Twisted front forks? – 29 Sep 2016.

Well folks, this could be a long post! Ever since I have owned The Fire Bike the handlebars have been turned slightly to the right when riding in a straight line. I’ve always thought that the handlebar mounts were a bit bent and just lived with it. As I’ve said before, I’m no riding god and pretty much just ride what I’m presented with. When I took the bike for its MOT test last week the tester commented on this trait and suggested the forks could be twisted in their yokes. I thought that I had better take a look.

The first thing I did was to clamp some timber to each side of the rear wheel. I then clamped the front wheel in straight-ahead alignment using some thin pieces of plywood on each side as shims.

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I could now see how far out the alignment of the ‘bars were.

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It doesn’t look much but, what you might just be able to make out is that the instrument binnacle is turned to the right as well, meaning the top fork yoke is the same.

I decide that I would undo the pinch bolts on the lower yoke to see if everything would spring back into alignment but, I found that to do this I needed to remove the screen/fairing first. The pinch bolt is actually a through bolt so I needed to be able to get to the nut on the back of it as well.

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Due to the way the indicators are fitted, these had to come off before the fairing. It was easy enough to go into the headlamp and disconnect the wires but the connectors had to be cut off as they won’t pass through the headlamp mountings.

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That was the easy bit! The indicators have rubber stalks with a square drive fitted up against the fairing. They are screwed into the fixings for the headlamp. Turning these square drives is pretty well impossible without causing damage to the fairing. I found that I could loosen the headlamp nut between the fairing and headlamp bracket. Then hold the indicator stem still with a spanner on the square while tightening the headlamp mounting up again. This gradually wound the indicator and stalk off and I managed to keep the headlamp in alignment.

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With the indicators removed I temporarily put the headlamp back together. I decided that I would remove the fairing leaving the chrome brackets fitted to the handlebar clamps and the short black brackets attached to the fairing by undoing the two nuts and bolts at each side.

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Now I could get back to releasing those fork pinch bolts. I slackened them completely. Lots of flakes of red paint were shed from the nuts and bolts. I’d noticed before that the front end of the bike seems to have been given a coat of paint while assembled.

I had already removed all the timber and bounced the forks a few times. Then, with the front wheel between my knees, I tried to force the handlebars from side to side. I re-clamped the wheels and took another look at the alignment.

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I’d say that’s a significant improvement. I re-tightened the pinch bolts and was pleased to see this hadn’t changed. I put some wood between the fuel tank and handlebar mounts to see if the gaps were the same on each side. Not very accurate I know.

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Front fork oil change.

At this point I decided I would change the oil in the forks. The original oil specified was 160ml of Shell Tellux 33, whatever that was. I did some research on the web and found a number of suggestions. Some people use 20W50 engine oil and others use 30W fork oil. There are also suggestions about increasing the amount of oil used. Some say 200ml and some 8oz (225ml). I decided to get hold of some 30W fork oil and to stay with the factory specified amount. My local shop expressed surprise at me wanting such heavyweight oil but sold me the one and only 1litre bottle of the stuff they had on their shelf.

So, with all my temporary timber work removed, I undid the four allen screws holding the instrument binnacle/bezel/whatever to the top fork plate. I could ease it up enough and block it out of the way to allow me to get to the plugs in the top of each fork leg. More red paint was shed as I undid these but I was careful not to get any inside the fork tubes.

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I removed any remaining paint when the plug and its washer were on the bench.

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Then the drain screws were undone. They are just a couple of Cheese-head screws with a fibre washer.

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I put a bowl under the first leg and watched as what looked like a 2-inch long black slug slowly oozed from the drain hole. This was then followed by cleaner oil. The same happened when I drained the other side. I’m guilty here as I haven’t changed the oil before. I had assumed it was OK!

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After draining the oil, the screws were replaced along with new fibre washers and I added 160ml of 30W fork oil to each leg before replacing the top plugs. The washers under the plugs look like they are too big until you realise that they match the ring profile of the underside of the plugs. I checked the wiring connections under the instrument binnacle before screwing it back in place.

All that remained now was to put the fairing back. Initially I held the fairing in position with some screws and washers in place of the indicators.

