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Old September 11th, 2018, 06:31 AM   #1
oakleaf
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2007 Wrong Plugs

Just swapped my son a 2001 Honda Civic for his 2007 Ninja 250R. (He needed a vehicle that works for work.) Other than a cracked front fairing (dropped on left side), looks beautiful, <5,000 miles.

The issue: NG CR8E plugs were installed accidentally and turned over. Replaced with correct ones but bike won't start. The sound of the bike being turned over is normal.

Initially, I'll do a compression test and probably get a scope to look into the cylinder. But before I do, I thought I'd ask here and see if any have experience and know what damage I can expect. (I saw the CR8E plugs. The ground electrode is flattened against the plug body pushing the center electrode in. The base of the body is angled very slightly, assuming from piston.)

Thanks!
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Old October 9th, 2018, 02:45 PM   #2
oakleaf
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I pulled the cylinder head. One piston has heavier carbon deposits then the other. Is this indicative that the carbs needs cleaning as well?
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Old October 9th, 2018, 03:41 PM   #3
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Could be. Might also be blown headgasket. Which tends to steam-clean that cylinder with coolant.

Did you do compression/leakdown test before removing head? Definitely do one after putting it all back together and before trying to start it again.

Please review all the linked threads here on carb-cleaning and what it takes.
https://www.ninjette.org/forums/show...1&postcount=22
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Old October 10th, 2018, 02:29 AM   #4
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Modern fuel typically does NOT leave deposits, carbon build up is generally from oil reaching the combustion chamber. This can usually happen 3 ways, through the intake, if crankcase is vented to airbox, check airbox for oil. Through worn valve guide seals, or through worn piston rings or piston/cylinder damage.

If the wrong spark plug was used, is it longer or shorter than the right one ? These bikes run tight cylinder head clearances, so if to long, there would be impact damage to piston & the side spark electrode on the plugs would be damaged. If neither then the plugs are not your problem.
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Old October 10th, 2018, 03:03 AM   #5
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Rich mixtures would definitely leave black sooty carbon deposits.
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Old October 16th, 2018, 05:54 AM   #6
oakleaf
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At the risk of being publicly humiliated/shamed/flamed let me share what I did in all it's ugly glory...

This was my son's bike. It was running rough, seemed to be firing on one piston. Weak spark on #1 so started by replacing plugs... with wrong plugs NGK CR8E instead of the correct CR8HSA! (Never trust the internet. Unfortunately I found this site too late.) Obviously the bike just turned over but could not run like that with holed pistons. So with that off my chest, some questions.

Should I be worried about the amount of carbon on the pistons, especially #1 on left? I have removed the engine and replaced the pistons with used using original rings. I'll be adjusting the valves and re-installing the engine hopefully this weekend. Engine has less than 5000 miles and bike is in great shape. Should I do anything with the carbs, or leave them be?

Thanks!
Attached Images
File Type: jpg OrigPistons.jpg (69.7 KB, 5 views)
File Type: jpg Piston1.jpg (77.6 KB, 5 views)
File Type: jpg Piston2.jpg (97.9 KB, 3 views)
File Type: jpg P1Under.jpg (89.5 KB, 6 views)
File Type: jpg P2Under.jpg (82.0 KB, 4 views)

Last futzed with by oakleaf; October 16th, 2018 at 06:24 AM. Reason: Trying to get image link to function.
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Old October 16th, 2018, 09:37 AM   #7
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That amount of carbon is normal, nothing surprising there.

B.T.W., you mentioned getting wrong/misguided info off the internet, have you gone to ninja250.org for maintenance documentation? That site has a very comprehensive "Technical and Repair Info" section. I guarantee you wouldn't have gotten the plugs wrong if you were reading ninja250.org directions.

It's amazing how brittle the piston alloy is, isn't it? Aluminum is a strange metal, makes good pistons but also makes good solid rocket booster engine fuel.
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Old October 16th, 2018, 09:59 AM   #8
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Quote:
Originally Posted by greg737 View Post
That amount of carbon is normal, nothing surprising there.

B.T.W., you mentioned getting wrong/misguided info off the internet, have you gone to ninja250.org for maintenance documentation? That site has a very comprehensive "Technical and Repair Info" section. I guarantee you wouldn't have gotten the plugs wrong if you were reading ninja250.org directions.
I have gone to ninja250.org "Technical and Repair Info" section. That site has been extremely helpful! I've also downloaded the Service Manual and purchased the 2007 Supplement off of EBay to assist in the piston replacement.

