Fuel starvation? – 4 May 2017.

It’s taken me a while to get around to writing this post. Other stuff has been going on!

On a couple of occasions recently The Fire Bike has come to a halt without any prior warning. I’d be riding normally and the bike would appear to run out of fuel. It would be just as if I needed to switch over to “reserve”. However there was plenty of fuel in the tank. The first time it happened, I had refuelled and the bike faded about 40 miles later. I pulled over suspecting a vacuum in the tank and opened the filler cap but there was no sound of air rushing in. The bike then ran without any problem for the remaining 50 miles or so home. On the second occasion I had ridden the 20 miles to Aberystwyth seafront where there was a MAG gathering. After an hour or so I left to call at some shops nearby then set off for home. After about 5 or 6 miles the bike ran out of steam again. Again I opened the fuel filler but heard nothing. The bike restarted and I carried on the rest of the way home as if nothing had happened.

I hate it when things like this happen and the fault can’t be recreated in the workshop.

General opinion amongst fellow Guzzisti supported my initial thoughts that the problem was caused by fuel starvation with a second possibility that the ignition coil was beginning to break down when hot. The brief stop being long enough for it to recover. I ordered a replacement coil, just in case, but decided to check the fuel system from tank to carbs and the ignition wiring.

Before doing that, I thought I would just see if I could get the fuel supply to the carbs to fail. I made sure there was a decent amount of fuel in the tank and that the cap was done up tight. I then disconnected the fuel line from the running tap (as opposed to reserve) and added a short hose into my fuel can. I turned the fuel on and watched as it all ran out! I had hoped that the flow would reduce until it stopped or sucked air up the pipe proving that the filler cap was blocked. However it all ran out unimpeded.

The next step was remove the tank so I could make my checks but, first the seat needs to come off.


Now the tank itself can be removed.


  • Electrical connections in the battery compartment. Especially earths. All good.
  • Connections at the coil. These were fine.
  • Connections to ignition switch. All good.
  • I rattled the key in the ignition switch but couldn’t make it fail.
  • Fuel lines. All clear.
  • Fuel taps and filters. Fine.
  • Fuel filters at carbs. Clear.

I went back to the fuel tank which was sitting on my bench in the sun. When I opened the filler cap I quietly swore as I heard it exhale! If the expansion caused by the tank getting warm can’t be vented then neither can air get in to replace the fuel as it’s used up. So, after going around the houses, I was back at my first suspicion that the fuel cap was the problem. This is despite the fact that the bike has run without any problem for the last 2 years.

I had always suspected the cap because, way back, I had puzzled about how it was vented. There were two small holes outside the area covered by the rubber seal but no corresponding vent hole inside the seal that I could find. I drilled a 2mm hole in the inner layer of the fuel cap where I would have expected to find a vent hole. In this picture you can see my newly drilled hole and the outer two holes to the left and right of the rubber seal.


To test it out, I squirted some WD40 into the hole I had drilled and saw it come out of the other two. I then washed it out in petrol and refitted it.

Before I refitted the tank I straightened out the rear mounting flanges. They had been crushed a bit. I had bought a stainless steel rear tank mounting bolt a year or so back so this was fitted as well. The old one was pretty nasty.


I haven’t got a replacement front bolt yet. This is a stepped bolt which prevents it being over-tightened and could be something to make on the little old lathe I’ve bought. It’s just about set up now.


Anyway, Everything went back together and a few days later I managed to complete a 55 mile test ride without any sign of trouble. Time will tell if I’ve really solved the issue.

I never did fit the replacement for what is probably a 45-year old ignition coil. It arrived damaged and was returned but I haven’t bought another. I wouldn’t have fitted it anyway until I was sure it wasn’t a fuel issue.


