August 2nd, 2017, 05:41 AM | #1 |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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Engine Feels Like It's Missing at Medium Speed. Any Ideas?
Hi Everyone,
I recently just started riding (about 3 weeks ago) and I got a hand-me-down 93 Ninja 250. I'm the third owner of the bike and I've had quite an exciting time trying to get it to run reliably (first owner used it as a track bike). Originally, I knew I was flooding the carb, as I could get it to run and idle, but then after a while it would die. If I let the bike run with the fuel valve turned off, and then only turn it on for a bit when I heard it bog down, I could get it to run indefinitely. After ripping the carb apart, soaking it in Berrymans chem-dip, and replacing the float needle valves, I believe I've fixed the flooding problem. Recently though, as I'm riding at about 50 mph, I feel like the engine is kicking in and out. Holding the throttle at a steady 25 - 30%, I feel power come in spurts. Opening up the throttle any more doesn't help. After getting home I checked the fuel line from the fuel petcock to the carb, and the fuel level inside of my inline filter looks kind of low, so I'm not entirely sure that I'm filling the bowls enough while I ride. I've done quite a bit to this bike so far, as some parts were beyond cleaning / repair. Here's what I've done to the bike so far: 1) Yoshimura RS-3 slip on Exhaust. 2) 112 size main jets (stock ones were beyond recovery). 3) New float needle valves. 4) New NGK Plugs. 5) Oil Change (Castrol 10w - 40) 6) K&N RC-1822 intake filters 7) New Battery 8) New Mid Throttle Needles (e-clip on third notch). 9) Idle screws backed out to 3 turns. 10) Chopped air box (to make room for filters). 11) New fuel petcock. 12) Clear fuel tube with inline filter from fuel petcock to carb. In the case that I'm not getting enough fuel to the carb bowls, does the fuel petcock use the vacuum that is supplied by the outlet of the carb to pressurize the fuel and push it into the carb, or does it just allow gravity to take hold and fill the bowls? If the former is true, then I might have a bad fuel petcock...which would suck cause it's new. I'm open to any suggestions at this point, as I'm getting kind of frustrated . By the way the attachment is a look at the fuel line from my fuel petcock to the carb after a ride. Went from 50mph, to about 25 (subdivision), to stop. |
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August 2nd, 2017, 09:24 PM | #2 | |
ninjette.org member
Name: Austin
Location: Minneapolis MN
Join Date: Jul 2017 Motorcycle(s): 2001 ninja 250r Posts: 10
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Quote:
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August 2nd, 2017, 11:40 PM | #3 |
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MOTY - 2018, MOTM - Nov '17
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Have you done the gas cap mod?
During this mid-range stumble, if you drop down a gear or two to increase RPMs, does it run smooth again? |
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August 5th, 2017, 05:25 AM | #4 |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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When I bought the petcock, I was under the assumption that it was an OEM replacement. Getting it, it came in a "Kawasaki genuine parts" box, and seemed good. Is there anything in particular that I can look for on the petcock to validate that it is a Kawasaki original?
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August 5th, 2017, 05:31 AM | #5 |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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I'm not entirely sure what you mean by the gas cap mod, but everything looks stock up top on the tank. Dropping down a gear does not seem to give me back my throttle response. I do find, however, that if the bike starts to miss at around 50 mph, if I pop the clutch in, rev a few times and hit the bogging point, the bike seems to open up again and I have proper throttle response. For kicks, I also rode around my neighborhood with the fuel valve shut off in order to see what the bike feels like when it's starving for gas. It feels very similar to what's happening at 50 ish mph. Also, from a stop sign or stop light to acceleration, if I'm pulling on the bike decently hard, say 8k to 10k rpm, the bike never bogs during that time and will bog directly after if I try to drop to just a cruising speed.
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August 5th, 2017, 06:40 AM | #6 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
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Is it possible the problem depends on the position of the twist grip, and not engine RPM?
From what I'm reading, it's starting to sound like you have a lean region somewhere like 1/2 throttle, maybe from the non-stock air filters and needles that may not be the right ones, or set to the correct position. You could try raising the needles a notch and see if the problem changes. |
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August 5th, 2017, 06:52 AM | #7 | ||
in your machine
Name: Scott
Location: Summer Shade, Ky.
Join Date: Oct 2014 Motorcycle(s): 98 Ninja 250/F12 aka ZX-2R "SERENITY", 91 Ninja 500/A5 aka ZX-5R "Phoenix", 84 Honda GL1200A "SIREN" Posts: A lot.
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Have you serviced the spark plug caps and renew the HT leads?
