Many thanks Andy for replying to the post.

Will work my way through the fuel system until I find what is the matter. Got to get the petrol tap flowing freely first. Also will soak the carb in cellulose thinners, acetone or white vinegar. Think I will experiment with all three on different parts to see which one performs the best. If there are still bubbles in the fuel from the pump, will have a look at that too. The chap who left me the machine had an ultrasonic cleaner, but I think it was sold along with his vast array of plant and machinery.

Agree about the throttle linkage, will make my own. Can get a pair of M5 ball joints for £5.20p off ebay which will give a stable mechanism. Have found original linkage rods going through holes that can enlarge over time. With a big single at tickover it can cause the throttle butterfly valve to flutter, so the revs are not as steady as they could be.

Agree again the most likely cause of the lack of clutch operation is sticking plates. My only doubt about this is when I picked the machine up there was zero resistance on the clutch lever on the handlebars. It was only by tightening both adjusters to their maximum, could I feel something was moving. Managed to download the service manual and it does go through the clutch itself, but limited info about the mechanism that operates it. The photos are not very clear. It looks to me the clutch lever at the gearbox end has a pawl on it that engages with the clutch trust sleeve that in turn presses against the clutch trust plate on the clutch unit. It is this area that I have concerns about as if something is broken there, it could be terminal for the machine. The other thought I had was the rotovator was used with the adjusters up too tight, inducing clutch slip, eventually completely wearing out the friction plates. Which may account for all of the adjustment used up on both ends of the operating rod before any ‘feel’ is felt by the clutch lever. Or the nut that secures the clutch unit onto the clutch shaft may have worked loose, so the whole assembly is pushed towards the engine. As previously, any advice is most welcome before I split the machine.

Grahame

Dear Andy,

A big thank you again for your sound advice.

Am 95% certain the rotovator was a good machine before it was put away 25+ years ago. The only nagging doubt I have is over the clutch, why is there some ‘feel’ on the handlebar lever only when both adjuster are tightened to their full extent. Do not want to spent time and money on it, only to find there is something broken that cannot be fixed with the clutch. If it is just worn friction plates, or the bearing knackered on the engine adaptor plate, then obviously can do those. But as you say, can only assess this once I have split the machine. Was really after advice from someone who had a lot of knowledge of Howard Gem clutches and what to look out for before I undo the bellhousing. Decided the re-commissioning process was to get the engine running first and if that was good, move onto the clutch. Like to do some research before I tackle a job I am unsure of. Find that the experience of others is invaluable in that respect. It can save time and possible damage if you try to disassemble a part that has a retainer you are not aware of.

Have always used petrol and an airline for small parts cleaning. Found Gunk and a pressure washer great for removing thick oily sludge on engines. Mostly petrol and a good brushing has removed gum on carburettor’s, except the really hard to shift historic coatings. Have googled ultrasonic cleaners for carbs and some say they are brilliant, others say so-so because the small passages are not fully cleaned. But am going to take your advice and see if I can find someone with one and chuck the carb in.

Have got a Zenith 24T2 carb with an adjustable jet on the Jap 5 on my Trusty. Replaced the original Jap carb with the Zenith and it was that that I made up the new linkage for. The Zenith was removed from a Trusty that was left outside for decades. Put a service kit on it from Villiersparts, that included a new throttle spindle. The old one had a big flat on the linkage side, so air could be sucked into the carb. The new spindle then made a huge difference at tickover and throttle pickup, which is so important on a Trusty. But sometimes it will start by the third swing of the starting handle, others not even after twenty on full choke. It appears it is not getting enough fuel to start it from the main jet to the orifice in the ventri, with the chamber not being clean and smooth, preventing the petrol from being sucked through it with a single swing of the handle. Luckily a Trusty can be started with a strap, so I can get it to go. But re-built it last year, so it has full compression, getting a bit long in the tooth to keep having to turn in over with the strap. When I find someone with an ultrasonic cleaner, will take both the Walbro and Zenith carbs for a clean.

Have attached the pictures. One way or another I know I can get the fuel system sorted out quite easily. Have a feeling it may be the petrol tap only delivering a fast drip, in turn making the original diaphragm on the fuel pump let air bypass it, delivering frothy petrol to the carb. That could be the real cause of the problem. But having the carb ultrasonicaly cleaned will not hurt either. Will be very interested to see the results to both carbs. Have you ever taken a clutch apart and if so, what did you find.

Grahame

Dear Andy,

If the pump is causing the problem will get a new pattern diapham from China a £5.80p. Always fit a fuel filter to my working machines as a small bit of rust can come off the inside of the tank, rubber particles from pipes, even with E5 petrol and dirt from the petrol can when filling up. A local hire company always fit a fuel filter to their new plant.

Looked at an Irish lad on YouTube undo the bell housing. Jack on the rear, a trolly jack under the engine, disconnect the fuel pipe, throttle cable, kill switch wire, undo ten bolts and it easily pulls apart. As you say, a piece of cake. But he found the adaptor plate bearing had broken up, it rattled around and damaged the six pins. Have heard all sorts of tales of broken shafts, gearboxes and bearings on Gems.

Have limited use for the rotovator and indeed have a low opinion of them. They are good for chopping in the crop ready for ploughing, or preparing a seedbed when the soil conditions are just right. If used when its wet, they compress the soil structure, especially in our Evesham clay and any clods produced dry out to big hard lumps that you cannot get down. But the Gem looks like a good machine and with little work, can find a use for it. Got a Clifford Mk IV I want to restore if only because I like the colour and shape of the bonnet.

Grahame