Rhino gets a new battery – 31 Mar 2017

The other week I finally got around to taking Rhino for his MOT (annual road worthiness test). Before I could go I had to charge the battery despite having charged it only a couple of weeks before. There are no parasitic drains on the battery of old bikes like these so I knew that the time had come for replacement. It is worth noting that the old battery was bought in March 2003. I’ve still got the receipt. 14 years ain’t bad. It was a Hawker Odyssey and was much smaller than recommended for an old Guzzi.

The new battery is a Motobatt MBTX30UHD the same as I have fitted to The Fire Bike. This is the correct size at 32Ah but is physically shorter than the original “wet” battery the bike came with.

I had soon extracted the tired old battery and the cage I made to hold it. Next I added two rubber buffers – one each side – to support the new battery. I had bought these during the rebuild but left them off to fit my home made battery cage instead.


I also bought the original style battery straps.



The hook on the longer strap appeared to have been fitted the wrong way up so I changed it. Now it won’t try and “dig in” to the battery.


Having never had these fitted before, I established from a photo in a manual that the longer strap with the hook goes to the back.

the straps locate behind and are then held down by tags. At the rear there is a tag on the frame and the strap is easily snapped in place because it can be pushed past the plastic lower mudguard section.


The front one is more difficult because the plate below the battery, joining the frame to gearbox has to be loosened to get the strap in place. It goes here.


I put a luggage strap around my new battery to make it easier to get in and out.


Then put the battery in place. It is a snug fit between the rubber buffers. Joining the two heavy rubber straps was tough going. I also added a zip tie to the long strap to stop me pulling it apart with my cack-handedness.


According to the parts book there should be a rubber bung in the middle of the long strap but it doesn’t seem necessary.

I ended up using diagonally opposite cable terminals as these just seemed easiest. I like the way these batteries have these connection options. My lifting strap was tightened so that it can’t move about but can be slackened to give me a hand hold if I need to lift the (heavy) battery out.



Too many volts! – 11 Mar 2017

I’ve mentioned before that, over the last few months, the voltage warning light on The Fire Bike has been “playing about”. I fitted this soon after getting the bike so that I will know if the charging system develops a fault and can do something before I get stranded with a flat battery. I have said that the light had flashed red on one occasion indicating low voltage. Well more recently it was flashing alternate green and red which indicates an over-voltage (more than 15.2V). It may be that this was what was happening the first time but I just couldn’t see the green colour in the sunlight. Anyway, an over-voltage is to be avoided because it will soon kill the battery.

My bike has a Magneti Marelli dynamo and mechanical control box. The original fitment. I consulted with my friends on the Guzziriders forum as there is a thread there about fitting a solid state control box/voltage regulator sold as a replacement for an old Fiat. Someone had bought one from Teo Lammers but they are currently out of stock. It’s here. I decided to see if I could find one at a classic Fiat specialist here in the UK and managed to get one from Motobambino. I thought the price was good and it arrived inside 24 hours.


There was some discussion on the forum about the current rating of the solid state regulator. The original mechanical box was rated at 25A and this replacement at 16A. The dynamo is also 25A. So far as I can tell, a 16A regulator with a 25A dynamo will work fine but, the output (current draw) is limited to the 16A of the regulator. I’ve done some searching and it looks like the Fiats had a 230W charging system as opposed to the Guzzi’s 300W. However the two systems seem to have had their ratings worked out differently.
– Fiat – 14.5V x 16A = 232W.
– Guzzi – 12V x 25A = 300W.

The lowered capacity of the system could cause issues on an original police bike running radio, siren, blue lights and other stuff but, should be fine for my “civilianised” one. I’ve used a “worst case scenario” of 12V x 16A which gives a maximum system capacity of 192W. I think my maximum constant draw is about;
– Lights (bike) – 75W
– Lights (trailer) – 10W
This leaves plenty for the ignition circuit. The intermittent draw from starter, indicators, horn and the like can be disregarded. I might have to think again if I add heated grips or stuff like that.

Changing the control box.

