porting

[2strokeforever]

looking at porting my jug myself till i have enough $$$ to get roosty and/or glen to do it properly...
ive heard enlarging boost ports gives more
and widening exhaust gives more
and i heard drilling extra boost ports gives a lot of bottom end
im thinking of doing all 3, but would like to know what the drawbacks to each are from people that have done it
im going to take my jug off and clean the rough castings up anyways so i might as well add a bit if its not too hard, i want the power to be angrier, so i can crack the throttle any gear, any rpm and break loose and spin like crazy

[OUTKAST INC.]

i have got a really nice 98 steely for sale in case you need another motor after you get done , of course paying somebody to do it right now is cheaper than the 2900 im asking , but youdogetalotof cool parts extra with my deal

[2strokeforever]

thanks but ill prolly end up getting a brand new jug/piston ported for trail once im done... unless i like my angry one for everything
and my motor is new so its easier to swap a jug than motor, and cheaper too

[dubious01]

for trail, and simple mods, I would mill .030" off the head, and radius / open the crankcase intake ports to the bottom of the transfer ports, blend the exhaust port to match the exhaust manifold.

This would be enough work for a beginning porter, and trust me you will be very happy with the increase in bottom torque,

Milling the head is the best mod for the least money on the CR500.
You can go more than .030 but then you might need higher octane race fuel. Before you machine the head you should use soldier or clay to measure the existing cylinder head clearance.

Trying to duplicate what the pro's do for porting on the first attempt would be a big mistake for 99% of the people.
I have owned 6 CR500 since 1987, and I have ported about 11 motors for myself and friends. It took a while before I got good enough to get half serious, and to collect about $400 worth tools for porting.
I still would call myself an ameteur.

More tire spin? what the base ball sized rocks aren't enough for you 250 and 450 buddys? lol

[2strokeforever]

for trail, and simple mods, I would mill .030" off the head, and radius / open the crankcase intake ports to the bottom of the transfer ports, blend the exhaust port to match the exhaust manifold.

i ended up smoothing out the casting flaws everywhere i could reach, open the crankcase intake ports to the bottom of the transfer ports, and getting the exhaust as smooth as i could with 120 grit paper
ride report coming in a few days
sorry no pics
i also noticed my head is perfectly clean, but the piston has a thick layer(.5mm ish) of carbon on it, the last 4 hours on it were tight trails, will all that burn off once i open it up???

[dubious01]

Its normal to have carbon on the top of the piston,
different fuels and premix will contribute to this
if the shape of the burn is equal you thats a good indicator the transfers are flowing equal.

Milling the head will very likely give the biggest boost in power for least $ or time involved. You will notice it immediatley.
Duncan perormance or machine in vernon can mill your head for you.

as for the exhaust and crankcase ports... I will post some pics for reference tonight.

see how Glenn opens up the intake port:






Notice how open that bottom intake port is, you could see the reeds from the transfers if they were bolted on

This picture Adam posted shows the stock closed bottom intakes, how they are closed to the transfers, and how small they are.
see the very bottom statement:



Notice how he opens up the exhaust manifold, and also opens up the exhaust port to match the same inside diameter of the exhaust manifold.

[2strokeforever]

well i kinda tested it, but the temp dropped huge, so i threw a 170 main in there, (was 165 but didnt have a 168) and it was pouring rain and very muddy so i cant tell much but it seems angrier,but that could be me just expecting it??????. once i test it on hard pack with the brass dialed then ill know