Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: guest27 on March 05, 2007, 08:17:16 PM
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Asking the more thinking masses out there. The TZRotax has - by dint of a rotax lump - a coaxial kickstart and gear change. TO run rearsets - which I have to even for a fairly old man riding position - I have to either move the kickstart or make the gear linkage removable. Not keen on the QD gearchange as I am not convinced that it would still clear the kicker and also it will probably fall off etc. So I have been mulling over the idea of a cross shaft for the kicker - thus moving the KS to the right of the bike too. However I am not too sure about this because of the possible loadings on the shaft and bearings (ahem). Today I was inspired to look again and it may be easier to move the gearchange to a RHS change and get the kickstart out from behind the frame and past the rear brake.
What have I missed? The loadings on the gear change are less and I have a good collection of rose joints - mind lil rose ends for a gear change are a lot less than ones that would do for a kickstart. I have ridden RHS change bikes before and currently do not have a lot on the go anyway.
What thinks you all.
Oh also selling a load of TZR bits on ebay to raise the oney to have the frame welded and the rear wheel machined - sofar I have got £14 coming - so not a lot of welding then.... bugger
R
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don't know what the left side of a rotax lump looks like, but could the gear change lever loop over the kickstart? this is what's usually done on brit bikes with rearsets where the kicker and shifter are both on the right.
www.oldbritts.com/13_710005.html (http://www.oldbritts.com/13_710005.html)
350bullet
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Good thought but on the Rotax the gearshaft runs up the middle of the kicker shaft, and tyo get the kicker behind the rearsets with a bent kicker would require it being about 2 feet long.
Will have another look mind
R
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How about a picture of the lefthand side of bike ?
Would it be possible to move the pegs far enough back so the kicker will miss them , with a long linkage for the gearchange with a rosejoint at each end, the front rosejoint instead of being bolted on to the shaft lever, is pushed on a round pin and is held on with a R-clip which faces down (so gravity prevents it from falling off).
When you remove the R-clip the linkage and gearchange lever fall down out of the way ??
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is it just for track use and sunny days? if so how about a decompressor and a bump start, if its good enough for a manx norton....
350bullet
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Will try a photo soon - have thougth about bump starting it - we live on a big hill - good if it starts very bad if it does not.
R
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Hi - as we can see the kickstart - with the kicker boss on it - is coaxial to the gearchange - nothing on it - and the rearsets are pretty far back anyway.
(http://i177.photobucket.com/albums/w230/Shaftoflame/TZRotax/GearchangeKickStart.jpg)
Will have to bend kickstart if I mount it on this side - rather than via some easy shear linkage.
R
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some brit trials bikes had kickstarts with a dogleg in them.
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when folded out it would clear the gear lever, but you'd need to fold up the foot rest.
like my technical drawing? should be enough for any engineer....
350bullet
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yup Dogleg it needs to both clear the frame and the footrest, but does not clear the problem that mid swing it has to pass through the linkage rod.
I am thinking I either need to shift the gear or the kickstart to the other side of the bike via a cross over (under, behind) shaft and a whole bunch of rod ends, or I need a splitable linkage rod, that is quick to dismantle - ie in traffic - and does not have loads of slop in it. Thinking on the rod and and R clip idea - not sure how to minimise slop - unless the R clip holds the linkage rod into the rod end sleve rather than the rod end through the splined arm on the gear. Would come apart real easy - then be a bugger to get back?
R
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Rog, not sure if you can visuallize this but. If you look at the picture you sent, take the current position of section the gear linkage that bolts to the gear shaft. Now put a bend in it and extend it backwards and under the engine. Run a linkage bar from this behind the frame section wher the chanin would normally run, since there isnt a chain on this side there should be room. Take the existing lever, instead of pivoting on the hanger, remove the pivot and drill through the hanger so it can take a shaft, attach the shaft to the gear leaver and a suitable level at the other end and then attach the linkage bar.
Did that make sense ?
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That made real sense and I will be looking at the plot soon to see if it will work - sounds like a real nice solution.
R
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The more I look the better the idea seems. It will require a convuluted gear linkage - to give the kick start clearance through a whole swing - but loads easier than cross shafts etc me thinks (which if it was a gear cross shaft I would have to have the smae twisted business end anyway)
Thanks for the idea
R
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I don't know if this idea is any good but how about longer levers on both the gear change shaft and the gear lever. Mounted so that the one on the shaft points upwards instead of down. this might make the dog legged kickstart lever complete its swing outside of the gear change linkage. if you can move the one on lever 180 degrees you will even keep the gear changes in the current direction. good luck Mart.
