August 8th, 2020, 07:31 PM | #1 |
ninjette.org newbie
Name: Daimian
Location: Washington
Join Date: Aug 2020 Motorcycle(s): Z1000, M109R, Husky FX450 Posts: 6
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Rough running at low rpm
Hi everyone, my first post here and I’m hoping I can get some help, or confirmation, on what I think is wrong with the 2011 250 I just picked up. I did some searching and I’m pretty sure this is what my problem is but wanted to confirm the symptoms I’m having match my suspicions. The previous owner had left the bike sitting (indoors) for at least a few years. She said it ran fine before that (which I doubt at this point) so I got the bike already knowing I would be rebuilding the carbs. First thing I did was drain all the old fuel out and refill with fresh. I got the bike to start but it ran very roughly and you couldn’t give it any throttle. Fast forward to today - I rebuilt the carbs with all new jets, needles, etc... and reset the idle air screws to 2.5 turns out. The first thing that made me think the bike hadn’t been running right before I got it was that the idle air screws were nearly all the way closed (not to mention the o-rings and washers were on the wrong side of the spring). Anyways, got it back together, went to fire it up, ran for about 30s and died. Cranked it over again and nothing, then a big backfire. Did it a few more times and it was the same thing. Pulled the plugs and they were wet so I grabbed two new plugs and she fired right up and idled, roughly. So now the bike is running roughly but will stay running on its own. If you slowly feed it throttle it roughly revs up until it hits about 3k rpm and then it runs great. Above 3k, it’s perfect. Let it fall below that and it’s rough, I would consider rough to the level of unridable. My question is, when I was in the carbs doing the rebuild, I’m 99% sure I did NOT see the needle jets in either carb. These would be part number 16017-1417 in the Kawasaki Microfiche. I’m going to pull the carbs back apart tomorrow to confirm but can anyone confirm that these are the types of symptoms I would see if those pieces were missing? Also, is there anyone who has a pair of needle jets they would be willing to sell me? It looks like there is quite a wait to get them from any of the normal sources and I was hoping to get this thing on the road sooner then later. Thanks for any input you may be able to provide!
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August 9th, 2020, 11:49 AM | #2 |
ninjette.org newbie
Name: Daimian
Location: Washington
Join Date: Aug 2020 Motorcycle(s): Z1000, M109R, Husky FX450 Posts: 6
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Pulled the carbs out this morning and confirmed what I thought. Looks like I’m missing the needle jets. Can anyone confirm this would cause the symptoms I described above or should I be looking elsewhere for additional issues? Thanks!
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August 9th, 2020, 12:59 PM | #4 |
Rev Limiter
Name: Jay
Location: WI
Join Date: Jul 2013 Motorcycle(s): '06 SV650n, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes Posts: A lot.
MOTM - Jun '18, Oct '16
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Absolutely will not run properly as is.
You need needle jets - no doubt. |
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August 9th, 2020, 02:03 PM | #5 |
ninjette.org certified postwhore
Name: Gordon
Location: new york
Join Date: Sep 2009 Motorcycle(s): '95 DUCATI 900SS/SP '07 DUCATI SS800 '19 HONDA CBR650R Posts: A lot.
MOTM - Nov '18, Mar '17
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DIY is often accompanied by do overs and trial by fire. OP should have determined critical parts missing in 1st go around.
Sorry but I can't accept the comment "running great" without needle jets, an integral component of the main mixing chamber. Predicting the need for further actions, beyond needle jet replacement, is impossible. Replace them, then reevaluate performance based on real world riding conditions.
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gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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August 9th, 2020, 02:21 PM | #6 | |
ninjette.org newbie
Name: Daimian
Location: Washington
Join Date: Aug 2020 Motorcycle(s): Z1000, M109R, Husky FX450 Posts: 6
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Quote:
With all that said, my main question is IF the needle jets were left out, is that the type of result one would expect (low rpm stumble with clean running in mid-high rpm range)? Unfortunately I have nothing to compare to as I’ve never had a ninja 250 or ridden one before. I’m sure I’m not the first person to have tried running one without the needle jets and there should be some sort of idea what stage of fueling they affect. Lastly, does anybody have any laying around the would be willing to sell? I can get them through my normal parts source but shipping is something like 3 weeks out and I was hoping to get this thing back on the road sooner then later. Thanks for any info in advance! Last futzed with by Macd7919; August 9th, 2020 at 05:01 PM. |
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August 9th, 2020, 06:49 PM | #7 |
ninjette.org certified postwhore
Name: Gordon
Location: new york
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I'm not sure of the compulsion to discuss what the exact running ramifications of missing needle jets entail, they absolutely, automatically need to be replaced.
I'd dissuade envisioning some sort of a "workaround", if thats where you are going with this?
