May 28th, 2022, 07:51 PM | #1 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Fueling help
Hi All,
I just picked up an '08 250R with OEM carbs and an off brand aftermarket carbon can. I am trying to get it prepped for race weekend next week. It was bogging bad. So I rebuilt the carbs, replaced the plugs (man the bike was run lean) and have backed out the mix screws 3 full turns. It now revs out really strong- no bog. But if I rev it hard and hold throttle at say 9000 rpm it dies off to 6000 or so as I holding the throttle in the same place. And the exhaust pops a lot. My guess is it is still too lean, but my question is should I continue to back out the mixture screws or shim the needles? It seems like shimming the needles would be the right thing since it would give more fuel through the whole rev range? Any help is appreciated. Thanks |
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May 29th, 2022, 12:37 PM | #2 |
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MOTY - 2018, MOTM - Nov '17
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Might be lean because carbs still aren't factory fresh clean. Bike ran perfectly fine when leaving showroom floor and revved to redline without any problems. When you get carbs back to factory-fresh clean, it'll run like that again. Some tips:
- complete disassembly down to every last nut, bolt and individual component. - scrub everything with PEA-based fuel-system cleaner. Spray "carb cleaners" no longer work due to removal of chlorinated compounds. don't forget secret hidden passages http://n4mwd.blogspot.com/2013/10/se...-passages.html - poke out all bleed-holes in carb-venturi, emulsion-tubes and pilot jet with matching size soft copper wire -ultrasonic soak and micro-soda blast everything - replace all rubbers when re-asembling: float-valves, fuel-rail O-rings, pilot-screw O-rings, float-bowl seals, even carb-diaphragms if needed - set float-levels & wet-test - sync carbs in bench and on bike do search on here for "clean carbs ducatiman" for guides and photos |
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May 29th, 2022, 02:16 PM | #3 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Cool. Thanks. I thought I got in there pretty deep and replaced almost everything, but didn't get as deep as your pic shows. I'm going to be good at pulling this carb when this is all done.
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May 29th, 2022, 04:04 PM | #4 |
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MOTY - 2018, MOTM - Nov '17
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Don't worry, many expert mechanics have had to pull carbs 4-5x for ever deeper cleaning before they were factory-fresh clean! One guy had to pull them 10 TIMES!! Might as well do complete restoration job 1st time around. I missed 1st race of my 2nd season because I thought I had "cleaned carbs" sufficiently, nope... Luckily, I had 2nd set of carbs professionally refurbished by ducatiman. Swapped those in and was able to do my remaining races that day and next.
Parts that you can replace are only 5% of job. Needs to scrub entire fuel flow-path from beginning to end. Some of those hidden secret passages have 90-degree bends you can't get scrub-brush through. Thus ultrasonic cleaner. Disassemble emulsion tubes pilot-jets from carbs and poke out all bleed holes with soft copper-wire. Dried petrol gets pushed out like little grains of sand. Your model has solid emulsion tube, but should still be scrubbed out inside. Don't forget petcock. If carbs are dirty, petcock most likely also. Replace screens, seals. Make sure petcock flows sufficiently, otherwise brand-new factory-fresh carbs still won't work. Also replace internal filtre. Many are wadded up from being installed backwards. Best to replace with inline filtre that can be inspected easily. Got pack/10 for cheap from off-road shoppe. |
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May 29th, 2022, 07:47 PM | #5 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Son of a carb. 10 times? I've got the inline filter already. Will add checking the petcock to the list. I am suspicious of it. I went ahead and did the needle shim anyway because the plugs were just about burned away.
Thanks for the info! |
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May 30th, 2022, 02:37 PM | #6 |
Its not a 250,its a Ninja
Name: Shaun
Location: Little Rock, AR
Join Date: Jun 2012 Motorcycle(s): '12 Ninja Kaw, '22 CFMOTO 300NK Posts: 275
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Never did a carb cleaning that was 100% without a minimum of 3 removals/cleanings. Blessed be those with fuel injection.
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May 30th, 2022, 03:15 PM | #7 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Yeah, when I upgraded my CRF I went for the '10 just for FI. I guess I never learn.
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May 30th, 2022, 06:10 PM | #8 |
ninjette.org member
Name: Ben
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It s all apart and being cleaned. Petcock passed the vacuum test. The question now is how do you know if the diaphragms are shot?
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May 30th, 2022, 06:37 PM | #9 |
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MOTM - Nov '18, Mar '17
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"The question now is how do you know if the diaphragms are shot?"
*any* holes, rips, tears, folds, etc. are no good, requiring automatic replacement. When reassembled, a *slight* blast of compressed air at the upper intake openings (see pic) should raise each slide. *Go easy with air blasts.
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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May 30th, 2022, 08:45 PM | #10 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Thank you! I had one with a small tear in the lip where it seats and the other has what seems like a "bubble" in the cone. Like it's stretched out in one spot- kind of worldly. Ordered new rubbers.
