Thumper Club Forum
Technical => Project Progress => Topic started by: guest27 on April 22, 2007, 07:06:23 PM
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Following on from that pain GC challenge to make a pretty cafe racer from the CG - I have actually started. Been hamming out a new seat pan and have some foam lined up - but may get some new. Looks OK with ace bars - which is good as I have those - do not think I have any clip-ons with a small enough dia and then I would have to modify the headlamp stays.
We will see what happens
R
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Started making a carb adaptor plate last night - all nice maths etc to find out I need a 1.6mm offset - why did I bother, then I drilled a large hole where I should have left a centre pop - so have to make a wooden back plate to mount it all in the lathe now...
Hi de ho
R
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Sort of finished the carb adaptor and found some real big steps in the inlet - also a bit on the interweb about making them go better - damn I am not unique - mind I have a number of other projects in mind for a CG now - need to start looking for some cheap examples....
R
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Rog, quick cheap tip.. GS750 piston, bored gives you 63mm and 156cc with no rod modification etc...
Ive got a xl125 here with poor compression that Ill be shortly testing the theory on....
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Ah hah - the kind of cheap mod I like
Must dig out the set of Z750 Kwak pistons I have - they make the K4 350 rather than 325 - to see if they are close - mind you will probably know being as you have the Turbo..
R
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Fluffer probably knows the inside of a turbo very intimately by now..think he has killed a few. :)
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Mik, pot kettle black, 26psi dead ht10b, do I need to say more?
Rog, I forgot to add, I have a spare gs piston knocking round if the xl experiment is a sucess. You can have it for free if so as my gs is never going to be a 750 again thats for sure.
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Ahh wondered where I was going to find some GS pistons - used to have a 750 - sold it to fund the Triton. Mmm what a black hole that was - could be again.
R
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Mik, pot kettle black, 26psi dead ht10b, do I need to say more?
Well they aint fun till you get around 20pounds of boost..and for the record I have only killed 2x750's, 1x810 and snapped 2 turbo shafts. And its fair to say too much boost was to blame everytime, but was it fun!
Hey rog I got 4 very low comp 66mm pistons
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66mm sounds good - just need to sort out how to get a new liner in cheap - there is only 3mm on the skirt of the standard one - the liner itself is about 6mm thick, but it is slimmed down on the OD where it projects into the crank case.
Well today I have been playing with some rotary burrs and lil grind stones and I now have a shiny paperweight that used to be a CG head. Just smothing out all the steps in the castings that Mr Honda leaves - probably for good reason. But the way I see it is I have not mucked too much with 4 strokes - more of a 2 stroke knackerer - so I am learning good stuff for the Rotax.
R
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Just a quick note, I remember when I was engineering (many years ago) I had an ES2 Norton and spent many hours polishing the ports and matching the carb, inlet manifold to ports, polishing the bottom of the valve guides and the valves themselves. NO discernible improvement in performance!
One thing that I did hear of though was that some of the casting surfaces should be left as this mixes the fuel en-route to the combustion chamber, creates swirls in the inlet tract...........but I'll never know!
SteveD
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The great god John Robinson says leave the ports rough as this helps break down the boundry layer - either they need to be perfect or rough. Also I understand the roughness can hold on to a little fuel and this is picked up by sudden increases in air - sounds like a guess to me. Realise that all this effort is only because I need the therapy - who ports a CG? However the inlet port by the carb flange is 26mm, the mating face of the inlet valve is 26mm, the inlet seat was between 25 and 23 mm and then there was a step to 25 mm in the casting - could feel the back of the valve seat. Pretty much the same on the exhaust port mind. The valve seats sat proud of the cylinder head by between 0.5mm and 1mm and thus were probably not even in straight.
Just wish the head would fit in my lathe as it needs a squish machining and a mite skimming off.
R
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Just wish the head would fit in my lathe as it needs a squish machining and a mite skimming off.
R
Well if I was still at the place of work I just left I would have done it for you, but as im not I cant!..how helpful is that haha.
Now then R my trusty Rotax should have a total new and uprated clutch in it this time next week..cost me a small fortune in parts tho, but will be good to have a clutch that holds.
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Mmmmm - yup and if I still worked in the place I used to I could probably have machined up a new head - now if I had thought 20 years ago..... thanks for the belated time challenged offer though
Trust the clutch goes well.
R
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thanks for the belated time challenged offer though
Im good like that :)..
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So the ladies say - thoughtful after the event...
<big grin as I duck the right hook...>
R
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So the ladies say - thoughtful after the event...
<big grin as I duck the right hook...>
R
Clutch all done and its now back into hooligan mode :)
PS you can stand up straight now the right hook went out into the next county.
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Good stuff - on the clutch, was it an OK job or a real pain as you were expecting?
R
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Good stuff - on the clutch, was it an OK job or a real pain as you were expecting?
R
Right Royal pain!.. I started it but found that I didnt have the correct pullers, in their infinate wisdom Rotax also built the motor with the left hand cover in one piece meaning cambelt an pulleys etc have to be removed to get to clutch, not just a quick case off job. So I bunged it over to a local bloke who had more than a little bit to do with CCM factory bikes.
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Mmm I notoced that on the cover - having popped the clutch cable off to see about length I could not get it back on - thought just whip the copver off and do it that way - ummm nope.
R
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Mmm I notoced that on the cover - having popped the clutch cable off to see about length I could not get it back on - thought just whip the copver off and do it that way - ummm nope.
R
Ahh see the clutch cable is actually a piece of pee on mine..does yours not have 2 screw in plugs on clutch cover? I dead centre of clutch for adjustment and one a bit lower and to front? the front lower one allows you to fit the cable.
