe was rejected on the V50 III and Monza in favour of returning to cb points, which on the face of it would appear to be a retrograde step.
As I wish to tour on my V50, when Covid will allow, I want the bike to be as reliable as possible so my questions are:
Does the standard electronic system have a bad reputation ? if not why was it rejected for the III and Monza ?
Is there a newer aftermarket system available and if so is it an easy replacement ?

My bike will be going on the workbench soon as it desperately needs a pair of decent tyres to replace the wooden Dunlops currently fitted.
I will also probably remove the heads to check the valves and bores as well as giving the braking system a thorough overhaul.
One mod that seems to be popular is to replace the front brake cable operated master cylinder with a seperate resevoir system. Any suggestions on a suitable replacement would be welcome.

Thanks Tony

From what I have read, (Never owned one myself) the V50 11 have a reputation of a bad flat spot due to a poor advance curve (more like a step )
TThe previous owner obviously had the nack of starting it. Usual proceedure on my Spada is fuel on, choke on if cold and press the button with little or no throttle. Did you leave the fuel taps on when bringing it home? Could it have flooded a bit?
Hope you get it sorted quickly.

Nope, taps were off when I got home.
It’s not just a starting scenario. I watched as the seller started the bike and the technique was perfectly normal. I have also spoken to the seller and he is equally mystified as he said it always started no problem and as I mentioned previously I am convinced of his sincerity.
The giveaway is the backfire which is almost immediate when pressing the button, it’s not as though lots of fuel has got into a hot exhaust to cause the backfire.
I have also tried with a brief whiff of Easy Start (normally don’t like using this stuff but worth a try) and result was exactly the same.
I am pretty convinced there is a malfunction within the ignition electronics so GutsiBits is probably my next move.

As D-S advises above - the ign system did have something of a reputation for producing a flat spot just as you approach 3k rpm. This due to an aggressive advance ‘curve’. Careful set up does alleviate much of that.

Outside of that the system is very reliable. Also, the boxes (one for each side) are fairly readily available used as they were fitted to a number of different Italian motorcycle back in the day. I have had to replace one on my 1980 model more recently - after 65k miles. It’s an easy swap out.

Note the two ign sides are completely separate, so if you did have a failure you would at least have a running 250cc single. I’d wager your problem lies elsewhere.

Finally found a spare half hour today so I removed the plugs, one of which is a 7 and the other an 8, cranked the engine over to blow out any accumulated fuel, cleaned and gapped the plugs and then refitted them.
Bingo, started on the button so my theories about ignition failure were misguided !!!

I suspect that my recent time with modern fuel injected bikes may have raised my expectations about how older bikes start.
Mind you my MZs start first kick !!!

Anyway now that at least I know it runs the carbs will come off for an ultrasonic clean as well as the other items that can be checked over during lockdown.

One further query.
I seem to recall hearing that the exhaust valves could be suspect as they were two part and welded and that the head could drop off causing mayhem within. Is there any mileage in this and if so is it possible to identify a two part valve ? I would happily replace the valves now when I remove the heads rather than risk a blow up.

Thanks for the comments.

Good to hear you have the starting problem resolved.
With regards the valves, I have read the same. Opinion seems to be to keep an eye on the clearances and if you notice them you be closing up then change them. Or if you have the heads off for another reason, it may be prudent to do them then.

The V50s are quite robust and simple in construction, so not many inherent problems. The valve problems, in the main, were more of a Lario thing with the four valve head and too strong valve springs factory fitted. The V50s didnt, as far as I know suffer with the valves and the only issue seemed to centre around the use of unleaded fuel being blamed for pocketing the exhaust valve seats. If you are worried run with a fuel stabiliser/lead replacement additive but personally I wouldnt be too worried


Plugs should be BP7ES

There are stories of the potential for dropped valves on this model as you have noted. Though I’ve not heard of instances of this in the 2 valve motors (the 4V Lario conversely is infamous for it). Never the less I chickened out and changed all four valves on my Veefer at 48k miles. If yours is a high miler I would consider changing them.

In theory you should notice any stretch starting to occur with regular clearance checks. They really shouldn’t move much at all - mine rarely need adjustment at 2k mile service limits.

Thanks for the responses.

My V50 is showing 27k on the clock but I am always sceptical about mileage on any 40 year old bike, it could have had a myriad of speedo changes. However the condition on the paint on the frame would tend to hold up the lower mileage theory. Also the tank, mudguards, panels are in lovely condition but may well have been re-sprayed.

