the next project.......

[gottagetacheaperhobby]

slowly opening the head up, exhaust was so restricted...

think im nearly there with the inlet

 

[my67xr]

good job on the ports.
it's surprising how well they actually go with the valve stem bosses taking up so much room isn't it

did you cut it back a bit and smooth it out on the intake sides' short return (bottom of the port) ?
exhaust flow is mainly on the roof of the port, so you can cut back the sides of the valve stem boss.

 

[gottagetacheaperhobby]

i should of got a photo of before, the exhaust port was a 17/18mm oval. just been working on that atm, will put some work into the valve boss today

 

[gottagetacheaperhobby]

getting a bit more done


rounded the valve stem boss off a fair bit through the exhaust port,not sure how much more to take out..


and the intake port has a heap more room now

 

[gottagetacheaperhobby]

so im thinking i would like to throw some h/d valve springs and a better cam, anyone got any ideas on cams for it?

 

[my67xr]

Classic Honda 50's Australia

 

[gottagetacheaperhobby]

was browsing through the cams they had, i just dont no what one would be suitable, i dont want a absolute ripper, just a little more torque and a little more power....maybe this one??
Classic Honda 50's Australia - TB Race Camshaft - For Stock Head [TBW0189]

 

[gottagetacheaperhobby]

or this one even, dont need new springs then...
Classic Honda 50's Australia - TB Race Camshaft [TBW0411]
only worry is it makes no mention of 72cc engines, just the 86cc and up...

 

[zwebx]

id go and talk to akunar or terry (fpm) imo cams dont need to be aggressive..
stronger valve springs may help it along and roller rockers if you can get them..

 

[gottagetacheaperhobby]

will do

 

[my67xr]

i'd be going for one that can use the stock springs
do you have your cam measurements ?

 

[gottagetacheaperhobby]

as in lift and duration or just the bearing diameter and length?

 

[my67xr]

yeah length and bearing sizes.

 

[gottagetacheaperhobby]

65.49mm long including the bearings 35mm front bearing, 32mm rear bearing

 

[my67xr]

ok, was wondering if a bigger Lifan cam would work too?

 

[gottagetacheaperhobby]

quite possibly, i dont have any lifan cams here, the gpx cam would be way to aggressive wouldnt it? also struggling to find new valves for it in aus, checked the obvious sites (ebay dhz and ch50's) any sites i should look at i havnt craig? i found some on ooracing but hoping for some closer to home

 

[my67xr]

new valves ?
as in better valves eg stainless, bigger valves, or just standard new ones ?
what diameter are the ones in it now ?

 

[gottagetacheaperhobby]

was hoping to find stainless, at the very least i want new standard ones, the old ones look nasty lol. i need a 23mm and 20mm..

 

[my67xr]

Vesrah, Wiseco, Genuine Honda and Aftermarket valves and kits here-
http://wwww.ebay.com/sch/i.html?_od...f+70+valve+&_nkw=honda+crf+70+valve+&_sacat=0



and a few more sets that could fit, double check you sizes
50cc Valve Set Intake Exhaust Valves Honda CRF50 CRF50F XR50 XR50R Minitrail 50 | eBay

Valve Rebuild Kit Intake Exhaust Valves Springs Honda CRF50 CRF50F XR50 XR50R | eBay

Pro X Titanium Inlet valve-
Pro x Exhaust Valve Steel Honda CRF50F 04 09 11 12 Z50R 91 99 XR50R 00 03 | eBay
Pro x Intake Valve Steel Honda CRF50F 04 09 11 12 Z50R 91 99 XR50R 00 03 | eBay
Pro x Stainless steel exhaust valve
http://www.ebay.com/itm/Wiseco-Exha...rcycles_Parts_Accessories&hash=item5affcea429

TB Big Bore valve kit-
http://www.ebay.com/itm/TBPARTS-TRA...rcycles_Parts_Accessories&hash=item233b279805

Wiseco Stainless Intake valve
http://www.ebay.com/itm/Wiseco-inta...rcycles_Parts_Accessories&hash=item2c842b9e61
Wiseco Steel exhaust valve
http://www.ebay.com/itm/Wiseco-Pist...rcycles_Parts_Accessories&hash=item5b02da2003
Wiseco Stainless Steel exhaust valve
http://www.ebay.com/itm/Wiseco-Exha...rcycles_Parts_Accessories&hash=item5affcea429


h/duty springs
http://www.ebay.com/itm/HIGH-LIFT-C...rcycles_Parts_Accessories&hash=item1c033ba504
h/duty for high lift cams
http://www.ebay.com/itm/HD-VALVE-SP...rcycles_Parts_Accessories&hash=item51a7c09def

 

[gottagetacheaperhobby]

none of them have sizes listed which makes it really hard, had found most of that stuff just cant find out if its compatible with my head.