old bones

Brucey, I am also having problems with the oil pump on my Cub, I had an LF Harriss plunger type fitted and after a short time it started to fill up with oil whilst running, the oil tank was draining and not returning so took it apart to clean the pump hoping to find a problem but none could be found. Put it back together and using the kickstart to see if oil was returning and it was ,so put it back in the garage. After about 4 days I noticed oil on the floor so stripped it down again and inspected the pump... nothing found. I left the cover off and the pump connected to a full tank of oil and found it was dripping from the supply plunger on a new pump with only a short time in use!! I am still trying to determine if the pump is at fault or something else I could be missing. So check the pump with it in place and see if your problem is the same as mine. Old Bones

nh014, Thank you very much for the ring gap info,

Hi, Would someone be able to tell me the acceptable piston ring end gaps for my Montesa cota 200 (1981). I dont know at the moment if the piston is standard or if it has had a re-bore( if that makes a difference). Thanks in advance.

Section Swept, sorry for late reply I've had a few computer problems. I hope you are right, it seems such a simple task but getting it right it is not so simple......but hey I love a challenge!! Cheers

OK, I've taken the wheel out again and looked to see if there is a spacer inside between the brake plate and wheel bearing......there isn't one but the brake plate has a steel boss pressed into the alloy brake plate so effectively the plate has a built in spacer that contacts with the bearing face and the fork ..so I think no spacer required?? Team ferret??? As yet I have not done as Section Swept has advised but will get round to it . 4stroke...Did you get to measure the spacers on yours. would appreciate any info you can give . Cheers

WoW! Thanks everyone for your input I have spent the day fitting as per Teamferret's suggestion ,no spacer on the brake side and I made up a spacer on my lathe for the speedo side it worked out that this spacer was 25mm and all seems to be well.even the anchor rod is straight But now that 4stroke and section swept have given me some more food for thought I will now go back to square one and at least check to see if its right. I did not check that there was a spacer between the brake plate and the bearing. Tayld, thanks for the PM . I dont think anyone has changed brake/hub of forks. Cheers

Teamferret, Thanks I will have a go at fitting as you say and get back to you, the brake plate does have a cast in boss as you say. Cheers

The previous owner of my 81 cota 200 removed the speedo drive from the front wheel and replaced it with an alloy spacer, I think he also replaced the other side as well with the effect that the wheel is not central in the forks. Would anyone know the length of the original spacer on the other side of the brake or the thickness of the speedo drive gearbox. Its very difficult to measure the spacers needed as it is quite awkward to be accurate also the brake arm from the brake drum to the forks is slightly bent is this correct or should it be straight? I hope someone can help, cheers.

Naichuff, Thanks for your reply. The PVL is on a plate that uses the crankcase bolts as its fixing and not the same as electrex which as I understand it uses the old stator fixings. The two crankcase bolts above and below the clutch are used to hold the plate on alloy hollow legs the third fixing is via a small block and the oil level bolt is reversed to fix this block to the case, the bottom part of the plate stops the case going on by about 4-5mm. I was considering beveling off the alloy to try and make it fit but I'm a bit reluctant to do this without asking for advice, Cheers

Naichuff, The timing is exactly the same procedure with the PVL mounted on a plate or when using the 3 post mod to the crankcase, The timing issue you suggest is not my problem only the fitting of the case. cheers

Could someone advise a solution to a small problem please, I fitted a PVL ignition to a cub I'm building, it has the plate that mounts on the crankcase bolts rather than the modification of the 3 posts. when I try to fit the primary chaincase the bottom plate mounting stops the case going on. So before I grind off anything and completely B***s it up does anyone have a suggestion? Thanks

RichardH, Your cub expert is right they are 1/4BSF (26TPI)

Hi, Could I beg some advice regarding the Mikuni carb for an 81 Montesa cota 200. I have managed to pick up at an auto jumble here in France a new old stock Mikuni VM26 (other markings are 8074) Firstly the carb is bare and only has a slide (#2 I think) My questions are; 1. Is this the right carb body? 2. What jets would I need to suit the Mont? 3. Will it fit the existing rubber or will it need an adapter of some sort? I have sent a few emails outlining the problem to Allens Performance and they just dont respond which baffles me a bit as their website seems to suggest they are the experts, anyway I hope that someone can help as the old amal Mk2 thats on it at the moment is well worn and makes it hard to start ( and more expensive to replace) Thanks for any advice.

As above, I worked from the front wheel being central in the forks and aligned the rear from it. my offset if it helps is 66mm approx from centre of rim to face of brake drum with no brake plate fitted.

Detective 21 I'm not sure if I'm reading your problem right but have you moved the engine over with spacers on the engine mounts? also I use a spacer behind the rear sprocket (an old sprocket with the teeth machined off) it seems to work for me. Thats assuming you have the right "offset in the rear wheel when it was laced to the new rim. Hope this helps, perhaps someone with specific knowledge will advise you better.