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I could then turn my attention to the upper mountings to the handlebar brackets. I loosened the screws in the top of the ‘bar clamps and loosely refitted everything before going round and tightening the lot. The aim of this was to minimise the stresses on the fairing.

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Getting those indicators back on and facing the correct way was a bit of a rigmarole. With the headlamp off again, I fed their wires into the shell. I added a washer between the square drive on the stalks and the fairing and then just kept fiddling with them until they were right.

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I then had to crimp replacement connectors to the wires and link them back up. With the headlamp back on I checked that everything worked as it should before going for a ride.

The test ride confirmed that the ‘bars are now straight. I can’t feel any improvement in handling but am reassured by knowing the alignment is now correct. However, even I could notice a huge improvement in the action of the forks. Compression damping is improved and there is less dive under braking. As I found with the V7Sport, less dive seems to improve braking performance.

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Speedometer cable – 23 Sep 2016.

It seems to all be about The Fire Bike at the moment. That’s probably a good thing and hopefully means that The Racing Rhino is sorted!

Anyway, last weekend I attended The Red Kite Camp put on by the South Wales and Mid-Wales sections of MGCGB. I went on The Fire Bike with trailer. I belong to the Mid-Wales lot. All was good and I had a great time but neglected to take any photos.

During the ride-out on the Saturday the speedometer stopped working. That’s not a great issue for me as I also have the push-bike speedo fitted. A few days later I disconnected the cable at the gearbox end and spun the inner with my fingers and the speedo worked. Hmm. I examined the end of the cable and found that the square section had rounded off. I’m not sure why this has happened as everything moves freely.

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When looking for a replacement cable I noticed that the same cable is used on the V7Sport. I had a cable with a damaged outer in my box of old bits that might work.

To remove the inner cable from the bike you have to obviously disconnect it from the back of the speedometer which is easy enough. First I had to remove the four allen screws securing the bezel, or whatever it’s called, from the top yoke. The two slotted screws just blank off some holes.

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There was just enough room to get my fingers in to unscrew the cable and pull it to one side and to pull the inner cable out.

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I compared the cable to the one from my “scrap” box and yes, they were the same. I squirted some oil down the outer cable before inserting the inner which pushed a lot of it out the other end. Once inserted I added some more oil for good measure then reconnected the cable to the speedometer.

I took a good look underneath the bezel to make sure no electrical wires had been displaced by my fumbling about before screwing it back to the top of the forks.

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The cable was then reconnected at the gearbox end.

It’s not something I would recommend but, The bike was then started and run in gear on the centre stand to confirm the speedometer was working again. It was.

A couple of days later the bike was taken for its annual MOT test which it passed with no advisory points. The only comment was that there appeared to be an oil leak – it was only more oil finding its way out of that speedo cable!

Correct front brake set-up – 7 Sep 2016.

I’ve been meaning to correct the relationship between the front brake cable and the brake arm on the front hub for a while. I was reminded about this while I was away at the Guzzi Festival last month.

For the best mechanical advantage the “angle of attack” between the cable and brake arm on the hub should be as close to 90° as possible when the brake begins to “bite”. On The Fire Bike the angle is obtuse (over 90°). The following photo was taken with the lever on the handlebars pulled.

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I know the brake shoes are not worn out so I decided to try and move the levers round one spline on their shafts.

To disconnect the brake cable at the lower (hub) end I had to disconnect it at the top (handlebar) end first. Then I removed the clamping screws from the two brake arms and marked their positions on their shafts. There is a casting mark across the shafts and I used this as a reference point.

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I made these marks in case the levers came off with a jolt and I lost track of where they had been originally.

I removed the link rod between the two brake arms (a split pin and clevis pin at each end) without altering its length. Both levers on the hub were pulled off then replaced one further tooth clockwise on their spindles. The fixing screws went back in and were tightened.

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I was pleased that I managed to do this without pushing the spindles into the hub brake plate. The alternative would have been to remove the wheel to carry out the job on the bench.

As both levers had been moved by the same amount, the link rod could be put back without losing the setting of the brake arms relative to each other. Of course, new split pins were used.

Refitting the cable was a bit of a job. It’s now just a bit too short – about 5mm at a guess – and I had to remove the support for the cable from the front mudguard to do it.