Also took off the Kleen Air system and ordered a block off plate. About ready to rip out that airbox too. But I don't want to have to order new jets. If I go to pods will needle shimming be enough do you think? Thanks again. |
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May 30th, 2022, 09:14 PM | #11 |
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MOTY - 2018, MOTM - Nov '17
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Why pods? Nothing but trouble. Search here for "pod filters" and all you will find are people asking for stock airbox to rip out their pods. Causes mid-range stumblings that cannot be tuned-out. When hitting cross-winds, bike will stumble and almost die. Way, way too many side-effects for zero gains.
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May 30th, 2022, 09:45 PM | #12 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Interesting. I was seeing a bunch of pods and people hating on the airbox. I don't have a problem with it other than I am pulling the carb a lot and its in the way. Is it going to be a problem that I ripped the snorkel off?
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May 30th, 2022, 10:28 PM | #13 |
ninjette.org certified postwhore
Name: AKA JacRyann
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MOTY - 2018, MOTM - Nov '17
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Fine-tune technique and you can pull carbs in under 10-min. I have write-up somewhere, might make DIY post. Maybe I update with video. I do it twice a day @ track, 4x in one weekend, no problems with airbox installed.
Removing snorkel's one way to increase power. Worth about +1 bhp! Can't believe AFM bans removing it in stock class! Last futzed with by DannoXYZ; May 31st, 2022 at 09:30 AM. |
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May 31st, 2022, 08:18 AM | #14 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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I remember seeing your 10min thread. I think maybe in the DIY list? I'll check it out.
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June 1st, 2022, 07:15 PM | #15 |
ninjette.org member
Name: Ben
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Update: Everything has been cleaned in all ways except for soda blast- cuz I don't have that. I ordered new diaphragms and slides and a new air cut off diaphragm- the old one looks all wavy.
Since I am determined to figure this out or destroy it in the process (then ducatiman rescue as a last resort) I need more help please. Question: Is the assembly of the air cut off valve in correct order and I seem to have a spring and a plastic washer I don't know what to do with- diagrams are not helping. I used the plastic washer with the flange under the throttle nut and two like this one are under the choke slide screws- this one needs a home. And I have the choke return spring in place. Pictures attached. Really appreciate all the help so far. This is my first dual carb and it turns out it's twice as much to keep track of. |
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June 2nd, 2022, 04:33 AM | #16 |
ninjette.org certified postwhore
Name: Gordon
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you seem to be missing the tiny oring/seal located in the cutaway between sections i've pictured.
The white seal in your pic is 1 of 4, located over/under 2 mount points of choke lever and your spring is the choke return spring or decel valve spring? Difficult to discern the length of the spring in your pic of decel valve.....? May be incorrect....length necessary to better judge it.
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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June 2nd, 2022, 05:08 PM | #17 |
ninjette.org member
Name: Ben
Location: Portland
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O-ring! Thank you!
Here are pics of the springs with measurement. The shorter one was what I had in the air valve in the previous post, the longer one is the loose one in my previous post. The other pic is of the two with the carb and choke slide bring installed for reference. Ducatiman, your pics look like you have the longer of the two in the air valve? I am thinking the shorter one may be part no. 92081B but in the parts diagram it is not clear where it goes in the butterfly shaft assembly- this could be totally wrong. Thanks again for the guidance. |
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June 2nd, 2022, 05:27 PM | #18 |
ninjette.org certified postwhore
Name: Gordon
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the longer of your 2 springs is, in fact, the decel valve spring. The shorter one goes between the 2 carbs, separating the throttle shafts.
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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June 2nd, 2022, 05:29 PM | #19 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Awesome! Thank you!
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June 3rd, 2022, 05:45 AM | #20 |
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may want to assure your needles are in correct orientation....
N9VU in LH CARB, N9VW in RH
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com Last futzed with by ducatiman; June 3rd, 2022 at 09:29 AM. |
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June 3rd, 2022, 09:25 AM | #21 |
ninjette.org certified postwhore
Name: Gordon
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curiously enough....i've found in the new-gen set I'm currently refurbing that exact scenario! Somebody previous had them reversed...made a big boo-boo.
Its a fairly common error I've encountered prior.
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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June 3rd, 2022, 09:27 AM | #22 |
ninjette.org member
Name: Ben
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Are these the needles themselves or the collar? I can't find what those numbers mean? The needles and collars look the same to me......
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June 3rd, 2022, 09:35 AM | #23 |
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the actual jet needles are marked near the top and differ left and right. No idea precisely what the numbers mean, though. Prior to any shimming, I'd suggest confirming correct orientation.
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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June 3rd, 2022, 06:24 PM | #24 |
ninjette.org member
Name: Ben
Location: Portland
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Thank you again! These are my needle choices. The silver ones are what was in the bike and they seem to be the first gen shape? But this is an '08. The gold ones are new and seem to be the correct shape, but they are unmarked. The silver ones have N9VU and N9VV. SO, it looks like I need to go with the old needles seeing as how the new ones aren't marked. I had to use my phone's extreme zoom and wear my glasses to even come close to reading those markings. Never would have noticed if you hadn't said something.
