mrpj6

Just wanted to say an extra thanks to Motovintage.. This formula really works! I did a full sized drawing and measured the spoke length then checked it against the formula... It came out to within a mill or two.. Looks like i need 175mm spokes!.

Thanks for the two posts above. I am in the UK So i checked out Central wheels. Fabulous parts! But sadly out of my financial range on this build. I looked up spoke rolling out of interest, and from what i could tell its a little roller box with three rollers with the desired thread on them. You line up your spoke to be cut and hand crank a handle and the rollers squidge the end in to the thread form.... Nice little bit of kit... The roller heads are about 25 quid a set. I think i could work out a way to turn the spoke in it, so that may be a way to go... I could probably use the spokes i have from the donor wheel then. That way it stays cheap and i get to do the rolling bit, and that will interesting! And at the end of it all. If i can work out all the jargon on the spoke calculator, i can check the length i end up with against the calculated length. Should be an interesting few days for me.

I had a go at cutting a longer thread on a spoke tonight. The one i tried it on turned out to be M4 i ran the die down the thread like a nut. at the end of the thread it dropped off on the the shaft of the spoke! there is nothing there for it to cut in to. Like you said the thread must be rolled or pressed on to the spoke as one piece. So there is definitely no chance that you can cut the thread on a spoke any longer than it is when its made. It makes finding the right spoke for the job first time all more important.

This is starting to get more confusing now. The donor wheel is looking like it has had a rebuild and that the spokes are not the right gauge. They are 3.1 mm and 180 mm long. The length may be ok but the diameter i am looking for is more like 3.6 mm. That is the diameter of the spokes from the 17`` wheel that are too short. So i am looking for a set of 36 spokes 180mm long and 3.6 mm diameter. Any ideas if these exist? And if they do. where i would get them at a reasonable price? I find it hard to look for spokes on ebay and the like,as the sellers dont normally give dimensions just the bike they fit. So i suppose the question is. What bike had spokes 180mm long and 3.6 mm diameter? I think this may be a long job!

I think i may have seen this said before, spoke threads are rolled? I dont really know what that is. Will this make it a non standard thread? If it is a standard thread rolled or not. Would you know why you could not add to its length with a die?

Thanks for the spoke calculators. I have looked at quite a few of these calculators and formulas, and if i am honest they all leave me scratching my head! They all use jargon i dont understand. I have fitted the spokes from the similar side of the donor wheel to one side of my old hub this morning. It looks like this could work out ok. But i am still not sure. I will now have to try and hunt down some more spokes of the same size. I am a bit surprised at the price of spokes! They are not really in the price range where you can take a chance and buy a bunch just to try them. I will see what i can turn up. Thanks again for the above info.

And if all else fails... I will get some long spokes as suggested and either cut the excess off or maybe run a die down to increase the length? Not too sure this is the done thing... But i cant see why it wont work... Thanks for the info its all good for options... Day off tomorrow! So i will give it a go.

Thanks Motovintage I will print the formula and see if i can work it out with the parts in front of me, Its a bit too mind blowing for me to try and get my head round all in one go! But as i have said in my last post... I may have something to test it against now. With the longer spokes from the donor wheel. Thanks for the advise.

The donor hub is different. It had two different diameters for the spokes, I have now checked and the larger of the diameters is quite close to the size of the hub i want to use. And the spokes on that side are longer than the ones from the 17`` wheel!! So. With your advice i would think that they may be the size i want? I will try and lace up one side of the rim and see how it looks. Thanks for the reply Its not a 123 wheel, its a project build i am working on inspired by a bike a saw on this site. its a KL 250 engine in a Monty frame. The problem i had was i used the KL wheels. I only found out that 17`` tyres were not available once i had put a number of hours in to getting the wheel to line up.. Thanks again for the reply.

Hi all, I just wondered if any one knows how to work out the length of spokes needed for a wheel rebuild? I am trying to rebuild a wheel that had a 17`` rim on it. I am now going to try and put an 18`` rim on instead. As the hunt for 17`` trials tyres was proving to be impossible... Many thanks in advance.... Pete.

The answer to that is no. But whilst i was looking on the web to try and see if 30mm extension would make a difference... I saw a picture if a Royal Enfield with a reed valve fitted behind the carb and ... What looked like 300mm of old car radiator hose connecting it to the engine? I also found a thing called a trombone inlet? This was concertina tubing to make it more compact.. And the statement was that the most efficient inlet was a tube a metre long! If i am honest, I moved on.. As i was a bit out my depth. I have now found an intake from a KLF Quad bike that is the right length,, And sort of fits. So that is where i am at the moment... Off now to look up rotax disc valve.

Ahh Master.. You are back? still got those pebbles in your hand? Kung Fu reference.... (long story)

Thank you to all the above for the info, I feel happy to go with the 30 to 40mm extension now. I am a long way from the picture stage, but i will try and post some when there is something to show. I may well be back for more help with the jetting and probably before that!.... Good to know you are not alone when you are out in the shed knocking the skin off your knuckles... Thanks again.. Pete.

Thanks Andy...Nice to know someone has been there and done that. I have cut the frame and welded it to get the engine in, but i want to keep it to a minimum.. so a longer intake would save quite a bit of work 45mm would be luxury! Thanks again..... Pete.

