97 YZ250 Bogging

viper420 · 03-27-2007, 09:35 AM

I have a 97 YZ250 that i had a good friend of mine who is a cert. motorcycle mech. bore it out to a 300cc, and did all the other stuff to it so it would run correctly, well over the years i have moved way out of state, and have lost touch with him, so now i'm here for help.

Anyways, my bike starts up fine ,idles fine ,spark plug looks good, have not touched the jetting at all, but when i turn the throttle about 1/2 way it starts to kind of bog down just a little bit. oh yeah the spark plug i got in there is a NGK B8ES, and it's pretty new, i got about 20hrs. on it, also i'm running a gas

il mix of 32:1

Also my rear mono shock is shot ,does anybody have one that they could sell me ,or know where i can get one

tigmaster · 03-27-2007, 01:37 PM

i assume that you were sayin that the bike has been sitting for a while. if so i would first take a look at the carb. remove the float bowl and all the jets in the carb. clean those and put them back in. i cant remember if two strokes have an accelerator pump but if it does clean that also because they can easily fall victim to gunk build-up. also did u always run 32:1? if you used to run something richer like 30:1 or something like that and u stepped up to 32:1 then your engine is actually running richer(30:1 = more oil, less gas to burn while 32:1 = less oil more gas to burn) many people dont take this into account. however if these arent your problems let me know and ill see what else i can think of.

viper420 · 03-27-2007, 10:07 PM

it has never really sat around without running it around the yard for like 15mins. or so. cause i know about gas mix getting goopy. I was thinking it might be that the needle is up just a little to much, like i said it bogs when i get to 1/2 throttle and up, so there might be to much gas getting to the carb, and not enogh air.

tigmaster · 03-28-2007, 06:19 AM

air filter clean, choke off? i kno these are obvious things and it looks as though i wont be able to help you, but i can get REAL technical, this problem will be solved. that really feels like an air flow issue. if it has always run fine with the needle where it is then it should not have changed, the needle is held on by a hefty circlip.

viper420 · 03-28-2007, 10:47 AM

well its got a Keihin PWM and when i turn the choke all the way open the rpm's go way up., so now if i turn the choke open it sounds like i might have some other adjustments to make???

tigmaster · 03-28-2007, 02:20 PM

so, im not understanding wat u are sayin. are you sayin that when u put the choke on the engine revs up, because that is normal or are u sayin something else.

JThompson · 03-29-2007, 12:34 AM

Depending on if when you moved and there has been a major elevation change you will need to rejet your bike.

viper420 · 03-31-2007, 07:21 PM

Thanks tigmaster, i got it straight, but do you know of any web site or if someone has got a rear mono shock that i can get for my bike?

tigmaster · 03-31-2007, 10:31 PM

well, those are a bit pricey, i would check out ebay or check out sending out your shock to get it re-built. plenty of showa shocks on ebay

tigmaster · 04-01-2007, 08:51 AM

by the way, what was your problem?

03-27-2007, 09:35 AM	#1 (permalink)
viper420 C Rider Join Date: Mar 2007 Posts: 9 iTrader: (0)	97 YZ250 Bogging I have a 97 YZ250 that i had a good friend of mine who is a cert. motorcycle mech. bore it out to a 300cc, and did all the other stuff to it so it would run correctly, well over the years i have moved way out of state, and have lost touch with him, so now i'm here for help. Anyways, my bike starts up fine ,idles fine ,spark plug looks good, have not touched the jetting at all, but when i turn the throttle about 1/2 way it starts to kind of bog down just a little bit. oh yeah the spark plug i got in there is a NGK B8ES, and it's pretty new, i got about 20hrs. on it, also i'm running a gasil mix of 32:1 Also my rear mono shock is shot ,does anybody have one that they could sell me ,or know where i can get one

03-27-2007, 01:37 PM	#2 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,659 iTrader: (1)	i assume that you were sayin that the bike has been sitting for a while. if so i would first take a look at the carb. remove the float bowl and all the jets in the carb. clean those and put them back in. i cant remember if two strokes have an accelerator pump but if it does clean that also because they can easily fall victim to gunk build-up. also did u always run 32:1? if you used to run something richer like 30:1 or something like that and u stepped up to 32:1 then your engine is actually running richer(30:1 = more oil, less gas to burn while 32:1 = less oil more gas to burn) many people dont take this into account. however if these arent your problems let me know and ill see what else i can think of. __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

03-28-2007, 06:19 AM	#4 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,659 iTrader: (1)	air filter clean, choke off? i kno these are obvious things and it looks as though i wont be able to help you, but i can get REAL technical, this problem will be solved. that really feels like an air flow issue. if it has always run fine with the needle where it is then it should not have changed, the needle is held on by a hefty circlip. __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

03-28-2007, 02:20 PM	#6 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,659 iTrader: (1)	so, im not understanding wat u are sayin. are you sayin that when u put the choke on the engine revs up, because that is normal or are u sayin something else. __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

03-29-2007, 12:34 AM	#7 (permalink)
JThompson Administrator Join Date: Aug 2006 Location: Bellingham WA Posts: 5,163 iTrader: (6)	Depending on if when you moved and there has been a major elevation change you will need to rejet your bike. __________________ Tired of ads? Become a member for an almost ad free site! Also we give away monthly prizes just for posting! Register today! Looking for places to ride! Want to review a riding area? Check them out! PRE-ORDER MOTOTIPS Stickers now. Help keep mototips running! Get your order in today! Buy NOW! Special Discounts for members only! Check out our new discount forum for retailers offering to help you save money! Mototips Discounts

03-27-2007, 10:07 PM	#3 (permalink)
viper420 C Rider Join Date: Mar 2007 Posts: 9 iTrader: (0)	it has never really sat around without running it around the yard for like 15mins. or so. cause i know about gas mix getting goopy. I was thinking it might be that the needle is up just a little to much, like i said it bogs when i get to 1/2 throttle and up, so there might be to much gas getting to the carb, and not enogh air.

03-28-2007, 10:47 AM	#5 (permalink)
viper420 C Rider Join Date: Mar 2007 Posts: 9 iTrader: (0)	well its got a Keihin PWM and when i turn the choke all the way open the rpm's go way up., so now if i turn the choke open it sounds like i might have some other adjustments to make???

03-31-2007, 07:21 PM	#8 (permalink)
viper420 C Rider Join Date: Mar 2007 Posts: 9 iTrader: (0)	Thanks tigmaster, i got it straight, but do you know of any web site or if someone has got a rear mono shock that i can get for my bike?

03-31-2007, 10:31 PM	#9 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,659 iTrader: (1)	well, those are a bit pricey, i would check out ebay or check out sending out your shock to get it re-built. plenty of showa shocks on ebay __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

04-01-2007, 08:51 AM	#10 (permalink)
tigmaster Administrator Join Date: Aug 2006 Location: Missouri, United States Posts: 7,659 iTrader: (1)	by the way, what was your problem? __________________ --'03 CRF450r-- --FMF Pipe, Pro-Tech Revavle-- --Vortex Basket With Tusk Disks And HP Springs-- --Pro Taper Triple Clamps And Bars-- --Devol Full SP With Moose HGs-- --Renthal 13/50 With R1 Chain-- --Now It Is The End, Probably...-- --'06 CBR F4I-- --Bone Stock-- Check Our Latest How-To Here

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