andy m Posted December 27, 2008 Report Share Posted December 27, 2008 Looking good Jon. Electric start in the sections will be handy. Quote Link to comment Share on other sites More sharing options...
jon v8 Posted December 27, 2008 Report Share Posted December 27, 2008 Knew you would take the mick,hopefully the engine will be less prone to stalling than my RTL was ! My right knee is not too good so sometimes starting bikes can really hurt - esp if they kick back.So to have an alternative 4 stroke from the Honda's I never really got on with will be a big treat,esp with the electric boot.Just hope it works. Quote Link to comment Share on other sites More sharing options...
andy m Posted December 27, 2008 Report Share Posted December 27, 2008 On the rare occasion that a trailbike class is run in a trial the Beta alps and the like have elec starts. Not taking the mick I just bet someone will have a whinge you know what folk are like. It will be well worth the wait especially if you have a dodgy knee. I damaged mine earlier in the year in a trial.... not good. Keep the pics/ update coming, Quote Link to comment Share on other sites More sharing options...
jon v8 Posted January 2, 2009 Report Share Posted January 2, 2009 Just added some more pics of the tank I've been making,now I cant decide what to do about painting it - or not to.I intended to paint it yellow as I really like the Majesty's with yellow frame/tank etc, but now I'm thinking it might be nice just to spray the frame silver and just polish the tank and exhaust properly - bit like a modern cub.Any ideas ? Quote Link to comment Share on other sites More sharing options...
andy m Posted January 2, 2009 Report Share Posted January 2, 2009 Pity to paint that tank really. Personal choice on the colours. Where are you going to put the battery. Is this your day job doing this kind of thing. Looks good. Quote Link to comment Share on other sites More sharing options...
jon v8 Posted January 2, 2009 Report Share Posted January 2, 2009 No,not my day job - thats the first alloy bike tank I've made,its not that good.Nor is the rest of it really,its taking hours and hours,but anything that does not work can be redone.The battery from the Serrow was quite large,so Im off up the village to look at what is used on the leccy start Kawasaki off roaders to see what size/shape I can get away with.... Day job is fixing Land Rover products,mostly diagnostic work.The tig welding was for repairing corroded and cracked cyl heads.(Surface finish was not an issue,porosity was.) Quote Link to comment Share on other sites More sharing options...
andy m Posted January 2, 2009 Report Share Posted January 2, 2009 (edited) It's going to be similar to a Cotswold. The Tlr 200 had it's battery in a case hung below the top of the shock absorber, of course never had elec start so they have all removed them by now. That's a good job for the first alloy tank you have ever made though. Fair play. Cotswold for those that don't know. Edited January 2, 2009 by bo drinker Quote Link to comment Share on other sites More sharing options...
jon v8 Posted January 2, 2009 Report Share Posted January 2, 2009 Thats sweet,just what Yamaha would have built if I had my way.Those Cotswolds are built by Jon Bliss in Cheltenham ? Theres a chap called Bob who used to ride one in the Bath club trials,think they had a Jiahling Honda copy engine.I was hoping to get the battery down below the air filter at the back of the engine to keep the weight of it as low as possible.Once the exhaust is done its only mounting the battery and nicking the wheels out of my Ty250 and it should be ready to try. Quote Link to comment Share on other sites More sharing options...
totalshell Posted January 2, 2009 Report Share Posted January 2, 2009 wow that carby sure gets in the way!! more than decent solution though Quote Link to comment Share on other sites More sharing options...
jon v8 Posted January 16, 2009 Report Share Posted January 16, 2009 Bo,dont know where you got the picture of the Cotswold from - any chance of a pic of the other side of it ? I'm hoping to start on the exhaust this weekend and a few ideas would help,cheers Jon. Quote Link to comment Share on other sites More sharing options...
andy m Posted January 16, 2009 Report Share Posted January 16, 2009 (edited) There you go. Edited January 16, 2009 by bo drinker Quote Link to comment Share on other sites More sharing options...
jon v8 Posted January 16, 2009 Report Share Posted January 16, 2009 Cheers ! Quote Link to comment Share on other sites More sharing options...
moleman Posted January 16, 2009 Report Share Posted January 16, 2009 Jon, Hopefully it`s the camera angle but the swing arm pivot seems a bit low in relation to the gearbox sprocket? img 011.jpg As it appears now, as the wheel moves through it`s travel, the chain wil get slacker and may even meet the bottom of the swingarm pivot , i assume the pivot point is through the top footrest hanger bolt? it`s a great looking bike , i built a Honda XL250 motosport engine into an OSSA MAR frame and it looked very much like yours in the swing arm dept. it was unusable and took a lot of sorting. The problem is not insurmountable, but would take a bit more of your obvious skill with the welder... I hope i am wrong, but if you havent already done so, put a loose wheel and sprocket and fit a chain and move it through it`s proposed travel Quote Link to comment Share on other sites More sharing options...
jon v8 Posted January 17, 2009 Report Share Posted January 17, 2009 Moleman,you are right its not the camera angle.Damn ! The chain will contact the bottom of the swinging arm at full travel,and the frame will need altering at the top chain run too.What did you do with your MAR to sort it ? I havent had time to really suss it out and take measurements etc,but one thought is that originally I was going to use a very small front sprocket to keep the size of the rear one down.Now I'm thinking it may be better to keep a big front sprocket and work out what I need in terms of a much larger back sprocket.I did quickly rule out turning the whole engine clockwise,(looking from the nearside to lower the output shaft in relation to the swinging arm pivot.It would just make the carb/top frame tube situation even worse - even if I did use a different carb.(Plus I REALLY dont want to go through make all new mounts again.) Ho hum, as lonbg as its ready for the Dartmoor 2 day ! Quote Link to comment Share on other sites More sharing options...
moleman Posted January 17, 2009 Report Share Posted January 17, 2009 Firstly, you must accept that whatever you end up with will be a compromise (as 99.9%of trials bike frames are) the basic ideals are to get the swingarm to pivot on the gearbox sprocket (has been done) next best is to have the pivot horizontally as close to the gearbox sprocket centre as possible. this will give the chain the easiest time and be easiest to guide. the next point is where to put the pivot point vertically in relation to the gearbox centre this is more crucial than you might first think.. it is a very complex subject, but it is possible to make the rear wheel rise under power or drop under power , (drawing pins and scale paper swing arms will make this very clear) this can end up with the rear suspension fighting the torque reaction and making it feel wrong i am sure that with the scale model you will make, you will quickly understand the principle Anyway as a starter for 10... i have kept a few jottings from way back when as you are working on the bike on a stand , these figures will relate to your current position i ended up with, distance between gearbox centre and swingarm pivot around 75mm as for vertical placement, ypu will need to take a straight edge through the gearbox centre and your proposed swingarm placement centre, now go to the rear wheel spindle and look for a drop from this centre line to the rear wheel spindle of about 75mm this is on the stand, weight off the bike when you have this it will determine the approximate shock length the higher the swingarm pivot, the lower the ground clearance, everything affects everything else.. in my opinion the placement of the swing arm pivot is the most important decision on a trials bike if you can modify a frame like you have, you can make a small scale model of the problem once you have, it will become very clear what you have to do and what will be your best compromise Accept it will need extensive chain slipper fabrication to compensate for the compromise (as all modern manufactures have...) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.