Planet Minis

RompKING282 · 10-15-2008, 11:02 PM

to start off this is my 1st posting. i have an 03 xr50 that i am building so far i hav aftermarket fork and shock springs, rev limiter, a bar kit, tall seat, black plastics and foot pegs. right now i am currently rebuilding the motor and i hav bored the stock cylinder 3 over stock, got a wiseco piston, xr70 carb. i have ordered clutch springs, valve springs, cam, air filter, shifter. i also plan on doin the head gasket , sprk plug, engine breather , exhaust, and choke mods. o ya and port and polish.

is their anything else that anyone recommends? and what exhaust should i get? cause i know that some dont work that well without a bore kit.

PitRacerVince · 10-15-2008, 11:23 PM

I just gotta ask y used stock cylinder and head? with the mods u have done u dont fit the stock class as far as I know. but its cool that ur doing it, going back to the roots of modding.

brucey 089 · 10-16-2008, 02:39 AM

get the fast 50s pipe they may not look the best but they flyy

firepower354 · 10-16-2008, 04:17 AM

If it's gotta stay 50ml

, I'd add some more gears that are closer together.

A milled 70 head, modded 82-87-ish piston(?), lightened flywheel.

RompKING282 · 10-16-2008, 09:17 AM

vince- im using the stock cylinder and head beacause i really just wanna see how much power i can get out of it.because no one else does it everyone just gets an 88 kit instead of seeing how fast a 50 can really go.

bruecy- i was actually lookin att he fast 50s pipe. but how does it work with a stock intake and cylinder? i dnt wanna lose bottom and mid range

firepower-are you saying to change the gears in the tranny? how did u mod ur piston? and i was lookin into lightening my flywheel but the motor needs the momentum from the heavy flywheel to continue to go faster.( thats what my boss told me) did u lose any top end? and if so how much bottom to mid did u gain?

KI6HNB · 10-16-2008, 09:22 AM

Inner rotor kit.

RompKING282 · 10-16-2008, 09:27 AM

what does the inter rotor kit help? i havent really looked into them yet

KI6HNB · 10-16-2008, 09:51 AM

Much quicker throttle response. SHould work great with your cam and head porting.

RompKING282 · 10-16-2008, 09:54 AM

o ok...il definatly look into it..it jus depends on how cheap i can get one for...ha hopeflly my boss can get me one....i work at a mx shop..

KI6HNB · 10-16-2008, 10:00 AM

My buddy bought a china bike take off one new for $25 complete. It works great. Instructions were in chinese though.

PitRacerVince · 10-16-2008, 10:05 AM

inner rotors lighten the rotating mass which allows the ,motor to rev faster, but on the other hand it loses revs just as fast so while shifting ull need to stay on the gas... I totally respect wut u r doing I didnt have the patience and just went 88.... U can also advance and retard ur ingniton

RompKING282 · 10-16-2008, 10:05 AM

hahaha did it hurt the top end at all?

RompKING282 · 10-16-2008, 10:07 AM

thanks man. ya i just started workin at Wickoff racing and its like my bosses and my project..haha he is just as into it as me and it isnt even his bike.ha
im hoping it wil b fast tho cuz their is a good amout of time involved in this thing.ha

RompKING282 · 10-19-2008, 12:03 AM

BlackBeard · 10-19-2008, 01:24 AM

the only way your going to see any gain in that motor is to atleast run a new cam and purchase a powroll high compression piston kit. Any other modification you do is just trivial

geof · 10-19-2008, 01:32 AM

Here are a few other things to make a stock 50 engine go well:

1 Inner rotor
2 Titainium valve caps
3 lighten the rockers
4 lighten the flywheel
5 lighten, balance & knive-edge the crank
6 Use a combination of Honda SS 50, Honda ATC70 and the Rovaza 4th gear to build a close ratio 4 speed gearbox.
7 Takegawa secondary clutch...or at the very least a TB billet clutch.

