July 23rd, 2019, 04:57 AM | #1 |
ninjette.org member
Name: Garry
Location: Bungendore Australia
Join Date: Jan 2019 Motorcycle(s): GPX250 1989 model and 1990 model Posts: 98
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Valve adjustment so far out?
Bought a pretty ratty looking 1990 GPX250 for a parts bike. It had 65000km on it and was real cheap. Got it running and couldn’t believe how well it went. Nice quite motor that idles perfectly with no carb problems what so ever. Runs nicely right through the rev range and topped out at 170kph. Only noise was the usual rattle from the clutch basket. So instead of using it for parts I decided to make a cafe racer out of it as all the plastics were wrecked.
Got most of the bodywork, frame and wheels refurbished and before putting the tank back on decided to do a valve adjustment. Found all the exhaust valves to be at 0.005”, just about perfect. Two of the inlet valves were at 0.004” which is also just about perfect but the other two (one on each cylinder) were set at 0.013”. Couldn’t believe it ran so well, and quietly also, with both these inlet valves so far out of adjustment? Both the suspect valve adjuster nuts were tight so I can only assume the previous owner set them this way accidentally on purpose? Go figure?
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July 23rd, 2019, 09:42 AM | #2 |
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Were those two valves on same cylinder?
Most likely whoever did adjustment didn’t have cam rotated to fully closed position when they measured clearance. |
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July 23rd, 2019, 03:18 PM | #3 | |
ninjette.org member
Name: Garry
Location: Bungendore Australia
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Quote:
It got me worried so I rechecked my adjustment again this morning just to be sure I didn’t do something stupid but all OK with all exhausts at 0.005” and all inlets at 0.004”
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July 23rd, 2019, 06:06 PM | #4 |
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Yeah, I think you've got it. Got units mixed up and grabbed wrong feeler gauge. I always stick with metric and rub-out or cover up the imperial measurements.
Good job on catching that! |
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July 24th, 2019, 06:17 AM | #5 |
Rev Limiter
Name: Jay
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Now you know they are set correctly just keep an eye on it.
If they are off next time you check you may have an issue, but chances are you are fine now. |
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July 24th, 2019, 03:48 PM | #6 |
ninjette.org member
Name: Garry
Location: Bungendore Australia
Join Date: Jan 2019 Motorcycle(s): GPX250 1989 model and 1990 model Posts: 98
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Yes definitely keep an eye on it. Apart from this glitch the bike seems to have been maintained properly mechanically even though it looks ratty. A bit of a diamond in the rough! This is my third GPX250 and like the other two has surprised me with what you get for such little money.
These bikes are cheap as chips in Australia as they are no longer very popular due to both age of the model and the fact that learners are not restricted to the 250 class anymore. Parts are very, very cheap. Example is a good set of carbs can be picked up locally from eBay for $80US. I tend to troll through eBay and buy cheap GPX stuff when it pops up. Got a radiator and fan off a 2006 yesterday for $40Aus (about $25US) delivered! I love these things. They can keep up with the traffic, are light, nimble, reasonable economical and are east to work on with an almost unlimited supply of cheap, good guality second hand parts available. Thanks Mr. Kawasaki
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August 10th, 2019, 05:52 PM | #7 |
ninjette.org member
Name: Nathan
Location: Brisbane, Australia
Join Date: Apr 2019 Motorcycle(s): GPX250r (pregen Ninja 250) Posts: 16
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I love mine too, it's definitely enough power for me also. Although 170kph is crazy good! Most I've managed it 140-150. I'm pretty heavy though.
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August 10th, 2019, 08:57 PM | #8 | |
ninjette.org member
Name: Garry
Location: Bungendore Australia
Join Date: Jan 2019 Motorcycle(s): GPX250 1989 model and 1990 model Posts: 98
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Quote:
Yeah! I’m pretty heavy too and the Speedo is probably a bit optimistic? But still pretty fast
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August 10th, 2019, 09:42 PM | #9 |
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Yeah, optimistic speedo. Actual measured top-speed is 155kph. Add in 10% optimistic speedo and you get... 170!
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September 13th, 2019, 11:47 AM | #10 |
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Name: Chris
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Wish i could do a screenshot on my computer. but I've been looking around to see what a good setting for tolerance when doing the valve adjustment on these ninja 250's?