Write up Even bad plugs should do something, unless they are totally shot. Did you renew the HT leads, and disassemble the caps? Make sure you disassemble the caps, and clean them, and yes the caps get cruddy. Here my write-up, Quote:
Wires are just 7mm copper core, with clear silicone jacket IMPORTANT NOTICE: make sure to use a proper screwdriver, make sure it fits, as the parts are made of brass inside the spark plug caps Important notice: the wire must be screwed on the spark plug cap, note the screw like object inside the spark plug cap? Important notice: be careful to not loose the ferrules on the HT leads, these keep the wire from falling out of the coil. Below is an example of ferrules on a pressure fitting, looks familiar? The gas cap mod is as follows, Sounds like it could be a venting issue, no worries it's a free and easy fix, Quote:
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violente et ignorantia ZX-2R BLOG Twitter and Instagram = Ghostt_Scott I'm not here to change your mind, just to inform. |
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August 6th, 2017, 12:54 PM | #8 |
ninjette.org guru
Name: AJ
Location: Green Valley, IL
Join Date: May 2017 Motorcycle(s): 2001 Kawasaki Ninja 250r(SOLD) 2006 Kawasaki Ninja 250r full Muzzy(my pride and joy) Posts: 331
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Slap these puppies on that bike so you don't have all the fluid reservoirs showing and hanging out. You can look and get them much cheaper. Does wonders for the looks too. If that's your bike in the pic of course. As far as your issue definitely look into what ghostt posted. That's some valuable info.
http://m.ebay.com/itm/1998-Kawasaki-...%257Ciid%253A1
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"A car or truck will get you from point A to B. But a motorcycle, that is the point." -unknown |
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August 8th, 2017, 09:56 AM | #9 | |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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Quote:
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September 24th, 2017, 06:11 PM | #10 |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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Engine still cutting out...
So as it turns out, I didn't solve the problem. I did the aforementioned items with the gas cap and spark plugs, but that hasn't fixed the problem. Cruising along at 50mph with the throttle maybe at about 35%, I still feel power cutting in and out. As you can see from my profile photo, I don't have a windshield, and so when it's really windy, it gets worse. I'm wondering if this is due to my needle height in the carb? I'm guess I'm asking you guys to tell me if this is a bad assumption to make based on the evidence I have. From what I've read, 35% throttle is in the ballpark of percentage where the carb is switching from pilot jets to the mid-needles. Along with the larger main jets that I installed, I put in the needles with adjustable e-clips. I'm guessing that when switching to the needles, the needles are seated too deep which starves fuel and causes me to run lean. Is this logical troubleshooting thought?
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September 24th, 2017, 07:17 PM | #11 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot.
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I'm not saying you should assume you need to do this, but I had steady throttle surging on my pregen until I shimmed the needles about 1/2 mm. Maybe Ducatiman can comment.
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September 24th, 2017, 08:11 PM | #12 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
Join Date: Mar 2017 Motorcycle(s): 2007 Kawasaki 250 Ninja, 1982 Honda Ascot FT500 Posts: A lot.
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Quote:
Bill
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Insanity: doing the same thing over and over again expecting different results each time. |
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September 24th, 2017, 08:22 PM | #13 | |
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Quote:
1. adjust needles one setting towards richer and see how bike responds. If it's better, it was lean 2. if not better, it was too rich already, so adjust needs one setting towards leaner from original position and see how it runs. This was the '60s method for carb-tuning before EFI and electronic datalogging was available. The process was to initially add too much fuel for safety so you know for sure it's too rich. Then gradually lean it out until HP-improvements level off. There was a saying that goes along with this process, anyone remember it? Last futzed with by DannoXYZ; September 25th, 2017 at 09:50 PM. |
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September 24th, 2017, 08:28 PM | #14 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot.
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You can also make a quick stab at the enricher lever for the same purpose. If it helps, it's too lean.
Bill, there is only one clip position, but you can use one or more washers (shims) under the clip to raise the needle. |
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September 24th, 2017, 09:55 PM | #15 | |
ninjette.org certified postwhore
Name: Bill
Location: Port Huron, Michigan
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Bill
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Insanity: doing the same thing over and over again expecting different results each time. |
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September 25th, 2017, 06:26 AM | #16 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
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I'm the one who speed-read the post, Bill. I missed that he had adjustable needles.
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September 25th, 2017, 06:33 AM | #17 |
Rev Limiter
Name: Jay
Location: WI
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A 112 Keihin Main Jet might be too rich. What do the plugs look like?
3 turns out on the idle mixture screws is unusual. Most of the time 2 to 2.5 is optimum. I would move the clip on the needle 2 spots leaner (up) and see how it runs. Another possibility is a damaged or misaligned carb diaphragm. Did you remove the idle mixture screws, clean the passages, and look at the condition of the o-rings before replacing the screws? Did you remove and clean the Pilot Jets? What gas are you running? How old is it? |
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September 26th, 2017, 05:29 AM | #18 |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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It's not a Keihin 112, it's a factory pro 112. I'm not sure if they're different, but I know that some jet brand sizes don't compare. The reason that I originally put it in was because the stock ones were corroded and far past saving. I'm trying to mod the bike around that, so i bought Yoshimura pipes and have been trying to tune ever since. Any idle screw setting under 2.5 won't let me start the bike even with full choke on. A while ago I tried one clip level up, and the bike in neutral would bog and die at anything past 1/4 throttle. I did not remove the idle mixture screws before cleaning, but I did remove and clean the pilot jets. Before I had the bike, I have no idea what gas was being run though it, but I stick with 91 octane ethanol free gas.