Alan, I think you are right on both points ,I had the same thought about an hour after I wrote the post but decided to leave it just in case someone came up with a solution. If you put a small shim behind the sprocket to allow the chain to sit down properly there will not be much thread to hold the nut, as it is there is only about 6mm of thread for the nut. If the sprocket was dished I could make a deeper nut and turn down the bit that contacts with the sprocket face and loctite it on instead of center popping it. Naichuff, I think the bearing/seal housing must be different as a 13T will not work on my cases. I know everyone says they are the same but clearly some are different or the 13T would work. I have received a 14T sprocket today and it looks like it may just be OK but its very close to the alloy I will put the chain on and see if it clears. trialsrfun, As it is I will try the 14T with the new 64T rear and see how it goes, As a rule of thumb if you go up one tooth on the G/box you would need to go up two on the rear to stay about right and I'm not sure if 15T and 16T sprockets with the corresponding size increase in the rear would be available. Anyway thank you all for your input and if you have any further advice ,please let me know.

Alan, thanks for the reply, I have no problem getting the socket on the nut to take it on or off, its just that if the sprocket I have is indeed the off-set one then I will not be able to use it as the chain will wear away the lip that keeps the seal in. The original cases were damaged by the chain which was 428 because the bearing moved and the bearing housing was worn away to the extent that the seal failed and was so badly damaged that replacing the seal was not possible ,so, I want to avoid the same thing happening so thought that I would go down a chain size on the new cases to avoid this problem not knowing I would have a problem of the same kind. This is so frustrating, I bet if I go back to the 428 size or bigger say 520 the diameter of the sprocket could well be a lot bigger and not be any where near the bearing housing. Perhaps you or someone could advise as to weather going up to a larger chain but still keeping the 13 G/box sprocket is viable? Your thoughts appreciated or anyone else who has an opinion also appreciated.

Many thanks for all your replies, I have what I think is a Talon stepped sprocket with apart number of TG402 13T (420). If anyone has one that is not fitted to their bike could they measure it and see if it compares to the one I have? Mine is as follows: The distance between the sprocket face and the boss that goes through the seals towards the bearing is 16.5mm with a 1.2mm recess where the sprocket nut sits with the part number stamped there. Does this tally with the off-set sprocket measurements? It beats me how someone would make different sprockets and give them the same part number but non the less that could be the problem, I even emailed Talon for the measurements but they did not reply. Anyway, thank you again gents your advice is much appreciated.

Has anyone had the same problem as me when it comes to fitting a 13T g/box sprocket and a 420 chain, The chain will not sit down on the sprocket as it contacts with the seal and bearing housing.The crankcases are twin roller bearing and the only difference I can see from the old ones that got damaged is that they have two seals on the g/box sprocket while the old ones had only one, This makes the sprocket too close to the bearing housing which would cause the chain to wear away the seal lip. Anyone have any thoughts ?

Alan, You are a star!. You must have spent quite a while on resolving this problem thanks again for all the info it is much appreciated. I will order the O rings and have a play around with the fitting. Thanks again.

Alan, Thanks for the info regarding the o rings, I seem to remember using simply bearings a while ago so thanks for pointing me in that direction again. I tried a dry build with the bottom seal in position and nothing on the top, but, when I did up the head bolts a bit the bottom seal was squashing out and deforming quite a lot and would certainly not seal. I installed the old seal and could get about 2.5mm gap on the tube, there doesnt seem to be much difference in the old seal and the new size wise, except the old one is more flexible. Do you use an "O" ring or two for the bottom seal as well as the top? It seems I have wasted a couple of quid on these new type seals that will NOT fit, so it may be worthwhile experimenting with original on the bottom and an "O" ring on the top? what do you think. Thanks for your time in answering my query.

Alan, Many thanks for sharing the solution to my problem and also an alternative to it as well. I will do as you advise regarding the dry build and see what top gasket to use ,I must say that the bottom black rubber ring seems very tight so I guess it will not compress very much so perhaps I will start with the thinnest one first. For the future in case the new type doesnt work that well and as an alternative to going back to the poorly designed originals where would I find a supply for the viton "o" ring that you use?. Many thanks again.

Could someone help with an answer to my silly question?. I have just purchased a set of the new type of tube gaskets, the set comes with a large black rubber seal which I assume goes in the bottom and two composite type gaskets of different thicknesses . The black one was a right pain to get in as it seemed too thick but I eventually got it in with the aid of some silicon lube, Now for the silly question; what do you do with the TWO composite gaskets?? I would rather ask the question and get advice before putting it together and it leaking. (My cub has a square barrel and head) any advice gladly received

All the above advice is good and It would be good to ride with someone else but not essential but most of all, have a great day, dont get flustered and dont worry about holding up other riders. When you are at a section watch someone go through the route you are doing and try to see what they do, If your not sure ask the observer or another rider which way to go.We all started where you are now. I do hope you have a bit of fun and a great day. Post up how you got on. All the best

Thanks 29markt for the speedy reply, your a star!!