RompKING282 · 10-19-2008, 10:24 AM

what exactly is knive-edging the crank?

firepower354 · 10-19-2008, 10:27 AM

A waste, at least with a clutch hanging it's ugly self on the end of the crank. There may be a fractional windage loss, but not at the RPM's the tiny stock valves will get it up to.

RompKING282 · 10-19-2008, 10:43 AM

how much better are the powroll pistons then the wiseco?

Kurlon · 10-19-2008, 10:54 AM

If you're going to retain an auto clutch, get a full set of Powroll Ti clutch weights. It'd also be worth looking into TB's billet basket to see if it's lighter, and has a lower moment of inertia compared to the stock cast assembly.

From there, high comp piston, lighten/polish everything, etc. That leaves you with head work. That's where 99.9% of your gains will really come from.

Or, if you want a REAL challenge, take the cam out entirely, and do some milling to the head/cylinder to set it up as a two stroke. : )

10-15-2008, 11:02 PM	#1 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	how to get the most power out of stock cylinder and head? to start off this is my 1st posting. i have an 03 xr50 that i am building so far i hav aftermarket fork and shock springs, rev limiter, a bar kit, tall seat, black plastics and foot pegs. right now i am currently rebuilding the motor and i hav bored the stock cylinder 3 over stock, got a wiseco piston, xr70 carb. i have ordered clutch springs, valve springs, cam, air filter, shifter. i also plan on doin the head gasket , sprk plug, engine breather , exhaust, and choke mods. o ya and port and polish. is their anything else that anyone recommends? and what exhaust should i get? cause i know that some dont work that well without a bore kit.

10-15-2008, 11:23 PM	#2 (permalink)
PitRacerVince 2nd Gear Member Join Date: Oct 2008 Location: Lancaster, CA Posts: 256	Re: how to get the most power out of stock cylinder and head? I just gotta ask y used stock cylinder and head? with the mods u have done u dont fit the stock class as far as I know. but its cool that ur doing it, going back to the roots of modding.

10-16-2008, 02:39 AM	#3 (permalink)
brucey 089 PM Newbie Join Date: May 2008 Location: gold coast australia Posts: 96	Re: how to get the most power out of stock cylinder and head? get the fast 50s pipe they may not look the best but they flyy

10-16-2008, 04:17 AM	#4 (permalink)
firepower354 3rd Gear Member Join Date: Oct 2006 Location: Flint MI Posts: 6,266	Re: how to get the most power out of stock cylinder and head? If it's gotta stay 50ml, I'd add some more gears that are closer together. A milled 70 head, modded 82-87-ish piston(?), lightened flywheel.

10-16-2008, 09:17 AM	#5 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? vince- im using the stock cylinder and head beacause i really just wanna see how much power i can get out of it.because no one else does it everyone just gets an 88 kit instead of seeing how fast a 50 can really go. bruecy- i was actually lookin att he fast 50s pipe. but how does it work with a stock intake and cylinder? i dnt wanna lose bottom and mid range firepower-are you saying to change the gears in the tranny? how did u mod ur piston? and i was lookin into lightening my flywheel but the motor needs the momentum from the heavy flywheel to continue to go faster.( thats what my boss told me) did u lose any top end? and if so how much bottom to mid did u gain?

10-16-2008, 09:22 AM	#6 (permalink)
KI6HNB 2nd Gear Member Join Date: Jul 2007 Location: Cameron Park, CA Posts: 718	Re: how to get the most power out of stock cylinder and head? Inner rotor kit.

10-16-2008, 09:27 AM	#7 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? what does the inter rotor kit help? i havent really looked into them yet

10-16-2008, 09:51 AM	#8 (permalink)
KI6HNB 2nd Gear Member Join Date: Jul 2007 Location: Cameron Park, CA Posts: 718	Re: how to get the most power out of stock cylinder and head? Much quicker throttle response. SHould work great with your cam and head porting.