Thanks Jon... Lost me i am afraid with tract resonance, But better low RPM torque can only be good. I will be making my own header pipe and air box i would have thought. So you are right about other modifications. When you say tune the carb.. Are you thinking fuel air mixture? or jetting?

Hi all. I am trying to build a trials bike using an engine from a 1978 Kawasaki KL 250. This build was inspired by some fantastic pictures posted on this site by Booma.... My problem is, i am not using the same frame he used and am having trouble getting the carb to fit in the frame. My question is... Can i lengthen the inlet manifold? If i can lengthen the tube from the carb to the head by about 30mm it will make fitting far far easier. The problem i have is, i have no idea what effect this will have on the mixture and running of the engine? If anyone has any knowledge of this subject? I would greatly appreciate the help. Many thanks.

I am slowly getting the bits i need together so i will soon be able to start rebuilding the frame and forks etc. I managed to get hold of a alloy front wheel minus brake hub, but that will come in time i am sure. I am not looking for a concourse bike. But i would like it as original as possible. I think i will get it up together and running with the engine as it is. It was not running that well but i fancy getting out on it again and trying to source as many engine/carb parts as i can and work on that at a later date. I think that may prove difficult, as it looks like pistons and rings etc are pretty much not out there. I have noted on this site that Bultaco pistons have been suggested? Some say it works others that its not a good idea. Not too sure what to do there, shame to have it all looking good and the engine like a bag of nails! PS. Manuel.I have sent you a PM with my email address hope you can send some pictures Thanks Pete.

Ye, the numbers are the same, the one on the frame is on the tube the bearings go in for the forks and is not too clear but it does match the engine. The covers on both sides have a large M then montesa in smaller letters, and as i have said the small A is on the separate cover. You are right Manuel pictures are beyond me, i tried last night! i was worried you were going to get all my holiday snaps at one point! but ended up with nothing being sent in the end. I did try to email you. But that didnt work either! Is it me?!!! On the bright side, i think i have worked out the front brake. As i have been offered a cable. It all became clear as the bit that fits to the fork leg came with the cable, So that sorted that out. THanks Pete.

I am not at all sure its a 74 model I have gleaned all my knowledge from pictures on the Internet and cotas for sale on ebay. As the side stand is on the left side,you nearly always get a good shot of the right side, and not much of the other side with the two piece clutch cover or not as the case may be. To be totally honest with my 2+2= 22 logic i thought as the frame/engine number had a 19 some 4s and a7 in it, simple! its a 1974 model...... Not so, by the sound of it. Looks like i have jumped the gun again...... Pete.

The engine and frame numbers are the same, so i would think the engine and frame started life together. The clutch case is badly damaged and filled with epoxy filler, this was then painted black as was the rest of the engine. The smaller A cover was not on the bike. I have now ordered two used covers of the same type, so if it is a mongrel its going to stay one for the foreseeable future. The covers that are on it look to line up well, and there are no extra holes or odd gaps. Looks like the exact year of the bike may not become clear. I will need some help in the future with how the front brake works, as the steel wheel that is on there now has a brake hub with the cable casing coming in to it and the cable running from the stop on the hub to the operating lever. I understand from photos that the proper way for the brake to work is for the cable casing to stop in some sort of lug attached to the fork leg and the cable to continue down the leg to the operating lever. There is no lug on the fork leg at present and i have no idea what this would fix to or what it looks like?

Manuel, your a star! loads of things sorted there. I have found out the front wheel is from some old British trials bike the brake hub has R.E.H. on it? I think i have located one for mine but it has no brake hub in it. The engine/frame numbers are the same I think, but i will check later. Chain oiler? Wow bit over the top for the 70s but i see why it has an oil cap on it now. I will track down some Akront bars now if it kills me! and be glad to sling those plastic covered things out. I will get some pictures if i can sort it out. The bike is in bits at the moment so not much to see. As always wise after the event. I should have taken the before picture so i could see if my hard work was all worth it in the end! As for that lug under the engine mount..... think that may just have to remain a mystery. Thanks again Manuel. Pete.

The bars are sold! I bid on them and lost in the last second as ya do! I was so gutted, as i thought i had them in the bag, now i want some more than ever. Thats why i wondered if they came up often. Sounds like i missed a snip there. Thanks for the reply.... Pete.

Hi. I have got a few, what i think are probably stupid questions. I am trying to give a 1974 cota a tidy up. It has had a hard life by the looks of it. And i think some alien parts have been added over the years. It has a steel chromed front wheel, I take it this is wrong? also black powder coated handlebars with a fixed cross bar, wrong again? I would also like to know. What are the two holes for in the right leg of the rear swinging arm for? I see in old photos, that they have a plastic bung in one like an oil filler cap? also in old photos i see some bikes with one rear shock upside down. Is this right? The clutch cover has a removable compartment at the rear that has the letter A of montesa on it. What is this for?Lastly, one of the engine mounts has what looks like a lug for a cable to go through, I can only think this is for the decompressor? If it is what route does it take to get there? Like i said all probably daft stuff, but if any one could help it would help a lot Thanks...... Pete.

Hi, I just wondered if anyone knows if there are still any Akront handlebar's about? Just saw some on ebay Akront super. Are these bars hard to come accross? or would i be able to get a pair from somewhere? Thanks... Pete.

Hi. I tried to PM you but it said it would not send as your in box was full. also tried to email, but that did not send! All going swimmingly! Is your address .com or .uk? maybe thats it? more likely me i expect.