I got the bike on the bench yesterday to check out the battery connections as the starter sometimes fails to engage first push. I suspect the starter and solenoid need a good clean and check over but I thought I would start with the battery and cables. Needless to say there was paint under the earth cable and dirty cable tags with a real cross section of bolts, nuts and washers. That has been dealt with but the “clicking” before engaging is still apparent so the next job is to attck the starter itself.

However whilst it was on the bench I also decided to look at the brakes and they are in a bit of a state. The rear brake lever would go right down with no obvious resistance although the rear caliper did seem to be gripping. Anyway I removed the caliper and no amount of pumping will move the pistons more than a few thou, enough to have given me the resistance but not enough to be able to examine let alone remove the pistons. The same situation of course occurs with the left front caliper. Obviously there is an issue with the rear master cylinder which will be coming off for a clean and rebuild.
The front brake caliper pistons can be pumped out as normal so I will probably connect the rear/front left calipers to the front brank master cylinder so that I can pump those pistons out also.
Next plan is to replace the front master cylinder with one on the bars, possibly one from an MZ which uses an identical slave cylinder, albeit with an MZ logo instead of Brembo !! Then I will also replace the rear master cylinder resevoir and fit it behind the side panel.

Finally I have removed the carbs as the aftermarket cone filters are absolutely minging. The existing filters don’t fit particularly well and I think are cheap eBay items so I will contact K & N to get a pair of their excellent filters which hopefully will fit better.

Any comments on the above would be appreciated.

There is a well known fault with the Guzzi starter circuit, known as click no crank. The power feed to the relay goes up through the loom, several connectors and the ignition switch. After that journey it has often run out of volts and doesn’t have enough power to activate the solenoid.
The answer is to replace the power feed wire to the relay that activates the solenoid. This can either come direct off the battery +ve (via an in-line fuse) or as I did pick up a permanent live in the fuse block (on the fused side)
Connect it into the centre terminal of the relay as shown. It is the red wire from the fuse box to relay you are looking at replcating. This is a bigblock model so will have a different fuse box, but the relay will be identical.

Relay wiring mod2 by Don West, on Flickr

After checking in Guzziology we measured the valve stems on my 1981 Monza and they had noticeably stretched. Fortunately fairly easy to change.

All information gratefully received.
I have almost finished extracting the brake pistons from the calipers and they are not looking too good so I hope Gutsibits have pistons.
I have very luckily received a decent copy of the workshop manual from a friend today and now have a good copy of the wiring diagram.
I can now see the issue with the power supply to the start relay and the solenoid and will do the mod to run a direct supply. I think I will replace the mickey mouse fuse box with a blade type which will also allow me to introduce a new fuse for the starter.
Thanks also for the comment about the valves - I will definitely be replacing mine.

Your caliper pistons are probably chrome plated steel, and very rusty on the exposed areas. Later (sometime in the 80’s) Brembo calipers came with teflon coated aluminium pistons and are far superior. I assume these are available for the small block calipers. They certainly are for the big block P8 calipers.

Quick answer: at 66k miles, my valves are as noisy as they were decade ago, so I am not bothered;
Front master conversion, I can only suggest to look into 12-11mm masters. Factory 13mm from V50III seems to be too wooden as later Guzzis (NTX) went down to 11mm one, and I got such, taken off Honda FES 250 scooter. That may look strange, but the smaller piston, the better grip - within limits, of course.
Caliper pistons - you defo need to escape from chrome zone into black alloy ones. Peace of mind, no need for overhaul twice a year!
Ignition: who cares what happens in Italian bike at 2500rpm??? Bash it and enjoy it!

Yes they are available for the smaller callipers. I’ve fitted to these to both mine and my pal’s V50s. Mine has done any number of salty winter trips since and with no signs of problems. They don’t come cheap though.

I have a big twin master on the handlebars on mine - so technically oversized. It does feel quite wooden but works a whole lot better than the OE setup that my pal still has (and that set up is shockingly bad). Mine will give enough grip to twist the forks alarmingly (with std plastic front mudguard). The trick of course is to mostly use the foot brake, you won’t often need any more than that.

All the calipers have now been stripped and two are fitted with rusty steel pistons whereas the LH front has nice anodised aluminium ones !!
Spoke to Gutsibits today and although they don’t have any aluminium pistons in stock they are waiting for a delivery so I have made an advance request for two pairs and will wait for an email. Despite the comment about price i thought they were quite reasonable.

