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Everything posted by brucey

  1. Is it a blind bush you are replacing? If it is, you may find a reamer will leave a small taper near the end. I usually skim mine very carefully in my lathe using a boring tool. But that advice is only useful if you happen to have access to a lathe I guess! ??
  2. I would make absolutely sure the pilot jet isn’t blocked. Even if it means sticking a small piece of wire through it.
  3. Oiled up/blocked exhaust maybe?
  4. Speak to Bob at UPB 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.
  5. brucey

    Riding a 4RT

    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. Hope this helps. Bruce.
  6. 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?? thanks for your advice ??
  7. 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 ?
  8. I’ve ordered a nice new alloy push rod tube. Apparently it has a better location and thermal expansion rate. Fingers crossed ??
  9. 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 ?
  10. 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!
  11. 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 ? Any help appreciated.
  12. 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? Hope this makes sense ?
  13. Ok, the solution is quite simple? I got a special bush from UPB. The OD matches the later Cub side points gearbox cover and the smaller ID fits the outer shaft of the earlier distributor R (or standard) camshaft. with the bonus that it is a blind bush so should reduce oil leaks A small amount of fettling will be required which includes drilling an additional lube hole to supply the outer camshaft bearing. Photo of old (top) and new (rbottom) plain closed bearings attached . Hope this helps others.
  14. 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 ?? Not too hard to swap back if it doesn’t work.
  15. Blimey, surely I’m not the first person to have done this??.
  16. I have acquired a new 'R' Cam and gear from an early Distributor Cub and want to fit it to my later Side Points Engine. I am running electronic ignition so points etc are not an issue. I am getting an earlier type outer cam bush (blind type) to match the 1/16" smaller diameter outer end of the earlier cam shaft. The gear and inner shaft fit into my engine without issue and the overall length looks the same (including the slotted distributor drive of the cam shaft) I will drill into the blind bush from the inside of the gearbox case to supply oil to the outer camshaft bearing. Is there anything else I need to do? It looks as simple as that! As always, any advice appreciated.
  17. On a slightly different note, I have stripped the engine and measured the crank alignment near the ignition rotor key way. It appears to be running out around 0.3mm (about 10 thou) total. I have been advised this is ok. The ignition rotor doesn't touch the stator (I recon about 0.5mm clearance). although it does 'wobble' a little bit ? Has anyone else measured the crank run out on their engine? Bruce.
  18. I too am running the UPB additional plate clutch in this Cub. The mains were replaced when I rebuilt the engine from all my spare parts only a couple of trials ago but I'll check them as I'm currently in the process of removing and stripping it to cure the oil leaks. From an engineering point of view, I think I prefer the standard (larger)duplex primary drive sprocket. It should also make the bike easier to start but I will have to get the close ratio 1st & 2nd gears from somewhere. As well as the trials ratio's, I would like to fit a side points 'R' Cam but am having extreme difficulty in finding one!
  19. Trialsfun, The noise is almost a mechanical whine. I have checked the tension several times and got it about as good as it's going to get but the primary drive duplex chain seems to take quite a tortuous route with such a small drive sprocket. I used a standard set up with close ratio gearing before which was much quieter. Time to note all the faults, pull the engine apart and put it back together properly this time ? I have fitted a diaphragm clutch and belt primary drive to my Armac Cub and it is amazing! Bruce.
  20. Or upgrade it Joan ? Trouble is it's my spare Cub so I don't get a chance to ride it and fettle it as much as I should. I filled it up with oil and ran it this evening. I have oil leaking from the crank case to gearbox cover, top push rod tube (straight onto the exhaust) timed vent in the cam bush and gear selector (even though it has the o ring plate fitted). Looks like I'm going to need to use more sealant next time! I think I'll take the opportunity to fit close ratio 1st and 2nd gears and replace the 16T trials primary drive with a standard 19? tooth sprocket as it does make a lot of noise.
  21. Thanks for your reply Naichuff. I will leave the sump guard off for a bit and keep an eye on the feed pipe at the engine end. The reinforced plastic pipe is at least 5 years old but still flexible.
  22. I continue to have problems with the Cub I built from all my spare parts for my Son to ride. It has a habit of leaking the contents of the Sammy Miller type top tube oil tank onto his shed floor!. The first time this happened I replaced the steel balls in the later type oil pump for a plastic ball and spring upgrade kit from UPB. But after sitting in his shed for a few months, it just did it again. I drained the remaining oil from the engine sump and got about 250 to 300 ml out. The total capacity is around 750 to 800 ml with the external oil filter and oil tank filled. I did notice the jubilee clip on the oil feed pipe to the bottom of the engine wasn't as tight as it could have been which may have caused the semi synthetic oil to leak out as the weather got warmer. My question is; Would there have been more oil in the sump if the oil was making its way past the oil pump and wet sumping? If it was wet sumping, where would the oil come out? The engine turned over fine when I took the spark plug out and pushed it down the road. I'm going to fill it up again, tighten the Jubilee clip and see what happens ? Does anyone else have this problem with their Cub? Bruce.
  23. Jimmy, I have run the bike for a decent test/practice session and all still seems fine. I am able to start the bike in gear and even select neutral if I'm careful ? I think I probably had a number of small issues rather than 1 single cause. Replacing the fluid, removing all burrs and drilling additional drain holes have all definitely helped. I didn't lube the used plates when I reassembled the clutch which may be the reason they needed a little 'slipping action' to get some oil between them. I'm starting to like the bike again! Thanks for all the advice. Bruce.
  24. Just an update. I carried out the drilling mod and fettled the clutch outer basket. I also lightly filed the fingers on the friction plates. I refilled with Elf oil and tried it up and down the road. It was dragging worse than ever?. I decided there was nothing to lose by ‘bedding it in’ so I put it in 4th and slipped the clutch for 50yds. Hey presto! A working clutch??. I can push it easily in 1st with the engine off and clutch in. It starts in gear and I can just about get neutral. I just need to see how long it will last. Hopefully a long time? Thanks for all your advice guys?
  25. Thanks Konrad. I also noted the Elf oil was very ‘runny’ ??
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