Recondition carburettors

   I managed to get the bike running sometime ago however it was as lumpy as a lumpy thing. I checked the coils for sparks. Yes good sparks. Fuel flow? Yes good. It should I had cleaned the tank out, fitted inline fuel filters and use clean new fuel. If I put my hand over one of the carb inlets the engine picked up. Essentially the carbs were massively out of balance and no amount of adjustment on the few adjustment screws was going to correct the situation.I resolved the recondition the carbs. I reasoned that the carbs were 30 years old and one or both items could be corroded on the inside. Since carbs are sophisticated items and very built to fine tolerances this would likely be the reason for the lumpy running. I was hoping for the simple problem of a torn diaphragm. I priced the items. It turned out to be more cost effective to buy a refurbishment kit than buy the diaphragm only and hope that was the issue. Whilst I was about it a thought it might be nice to fit individual choke levers to the carburettor and do away with standard cable operation. More on this later.

 
I had toyed with the issue of getting an ulta-sonic bath to clean the carbs on the inside but I could not live with the cost. Of course I needed a large volume bath to contain the carburettor and they were expensive. I ordered the parts from Motoworks but not after extensive measuring and research to work out exactly which carburettors I had.

   Parts ordered and duly delivered they sat in their delivery bags for an age. I was worried that I would not be able to disassemble or reassemble the carbs. I picked up and mini set of sockets that came with screw driver bit to for the sockets. That meant I had small tools to tackle the intricate parts. I was also concerned that items to be replaced being brass might secured themselves to the Magnesium alloy of the carb body.
 


   I cleared my work bench, made sure there was plenty of light, got my mini tool kit, laid out the refurbishment components and made a brew! 

    To my great surprise and relief the screws and nuts came undone without much drama. Having the correct tools for the job helps. I remembered to take careful note which way round the moving parts worked. I removed one item at a time and worked as methodically as I am able until each component had been replaced.

  I had particular bother with the float needle. There are knack to removing it. The clip that held it in place was in a deep recess so I could not get at them. I worked out the way to twist the needle to expand the clip and slide it free. Luckily it went back in the same way. I discovered that the float needles were set to different heights. Well that is not going to help the engine run smoothly. They are now both the same setting, right or wrong they are the same. It was not surprising to find wear on any part that touched another part or any part that had been in contact with the fuel. The engine had been burning oil before it was refurbished and there was evidence of burnt oil residue of many of the parts.

   The final element of replacing the diaphragms proved to be tricky. The plastic grommet holding the diaphragm to the metal venturi slide was a very tight fit. However came away quiet easily but snapping it back in place was difficult. The shape of the lip retained the ring was such that with the extra thickness of the new diaphragm the metal lip and plastic ring worked against each other. Breaking either item would be expensive to replace. Hum what to do?

  Tea and a think. I figured if the plastic was to expand I might get the room I needed to snap the ring into place. Well how about I put the metal slide in the freezer for a while and I put the plastic ring in the bowl of boiling water. The former will shrink and the later expand. It might be enough.....and it was. The plastic ring fairly popped into place and captured the diaphragm inner edge as neatly as if it had been done in the factory.

    Next up was to fit the manual chokes. 80/7s have a choke lever

attached to the air box. Two cables run from the lever, one to each carb. The lever is always difficult to engage as the cables have a tight track to follow and get corroded. The conversion junks the cables and the lever. It was and easy job.














The new choke pulls simply slide into the vacant choke cable guide on the top of the carb: a small plastic insert fits into the guide to create resistance so the choke pull stays where it is positioned. The choke on the carb body is placed in the "on" position, the pull wire is fed through the capture bolt on the lever and the bolt done up. It is that simple.

  


The not so simple bit is that a decorative plate supplied with the kit. The plate blanks off the hole in the air box left by the missing choke lever. The blanking plate does not fit properly because the air box has been powder coated. It was either file of the powder coating on file down the shoulders of the blanking plate. Easy choice - the Dremmel made quick work of the Aluminum blanking plate. A couple of try outs and more Dremmel adjustments and the plate slipped snugly into position. A couple of turns with the Allen key and the plate was secured.      

Now to top up the battery and put it on charge.