Interesting comments from Cyclobutch about the perceived flat spot. I have not ridden my bike on the road yet, only up the drive, as I had no insurance, the bike has been off the road for some time, the rear brake was “iffy” (see below) and also the tyres are like wood.
However I will now treat the pickups with care and be sure to leave them alone unless absolutely necessary.

One other isssue that has come to light with the brakes is an odd one.
When I removed the rear caliper from it’s mounting on the disc cover I heard a tinkle and found that an 8mm washer had dropped out from between one of the mounting lugs and the disc cover. After stripping the caliper and rebuilding it as a temporary measure prior to getting new pistons I decided to refit it to see why there had been a washer fitted by PO.
Tightening one mounting bolt showed that there was a small gap under the other lug and when that bolt was tightened the pads jammed against the disc.
It would appear that PO had found a point where a washer under one of the lugs squared the caliper relative to the disc.
I have not had enough time to investigate further but definitely an odd one which might take a bit of head scratching to resolve.
Any thoughts would be appreciated.

I have also been thinking about tyres and I am considering a set of Avon AM26 Roadriders. Available in 100/90 and 90/90 at a quite reasonable price.
Again, any thoughts would be appreciated but I do appreciate that one man’s poison is another man’r medicine when it comes to tyre preferences !!!

With regards the caliper mounting, make sure the caliper is sitting straight and parrallel relative and that the disc is central within the caliper. Does the wear on the pads look to be parrallel, ie not worn more at the front or rear? Pushing the piston back into the caliper a bit would stop it binding with out the washer spacer, but priority must be to make sure the caliper and disc are parrallel with each other.
As for tyres, Avons are good, or dare I say it Bridgestones BT46 (I can still remember the days when people would remove Bridgestones from brand new bikes, they were that bad in the 70’s! )

Not sure about the small blocks, but on the big blocks it wasn’t unusual to have shims between the caliper and its mounts. Think one size was 0.5mm can’t remember what the other is. 0.75? The idea is to get the disc central in the caliper. Although of course they would be fitted in pairs, one on each bolt, both of the same thickness (or even doubled up on each bolt, either both same thickness or one of each different together). They would have M8 clear holes.

Yes, the small blocks did. I’ve long since thrown mine away. Working on my pals bike recently he got quite shirty when I said I would be doing the same with his. If you compare the shim size to the pad material thickness I really can’t see the point.

An update on some of the issues raised above.

I have replaced the caliper and rear master cylinder seals but I have been unable to replace the two sets of scabby steel pistons as according to Gutsibits the “new” aluminium pistons are no longer available and Brembo are not proposing to re-manufacture. This might prove an issue with a lot of bikes as this caliper is used extensively. Whilst continuing the search for replacements I have refitted the scabby units which appear to work ok with no leaks.
I have also replaced all the brake lines with Venhill self assembly braided hoses from Up The Shop.
I carefully checked the centreline of the calipers against the discs when fitted and found I had to shim both the rear and front right to get them centralised. Fortunately my stock of 8mm stainless washers were the exact thickness required.
I have also removed the front master cylinder and replaced it with a handlebar mounted type from a Honda CB125 which statically feels fine. Just need to hope it is ok on the road.

All the valves have been replaced, for peace of mind, if nothing else. One head gasket was showing signs of blowing so I am glad the heads came off anyway. Bores look great so the barrels and pistons were left undisturbed.

Original fuse box has been replaced by a blade type and some of the duplicated circuits given their own fuse. I have also run a seperate supply from the battery via the fuse box to the start relay to cure the “click no crank” syndrome.
Now I need to draw a modified appendix to the wiring diagram to show the new additions for any future owner.
Wiring loom has been removed and fully inspected on the bench and the starting issue wasn’t helped by the fact that one of the wires to the switch was hanging on by just one strand !! Interesting game refitting the switch toggle and spring after re-soldering the switch wire though !!
Several other wiring issues came to light once the loom was refitted but with the help of my trusty RS meter they were eventually resolved, mostly caused by poor earths.
The starter motor had a broken brush post but I was unable to find a replacement post so a new Valeo motor with the planetary gearing is now fitted.

Carbs have been stripped, ultrasonically cleaned, re-assembled and checked for leaks with my external fuel supply bottle. Just need to refit them now with some new aftermarket conical air filters.

Just about ready to rock and roll once Boris has loosened the shackles.