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Yup two screw in plugs - one of which I can move. Big fingers, shed full of junk and engine held in by string all add to the excitement.
R
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Ah ha - resurected after more than 120 days it says here...
Have been playing about with a different carb - do not want to make progress you see - and have cut some hardboard patterns for a fuel tank (cover). Will troll off to the local surfboard maker soon - he has a shed load of old foam block - too small for surfboards big enough to make a buck for a fairing ... ummmm and get the foam roughed to the patterns. Then buy some resin from him and blag a load of woven roving off cuts.... If it all works will have to try the same for the TZRotax.
R
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Picked up the TLS wheel yesterday - spokes are in better knick that the wheel in it so I will not bother with rebuilding it - just have to work out how to get it to fit - oh and some brake arms - now do any of you have some old TLS brake arms about...
R
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Funnily enough I was offered a 6v (pre-brazil) CG125 for £65 today. I think I'll buy it with a view to Ebaying it either whole or peicemeal.
GC
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Sounds good to me.
If I had £75 you could have a £10 profit with no trials. But I do not so bottom!
R
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Well I have the TLS front wheel for it now - was sold as having crap rim and spokes - but they are better than the ones on it. I need to turn back the hub a little to get it to fit and decide whether tho cut back the lug on the forks or come up with some other method of fixing.
However the guy could not find the arms for it - so if anyone has some old small brake arms about - not sure of the correct size - suppose I could measure it - I would really like some - even if I just use the splined bit to make some new ones.
Still have not cut out the tank as I am making hobbyhorses - or was until the router died...
R
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Some steps forward some steps back....
Have the TLS fitted though the wheel is not aligned - need to decide if it is enough to make the MOT man see cos I am sure it will not upset the handeling - CG you see... Else I have to learn about wheel building - or adjusting the offset with out upsetting the concentric nature.
Still have no brake arms, but thought the CG one might fit - as a start. fits fine but the arm broke taking it off the CG - after half a curse I saw what luck this was - rather have it break when playing than when riding.
Bored out a carb to suit the inlet ports - but not sure I have not over done it - slide does not sit down fully now - so do I need to make a cutter to do this and if I do will I bore a hole through the carb...? (Probably)
Mind the TLS looks good on it.
R
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Well have been playing with the front wheel for a bit and have got it more central but is now less concentric - will fiddle some more later, having problems with 40 year old spoke nipples so I will probably need to get some new ones. One of them I cannot shift so I guess some new spokes are in order - Alf Hagon only does them by the 10 and I really only want 1 or 2 and a set of nipples...
About it but hey - have actually found the time with kids etc to get something done.
Garden is coming along but the slugs are eating stuff as fast as I put it in - where oh where is the summer?
R
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Come on Rog, let's have some pics :)
I will have a look in the garage this week and see if I have some CG brake arms for your TLS brake. I'm fairly certain I should have two spare for you. I'm not hopeful that the cable barrels will still be in place, is that a problem?
As an aside, later tonight I will post pictures of the few bits and pieces I've amassed for my CG project. I'm going for a 70s street scrambler look.
Cheers
GC
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Nope not a problem - what I really need is the 11mm splined sections - I will have to extend one to be the 'master' arm and re-drill the other etc.
No probs on the bobbins I have one and a lathe so can make more.
Currently a real pile of bits -
R
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A little inspiration... ;)
Some of the "Honda powered specials" appear to have suspiciously CG engine styles...
http://www.elsberg-tuning.dk/honda.html#replicas
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That is the idea - look more like CB lumps than CG - but all the same if it is ever 50% of any of those I will be happy - now who would like to buy a wife and kids to give me the time and income to build the littl thing?
R
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Sorry Rog, I forgot to dig out those brake arms, will try and sort it this week.
GC
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Something actually happened!!!
Built a hot wire cutter and carved out the startings of a tank - do not know if it will be a tank or a tank cover.
Had to use copper wire for the cutter as I could not find my 0.7mm stainless and a violin string was too short. Will have to wander round the music shops and see if they have a high E or the like knocking about. Will do a better job, get hotter, stretch less etc.
Pics below. You will see that the front TLS wheel has no arms, still waiting on GC to send some old CG ones over to act as a starting point - if anyone has any old buggered gear levers with an 11mm splined hole - I have a home for them, CG gear levers also fit and would be a good start - shame the guy I got the wheel from had lost the arms etc - it is from a 60's / 70's Yamaha
Seat is a bit rakish as it is proped up on some bee boxes and is for a 350K4, so too narrow on the nose. Will block it out and make a mold so I can have on on the CG and one on the K4 - GC are you going to help?
Couple of pics, cannot get in the shed too well so funny angle. Will have to attack the CG with a drill soon, there is a short in the points wire and it seems to be behind the coils and two of three screws are nerfed...
R
(http://i177.photobucket.com/albums/w230/Shaftoflame/CG125/PICT2995.jpg)
(http://i177.photobucket.com/albums/w230/Shaftoflame/CG125/PICT2996.jpg)
(http://i177.photobucket.com/albums/w230/Shaftoflame/CG125/PICT2997.jpg)
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GC says he cannot see the new pics, yet I can on two machines, is the probelme with my links or GC's PC?
R
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GC says he cannot see the new pics, yet I can on two machines, is the probelme with my links or GC's PC?
R
Sorry, Rog, when we talked the other day I was talking about the email with images you sent me off-forum.
BTW, did the trailer clamp do the job?
GC
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Clamp works well - well as soon as I worked out that the bar does not go through the wheel - the holes are too small. ::)
Just need to pack the trailer to go on hols now - I think the campsite may turn us away. Coleman Extenda tent, big trailer, two dogs, more cookers than are really needed, etc etc
R