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gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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August 9th, 2020, 08:09 PM | #8 |
ninjette.org newbie
Name: Daimian
Location: Washington
Join Date: Aug 2020 Motorcycle(s): Z1000, M109R, Husky FX450 Posts: 6
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Well, the first question regarding what that particular circuit in the carb affects is for my own personal knowledge, and, also because I like to know that I’m more or less OK to leave the remainder of the carb as-is and not go digging deeper for “other” possible issues while I have it out. It seems to be a relatively straightforward answer as carbs are relatively simple contraptions but maybe there is something I’m missing that makes it more complicated.
Your second question I’m not quite seeing where I was asking for a workaround. I’ve asked multiple times in this thread if anyone has a spare set of needle jets they would like to sell. To me, that’s painfully obvious that I’m planning on replacing them and even went as far as to explain that they are 3 weeks out from my parts distributor and I’d like to get the bike back on the road by then. In my first post I said it was unridable as is, so putting it back together just to be in the same manner really wouldn’t do me much good. So, again, I’d be interested to hear what that circuit (the one with the needle jet) affects so I have a better understanding of what I’m working on with this particular carb. Also, if anyone has a couple needle jets available they would be willing to sell I’d be happy to buy them from you. Thanks! |
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August 9th, 2020, 09:33 PM | #9 |
ninjette.org member
Name: Emu
Location: Oklahoma
Join Date: Jun 2019 Motorcycle(s): 2011 Ninja 250r Posts: 55
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https://www.ebay.com/itm/Kawasaki-20...75.c1#viTabs_0
Found a listing on ebay for what looks like a US stock of this part. Says 3 in stock. I'll poke around some more if you want. |
1 out of 1 members found this post helpful. |
August 9th, 2020, 09:54 PM | #10 | |
ninjette.org newbie
Name: Daimian
Location: Washington
Join Date: Aug 2020 Motorcycle(s): Z1000, M109R, Husky FX450 Posts: 6
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Quote:
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August 10th, 2020, 11:19 AM | #11 |
ninjette.org certified postwhore
Name: Gordon
Location: new york
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MOTM - Nov '18, Mar '17
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needle jet = spray nozzle of sorts, placed prominently smack center of venturi. If its missing, proper atomization and spray will be compromised. As the throttle plates are opened, venturi velocity increased, slide rises, needle taper determines clearance...normally creating an atomized fuel "spray". But without the needle jets, the sunken emulsion tube is then the next surface exposed to venturi. The ID of the (now missing) needle jet and the ID of the emulsion tube differ, as well as their placements.....resulting in unmetered fuel entering the venturi.
Think of your garden hose with spray nozzle on, then removed. As the presence of needle jets (all parts, for that matter) is confirmed both in receiving from user and final shipping of finished carbs within my service...never an issue, nor ever needed to become one. I'll now yield to other members further comments.
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gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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August 10th, 2020, 01:02 PM | #12 |
ninjette.org certified postwhore
Name: AKA JacRyann
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MOTY - 2018, MOTM - Nov '17
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The reason it’s worse at idle is due to variable AFR due to change in air-flow volumes at idle versus high-RPM/WOT. Without needle-jets in place, idle AFR is way too rich given full-flow from emulsion tube. With more air-flow, this large amount of fuel isn’t as overwhelming, so it appears to run better. But is still too rich. Less bad is still not good or perfect.
Yeah, shops all suck at working on carbs. Mine sat at shop for 3-days before they called me asking how to plug in OBD-scanner! |
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August 10th, 2020, 05:38 PM | #13 |
ninjette.org newbie
Name: Daimian
Location: Washington
Join Date: Aug 2020 Motorcycle(s): Z1000, M109R, Husky FX450 Posts: 6
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Thanks guys, that’s the info I was looking for. I suspected it was running way rich on the bottom end and then once it got past the point where that circuit was having a large effect, in my case, about 3k rpm, it got back to a reasonable AFR and ran clean. Well, I bought the bike knowing it needed a carb rebuild so overall it’s not a huge deal but now the picture is much more clear as to why the bike was sitting. I understood, or they knowingly let me believe at least, that they just stopped riding it for personal reasons and it sat until they were moving to Chicago and didn’t want to take it with. They conveniently forgot the part about it running like crap prior to parking and not being able to fix it. My first inkling something was wonky was the idle air screws being turned nearly all the way in (like, 1/8 turn from bottomed out). Oh well, in the end not a huge deal. Thanks again for the info!
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August 11th, 2020, 10:05 PM | #14 |
ninjette.org certified postwhore
Name: AKA JacRyann
Location: Mesa, AZ
Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot.
MOTY - 2018, MOTM - Nov '17
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Never ever believe anything bike-sellers tell you! There’s ALWAYS something to hide.
Oh, BTW, when those needle jets come in, be careful not to install them upside down. Tapered end faces needle! |
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August 14th, 2020, 07:09 PM | #15 | |
ninjette.org member
Name: Emu
Location: Oklahoma
Join Date: Jun 2019 Motorcycle(s): 2011 Ninja 250r Posts: 55
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Quote:
It's taken me a little time and a little money but I am slowly getting the bike where I want it. |
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