Newly acquired 2003 w/ Muzzy - stumbling on off/on throttle and gas smell.

fierostetz · August 20th, 2012, 01:24 PM

Hey all - I just recently purchased a 2003 250, 1400 miles on it. Stock other than full Muzzy system. The PO says they had it rejetted at the shop they had the exhaust installed at. Bike feels pretty good (pulls thru rpm's ok, 95-100 without much effort with my 280lbs on it.) I want to get the bike running well so I can hand it off to my wife - all is good so far (ordered springs, valves, rear shock already) except for some strange throttle behavior. When riding, if I drop throttle and rapidly transition back on throttle, the bike seems to plug up for a minute then resumes acceleration. At idle or after decelerating there's a fairly prominent gas smell. Any thoughts on my description? I'll eventually order some jets and properly rejet the bike myself, but any input would be very welcomed

not too familiar with ex250's yet. I know I need to adjust the float bowl height, but any other recommendations would be awesome.

choneofakind · August 20th, 2012, 05:29 PM

Gas smell + bogging = symptoms of rich.

Open up the carbs to get an idea of what it has inside after being "jetted"

How far are you getting back into the throttle after letting off it when you experience the rich symptoms?

Read through this guide to get some idea how to jet, and think back through your rides and how the bike handles/responds. That should give you some idea of what needs changed in the bike.

fierostetz · August 21st, 2012, 06:33 AM

Quote:

Originally Posted by choneofakind

Gas smell + bogging = symptoms of rich.

Open up the carbs to get an idea of what it has inside after being "jetted"

How far are you getting back into the throttle after letting off it when you experience the rich symptoms?

Read through this guide to get some idea how to jet, and think back through your rides and how the bike handles/responds. That should give you some idea of what needs changed in the bike.

See, that's what's strange - bike runs great! It's maybe 1/3 back on the throttle that it bogs. I'm going to have to tear into it

thanks for the reply!

fierostetz · August 23rd, 2012, 02:45 PM

bah- found the gas smell. looks like PO de-california'd the bike and didn't cap the vent line on the back of the tank. Still stumbles with on/off/on throttle transitions, but runs great otherwise. Hard to tell if its not pulling well as I have nothing similar to compare it to. Feels weak compared to my klr650 and FZ1, but :shrug: - seems to top out at around 80 (indicated) with me sitting upright on it, and 95 or so (indicated) when I tuck in. I'm ~270 and dropping fast, so the bike will get faster as I get slimmer :P

any thoughts on the on/off/on throttle stumble?

choneofakind · August 23rd, 2012, 03:33 PM

play with your idle mix screws

fierostetz · August 23rd, 2012, 03:35 PM

Quote:

Originally Posted by choneofakind

play with your idle mix screws

really for bogging up top - hadn't thought to play with idle for that but I guess it makes sense. I'll google up how to get to them; hopefully I can remove the idle mix plugs without pulling the carbs. Or hopefully the PO already removed them

choneofakind · August 23rd, 2012, 03:37 PM

oh, pause.

Up top? I thought it was when you were from off the throttle to back open to 1/3 throttle?

fierostetz · August 23rd, 2012, 03:40 PM

apologies for a failure in conveying my issue properly

On the road, 65-70mph (actual) if I drop throttle to 0% then open the throttle again, it bogs almost like there's too much fuel, then it pics back up again. It's fairly pronounced, and exacerbated by the soggy front springs (replacements get here tuesday!) as the bike dives for a split second.

choneofakind · August 23rd, 2012, 03:46 PM

ok, so 65 mph, 7k-ish rpm, mid-throttle imput. Would you say that's about right?

If it feels like a bog, try leaning up a section of your carbs. If it's the middle of the throttle range, try lowering the needle a tad. If that's better, you're good. If that's worse, try moving the needle the other way.

EDIT: just don't forget what settings you have now. This is a safe setup to come back to and adjust differently. You want to only change one thing at a time

fierostetz · August 23rd, 2012, 03:50 PM

ok cool - I was just wondering if it was something ninja 2fiddy specific :P

some bikes have quirks, and the uninitiated can dump a lot of hours into trying to fix an accepted characteristic

thanks!

choneofakind · August 23rd, 2012, 03:53 PM

Read through that tuning guide I linked earlier as you go.

fierostetz · August 23rd, 2012, 04:00 PM

Yeah, if you think it's just carb tuning, I'll look into rejetting.
I was more concerned with the strong gas smell, but otherwise running mostly fine

thanks for the links, etc. I've got a bunch of goodies on order, and when I get to my dad's house this weekend, a healthy supply of extra jets. I may, in time, get ahold of an ex250 header and weld in a bung for my 02 sensor. If I decide to play with the lil ninja for long. I bought it for my wife but so far it's a hoot! 14k rpm! and not doing anything illegal! thanks!