A day of two halves

I had a few hours free on Saturday afternoon. During the week my ebay purchases had arrived, a tank, front brake master cylinder and a head light. I offered the headlight up to the shell and was happy to find it would fit once I had tidied up the wiring in the shell. I set the tank to one side. It look fine when a collected it on Wednesday evening. I stripped the master cylinder of the braided lines and the hand lever cable. In the process I dropped the spacer pin and could not find it. I knew it could not get far. I took the wire brush to the metal body and gave it a good scrub. I finished it off some wire wool. It came up to a fair finish. I had some spray enamel paint in the cupboard so I gave it a few coats, setting it aside between coats to dry. I cleaned the rubber boot. The unit must have been sitting in water for all the rust to be seen. I took the reservoir cap off and was pleased to see uncontaminated brake fluid slowly swishing about. I had picked up a new 70mm Jubilee clip during the day. I place the master cylinder where I thought it should go on the frame and fitted the Jubilee clip to loosely secure it in place. Then I put the rubber tank buffer in place and dry fitted the tank but no matter now a fiddled with the position of the master cylinder and buffer I could not make the tank sit correctly. I took the buffer off and low and behold the tank sat perfectly on the forward and rear tank mounts. I had another look on the floor for the spacer pin and the tank mount finger nut. I found both of them. I did the jubilee clip, fitted spacer pin and did up the hand lever cable. I left the brake light and fluid level sensor disconnected for the time being. Whilst I had the tank off I re-routed the throttle cables. I am get a dab hand at whipping the cable on and off the carbs. The throttle now returns to the shut position, if slowly.

With the master cylinder fitted the tank sat properly on the bike. During the week I had made my mind up to use the existing fuel taps as the ones that came with the ebay tank where rubbish. I took them to pieces and left the parts to soak in a cleaning solution. On Saturday and scrubbed and polished every piece of the two taps and put them back together and fitted them to the new tank. I got the new fuel hose out along with the fuel filters. I polished up the metal tee pieces that make up the balance tube on the fuel lines. I had to loosen the air filter casing yet again to fit the fuel balancing tube. Working from the bottom of each carb I cut the hose and pushed the hose on to the tee. Above the tee came the fuel filter, remembering to fit it in the correct flow direction. Then the last piece of hose on to the union at the bottom of the fuel tap. I did the job on both sides. It was a tight fit including the filters into the lines.

Now for the moment of truth. When I started the bike for the very first time it would not fire or run on the right pot. I hoped it was just a fuel issue which all the work on the tank and taps would resolved. I put petrol into the tank but something was not right. Petrol was pouring out of the bottom of the tank even though the taps were switched off. I put the fuel can down and rush round to far side of the bike. Petrol was gushing out of the top petrol tap union. I tightened it up with spanner but it made no difference. A closer look showed the fuel was coming out of the tank. I picked at the paint which opened flood gates. I managed to catch some of the fuel. when all the petrol was gone I took off the tank and found big hole in the tank which had been covered by paint. There was language! I cleaned up the garage. I had to take up the carpet in the garage and throw it out. It had soaked up the petrol. I opened all the windows and doors in the house, lucky it was a nice day, to rid the house of petrol fumes. H was not impressed when she came home.

I switched over the fuel taps from the "new" tank back onto the old tank. I put the old tank back on the bike, connected the fuel hoses and put some fuel in it. I slipped on the silencer and offered up a small prayer. I turned the key in the ignition, put the choke and thumbed the starter button. In two turns the bike burst into life. What a result. It was running a bit lumpy but after adjusting the throttle cables it was much smoother. I wanted to jump on it and ride away but I have no front brake, seat and a knackered rear wheel bearing. I had to be content blipping the throttle. The down side is that oil is pissing out the oil filer cover. I hope that is nothing but the oil light would not go out. I hope that is a electrical problem.

I am going start a new list on the blog...................jobs to do to finish.

A rainy day

Saturday 17th July was a rainy day. I had got soaked at the allotment in the morning so not having much to do on on rainy Saturday I had a look at the the bike. The electric clock had run down the battery. I had some acid left over from the initial fill so used it to top up the battery acid level. The voltmeter started to register an increase almost immediately. I plugged in the battery charger and watched the volts increase.