I removed the battery and, before I did anything else, photographed the original mechanical box in situ and made a note of all the connections.



I disconnected the wires and undid the nuts securing the box to its bracket but I couldn’t shift it! The two bolts were too tight in the mountings and appeared to need to be unscrewed from the back. To get to the first bolt I removed the nuts and bolts securing the left hand tool box which released the mounting bracket for the control box on that side.


I then realised that I didn’t actually need to take the tool boxes right off. I could just remove the top fixing.


This done you have access to the back of the bracket. Here the bracket is fully floating and the old Marelli box has been removed.


The mountings for the box weren’t threaded. Just tight and the screws had to be wound out.

Here are the two control boxes for comparison.


The mounting holes are at the correct centres but needed to be drilled out. There was also an earth/ground terminal on the original. I found this area could be drilled to accept a terminal while still clearing the mounting bracket.



Being a mechanical device, the old box had mountings to protect it from vibration. These are not removable.


I don’t think these are strictly necessary for the solid state replacement but I punched some bigger holes in some rubber washers and used them to mount the plate. You’ll notice that I filed all the corners off that plate. Twas flippin’ sharp.



You can see in the photos that the wiring connections were in the same order as on the original. I had to do some checking in my manuals to make sure this was the case as the terminology on the two boxes was (of course) not the same.
– Marelli box.              “D+ 61”  – “DF”      – “51 B”.
– Replacement box.   “51”        – “67”       – “30 +12V”.
– Guzzi manual says. “D+/51” – “DF/67” – “30/B+”.
This is the illustration from the V7 workshop manual which explains things.

Marelli Regulator Unit

With everything back together again the bike was restarted. All seemed good then it stalled. Once I’d turned the fuel on all was well!

Today I’ve been out for a test ride. Just the 20 miles up the A487 to Aberystwyth for coffee and cake on the sea front then back home. I have to say that the new regulator is an improvement. The strange messages given by my voltage light have stopped. Not only that, the light turns green (signifying normal charging) at lower engine revs than before. This means I don’t have to change down to keep it “in the green” and can potter about in a lower gear.

I have had a look inside the old control box which is clean with no obvious faults. Interesting.

Re-torque heads and adjust valve clearances – 22 Feb 2017

I’ve now ridden about 230 miles since doing the work to change the cylinder head gaskets on The Fire Bike so, it’s time to retighten the six nuts securing each head and barrel. I like to do this around the 200, 500 and 800 mile mark. That’s about 320, 800 and 1290 Km.

Before doing anything, I wanted to check something out. My Moto Guzzi factory manual for the V7 700 and 750 models and the Chiltons’ Manual both quote the torque figure for the nuts as 27.5ft.lb (3.8Kg/m). This just feels a bit low. I checked the Guzzi factory manual for my V7Sport and this quotes 29 to 32ft.lb (4 to 4.5Kg/m) for the same fixings. They’re basically the same engine so I thought I’d get some advice from members of the Loopframe Guzzi Group. The consensus was that I should use 32ft.lb (4.5Kg/m) and, given the size of the fixings this makes more sense to me. So, on to the job in hand.

The first thing I do is remove the dynamo belt cover and the spark plugs so that I can turn the engine over with a 26mm spanner or socket. The engine rotates clockwise seen from the front.


I started with the right hand side and removed the rocker cover. Turn the engine (clockwise) with something resting on the piston to tell when the piston is at the top of its stroke. If the rockers are loose then it’s on the compression stroke which is what you want. If not turn the engine till the piston comes to the top again.


Once you’re sure you’ve got the piston at the top and both valves shut work can begin. A word of warning. Be careful what you rest on the top of the piston. You don’t want to get anything jammed in there or to damage the piston or spark plug hole. I used a long Allen key this time.

The reason I find this setting is so that there is no pressure on the valve gear when I remove the rockers and shafts to access the cylinder head nuts. I would have to do it later anyway to set the valve (tappet) clearances.

