Check behind the clutch. Most trials Cubs have been modified to fit a final drive sprocket access plate (similar to T100 twins). This lets you change the final drive sprocket without having to split the crank cases!
If it has been modified, the thin plate should have an oil seal fitted (with the spring side of the seal facing the clutch).
ATF is fine for the clutch. You only need enough to cover the primary drive chain so I put 100ml in instead of 200ml as stated in the manual.
If the clutch slips when kick starting you can fit stronger springs and add an additional plate with billet ally pressure plate if required which available from a number of Trials Cub Specialists.
I’m 63 and have been riding trials bikes since I was 15. I don’t really enjoy the whole competition thing as I am not that talented. However I love tinkering with things.
I therefore built a couple of trials Cubs and really enjoy doing the easy route in club and pre65 trials. There are a lot of people like me just out for a good day out without trying to kill yourself! 😊
I guess there are not too many big climbs in Holland, however I'm not sure about rocks etc.
I'm 62 years old and mainly do club level pre 65 trials. I wear pull up mountain bike shin and knee protection (purchased on line) under normal (unpadded) trials trousers. I find this gives adequate protection and is comfortable.
Petroleum 😊. Super unleaded (97 octain) if possible as it has little or no ethanol.
Cubs already have hard valve seats so lead substitute not really necessary but you can use it if you wish 👍
Yes you can fit a diaphragm clutch to a Tiger Cub.
They include a belt primary drive and are available from Pete Kirby.
I have one fitted to my Armac Cub and it is very good. light action and no slip.
I also have an upgraded UPB wet clutch on my other Cub which also works well.
A standard clutch can be made to work well. It all depends on how deep your pockets are! (How much money you want to spend)
Look on Ebay for the replacement bolt sets. That should tell you the thread size. Failing that, phone Meriden Off Road, UPB or Greystone.
I had a 'well used' set of Crank Cases which I tapped the small bolts to M5 and Heli-coiled the larger ones to M8 as most were stripped and I already had metric inserts and bolts bolts in my shed.
However, if only a couple are stripped I can understand your desire to keep original.
Buy a second hand assembly from Ebay. They aren't expensive. I extended the length of the arm to make my clutch lighter. Then got really carried away and fitted a clutch lightening kit from UPB which does away with the arm altogether!
I have built and ride several Cubs. I do not use oil seals in any. My advice would be to fit new valves and Phos Bronze Guides if you are concerned about smoking.
A good friend (who is no longer with us) did fit some old Ford Valve Seals to one of his Cubs which reduced the smoking effects caused by worn guides but not a cure!
Also Chris at Meriden Off Road is a wealth of knowledge if you don't mind travelling to Birmingham
............But lock up your credit card first ?
The other option is to do it yourself. These require a couple of cheap special tools and are pretty basic engines depending on your mechanical ability.
I'm an average Club rider and at 60 ride a Tiger Cub and 4RT (both 4 stroke). I have also ridden Gas Gas's in the past.
In all honesty, I can get away with more on a Gas Gas as they are lighter but ridden at Club level in non stop trials and trying not to use the clutch (old school), the 4RT is a great bike to ride. My 2014 Repsol has brilliant suspension and build quality. If anything,it's a bit too powerful and makes my 60 year old arms ache after a day's riding, however I'm not that fit!
If you are anywhere near Kent, you are welcome to try mine. Technique is key with these bikes and I love mine although I tend to use my Cub on the easy route for club trials these days.
You really need to try one around some simple sections and compare it with a 2 stroke to see which you prefer.
Just a quick update. I fitted the alloy push rod tube without push rods and gaskets and measured the clearances as Thai-ty has mentioned above. I then select the appropriate top gasket to give me about 1mm clearance at the bottom of the tube. I also used a bit of tribond (?) sealant for good measure either side of the top gasket. Hey presto, no leaks......yet??
Tounge in cheek the oil may be coming from the big hole just above it.
Seriously what is this hole for? Is it made so that the pushrods can be located easily?
I have also had problems with sealing but used a thicker softer material (cannot remember what) but more like a square edged O ring (which I got from Martyn Adams I think).
Lets us know if the alloy tube does the trick.
Yup, It's a mod I did to both my Cub engines (shown to me by a guy called Henry Boudery) to help locate the top of the push rod. I normally dab a bit of grease on the bottom of the push rods and hold the rockers in their 'up' position with an elastic band.