Whilst I was pondering what needed to be done I started rummaging in the boxes. I got the handle bars off the garage rafters and fitted them to the headstock. I found the clutch side handle bar cluster. A bit of digging and I found the lever and pivot pin. I assembled the cluster and fitted it to the handlebar. More rummaging turned up the brake side cluster, pivot pin, throttle twist grip, the throttle cable pull and the cover. I had hung up the throttle cables months ago and had soaked them in oil. Now that I need them I just got them off the rack all ready to go. I assembled the brake/throttle cluster. It was a bit fiddly but it went together without much trouble. I routed the throttle cables down to the carbs then positioned the switch cluster. That turned out neat enough.

The handlebars look fairly complete but there are some bits that need work. The clutch cut off switch looks a bit tired. The hand grips are heated but I have not tested them for operation. The wires for the heating elements run inside the handle bars but the wires on the end of the grip are not long enough so the handle bars are going have to come off again for the grips to be wired properly. That is a job for another day. There is another problem...where are the switches to control all these gadgets to be located?

I fitted the ends of the throttle cables to the carbs. It made a nice job. I turned the ignition on and cranked the engine. The engine made no effort start which was a shame. I resolved at that moment to get a new, second hand pair of carbs. The bike looks a lot more finished but there is still a bit to do.

Perhaps the biggest day yet

Last night's triumph has been haunting me all day. Whenever I have had a spare moment I have been thinking about how to get fuel into the bike. When I got home today and after I had my tea [the northern meal taken after work not the hot brown liquid] I went into the garage to way up the possibilities. I had a good look inside the tank and gave it a shake. What I could see of the inside of the tank was rusty. Shaking the tank gave the telltale sounds of flaky rust loose in the bottom of the tank. I thought about when I might get a tank and whether I was prepared to wait that long. The decision was made very quickly.

I had fuel filters in the spares box. I cut down the existing fuel lines to accept the fuel filters. I hoped the filter would keep the smeg from the tank out of the carbs. I then connected the fuel lines up. I had a Jerry can of fuel in the Land Rover. I sploshed a gallon into the tank and checked the petrol taps flowed. One was OK but the other was a bit slow. When turned on the fuel the leaks appeared. After close inspection I found that the bends required in the fuel lines to fit the filter were causing a poor seal to the fuel spigot on the carbs. I took off the carefully made fuel lines and replaced them with the spare fuel hose. No filters this time. I resolved that cleaning the carbs would be a price I was willing to pay if I got the bikes started this evening. I put a bit more fuel in the tank since I did not fit the balance pipe on the temporary fuel lines. I took the float bowls off and checked the float was doing its job. Just as well I checked one float was stuck. It just needed a tap to free it. Float bowls back on. I then dury-rigged and couple of throttle cables with some spare electrical wire. That took a bit of doing but finally got a secure fix. One last deep breath. Then I remembered the spark plugs were not screwed in. That job done and the suppressor caps pushed on I stepped back for a deep breath before the big moment.

I put the choke to full on, switched the ignition on and hit the starter button. The starter motor engaged and engine heaved round and round but it sounded flat. I moved the ignition unit a little and the biked coughed into life but running very lumpy. In fact just one cylinder was firing. I let the engine heat up a little and did the usual sort of tests. I pulled the plug of the cylinder that was not firing. It made no difference which meant that pot was not even tying to fire. I turned the engine off and looked for the spark monitor. I fitted the monitor between the spark plug cap and the spark plug and restarted the engine. The monitor flashed as the spark passed by. The issue must be fuelling. I took off the air inlet tract to the offending carbs. I restarted the bike again and did the old two-stroke trick of putting you hand over the air inlet. Your have to be careful when you do that with a 400cc cylinder. The induction can bend you fingers painfully the wrong way. I noticed the carbs seemed very dry. Engine off, fuel off and the carb dismantled. I cleaned the jet and made sure everything else was working. I had the carbs top off to check the diaphragm. All looked ok. I put the carbs back together and turned the fuel on. I hit the switch again, the engine turned. Using my hand I was able to get the cylinder to fire but only intermittently.