To remove each rocker you have to take out the locating screw.


Then slide out the shaft.


Above each rocker there’s a spring and washer.


Keep the sets of components together and put them to one side. The pushrods can be left where they are.

Remove the 26mm blanking plug over the sleeve-nut at the top then slacken the 6 nuts just a quarter turn.


Do this in the reverse of the diagonal tightening sequence. So

  • Top (10mm Allen sleeve-nut).
  • Bottom (below spark plug).
  • Bottom right.
  • Top left.
  • Bottom left.
  • Top right.

Now get the torque wrench out, set it and do them all up again. This time the order is

  • Top right.
  • Bottom left.
  • Top left.
  • Bottom right.
  • Bottom.
  • Top.

Check the state of its crush washer then replace the 26mm blanking plug.

The rocker gear can go back on now. Often the adjusters have to be slackened off a bit because, having tightened everything down, the gaskets have been compressed a bit more and reduced the clearances.

Adjusting the valve clearances.

Before going any further, I always re-check that the piston is at the top of its compression stroke. I generally turn the engine backwards a little way then forward again while checking for the top of the stroke with a rod again.

Settings are 0.15mm inlet and 0.25mm exhaust.

Use a feeler gauge between the face of the rocker and the valve stem to check the gap and adjust this by turning the top of the adjuster with a slotted tool and locking it in place with the nut on the adjuster. You’re looking for a snug, sliding fit. It should be possible to remove the gauge and then reinsert it. If the feeler gauge is gripped then the gap is too tight.



Often tightening the lock-nut will mess things up. I never seem to get it right first go!

With the rocker cover back on I can turn my attention to the other side then finally replace the belt cover and put the plugs back in.

Other stuff.

I don’t know what was going on with my voltage warning light the other day as it’s now working properly again! All the same, one day I’ll wire it via a relay because it’s always been affected by a voltage drop across the ignition switch contacts.

I’ve got to paint that ding in the tank. I’ll probably just use a small brush to fill in the damage.

My V7Sport needs an MOT test but I might leave it for a week or two so that it comes around each March instead of every February.

I did manage to get hold of a small lathe and have been spending a bit of time cleaning it up and sorting out the motor arrangement. It came with a big but slightly wobbly home-made metal stand which I shan’t be using. I’ll make something more suitable with some second-hand timber salvaged from some work I’ve just done on the house. My friend, Bunny, has been busy producing stuff for it on his bigger lathe.

It’s not been a bad Winter but Spring will be here soon, the roads will be free of salt and the riding, camping and show season will be upon us.

The cylinder heads are done – 5 Feb 2017

It’s taken me some time but The Fire Bike is now back together. As indicated last time, I did buy the posh type of exhaust nuts with a lock ring. Here’s one alongside my repaired original type.



Before fitting the new ring-nuts I made up a longer version of the c-spanner needed to tighten them. I didn’t want to have a repeat of the thing slipping and hitting the tank again because of my ham-fistedness!


Some time I’ll thread the hole in the tube and threadlock a grub screw in it so that I don’t need to have the head of the bolt or a nut sticking out but, for now, it worked well.


I removed the rocker covers again to adjust the valve clearances. I’ve written about doing this on my other Guzzis but not the V7 700. I’ll write this up when I have to do it again (after re-torqueing the heads).

Thick rocker cover gaskets were coated in grease and the rocker boxes refitted. I find that by doing this the gaskets last ages.

I went out for a shortish run on the bike today. I had to speed up the tick-over a little to stop it cutting out. It looks like I’ll have to give the bike a good tune up soon.

The other thing that happened was that the voltage warning light, which I fitted when I got the bike, was flashing away showing a low voltage although the bike ran well enough and the original dynamo light never came on. When I got home I let the bike stand for a bit over an hour then checked the battery voltage. 12.95V is good and suggests that the problem was not with the charging system but the voltage warning light so, that’s something else to have a look at.