10-16-2008, 09:54 AM	#9 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? o ok...il definatly look into it..it jus depends on how cheap i can get one for...ha hopeflly my boss can get me one....i work at a mx shop..

10-16-2008, 10:00 AM	#10 (permalink)
KI6HNB 2nd Gear Member Join Date: Jul 2007 Location: Cameron Park, CA Posts: 718	Re: how to get the most power out of stock cylinder and head? My buddy bought a china bike take off one new for $25 complete. It works great. Instructions were in chinese though.

10-16-2008, 10:05 AM	#11 (permalink)
PitRacerVince 2nd Gear Member Join Date: Oct 2008 Location: Lancaster, CA Posts: 256	Re: how to get the most power out of stock cylinder and head? inner rotors lighten the rotating mass which allows the ,motor to rev faster, but on the other hand it loses revs just as fast so while shifting ull need to stay on the gas... I totally respect wut u r doing I didnt have the patience and just went 88.... U can also advance and retard ur ingniton

10-16-2008, 10:05 AM	#12 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? hahaha did it hurt the top end at all?

10-16-2008, 10:07 AM	#13 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? thanks man. ya i just started workin at Wickoff racing and its like my bosses and my project..haha he is just as into it as me and it isnt even his bike.ha im hoping it wil b fast tho cuz their is a good amout of time involved in this thing.ha

10-19-2008, 12:03 AM	#14 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? bump

10-19-2008, 01:24 AM	#15 (permalink)
BlackBeard "ZBBT" Join Date: Oct 2007 Location: 50 riders Posts: 1,772	Re: how to get the most power out of stock cylinder and head? the only way your going to see any gain in that motor is to atleast run a new cam and purchase a powroll high compression piston kit. Any other modification you do is just trivial

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10-19-2008, 01:32 AM	#16 (permalink)
geof Moderator Join Date: Feb 2004 Location: "Over the Pond" Posts: 74	Re: how to get the most power out of stock cylinder and head? Here are a few other things to make a stock 50 engine go well: 1 Inner rotor 2 Titainium valve caps 3 lighten the rockers 4 lighten the flywheel 5 lighten, balance & knive-edge the crank 6 Use a combination of Honda SS 50, Honda ATC70 and the Rovaza 4th gear to build a close ratio 4 speed gearbox. 7 Takegawa secondary clutch...or at the very least a TB billet clutch.

10-19-2008, 10:24 AM	#17 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? what exactly is knive-edging the crank?

10-19-2008, 10:27 AM	#18 (permalink)
firepower354 3rd Gear Member Join Date: Oct 2006 Location: Flint MI Posts: 6,266	Re: how to get the most power out of stock cylinder and head? A waste, at least with a clutch hanging it's ugly self on the end of the crank. There may be a fractional windage loss, but not at the RPM's the tiny stock valves will get it up to.

10-19-2008, 10:43 AM	#19 (permalink)
RompKING282 1st Gear Member Join Date: Oct 2008 Location: Yorba Linda Posts: 195	Re: how to get the most power out of stock cylinder and head? how much better are the powroll pistons then the wiseco?

10-19-2008, 10:54 AM	#20 (permalink)
Kurlon Baron Von BanHammer Join Date: Feb 2005 Location: Windham, ME Posts: 7,865	Re: how to get the most power out of stock cylinder and head? If you're going to retain an auto clutch, get a full set of Powroll Ti clutch weights. It'd also be worth looking into TB's billet basket to see if it's lighter, and has a lower moment of inertia compared to the stock cast assembly. From there, high comp piston, lighten/polish everything, etc. That leaves you with head work. That's where 99.9% of your gains will really come from. Or, if you want a REAL challenge, take the cam out entirely, and do some milling to the head/cylinder to set it up as a two stroke. : ) __________________ http://www.x386.net/TTR 2004 ST3 - 'Duckie'?!?! 2005 CRF70RR - MiniGP Weapon 2005 CRF70 - Dirt Donk 2008 Pitster Pro X4 Motard 1991 GS500E - LRRS/CCS #771