August 20th, 2012, 01:24 PM	#1
fierostetz ninjette.org member Name: Shawn Location: santa ana, ca Join Date: Aug 2012 Motorcycle(s): klr 650, fz1, nighthawk 750, dr650, ex250 Posts: 39	Newly acquired 2003 w/ Muzzy - stumbling on off/on throttle and gas smell. Hey all - I just recently purchased a 2003 250, 1400 miles on it. Stock other than full Muzzy system. The PO says they had it rejetted at the shop they had the exhaust installed at. Bike feels pretty good (pulls thru rpm's ok, 95-100 without much effort with my 280lbs on it.) I want to get the bike running well so I can hand it off to my wife - all is good so far (ordered springs, valves, rear shock already) except for some strange throttle behavior. When riding, if I drop throttle and rapidly transition back on throttle, the bike seems to plug up for a minute then resumes acceleration. At idle or after decelerating there's a fairly prominent gas smell. Any thoughts on my description? I'll eventually order some jets and properly rejet the bike myself, but any input would be very welcomed not too familiar with ex250's yet. I know I need to adjust the float bowl height, but any other recommendations would be awesome.

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August 20th, 2012, 05:29 PM	#2
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	Gas smell + bogging = symptoms of rich. Open up the carbs to get an idea of what it has inside after being "jetted" How far are you getting back into the throttle after letting off it when you experience the rich symptoms? Read through this guide to get some idea how to jet, and think back through your rides and how the bike handles/responds. That should give you some idea of what needs changed in the bike.

August 23rd, 2012, 02:45 PM	#4
fierostetz ninjette.org member Name: Shawn Location: santa ana, ca Join Date: Aug 2012 Motorcycle(s): klr 650, fz1, nighthawk 750, dr650, ex250 Posts: 39	bah- found the gas smell. looks like PO de-california'd the bike and didn't cap the vent line on the back of the tank. Still stumbles with on/off/on throttle transitions, but runs great otherwise. Hard to tell if its not pulling well as I have nothing similar to compare it to. Feels weak compared to my klr650 and FZ1, but :shrug: - seems to top out at around 80 (indicated) with me sitting upright on it, and 95 or so (indicated) when I tuck in. I'm ~270 and dropping fast, so the bike will get faster as I get slimmer :P any thoughts on the on/off/on throttle stumble?

August 23rd, 2012, 03:33 PM	#5
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	play with your idle mix screws

August 23rd, 2012, 03:37 PM	#7
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	oh, pause. Up top? I thought it was when you were from off the throttle to back open to 1/3 throttle?

August 23rd, 2012, 03:40 PM	#8
fierostetz ninjette.org member Name: Shawn Location: santa ana, ca Join Date: Aug 2012 Motorcycle(s): klr 650, fz1, nighthawk 750, dr650, ex250 Posts: 39	apologies for a failure in conveying my issue properly On the road, 65-70mph (actual) if I drop throttle to 0% then open the throttle again, it bogs almost like there's too much fuel, then it pics back up again. It's fairly pronounced, and exacerbated by the soggy front springs (replacements get here tuesday!) as the bike dives for a split second.

August 23rd, 2012, 03:46 PM	#9
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	ok, so 65 mph, 7k-ish rpm, mid-throttle imput. Would you say that's about right? If it feels like a bog, try leaning up a section of your carbs. If it's the middle of the throttle range, try lowering the needle a tad. If that's better, you're good. If that's worse, try moving the needle the other way. EDIT: just don't forget what settings you have now. This is a safe setup to come back to and adjust differently. You want to only change one thing at a time

August 23rd, 2012, 03:50 PM	#10
fierostetz ninjette.org member Name: Shawn Location: santa ana, ca Join Date: Aug 2012 Motorcycle(s): klr 650, fz1, nighthawk 750, dr650, ex250 Posts: 39	ok cool - I was just wondering if it was something ninja 2fiddy specific :P some bikes have quirks, and the uninitiated can dump a lot of hours into trying to fix an accepted characteristic thanks!

August 23rd, 2012, 03:53 PM	#11
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	Read through that tuning guide I linked earlier as you go.

August 23rd, 2012, 04:00 PM	#12
fierostetz ninjette.org member Name: Shawn Location: santa ana, ca Join Date: Aug 2012 Motorcycle(s): klr 650, fz1, nighthawk 750, dr650, ex250 Posts: 39	Yeah, if you think it's just carb tuning, I'll look into rejetting. I was more concerned with the strong gas smell, but otherwise running mostly fine thanks for the links, etc. I've got a bunch of goodies on order, and when I get to my dad's house this weekend, a healthy supply of extra jets. I may, in time, get ahold of an ex250 header and weld in a bung for my 02 sensor. If I decide to play with the lil ninja for long. I bought it for my wife but so far it's a hoot! 14k rpm! and not doing anything illegal! thanks!