My trip out had been to buy some “Fiat Racing Red” paint. I’ve got to make good the damage caused by that slipping spanner.


There is a suggestion that the tank was blue once upon a time.

Off with his head, part 3 – 29 Jan 2017.

As I said yesterday, I’ve decided to repeat the work on the left hand cylinder, mainly for the sake of thoroughness. It’s also a chance to examine the condition of the cylinder bore and rocker gear.

Oh what fun I had! This time the exhaust header nut was very tight. Not only that, the notches for the c-spanner were a mess. I had to start by knocking the ring nut back and forward a tiny amount and dosing it with WD40 just to get it started. It was clear it had been hit with a punch or possibly a chisel before. It took me about an hour and a half to get it undone. When it did turn, it would still bind at the same point in every rotation. Once off I could see it was clearly distorted. It wasn’t me, honest! However, it was me who let the c-spanner slip and chip the paint on the fuel tank. It was clear that a “Gun Gum” type sealant had been used and was the main reason the thing had been stuck. Happily the exhaust port threads on this side were undamaged.


The cylinder head nuts were tighter on this time but, when I lifted the rocker bracket, there were no O-rings where they should be. It turned out that they were fitted to the four long studs under the head gasket! Don’t do it like this.


Again the rocker gear is in very good condition. It looks nearly new. It’s strange that this (expensive) work appears to have been undertaken but basic mistakes made.

Once again the cylinder barrel is the chrome plated type and in very good condition. The two bottom O-rings were where I would expect to find them.

Putting everything back together was easy enough but I discovered this chip out of the rocker bracket.


It’s where the shaft-locking screw goes on the exhaust side. When reassembling the gear I was careful not to let the end of the lock-washer catch in the hole. I don’t feel able to weld the chip as the bracket is a casting. I think, at some point, I’ll run the engine with the rocker cover off to see if oil is pumped out of here instead of lubricating the rocker and shaft. Hopefully it will seal. If not, I might look for some sort of “plastic metal” to repair it but an oil-soaked casting might prevent it “taking”.

Again I have put the rocker cover back on without adjusting the valve clearances. This is while I turn my attention to the mullered exhaust head nut.

Replacements are quite pricey and the original type don’t seem to be available any more. Instead the better type with a lock-ring (as I have fitted to the V7Sport) can be had for about £50 a pair. Here’s what I mean on Rhino.


I do have a couple of exhaust nuts which have been sawn lengthwise. I did it over 30 years ago to allow the rings to spread a bit to get around the sharper turns on a 850T3 shaped exhaust header. Once past the obstruction they would go back to their original size and screw down on the exhaust and still compress the gasket. The trouble was they would (unsurprisingly) come loose if not wired to a drilled cylinder head fin. At the time this was OK as they’d always had to be lock-wired anyway.


In an effort to save money I decided to try and braze the gap. It wasn’t entirely successful because I couldn’t get enough heat into the job with my little oxy-propane set-up.


I haven’t fitted it to the bike other than to check that it threads into the head easily. The repair seems robust enough. However, I think I’ll be making another order on the Stein-Dinse website. I’ll be hit with the minimum shipping cost again but, what can you do?

Off with his head, part 2 -28 Jan 2017.

I ordered the necessary parts from Stein-Dinse in Germany on Sunday, arrived here in Wales on Wednesday. Even with the minimum postage cost it was still worth it as no one in the UK had all I needed in stock.

I did include base gaskets in my order so the next job was to lift the cylinder barrel. This gave me a chance to properly examine the bore. Unmarked and in good condition.

The pistons are fitted with four rings. Three above the gudgeon pin and one below. I knew early V7s were fitted with these but wasn’t sure if they kept on with this for all the 700s.


I evened out the ring gaps out around the bore then replaced the base gasket. There is an oil drain hole in the face of the engine block. If the gasket is fitted upside down it will block the hole and the rocker box will fill with oil which can’t drain back to the sump. O-rings go on the two short studs (at 6 and 12 o’clock).


