Milk bar racer

[guest27]

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

[guest27]

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

[guest27]

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

[MrFluffy]

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....

[guest27]

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

[guest207]

Fluffer probably knows the inside of a turbo very intimately by now..think he has killed a few.

[MrFluffy]

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.

[guest27]

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

[guest207]

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

[guest27]

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

[steveD]

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

[guest27]

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

[guest207]

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.

[guest27]

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

[guest207]

  thanks for the belated time challenged offer though

Im good like that ..