brucey

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.

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.

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!

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.

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.

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.

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.

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.

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?

Thanks Konrad. I also noted the Elf oil was very ‘runny’ ??

Yup, I'm super fussy ? However I made the assumption that the clutch on my £3.5K Montesa would be at least as good as the clutch on my previous £1.5K Gas Gas so that is my objective. I'm pretty sure there are no major faults with the clutch but the dragging is a constant distraction from what is otherwise a beautifully (if not slightly over) engineered bike. I'm also a Chartered Mechanical Engineer ? Bruce.

Thanks Gaspgasp, it sounds like something to try. Slightly gutted I have spent 2 nights filing all the edges on my Apico clutch plates though. However I'm prepared to try EBC fibre plates if there is a good chance of improving the problem ? Can you confirm a couple of things: I'm assuming you still used your Apico dimpled plates with the EBC friction plates. The 3mm holes in the inner alloy hub are spaced in a spiral pastern. How close to the existing hole did you drill the additional hole? and do you remember which side of the existing hole you drilled it? I'm assuming you drilled the 4mm hole in the outer basket fingers in the middle of the thickest part near the base of the fingers (about 10mm from the base). Is this right. Are these holes to allow the oil to be flung away from the clutch plates? Interesting about the 4 springs although I'm not sure my OCD will allw me to choose which 2 springs to remove!

Thanks guy's I'll try all of those ideas ?

2/4/ thanks for your reply. When I say 'clutch drag' I mean it doesn't appear to completely disengage when the clutch lever is pulled in. I can feel the bike trying to move slightly when the engine is running, the bike is in gear (1st) and the clutch lever is pulled fully in. There doesn't appear to be any adjustment apart from the lever to master cylinder free movement. Mine is set to around 1mm. I appreciate that I should only use the clutch occasionally (especially on a 4 stroke bike) but the Diaphragm Clutch on my Armac Cub and the Friction Plate Clutch on my other Cub are both far better!

O.k, I know it's been covered many times but I'm looking for something I may have missed. I recently replaced my 2014 clutch plates with a set of Apico friction plates and dimpled discs. I also used the correct Elf oil. However I continue to get enough clutch drag to have to put it in neutral to start (Just like my Tiger Cub!). Selecting gears becomes difficult once the bike is hot and neutral is pretty much impossible to find at any time with the engine running. I currently have the clutch out and have polished out some very shallow marks in the clutch basket fingers with 800 wet and dry. (mainly on the drive side). I will also dress all the fingers on the virtually new Apico plates to see if that helps. I have read all the posts on this subject and am at a loss as to what else I can do. The hydraulics and slave cylinder all appear to be working perfectly. A guy at a recent trial said he removed several clutch plates from his 315 to cure his clutch drag problems! I have to say the problem is taking the fun out of riding what should be a very nice bike. Any further advice before I put it back together would be gratefully received. Bruce.

I’ve always taken the engine out as it doesn’t take that long. I also put an access hole and made a cover in the head where the top of the pushrods are to help reassembly. Use elastic bands to hold rockers up on assembly.

I didn’t need to put any shims in the 3 Cub engines I’ve built? i guess assemble and check endfloat.

My mistake. Duncan does indeed supply REH forks (which look beautiful by the way) ??.

Depends how much money you want to spend and how original you want the bike. For something over £1000 Duncan MacDonald can supply new MP forks and yolks I fitted Betors (from a Montesa) to 1 Cub and Marzocci’s to my Armac Cub. Both out perform my ability. They are also a vast improvement over the original heavyweight forks! It may take a bit of fettling to make them fit and to get the length right. Hope this helps.

Err, yup.....I have to admit, I got a bit carried away after that!

Depends upon how late you crank cases are. The chances are yes if you are replacing an older type pump. Chris at Meriden off road can advise either way as he does a conversion kit and can also machine the case if required. Photo shows later pump fitted. Web on left of pump has to be machined to clear pump slider blocks. You also need a longer drive spindle to run the later type pump. These all add up! I also just put an upgraded Morgo standard pump in one of my Cubs which has worked fine for the past 10 years. Hope this helps. Bruce

Not sure about suitable bikes but you could try Jason at Tricks in the Sticks. Google the name for details. I did a days training with him, my 2 Sons (in their 20's) and a couple of friends and had a great day. Hope this helps. Bruce.

Talk to someone like Chris at Meridan off road. He refurbished and rebuilds these engines daily. I have a feeling they can be refurbished. Hope this helps. Bruce

Just an update; I sent my shock to Splatshop to have it refurbished by their specialist. He stripped it and found it had no oil, the bladder had split and someone had previously fitted a non standard seal head (which had worn badly and probably caused the first two faults!). He will be fitting the correct new parts. Great service by people who take pride in what they do. Can’t wait to get it back and see the improvement in my bikes handling with a shock that actually does something?

Now you’re frightening me??