Fitting the cylinder barrel isn’t difficult but can be a little hard on the fingers. First I turn the engine by the front crankshaft bolt until the piston is right at the top of its travel. I like to lightly oil the spigot of the cylinder which fits into the engine block as well as the bore itself. The barrel is dropped over the studs and the top of the piston started into the bore. There is a little chamfer at its lower end. This means that you can squeeze the top piston ring with your fingers until it goes into the chamfer. The cylinder should then slide further onto the piston till it meets the next ring. If it won’t go, don’t force it! Check the ring has gone into the chamfer. Repeat the procedure until all the rings have gone into the bore. The last one is the hardest because there’s not much finger space.

It’s now time for the head gasket. I think the gasket I’ve just removed was meant for a 750 as the bore is about 83mm whereas the new one (specific to the 700) has a bore of 80mm. Here the old is placed on top of the new and you can see the difference.


The gasket was fitted but, before I put the cylinder head on I searched in the exhaust port for the old exhaust gasket. There should be a (squashed) copper ring in there. I scraped and picked at the port but couldn’t find the gasket. Now, I know that sometimes these can appear to be part of the head and hard to find so, I decided to get a second opinion. I measured the depth of the threaded section as 18mm and asked the members of the Yahoo Loopframe Group if anyone had a head they could check. Inside the hour I had a response from Charlie saying he had just measured a head and found the depth to be 17mm. I was right then. Someone had fitted the exhaust header without a gasket.

The design of this exhaust fitting means that, if the header becomes loose, it can vibrate in the port and damage the fine threads. There is some damage on this head but it’s still serviceable. A repair can be very expensive.


Before putting the head on, I double-checked that the gasket was on the right way round. Again there is an oil drain hole which must line up with the hole in the barrel.


The head was fitted on the studs then O-rings fitted to the four remaining (long) studs.


The bracket for the rocker gear goes on next and the six nuts (five plus the sleeve-nut) can be torqued down in a diagonal sequence. I do;
– top right,
– bottom left,
– top left,
– bottom right,
– lower one by spark plug,
– top 10mm hex sleeve-nut.
The torque figure is 27.5 ft.lbs. This figure seemed a bit low to me and conflicted with the figure of 29 to 32 ft.lbs (4 to 4.5 Kg/m) given for later Guzzis. After taking advice fro members of the Loopframe Group, I’ll use 32ft.lbs in future.

Fit a new crush washer and refit the 26mm blanking plug over the sleeve-nut. Then refit the rocker gear. Drop the pushrods back where they came from. I like to turn the engine again to get the pushrods as low in the head as possible. Squeeze the relevant rocker, spring and washer back in place on the bracket and a bit of wiggling will allow you to get the spindle back in (screw hole at the top). Turn the spindle with a screwdriver until the locking screw can be refitted.


Only ever use the original type and length of screw. It locks the shaft in place but mustn’t go too deep. The other side of the hole is an oil supply which then goes down the centre of the shaft and out again halfway along it to lubricate the rocker arm on the spindle. The wrong screw might restrict this oil flow.

At this point I refitted the exhaust header but now it does have an exhaust gasket. The threads of the exhaust nut were given a smear of copper grease.


I didn’t do it up tight until I’d got the frame-to-header clamp in place in an effort to get everything lined up properly. I tighten up header nut, silencer clamp and frame-to-pipe clamp in that order.

The oil feed to the head was reconnected using the banjo bolt and new crush washers. I’m careful how I do this as the bolt is naturally fragile, being hollow with a cross-drilling. I use a short spanner.


The inlet manifold and carburettor were refitted and the spark plug screwed back in. I’ve decided to repeat the job on the left hand cylinder so I’ve left adjusting the valve clearances for now. I put the rocker cover on with a couple of screws to keep the muck out for now.