I'm glad that amount of carbon is normal. I bought two used pistons that came very clean and most of the pics I've seen on the ninja boards seem a lot cleaner.
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Old October 18th, 2018, 07:11 PM   #9
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Question about adjusting valves... 7 of 8 gaps were under spec. I would think it would be the other way. I adjusted all intake valves to between .004" and .005" and all exhaust valves to between .005" and .006". What effect would gaps between .002 and 003 on all valves but one intake have had?
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Old October 19th, 2018, 06:18 AM   #10
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Very little effect, as long as there was some clearance. The trouble is that with only 0.002" clearance, it's not long before that becomes zero, and you start to get some obvious hard-start and long warmup symptoms. On this engine, the clearance grows as it warms up.

Valve seat wear causes the closing of the clearance.
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Old October 19th, 2018, 07:48 AM   #11
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Quote:
Originally Posted by oakleaf View Post
Question about adjusting valves... 7 of 8 gaps were under spec. I would think it would be the other way. I adjusted all intake valves to between .004" and .005" and all exhaust valves to between .005" and .006". What effect would gaps between .002 and 003 on all valves but one intake have had?
Getting "tighter" is what the valves naturally do. The aluminum alloy of the cylinder head is the softest metal in the whole mechanism (everything else involved is harder: the valves are steel, the camshaft lobes are steel, the rocker arms are some sort of alloy that's harder than the cylinder head) so they (the valves) slowly seat themselves a bit deeper into the head over time.

Some of the really high-mileage guys (like the Iron Butt Rally riders) used to have valves that ran completely out of the ability to be adjusted. I remember reading forum posts where they were experimenting with shaving the bottoms off of the rocker arms on the adjustment screw side to create more clearance.

What effect does a too-small gap have? I've heard that an EX250 becomes harder to start as the valve clearances get tighter. But this is just a "cold engine" effect, which isn't very important because the valve clearance is a setting that's intended to have its proper effect when the engine is at normal operating temperature.

The changes that take place as the different metal alloys in the valve train (valves, cylinder head, camshaft lobes, rocker arms) heat up and expand at differing rates are sure to create a really complex and dynamic situation that only an engine designer/metallurgist could understand/explain.

I've never found/read a truly complete analysis of what the overall effect of temperature change is on the EX250's valve clearance. Does the clearance gap stay the same as the metals of the various parts all expand with heat? Or is there an overall tightening or loosening as the engine reaches normal operating temperature?

But at the extreme end of the situation: bigger clearance gaps mean the valve will spend more time on the valve seat in the cylinder head. When the gaps are allowed to get smaller/tighter you're running the risk of a valve than never really seats that well on the cylinder heat valve seat. On the exhaust side valves this can result in overheated, deformed valves because they never get a chance to transfer enough heat away into the cylinder head.
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Old October 22nd, 2018, 06:49 AM   #12
oakleaf
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Thanks, makes sense about the aluminum cylinder head wear where valves seat! I guess I thought wear would occur between valve stem and rocker tip, or cam and rocker.

Next question...

I exchanged the pistons, buttoned up the engine, reinstalled it, put in new CORRECT plugs (LOL), and ran the bike.
The good news: The bike runs EXACTLY like it did before I stupidly installed the wrong plugs.
The bad news: The bike runs EXACTLY like it did before I stupidly installed the wrong plugs.

I was hoping the initial problem would have somehow gone away. But it continues to bog down. Starting in first gear, when I crack the throttle a bit to get going it seems initially ready to take off for a fraction of a second, but it then seems to bog down and go blahhhh. I run it through the gears, max speed is 50-55. Now I'm a big guy (235#) and I know this is a 250, but I'm assuming the bike can do better than that?

Spark appears very good. Assuming fuel issues. Any ideas, or how would you suggest I troubleshoot?

Thanks in advance!
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Old October 22nd, 2018, 07:36 AM   #13
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Need to completely tear down carbs.
Poke copper wires of various gauges through all jet openings.
Floss all secret hidden fuel circuits
Soak everything in ultrasonic cleaner using chlorinated solvents
Soda-blast all holes and passages where fuel flows.

Search for ducatiman’s handiwork in refurbishing carbs.
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Old October 22nd, 2018, 07:53 AM   #14
oakleaf
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Thanks Danno. I read through the carburetor cleaning posts you provided and it seems to me the smart solution is to get it done correctly the first time by a professional. Do you know if Ducatiman still does carburetor refurbishing?

With the winter very near, this is probably a good time to fill tank, put in some STA-BIL, park it in garage, and remove carbs to have someone clean.
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Old October 22nd, 2018, 09:56 PM   #15
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I had set refurbed by him little while ago. Best bet is to PM/email him. But yes, he does get busy with these carbs, so schedule ahead of time. It'll be running like brand-new bike, you'll be amazed!!!
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Old November 23rd, 2018, 08:25 PM   #16
oakleaf
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Cleaned the carbs. My Ninja now runs great!!!! Thanks everyone.
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