I have a 2006 ex250f so I believe I have the little rocker arms & not buckets/shims to check. I'll know when I open it up. anyways, I'm thinking I shouldn't even have to check the clearance since I only have 1800 miles on the bike. I purchased used not long ago from a guy had it sitting in garage without title. find out the bike hasn't even been registered for 10yrs and no clue who last person to register the bike was. lol. I got the bike running the other day after cleaning the tank, new ignition, carb check ect. ect. Anyways, the bike boggs down under throttle & acts as if getting too much fuel. First time the bike fired up in years & I didn't even need to choke the carbs.. hmm. I'm trying figure out where to start, pretty sure I'm need the completer carb tear down & cleaning. was just thinking I should double check valve tolerance while I'm at it?? I see allot about using the .005 feeler gauge on exhaust & intake valves, but what I found in the FSM for tolerance is different. I copied and pasted the specs from the FSM. I'm curious if anyone has done the tolerance to these specs & how it turned out? Or if .005 is the way to go?? & this is why I feel the need to open'r up & check what they are set to. since the bike is nearly new engine wise, I feel they couldn't be far off from what the factory set them to. Engine Top End Valve Clearance: Exhaust 0.22 ∼ 0.29 mm (0.0087 ∼ 0.0114 in.) – – – Inlet 0.15 ∼ 0.24 mm (0.0059 ∼ 0.0094 in.) Thoughts & Opinions Greatly Appreciated 8) |
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September 13th, 2019, 11:55 AM | #11 |
Rev Limiter
Name: Jay
Location: WI
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Read through this section -
https://faq.ninja250.org/wiki/How_do..._the_valves%3F "The factory clearance specifications are .08 - .13mm (0.003-0.005 inches) for the intake valves and .11 - .16mm (0.004-0.006 inches) for the exhaust valves." |
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September 13th, 2019, 12:22 PM | #12 |
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If you're on PC.
- Hit that button that says PrntScrn on your keyboard - open up MS-Paint application - Hit CTRL-V to paste captured image - From menu -> File SaveAs and select location and filename for your screen shot. If you're on Mac OS-X - press Command-Shift-3 all at once - The screen shot will be automatically saved as a PNG file on your desktop with the filename starting with “Picture” followed by number If you're on iPhone - Press and hold Power button and Home button at same time - screen shot will be saved to Camera Roll |
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September 13th, 2019, 01:33 PM | #13 |
ninjette.org member
Name: Chris
Location: chicagoland
Join Date: Sep 2019 Motorcycle(s): 2006 Ninja EX250F Posts: 12
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[QUOTE=DannoXYZ;1255980]If you're on PC.
- Hit that button that says PrntScrn on your keyboard - open up MS-Paint application - Hit CTRL-V to paste captured image - From menu -> File SaveAs and select location and filename for your screen shot. I'm have to use that time to time.. using window 7 here |
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September 13th, 2019, 04:08 PM | #14 |
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September 13th, 2019, 04:35 PM | #15 |
ninjette.org member
Name: Chris
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Thx Danno.. that info will be handy for sure...
Just finished valve adjustment actually. no need remove radiator 8) little over 2hrs take apart & put together. I did adjust them to the specs noted above. went for the loose ene of the tolerance tho for the low-end power. I'm not need the top-end, just planning use it to cruise on the nice days & rent to people going for motorcycle license. I have to note that the bike was actually little tighter than recommended clearances noted above. I had to force in the gauge for minimum tolerance & it would feel stuck trying get it out. If they fit a little easier I prolly wouldn't have adjusted them at all. I'm wondering it these tolerances being so tight would be a reason to bog down a little when in low rpms? long story short, I went for the other end of the spectrum & did .13mm(.005in) on intake side & .16mm(.006in) on the exhaust hoping this would help a bit towards the symtems I'm having. symtoms: starts no problem without choke, even cold. bogs down(not sputter) under throttle at low rpm. acting like too much fuel maybe? |
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September 13th, 2019, 07:06 PM | #16 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot.
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These engines tend to close the clearances with use, and it's worse when the engine is cold. When they get to where the valves don't quite close with the engine cold, it's hard to start and doesn't want to idle in a stable way.
I doubt if you'll notice much extra low end torque with only a thou or two more clearance, but I think it's wise to go on the big side of the spec since miles will make it smaller. Last futzed with by Triple Jim; September 13th, 2019 at 08:13 PM. |
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September 13th, 2019, 08:09 PM | #17 | |
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Quote:
Search for "clean carbs ducatiman" to see examples of clogged carbs and what needs to be done. |
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September 13th, 2019, 08:44 PM | #18 |
ninjette.org member
Name: Chris
Location: chicagoland
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That stuff looks gorgeous & I've already PM'd Ducatiman about sending mine out. I've rebuilt & supercleaned carbs removing varnish & ish, but not like what I seen ducatiman do with his work. Haven't sent anything to him yet, but I intend to for sure. I'm actually putting my carbs back together now. a few before & after pics are attached. deff had some problems with a stuck float & dirty jets on one carb.