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Once the cable was re-attached at both ends the cable support could go back. All that was left was to adjust the brake and take the bike for a ride. I can’t say that I noticed any improvement but am happy to have “got it right”. That front brake is not brilliant and I need all the mechanical advantage I can get. This is the right-angle between cable and lever that I was looking for. Again this is with the lever pulled till the brake is just “biting”.

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A squeak from the front forks?

When talking to Dave P at the Guzzi Festival I mentioned that I would probably rebuild the front forks over the winter as they squeak. He explained that his are the same. He has found that the squeak is caused by the front brake cable rubbing on that support screwed to the front mudguard (fender for our American friends). It went away when he put some grease there. Sure enough, that’s my suspension squeak!

Carburettor refitting and tuning – 7 Sep 16.

After rebuilding the Dellorto VHB carbs on my V7, and bench-testing the one which previously leaked as best as I could, It was time to refit them to the bike.

I smeared a little copperslip on the carb mounting stubs. This made it easy to refit the carburettors to the manifolds and hopefully they’ll come off easier next time. I also screwed on the aluminium intakes (which connect to the rubber boot) before fitting the carbs to the bike. New gaskets were used between the intake manifolds and cylinder heads. Old Guzzis with solid (rather than the later rubber) inlets use two gaskets stacked on each side to act as heat insulation. There are also insulating washers under the heads of the intake mounting screws for the same reason. I have wondered about getting some PTFE (Teflon) to make insulators from. These might not stick to the inlet manifolds and cylinder head and be destroyed like the conventional gaskets on dismantling. For the moment, I just used lightly greased replacement gaskets.

Once I was sure the carbs were at the angle I wanted, I tightened up the fixing clamps and fitted the fuel hoses.

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I turned on the fuel at both taps and thankfully everything was fuel-tight.

I reconnected the throttle cables

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and those for the enrichers (chokes)

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Just after taking this photo the choke spring was launched before I could get the piston back into the carburettor. Once inserted it can’t get free. It only took 40 minutes to find where it went!

I got the rubber intake boot back on but, as I expected, I had to remove the battery before I could refit the air cleaner box. To do this the other side panel had to be removed and was left dangling on the speedo cable.

I put a little grease on the air cleaner box before offering it up to the rubber boot. This fits around the outside of the lip on the box, just pushing up against it.

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Once the air box is back on, I wipe off any grease I can see so that it doesn’t attract the muck.

Once the battery and side panels had been refitted I gave the carburettors some initial settings so I could get the bike running and warmed up before tuning the carbs properly. I set the left carb mixture screw to 1½ turns out and the right to 1¾ as per the workshop manual. I set the throttle stop screws to about 12mm out on each side.

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It’s important that these screws are never turned while the carburettor slides are resting on them. Always hold the throttles open with the twist grip when altering them to prevent damage to the slides or the tips of the screws.

I checked there was slack in all the cables and started the bike. I had to turn both the throttle stop screws in a full turn to get the bike to run, albeit very badly. It was time to get the vacuum gauges out again.

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I’ve described how to set the carburation using vacuum gauges before when I did this on The Racing Rhino so I shan’t do so again. You can refer back to it here.

Later, I took the bike out for a short run to make sure it behaved properly. By then it had cooled properly so I was able to start it using “choke” and ride it to warm it up. It seems to be running well.

However, before going for a ride I tackled another job I’ve been meaning to do for a while. I’ll post about that in a minute.

Carburettor cleaning and refurb – 3 Sep 2016.

Removal and dismantling.

In my last post I had got as far as removing and partly stripping the left hand carburettor on The Fire Bike. I asked for advice about removing the float pivot on the Yahoo Loopframe Group. As usual, I got sensible advice from someone who has had the same issue.

There was the slightest gap between the float and its mounting exposing about 1.5mm of the pivot rod.

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I pushed the float to the left and used a small pair of side-cutters to grip the pivot rod. I was able to move it a just tiny bit at a time.

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Eventually there was enough of the pivot sticking out for me to pull it the rest of the way. It hadn’t actually been tight but just hard to get a hold of.

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Having released the float I gave it a shake but couldn’t hear any fuel inside. The end of the float needle-valve had an indentation in it but didn’t look too bad.

