Portinghelp 490

[ola_martin]

Ok, the liner's straigth.
12mm guides didn't work, the machined grooves was off center of the the headboltholes when the ports lined up, but it tapped easy in place and I put it in the press.

I was thinking to put the cyl on each crankcase while they're apart, and match the outside of the case/cyl ports...but I'm unsure on what to do on the liner-side of them.

On the rest of the ports I guess I put the piston in "bottom dead center" and mark of the bottom on all transfer and the exhaust on the liner?

Rest I'm unsure of, other than to just match the liner to the cylinderchannels? Angle on liner etc?

[ola_martin]

Looked a bit at the bottom ports last night.
They don't match up very well at all... What can be gained by doing an effort here?
And the two grooves, whatever they're for ends up square against the lines, so I guess if they should work for something they need to be followed through the liner?


Here I have marked with black marker how much the cases would need to be taken out for the ports to match.... Makes a very narrow base for the gasket... Also everything looks so square and edgy, can't give much flow?


Please bear with me, I've only been performanceworking with 4strokes before...

[Lozza]

Doesn't hurt matching it all up but doesn't make any difference to output either, it's a "feel good"  modification.

[80-85 husky]

Disagree, matching the cases can give the bottom end a big lift.

smooth out all the dags in the transfer ports to barrel interface, match to the gasket edge and smooth radius any curves in the transfers. unless you have good porting specs from genuine hot up notes from the period, I dont touch the std timing. The main aim is to smooth any radius's or bends to a nice constant curve if you can and then just smooth the liner to barrel interface and smooth off the outer port edges with emery to prevent a sharp edge catching a ring. its at best a blueprinting process. In some cases of poor casting control, it can give a solid kick.

cant get a pic on ...

[ola_martin]

Ok, I'm a bit further, the engine came totally disassembled in a big box, with some missing shims, so it's a bit of a pussle for me as I've never seen one before.
So I've got the gearbox together and it shifts fine, the kickstartspring needs to be wound up one more turn, but I have an issue with the clutch.

First I put on a thrustwasher, about 1mm thick, then the basket, then the hub. I put on the long nut with the conical edge down as it looked to fit the hub that way. But now that I've tightened the nut all the way down on the threads I have an axial clearance on the basket and hub of 2-3mm, seems too much, but I can't figure out what's missing...?

Also can someone please tell me what ()()((( etc. setup to use on the clutchsprings?

Thanks for any help! 

[paul]

 
http://ozvmx.com/community/index.php?topic=24303.0

[ola_martin]

Thanks, but I already have those. And I built it up according to that, except it doesn't say the thickness of the shims.
 
And they don't say if the clutchhub should have axial clearance, or if it should be tightened down tight with the nut.
And they don't say wich way to put in the clutchspringwashers...

[Lozza]

Disagree, matching the cases can give the bottom end a big lift.

smooth out all the dags in the transfer ports to barrel interface, match to the gasket edge and smooth radius any curves in the transfers. unless you have good porting specs from genuine hot up notes from the period, I dont touch the std timing. The main aim is to smooth any radius's or bends to a nice constant curve if you can and then just smooth the liner to barrel interface and smooth off the outer port edges with emery to prevent a sharp edge catching a ring. its at best a blueprinting process. In some cases of poor casting control, it can give a solid kick.

cant get a pic on ...

Unfortunately  dyno's and stopwatches tells a different story to the 'bum dyno'. Our dyno will measure down to 0.1HP and yet to see any difference in a engine that has had countless hours smoothing and flowing etc etc.
It doesn't hurt but makes no measureable improvement in output.

[09.0]

(()) (()) (()) . 20 all up. Conical edge out. There should be a lock tab under the nut. The basket runs a needle bearing.

[ola_martin]

Thanks you very much 090!

But on mine it seems that the locking plate has went over/around the nut (it has a 17mm 6-edge hole) and is held on by the springs...
Mabe I put the nut upside down, should the rounded edge on the nut face the hub or the clutchcover?

[ola_martin]

Sorry, missed the conical edge out part...
Thanks again!

[JohnnyO]

Thanks you very much 090!

But on mine it seems that the locking plate has went over/around the nut (it has a 17mm 6-edge hole) and is held on by the springs...
Mabe I put the nut upside down, should the rounded edge on the nut face the hub or the clutchcover?

Mine is the same Ola, the inside of the lock plate has been rounded out by the nut. It doesn't matter, just use some blue loctite.

[ola_martin]

Cheers

[KTMaico]

Ola,
      Have you considered changing the clutch washers over to springs? I know mine has the spings and it seems to be OK. I have also started doing the ports on mine while I had the cylinder off getting the 18mm decompressor adapted to my cylinder. I am only doing a port clean and polish and not overly increasing the sizes and definately not playing with the port timing. I will post some photo's for you after I get it done and before assembly.

Regards,
            Kevin

[80-85 husky]

Disagree, matching the cases can give the bottom end a big lift.

smooth out all the dags in the transfer ports to barrel interface, match to the gasket edge and smooth radius any curves in the transfers. unless you have good porting specs from genuine hot up notes from the period, I dont touch the std timing. The main aim is to smooth any radius's or bends to a nice constant curve if you can and then just smooth the liner to barrel interface and smooth off the outer port edges with emery to prevent a sharp edge catching a ring. its at best a blueprinting process. In some cases of poor casting control, it can give a solid kick.

cant get a pic on ...

Unfortunately  dyno's and stopwatches tells a different story to the 'bum dyno'. Our dyno will measure down to 0.1HP and yet to see any difference in a engine that has had countless hours smoothing and flowing etc etc.
It doesn't hurt but makes no measureable improvement in output.

Find that interesting but your right, the figures dont lie... The Psychology helps though