The top of the exhaust push rod is also painted red.
Probably all a bit over the top but nice to know everything is correct before tightening the head down ?
I have high hopes for the alloy push rod tube and I will also be using a bit of sealant as recommended by Bob at UPB ?
What type off gaskets do you use I use an o rings top and bottom A black square section type on the bottom and a red round section at the top If the tube is seated properly and no damage it should seal mine do alright
I'm using the black one at the bottom and what's meant to be a superior gasket at the top that comes in 2 thicknesses. Saying that, I may try fitting the original red 'O' Ring ?
Cub engine modified to allow me to run with outer cover removed to spot oil leaks. Unfortunately not required as the oil is easy to spot running out of the top of the push rod tube!
O.k. I fitted the earlier 'R' Cam to my late engine, no problem. Replaced the primary drive chain and it now runs smooth and quiet. Made some parts to allow me to run the bike without the right hand outer cover on. This would allow me to spot any oil leaks from the gear lever shaft and outer cam bush. I also replaced the push rod tube top and bottom gaskets with new items.
All is well apart from oil spewing out of the top of the push rod tube around the gasket. (see photo). I tried the thicker one when I assembled engine (without the push rods fitted) but it seemed to be holding the head off the barrel.
I put a smear of sealant around the push rod tube flange on assembly and straightened a small dent in the flange which I was convinced was the cause of slight oil leak I had originally.
Oil now drips out of the top of the push rod tube as a constant rate as soon as the engine is warm. I am running out of ideas. This engine was built from spare parts so the barrel and head haven't actually been together for any length of time but the barrel and push rod tube were together on my other (Armac Cub) engine. I upgraded the Armac Cub engine to 230cc and had barrel, piston and push rod tube left over.
I'm beginning to wonder if the head and/or crank case has been modified in the past for the oil to return down the barrel stud holes but the 2 original oil return holes in the head are both clear. I therefore can't see why it should make any difference.
I also ran the engine with the top push rod inspection hatch (in the head) removed. The push rod tube doesn't appear to be flooding, there is just a steady stream of oil from the head running back down the push rod tube.
I'm fast running out of ideas. I guess I can try and lift the head enough to put the thick top gasket on as I have nothing to loose. Otherwise its engine out again after just 10 minutes running ?
well been thinking about that just going leak oil out so I better get one of them bushes have you got the part number I will get one upb thank brucey
Just speak to Bob. However I would warn you that I ground about 1mm off the outer end of the camshaft to give me the required clearance at the end of the closed bush. I also skimmed about 0.1 mm from the ID of the bush on my lathe to give me the required fit. Also as said previously, an additional 3mm diameter lubrication hole needs to be drilled at an angle from the inside of the gearbox case so it breaks through just over half way down the bush.
If you are not happy carrying out these operations, get an expert to do it.
Another option would be to do what Naichuf has done and simply make an ally cap to cover the open end of the bush sticking through the gearbox case. Not sure if this needs the additional lube hole?
You will find there is two types of gearbox/cam cases as the o/d of the cam bush are smaller on the distributor engine I managed to get the correct one for one engine The other engine I made a sleeve to fit over the bush and into the case I made little top hat to fit over the end of the bush and bonded them on with epoxy glue Tried the R cam made it harder to start and lost some bottom end power Reverted to standard cam The engines can vary in power a lot one engine runs sweet the other not so yet both built to the same spec
Many thanks for the information. I have a lathe and some phos bronze so if the worst comes to the worst I’ll turn a new top hat outer bush.
My Armac Cub is running an ‘R’ cam and goes very well so worth a try ??
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Tiger Cub Oil leak primary chain case onto drive sprocket
in Pre-65 Bikes
Posted
Check behind the clutch. Most trials Cubs have been modified to fit a final drive sprocket access plate (similar to T100 twins). This lets you change the final drive sprocket without having to split the crank cases!
If it has been modified, the thin plate should have an oil seal fitted (with the spring side of the seal facing the clutch).
ATF is fine for the clutch. You only need enough to cover the primary drive chain so I put 100ml in instead of 200ml as stated in the manual.
If the clutch slips when kick starting you can fit stronger springs and add an additional plate with billet ally pressure plate if required which available from a number of Trials Cub Specialists.