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Peering into its housing at the seat, I could see it was very dirty and was likely the cause of the flooding.

I put the float in a bag in the freezer for a few hours then put it in some warm water. The idea is that, if the float has a leak bubbles will be produced as the air inside warms up and expands. My float looked to be OK. As a second check I wired a weight to the float then dropped it in a jar of petrol.

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I left it for the best part of a day. I didn’t see any bubbles and, when I retrieved it, no fuel seemed to have got inside (shaking it and listening again). I decided the float wasn’t the issue.

I stripped everything else from the carburettor and dismantled the accelerator pump. I had to spend time getting this apart as everything was gummed up.

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I didn’t take photos as I went along but there is a good guide to rebuilding a Dellorto VHB carb as fitted to both my bikes here on Greg Bender’s This old Tractor site.

Once the accelerator pump is out of the carb you should be able to put your finger inside the carb venturi and push the atomiser out. It’s the part the main needle goes through. On this occasion it was stuck. It’s made of brass so I used a plastic tent peg to drive it out.

Having now reduced the carburettor to a pile of parts I decided to remove the main body from the inlet manifold. I held the manifold in the vice with a couple of bolts and washers.

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Then knocked the carb off the manifold using a bit of plywood. Alternating sides in an attempt to keep it straight.

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You can see that I was careful to only hit against the end of the carb flange. It became easier once everything had started moving.

I went on to remove and dismantle the other (right hand) carb in the same way. This seems to be in much better condition. It doesn’t show any corrosion and came apart properly as well.

Carb Spec.

I have already said that I was surprised to find that the main jets fitted were quite a bit smaller than those quoted in various manuals (including the factory one). They state a 145 jet should be fitted while I have 135s.

Finally I checked the 1971 parts book for the V7 700. The main jet is given there as;

Guzzi part no. 12 93 57 01, “Getto massimo”, Dellorto part no. 1486.135.02.

So that would suggest my 135 jets are correct.

To be certain I found a parts list for a 750 and that shows the main jet as Guzzi part 13 93 57 00, Dellorto 1486.145.02. So they are different.

For the record the following parts are fitted to my carbs.

  • Main jet – 135
  • Pilot jet – 45
  • Enricher (starter jet) – 80
  • Needle – V5 in second notch.
  • Atomiser – 265
  • Slide – 7454-60

Cleaning and reassembly.

I ordered some parts to rebuild the carburettors from Eurocarb.

  • 2 gasket sets
  • 2 float needles
  • 2 choke (enricher) pistons
  • 1 choke piston return spring (as one was deformed)

Then from Gutsibits I ordered 4 inlet manifold gaskets.

While I was waiting for my orders to arrive I started on the cleaning.

I assembled a supply of rag, cotton buds and cocktail sticks and cleaned everything with carb cleaner and compressed air as per the guide on This old Tractor.

Some of the O-rings were so hard I cut them off.

Advice from the Yahoo Loopframe Group was to clean the seat for the float needle valve with a cotton bud plus fine grinding paste. I decided that Solvol metal polish was probably less aggressive and used that. Afterwards, I made sure any residue was removed with carb cleaner and compressed air again.

Today the parts I ordered were here (next day delivery from both suppliers) and I put both carbs back together as per the guide.

New and old enricher (choke) pistons.

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The replacement “choke” return spring is different to the 44 year-old original. Its shorter but stiffer.

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While reassembling the carburettors I checked the float heights as per Dellorto’s instructions. Elsewhere I have seen advice to set this with the carb inverted. However, as the VHB is a carb with connected floats it should be done this way – inlet downward.

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The setting is 24mm +/- 0.5mm and neither carb needed any alteration despite how it looks in my photo!

Testing.

The final job for today was to put some fuel in the left hand carburettor to see if it still leaks fuel from the air vent.

I carefully mounted the carburettor in the bench vice. There’s hardly any pressure on the carb bowl here. I added a short length of fuel line and a syringe body to hold the fuel.

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There was no leak from the vent hole. I added the plunger to the syringe and put the fuel under pressure. I couldn’t force any more fuel in or cause a leak. I think that’s a result! Just got to refit and tune everything now.