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September 26th, 2017, 06:02 AM | #19 | |
Rev Limiter
Name: Jay
Location: WI
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Quote:
That tells me something isn't right with the carbs. Partially plugged idle mixture passages, or damaged o-rings, may be some of the problem. Most likely the carbs need additional attention as well. Check around for more info, but I still think a 112 Main Jet is too much. We ran pods, a leaky factory system (that was loud), and 108 Keihin Mains and a shim or 2 on the factory needles. Pulled strong and clean all the way to redline, where it spent a good amount of time. We were running 87 octane ethanol-free. Gas without ethanol does give you a slightly richer mixture than gas with ethanol. |
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September 26th, 2017, 06:38 AM | #20 |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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I'll see if I can open up the carb on the weekend and check out the idle screw passages. Shouldn't be anything some compressed air and some new gaskets couldn't fix. I'm a college student so time is scarce. I'm not sure what I've got on hand, but I think I've got 110 jets sitting in the jet kit I received with the bike. Assuming that I'm running lean right now, and I switch out my 112's for 110's, would I have to shim (or shift my eclips down), even more? It's to my understanding that the needles even though the 25% to 75% throttle range still pull gas through the main jet. In this case am I right to assume that less gas will make it though? I do believe I'm running lean as, shifting my needles down really killed my throttle response last time I tried. I know for sure that I'm running rich on idle, as blipping the throttle at idle, the tach dips below idle before returning to normal. Also, I've never had to use choke on a cold morning. I'll play with idle screws a bit more before I decide to totally take them out and screw up any gasket I might have left in there.
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September 26th, 2017, 06:46 AM | #21 | |
Rev Limiter
Name: Jay
Location: WI
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Quote:
I think the carbs may need more than just carb cleaner and compressed air to be right, especially because you said the Main Jets were beyond cleaning when you got it. Overall, a few things don't make sense to me. I would consider shipping the carbs off to ducatiman to have them gone though thoroughly if you don't have access to proper tools and have limited time. |
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September 26th, 2017, 08:41 AM | #22 |
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Yeah, the not starting with mixture screws in more than 2.5 turns even with choke is clue that some of circuits are clogged.
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September 26th, 2017, 09:51 AM | #23 | |
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Name: Bill
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Bill
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Insanity: doing the same thing over and over again expecting different results each time. |
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September 26th, 2017, 07:23 PM | #24 |
ninjette.org guru
Name: C
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Not sure this applies to you but recently my bike started bogging, kept cleaning the carbs and playing with the jetting but nothing worked. Ended up that some of the vacuum lines on the carb had cracks in them. Replaced all the vacuum lines on the carb and the bike was good to go.
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September 27th, 2017, 03:28 PM | #25 |
ninjette.org member
Name: Patrick
Location: NC
Join Date: Nov 2015 Motorcycle(s): DR350, Ninja 250 Posts: 69
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The amount of air passing through the carb at idle is significantly less than that at 35% throttle. Gut feeling tells me that even with a screwed up idle circuit, that's probably not the smoking gun.
Often, aftermarket exhausts combined with different air boxes / filters can be a real bear to jet correctly. I had some serious surging issues at cruise RPMs when my jetting wasn't sorted out, and I bet you do, too. |
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November 24th, 2017, 08:32 AM | #26 |
ninjette.org member
Name: Ethan
Location: South Lyon, Michigan
Join Date: Jul 2017 Motorcycle(s): 1998 Kawasaki Ninja 250 Posts: 24
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Whelp given the time of year the bike is back home in the garage while I'm off at university. For a bit, getting it to start in the morning took about a minute of cranking, which isn't good. Kestrel you are correct in that I get surging issues when it comes to cruising RPM's. I'm not sure why it took so much cranking at cold to get the bike running. It felt as if I was getting combustion, and I just needed to hold the starter down long enough for the combustion to warm the block so that it could self sustain. Yesterday I prepped the bike to be stored for the winter (took all the fuel out and drained the carb bowls), and I decided to take the plugs out. The left plug (left if you're sitting on the bike) was covered in oil....uh oh. The right plug was white on the tip (makes no sense since I think I'm running really rich). I've definitely got some work cut out for me. I think I'm going to try a couple of different things with the carbs, but if I can't come up with anything I'm going to send the carb off to ducatiman. Also, does anyone know a good resource for learning the tear down process of the engine? I'm guessing that I need to replace piston rings if I'm seeing oil on the plug. I'm sure I can get the engine apart, but I'm not so sure that I would re-assemble it correctly. I'm not to keen on the whole timing chain and cam shaft positioning when assembling the upper.
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December 1st, 2017, 09:57 AM | #27 | |
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https://www.ebay.com/itm/Kawasaki-Se...tY5oww&vxp=mtr It's a good price too. Kawasaki wants about $50.00 for the same thing. Bill
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December 1st, 2017, 10:26 AM | #28 |
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Name: AKA JacRyann
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Oil leaking into cylinders can come from multiple sources. Aside from rings, it can also be from valve-guide seals. Which can actually be replaced without tearing down the engine or even removing the head! Do a leakdown test to determine if it's rings or valves that's leaking.
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