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Why not just get a leccy leg for it? Rotaxes (Rotices??) can easily be fitted with same and then there's no problem.
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Ahh - leccy boot - thought of it - requires more battery space, and different crank cases, leccy boot itself and the wiring. There was a set of ES cases for sale on ebay a while back and I enquired of the Rotax man whether this was the answer to my problems, he thought it was just the start of them. Guess if I was to find a racer who was going to rip the leccy bits of their engine I could just swap mine for theirs?
This is all being done on a budget of about 50p BTW
R
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Really simplistic, but why not have a detachable toe piece for the gear lever? If it had a nice spring clip arrangement you could whip it off, kick the bike over, then click it back into place.
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You could fork the end of the gearchange rod instead of terminating it with a rod end, and have a hole on the stub that stays on the engine, then pull out a pin on the fork thats held indented by a spring to release the fork from the stub, do the business with a doglegged kickstart to miss the levers and then pull the pin again and slip the fork back in place. I bet you could be quite fluid with doing that, fluid enough to get you out the crap when it stalls at the lights and you have nowhere to bump it...
With time the pin would wear, but you could always push in a small liner of nylon bush into the engine stub side to form a bearing.
For pin design, it would just need to be a simple bayonette mechanism, so it could have a out position you could lock it in if needs be too. I can probally dig out what I mean, theyre common on rotatry table indexers, and if they can hold a workpiece indexed while its being milled, they can keep a gearchange linkage pin in place.
Also if the gear lever itself tended to foul the kickstart in its current position, theres always the side effect that it probally will swing down when free of the motor side of the linkage giving you more room, and you still would have your rod length adjustment at the other end, since you'd be free to rotate the rod to adjust once the fork is free.
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Thanks guys - loads of good ideas there need to look at them closer up on the bike.
Now another question - I need to bend the kickstart lever to get it to clear the frame etc. I am guessing that being as it is cast it will be steel not iron, and that if I heat it to cherry red I should be able to bend it to shape (and burn my fingers doh!). Will I then need to anneal it or anything - cherry red and air cool?
Again any thoughts would be helpful. I would tend to go for the heat and bend, anneal option.
R
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Just like you say, dull to cherry red heat, bend it to shape while it still is red, and then let it aircool slowly to keep the stresses down in the metal structure, if you want hard and brittle quench it in a bucket of water or oil or the like. Ive never annealed my kickstart on my sp and I have to build it back up with weld once or twice a year when it wears, and this kickstart is a homemade one after the oem one got tired of being repaired, its some funny steel chrome alloy rather than straight steel though but that doesnt seem to matter. You will destroy any finish or chrome on it, so its black paint time or rechrome afterwards, and youll of course need to regrease all the moving bits too. Welders gloves and a big vice come in handy but dont hold on too long as youll get burnt inside the gloves after a couple of seconds, you want to be doing the bending with something that wont mind getting hot, like a big adjustable spanner or the like or a pipe slipped over the end and position the jaws of the vice to encourage it to bend in the right place.
What might be a idea is to make a test piece of something you can bend to shape a lot easier, like thick wire or the like, and use it to check that nothing unexpected will foul or suprise you with the valve lifter operated or the plug out, before you bend the original one as itll end up being a right shape if you have to take 3 or 4 bites at it getting it right, and youll be able to use the test piece as a bending pattern to get it right first time too.
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This is all being done on a budget of about 50p BTW
R
This probably isn't the time to tell you that your wheel is already being worked on, I misunderstood the brief, I didn't ask for a price and just slapped it in to be done. Having said that the engineer is nearly always astoundingly cheap for the work he does. He was having a grizzle about the three snapped studs today, one came out easily, one snapped the 'ez-out' and the other had to be drilled until only a micron of it remained.
On the plus side, he got the remaining cush drive plates out without having to drill and tap them. This acheives next to no advantage for you, but he seemed pleased with himself :-)
Given that I am transportless for the next couple of days, could you send me the rear wheel spindle in the post? He wants it to centralise the wheel when he machines the sprocket mounts.
And don't worry, it will be cheap enough.
GC
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Not too worried GC - I have 50p for the kick start and a budger of £2.50 for the wheel - things that need to be paid for need to be paid for. Will sort out the spindle and send it to you - Wont ask Jen to drop it off she will only stress. Not my fault the studs sheared off when I took it apart - Mr Aprillia did not lube them on the way in. - Mind I would have left them in and turned it down - kerchunk-kerchunk-kerchunk
R