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Old October 28th, 2020, 11:25 AM   #1
Zcudi
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Name: Malique
Location: Florida
Join Date: Oct 2020

Motorcycle(s): 2007 ninja 250 with a blown head gasket

Posts: 1
Blown head gasket. Need advice

Hey guys itís nice to join you all.

Been on a Facebook page for the 250 for a few weeks asking questions and getting some advice. Fixed up my project bike real nice with freshly cleaned and coated tank, carbs, new tires, chain & sprockets, brakes and all fluids.

I Then took the bike for a spin, not realizing there was a cooling system issue, and the bike overheated multiple times. By overheated I mean it went halfway or deep into red and I just stopped the bike. I smelled burnt toast close to home when I stopped.. The next time I tried to ride it 20 minutes later just to get it home, I blew the head gasket (coolant was boiling away in reservoir.. Idk why).

So at this point understanding the damage I may have done to this bike, Iím thinking I might as well just replace the whole motor instead of paying for the head gasket repair and finding out I cracked some engine components. The bike struggles to start up for some reason but it will. Carbs were done professionally so I donít understand what the problem is. Choke doesnít seem to make any difference in cold starting. In fact choke makes it unable to start from cold. Runs and idles well. Light White smoke from right exhaust

Any advice here? Thinking of buying a motor for $400 that was used in a go kart, install it myself, Then maybe get a used water pump for radiator/cooling system.

I really donít want to let my money go straight into a part out and be left with no bike again.

Any advice is appreciated
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Old October 29th, 2020, 08:59 PM   #2
DannoXYZ
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Motorcycle(s): CB125T, Ninja250R racer,Ninja250R street EX250F#1 EX250F#2 EX250E CBR250R(MC19) CBR250RR(MC22) VF500F CBR600RR

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MOTY - 2018, MOTM - Nov '17
Hi Malique and welcome to Ninjette!

There’s multiple paths you can take to recover, depending upon your mechanical skills. Headgasket can be replaced in less than 1/2-day if you’ve got the skillz and tools. Otherwise, replacement used engine would be easiest. Make sure you get compression-test done; otherwise you may be buying another engine with blown headgasket as well. Best to see and hear that engine in operation before buying.


Bubbling coolant overflow tank is due to blown headgasket allowing combustion pressure into coolant passages. That’s literally exhaust bubbling in your coolant tank. Note that blown headgasket is just effect, result of real problem which caused overheating. You should track that down otherwise your replacement engine will also overheat and blow headgasket. TEST and repair/replace:

- radiator, backflush and clear out. Verify it flows plenty of liquid in forward direction

- radiator cap... need pressure-tester to measure pressure when it opens. Might be easier to just replace it

- coolant hoses, test and verify they all flow cleanly with no cloggs

- thermostat, verify opening temperature by bringing to boil in pot

- fan, disconnect and apply power & ground directly and verify it’s operational

- fan thermoswitch, again, test in boiling pot and verify temperature where switch closes contact

- fan circuitry, re-connect fan, key ON, jumper terminals at thermoswitch connector and verify fan turns ON. If not, you’ve got blown fuse and/or bad fan wiring. If fan doesn’t run in this test, find out WHY and fix it! DO NOT skip past this test until you CAN ABSOLUTELY 100% for sure manually trigger fan to run!!!

- water pump, hardly ever causes overheating due to lack of flow. Most of time, shaft seals wear out and they end up leaking well before fins wear out. Last place to look for overheating issues. Most likely one or more above is cause of overheating problem.


When you’ve got it all back together, warm up bike by letting it idle. Temperature will increase to point where cooling fan turns on at about 2/3rd way up temp-gauge. If not, turn off engine before it overheats and blows headgasket. Go back up to top of list and verify everything is operating correctly and measures within specs.


Good luck!

Last futzed with by DannoXYZ; November 3rd, 2020 at 09:57 PM.
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Old October 29th, 2020, 09:28 PM   #3
DannoXYZ
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Name: AKA JacRyann
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Motorcycle(s): CB125T, Ninja250R racer,Ninja250R street EX250F#1 EX250F#2 EX250E CBR250R(MC19) CBR250RR(MC22) VF500F CBR600RR

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MOTY - 2018, MOTM - Nov '17
@Zcudi
Don’t try to run engine anymore. Water in combustion chambers will make starting difficult (and source of white smoke out tailpipe). Water will also score your cylinder walls, making repair impossible. I suspect if you’ve run it any more than 30-second after headgasket blew, engine is goner, kaput! Cylinder walls are scratched deeply. Crank and rod-bearings are toast. Cam lobes and rocker-arms are galled beyond repair.

Luckily, used engines are cheap. I’ve seen them around $200 all the time. Call around to breakers, check Craiglist and eBay.

There’s guy on Craigslist with two spare engines! Buy them both and build twin-engine 2-wheel drive Ninja 500!!!

Last futzed with by DannoXYZ; October 29th, 2020 at 11:02 PM.
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Old October 30th, 2020, 06:30 AM   #4
jkv45
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Name: Jay
Location: WI
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Motorcycle(s): '06 SV650n, '00 SV650n project, '00 Derbi GPR, '64 CA77 Dream 305, '70 CL450 Scrambler, numerous dirt bikes

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MOTM - Jun '18, Oct '16
I'll second Danno's comment - don't run it anymore!

You will need to do some investigating to see the extent of the damage. It may not be catastrophic.

You will need to drain the coolant and start disassembling the engine to see what it looks like. You will need to remove the head and take a look at the cylinder walls for damage.

If that looks good, you may be OK. The head will need to be planed or dressed in some way to make sure it's flat. I have used a piece of quartz or granite and valve grinding compound to dress the head on one of our Ninjas that blew a head gasket. After a new head gasket and dressing the head it was fine.

Make sure to at least check the condition of the oil when you complete the repairs. If it got water in the oil it will be a milky white color. Don't run it like that. Change the oil and filter first.

We bought a Service Manual for ours, and would recommend it if you are planning to disassemble and reassemble the engine yourself.
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