I finished my gen3/86 conversion took it for a short run and then stripped my motor for a complete rebuild and porting. Woods/ harescrables and enduro is the terrain the bike will spend most of its time and of course that is the porting I need, but being a novice porter there is questions.
The exhaust port will be widened by 2mm on each side but the duration is the thing I don’t want to run away with and turn it into a dessert bike. Would a port of 183-185 or 186-188 be good, if I am right that’s 8500-9000rpm?
I have a PC Service Honda pipe that was a straight fit with bracketing and would like to use it, but I also have a FMF Gnarly Gold Series and would like to know which would work best with this type of setup.
Woods porting
-
2strokeforever
- Posts: 1524
- Joined: November 13th, 2009, 1:04 pm
- Location: Vernon B.C Canada
i used to be all about the high revving powerband for everything, but on a 500 for woods you will be much better off leaving it stock, or if anything lowering the ports
if you actually ride woods then you need to be able to do a 40-50 mile loop, low revving=good mileage
i think the biggest drawback to the 500 in the woods is trying to hold it at exactly 5/16 throttle (to avoid looping out) while going thru rough terrain, it takes a huge amount of energy and concentration.... an engine with less mid top would be much more forgiving cause if you accidentally went from half to full throttle wouldnt be instant death
for woods the 250 ignition is gonna be 10 times more useful than any porting, the bike wont stall and it will turn better too
if youre determined to have it ported then:
A: get roosty to do it, its not cheap but its good
B: blueprint it and if you have to change heights then lower them
i have spent the last 2 years racing hare scrambles on the 500 and ive figured out smooth is fast
and if i could change anything id want more low end to drive out of corners better when im in 3rd but revving 1000rpm , a lower rpm but still powerful midrange, and a flatter top end so i dont have to be so precise in the fast bumpy sections
if you actually ride woods then you need to be able to do a 40-50 mile loop, low revving=good mileage
i think the biggest drawback to the 500 in the woods is trying to hold it at exactly 5/16 throttle (to avoid looping out) while going thru rough terrain, it takes a huge amount of energy and concentration.... an engine with less mid top would be much more forgiving cause if you accidentally went from half to full throttle wouldnt be instant death
for woods the 250 ignition is gonna be 10 times more useful than any porting, the bike wont stall and it will turn better too
if youre determined to have it ported then:
A: get roosty to do it, its not cheap but its good
B: blueprint it and if you have to change heights then lower them
i have spent the last 2 years racing hare scrambles on the 500 and ive figured out smooth is fast
and if i could change anything id want more low end to drive out of corners better when im in 3rd but revving 1000rpm , a lower rpm but still powerful midrange, and a flatter top end so i dont have to be so precise in the fast bumpy sections
the 450 will have less power and will be harder to start, and will be heavier, but to make up for it it will require more maintenance.
4stroke=dead fish
4stroke=dead fish
-
Rhino89523
- Posts: 1230
- Joined: November 18th, 2010, 1:45 pm
I hear you guy’s advice and going to take it even if it feels so wrong having a 2 stroke that revs so low. Ill only smooth everything out, remove some exhaust port tunnel floor, match all and do the head squish.
Did not have any real off-road time on the bike just ridding it on the tarmac and considering it can be looped in any gear on throttle only, I guess it will be a handful in the woods.
Did not have any real off-road time on the bike just ridding it on the tarmac and considering it can be looped in any gear on throttle only, I guess it will be a handful in the woods.
-
blownbillybob
- Posts: 391
- Joined: March 13th, 2008, 9:50 pm
- Location: FRISCO
I would lower the base .020
Raise the exh roof .040 ( leave the floor alone)
2 mm wide won't hurt
Square up exh ports ( above the int transfers)
Epoxy rear transfers
15 mm squinch band
Use the FMF pipe
VF-3 or 2 reeds
You'll have a tractor torque bottom, strong mid, and still keep a good top end!!!!
Raise the exh roof .040 ( leave the floor alone)
2 mm wide won't hurt
Square up exh ports ( above the int transfers)
Epoxy rear transfers
15 mm squinch band
Use the FMF pipe
VF-3 or 2 reeds
You'll have a tractor torque bottom, strong mid, and still keep a good top end!!!!
00'cr500 trailclimber
93'cr500 beater
92'cr500 hillclimber
08,KTM SR500r hillclimber (conv)
89'cr 500 bent frame
04'crf230(wifeys)
02' cr125(sons)
02,pro jr 50 open exh. hill climber(sons)
02'sx65(sons)
03'xr50(sons)
93'cr500 beater
92'cr500 hillclimber
08,KTM SR500r hillclimber (conv)
89'cr 500 bent frame
04'crf230(wifeys)
02' cr125(sons)
02,pro jr 50 open exh. hill climber(sons)
02'sx65(sons)
03'xr50(sons)