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September 14th, 2019, 12:32 AM | #19 |
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Yup, dirty jets are just beginning. Need to disassemble emulsion-tubes and floss out every single bleed-hole with wire of matching size. That will push out plastic plug about size of grain of sand. I like to verify cleanliness by dripping dye (Kool-aid or FDA red #3) through and checking that every single hole bleeds properly.
Basically follow complete path of petrol from tank to cylinder, ensuring everything's clear along way. Jet is just start of journey. |
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September 16th, 2019, 02:08 PM | #20 | |
ninjette.org member
Name: Chris
Location: chicagoland
Join Date: Sep 2019 Motorcycle(s): 2006 Ninja EX250F Posts: 12
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Quote:
I did the same with this bike & no issues since re-installed. Bike fires with a small choke idles smooth without choke after a minute, give/take(still warm here). When cold season comes I am planning pull them and send to ducatiman for the full cleaning. I had to clean this tank twice and I'm sure some particles will make it down to the carbs. Even if they didn't, I didn't do the 100% clean that the carbs needed. Although I wonder what an average idle is for these bikes?? I can get mine idling good around 1100-1200rpm, with no problem taking off, no *bogg/sputter or anything. Anything under & I get a small bogg before rake-off. But cars can use under 1k no problem, usually around 800rpm give/take. *Been a car guy 15yrs & just started getting serious into bikes last 2-3yrs* |
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September 16th, 2019, 02:45 PM | #21 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot.
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1,100 to 1,200 is not a bad idle speed, but bogging when you have a lower idle may mean you could tweak your idle mixture screws a little. Adjust for highest idle speed and maybe just a little richer, and you may find that the bog is gone.
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September 16th, 2019, 03:59 PM | #22 | |
ninjette.org member
Name: Chris
Location: chicagoland
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Quote:
Appreciate the info tho. I'd feel better if I could have the idle around 900-1k honestly. but if consensus says 11-1200 is fine, then I'm happy where I'm at for now. There isn't much time left in the season here. One big reason is my carbs are still capped for the mixture screws. I should of drilled them out when I recently cleaned carbs so I could clean the passageways there. Maybe if it becomes a bigger problem when starts getting a little colder I'll adjust them. One issue I don't like about allot of these idle/air mixture screws is that they are majority of the time located under the carb, requiring a right angle screw driver or a super short screwdriver you made. I lost my super shorty I had in the many moves I've made over the years & messing with those I find it easy to become un-synced if you don't pay close attention to what you are doing. I'm just trying make it to the winter with this honestly & I'll send them out be professionally & fully taken care of. Its enough of a pain re-attaching the airbox on these bikes after removing the carbs & trying do that minimum as possible. & that's why I'm a fool for not drilling out when I had them out the other night. 8/ *appreciate all the info you guys*love this forum, No Lie* |
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September 16th, 2019, 04:02 PM | #23 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
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Yeah, I made one from a short screwdriver bit and a piece of rubber tubing jammed over it for grip.
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September 17th, 2019, 05:40 AM | #24 | |
Rev Limiter
Name: Jay
Location: WI
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Quote:
If you want a smooth idle you need to clean the passages, check the condition of the o-rings, and precisely adjust the idle mixture setting. It's not difficult. Starting at 2.5 turns out gets you close. It's usually set leaner than that from the factory. You also need to sync the carbs. Idle mixture info - https://faq.ninja250.org/wiki/How_do...dle_mixture%3F Sync info - https://faq.ninja250.org/wiki/How_do...carburetors%3F General carb info - https://faq.ninja250.org/wiki/Intake |
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September 17th, 2019, 10:44 AM | #25 |
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I prefer to have idle on high side of range. There's not a lot of oil-pressure at 1400rpms, so I don't like going lower due to wearing out engine faster.
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September 17th, 2019, 12:54 PM | #26 |
Guy Who Enjoys Riding
Name: Jim
Location: North Carolina
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The forces involved are minimal at idle. Idling engines have been known to run amazing lengths of time without damage with no oil in the sump. Therefore I doubt if there's an engine wear problem at any idle speed.
Now if you're talking about lugging it in gear at sub-1,000 rpm engine speeds, I'd agree that it's not a good idea. |
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