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June 4th, 2022, 05:51 AM | #25 |
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N9VU in left carb, N9VW in right carb .....verify and confirm!
unless aftermarket, part # markings will appear on the thick area beneath head
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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June 5th, 2022, 06:06 PM | #26 |
ninjette.org member
Name: Ben
Location: Portland
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EDIT: found where it goes. Finally found a video where it was clearly there behind the synch adjust screw. ONWARD!
OK. Race weekend. No carb work to date other than getting parts in the mail. I got an email that said DannoXYZ commented on the needles even though I can't see it here. Thank you for that. SO, my new air valve (deceleration) diaphragm came in the mail. Turns out the spring that cam with it is the same size as the one the previous owner had between the choke levers. (You can see how it is all weird in my previous post. I compared it to Ducatiman's air valve picture and it the same. SO, I have three springs. One is the longest- seems to be decelerations air valve spring. Then there are the two I posted earlier. I assume the longest of those two is the spring between the chokes. It seems to fit well there. Then there is the shortest one. It is not for the needles and it is not for the synch screw. "The shorter one goes between the 2 carbs, separating the throttle shafts." Where is this exactly? I don't see another external spring on any pictures I can find. I am hopeful the wrong spring being in the deceleration valve is the root of my problems once this is all back together. |
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June 6th, 2022, 04:57 AM | #27 |
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ok?
__________________________________________________
gordon@customcarbservices.com Custom Carb Service www.customcarbservices.com |
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June 6th, 2022, 09:07 AM | #28 |
ninjette.org member
Name: Ben
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Yep! That's the one. Thanks! I don't know why I didn't see it before.
The two spring here are the new air valve and the one that was originally between the chokes Whoever worked on this before obviously didn't join ninjette.org |
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June 6th, 2022, 05:27 PM | #29 |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Success! Winds out strong. No bogging. No midrange loss (adjusted mix screws 2 3/4 out, added two 3mm washer shims- also removed Kleen air and installed block off plate.)
Things learned: clean means clean not half clean. Don't mix up your springs. And, if you buy a used bike never trust the "work" that was previously done to it. Thanks for all the help. Seriously couldn't have done it without you Ducatiman and DannoXYZ. Really appreciated. |
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June 23rd, 2022, 11:24 PM | #30 |
ninjette.org member
Name: Ben
Location: Portland
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Workin' good now! Thanks again!
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July 3rd, 2022, 04:19 PM | #31 |
Its not a 250,its a Ninja
Name: Shaun
Location: Little Rock, AR
Join Date: Jun 2012 Motorcycle(s): '12 Ninja Kaw, '22 CFMOTO 300NK Posts: 275
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July 10th, 2022, 05:06 PM | #32 | |
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Quote:
I ran across this thread and saw that someone mentioned 2 different needles. I so I guess I have to pull the carb again to see if they are placed correctly. Is there anything else sided in this carb? I don't have a FSM (yet) and I wanted to get moving on this project but I guess i'm paying the price now. |
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July 11th, 2022, 01:48 AM | #33 |
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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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Did you scrub out secret hidden passages?
http://n4mwd.blogspot.com/2013/10/se...-passages.html Poke out all bleed holes with soft copper wire (especially ones in carb venturi)? Ultrasonic soak is only to clean up chads and scruff left over from these processes. Micro soda-blast everything? ultrasonic does very little without these other steps You'll also need to replace all rubbers: Fuel-rail O-rings, pilot-screw O-rings, float valves, float bowl seals. Then adjust float-level with wet-test ultrasonic is just 1st 5% of getting these carbs working... Many experts who know these bikes like back of their hands have had to pull carbs 4-5x for ever deeper cleaning before they got them factory-fresh clean. One guy had to pull his carbs 10x!!! http://n4mwd.blogspot.com/2013/10/se...-passages.html Last futzed with by DannoXYZ; July 16th, 2022 at 08:51 PM. |
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July 11th, 2022, 06:13 AM | #34 |
ninjette.org member
Name: Paul
Location: arlington
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I did not soda blast the carb but it is all cleaned out. Passages are all clear (even the tiny ones on the choke circuit).
I did notice 2 things after reading this thread. First I didn't realize there were 2 different needles, second the needle seal/collars were in the bottom of my ultrasonic tank (didn't realize these were not pressed in). Will order new rubber orings and get this back together with the collars and needles in the correct position. |
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July 11th, 2022, 06:13 PM | #35 | |
ninjette.org member
Name: Ben
Location: Portland
Join Date: May 2022 Motorcycle(s): '10 Ninja 250R (track), '20 Street Triple 765 (street), '12 CRF150R SM (racing) Posts: 55
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Quote:
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