After an 30 minutes of single pot running and one and a half pot running, I stopped. I tidied up and retired to consider the position. Although the bike fired and runs, after a fashion, and that is great, it shows that there are some problems left to sort out. If the carbs are knackered or the wrong ones then it could be expensive to resolve. The mechanicals of the engine sound fine when running which means the engine re-build was a success and that is a major plus point. There is a little oil leak on the sump pan seal. I got about three turns on each of the sump pan bolts. I guess the heat of the running engine made the seal move and the bolts loosen. There is good access to this seal so it should be easy to resolve.

A Tiny Job

When ferreting about the in the box the charging and ignition kit came in I found the small packet that contained the float bowl seals. I knew I had ordered them and had in fact seen them but I could not find them all summer long. It took less than five minutes to fit both the seals. I just had to ping off the float bowl retaining clip on each carb, drop out the bowl, position the seal, reposition the bowl and refit the clip. Another job ticked off.

Carbs

I bumped into my friend with the parts washer and ask if I could use it. He said yes but I would have to wait until he was back from Zurich at the weekend, flash bugger. We arranged to meet at lunch on Saturday. H came along too. H and my friend's wife have been buddies for a long time. We pitched at the appointed time and found lunch was to be Spag Bol and all the trimmings as well as nice spot of red wine. Very civilised. I was expecting was my usual Saturday lunch......a cheese sarny!

The ladies were "catching up", K had to make a phone call and I was left to play with the parts washer. I soon discovered that some of what I thought was ground in dirt, was in fact, black paint. I got the proper dirt off and set the carbs aside to dry off. I used K's big vice and tools to break the grip the set screws that held on the top cover. Job done. I cleaned and packed up and went back inside to finish off the wine.

The four of us got quite comfy as you do with old friends but both of us had appointment that evening with other friends. You will have to read my other blog to find out what the evening was about. It was not a boozy evening so I was up at my usual time. It had been frosty when we left the venue but then it blew a gale all night and rained so no allotmenting today [Sunday].

Never mind I will just have to fettle the carbs. I got some mini wire brushes that fit in the cordless drill. I send about cleaning the paint and tough dirt off the carb bodies. It worked really well and it polished them too. I took off the carbs top to find that the slides were stuck in the throttle bodies. Lots of WD40 and progressively less gentle tapping later the slides came free. I took them out and cleaned up the inner face of the throttle bodies which were gummed up with petrol residue. It took some careful cleaning to get rid of the residue. A carburettor is engineered to fine tolerances so one has not to be too heavy handed. Eventually both carbs were cleaned, inside and out, and reassembled. I thought I will just see if I have all the parts to mount the carbs. There are five jubilee clips, two rubber bushes and an air duct for each side. I found I had all the bit so I just cleaned everything up and offered the bits up to the bike for a trial fit. They fitted so well the parts are now fully fitted. So why not try the choke cables, that were fitted last week, to the carbs. Yep they fit. Another tick in the box.

H brought in a cup of tea. Whilst pondering what to do next I spotted the exhaust headed pipes. I offered them up and they just slipped on. I slotted in the balancer pipe and did up the nuts finger tight. I tried the silencers on but I did not have the brackets. I took the silencers off again and put them back in the store. I thought I would have another rummage in the parts box. I found the two tank mounting bushes which was an unexpected result. I could not find the nuts for the engine mounting bolts. The riders foot rest and the exhaust header brackets fit to the rear engine mounting bolts so the nuts do five jobs. Alas no nuts but I did find the silencer brackets and the rear mud guard brackets. They are filthy so I have to consider having them cleaned and power coated like the other stuff on the bike. I now have to find a powder coater locally. I also have to make a list of the bits to be powder coated.

I even had a toy with mounting the coils but stop before things got silly. I started making two lists. One for missing or replacement parts. Some bits are just too knackered to refit and a second list of bits for coating. Whilst looking round the bike I wondered if I had all the bits for the back brake linkage. I did and now it on the bike. The rear actuating arm needs moving round the splines but that is small job which I will do when I have the rear wheel off to do the bearings.

A lots of progress has been made with the mechanical elements but I am still short of the charging and ignition circuitry and without them the bike will never get a chance to start.