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Old December 4th, 2017, 07:46 PM   #1
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What do I need to know to rebuild my engine?

I was greeted with coolant in my oil today... Woohoo...

Anyway, FSM is already being shipped to my house. I've done just about everything on this motorcycle except for monkeying around in the engine.

What should I replace while I'm in there? What should I check while I'm in there? What special tools will I need? Do I need to get the head machined? I'm just very new and lost when it comes to open heart surgery.
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Old December 4th, 2017, 07:52 PM   #2
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Don't do more work than you have to, Yes. Figure out where the leak is before you tear into the engine. Maybe a head gasket change will fix the problem, for example. Have you looked at the spark plugs? If coolant is getting into a cylinder, that plug will look unusual, probably very clean.

I can't tell you how many times I've assumed the worst and made myself extra work, but now that I'm almost 60 I do it slightly less often.
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Old December 4th, 2017, 08:16 PM   #3
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Its pretty much a head gasket or... water pump shaft seal ?? I cant think where else coolant could sneak in.
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Old December 4th, 2017, 08:37 PM   #4
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Do compression-test, identifies blown headgasket pretty easily.

When headgasket goes, intake-stroke creates vacuum in cylinders and that sucks in coolant. Especially when warmed up as there's maximum vacuum in cylinders and maximum pressure in coolant-passages. Coolant then gets forced past rings by compression-pressure and bingo! it's in your coil!

Another possibility is bent con-rods from hydrolocking cylinders.

For this engine, I'd disassemble, clean up and measure everything. Then replace just what's needed: headgasket, rod/main bearings if worn, valve-stem seals, maybe valve-job if seats are worn past limits. Wouldn't hurt to do some porting & polishing of intake while it's out.
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Old December 4th, 2017, 08:59 PM   #5
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Come on, Edware-Hubert, you think Yes should disassemble his whole engine, inspect and rebuild, rather than install a low-cost whole replacement engine as you suggested to another member recently?

I'd do a little diagnosing and see if there's a fairly easy fix, and if not, swap engines.
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Old December 4th, 2017, 09:07 PM   #6
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In this case, amount of disassembly and measuring is really minimal, probably 3-hrs. As is rebuild, perhaps 5-15hrs.

Compared to 10x more work and cost of milling and machining that other destroyed engine.

Yes, I've replaced blown-headgaskets in the parking-lot of Willow Springs. But if I had it at home, I'd spend a little more effort and just replace all worn or half-worn components while I'm in there.
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Old December 4th, 2017, 09:45 PM   #7
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Let's not get way ahead of ourselves. He has a coolant leak, not a worn out engine.
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Old December 5th, 2017, 12:13 AM   #8
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I was under the impression that this was, for sure, a head gasket issue if there was coolant in the oil. Where else would it be coming from?

Compression test is a good idea, though.
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Old December 5th, 2017, 12:17 AM   #9
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Just buy a pre-owned motor for a few hundred bucks.

Easy-steasy.
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Old December 5th, 2017, 01:27 AM   #10
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Originally Posted by dcj13 View Post
Just buy a pre-owned motor for a few hundred bucks.

Easy-steasy.
$400 was the cheapest halfway-decent looking one I could find, and I'm really not so sure that investing $400 in my $600 motorcycle is a good financial decision.
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Old December 5th, 2017, 02:09 AM   #11
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Just buy a pre-owned motor for a few hundred bucks.

Easy-steasy.

With the same problem or worse?

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Old December 5th, 2017, 06:53 AM   #12
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The factory "base manual" has a nice step-by-step procedure for removing the head on page 4-12. Not the supplement, the base manual. If the engine is otherwise symptom free, there's no need to remove it or get into the bottom end, just to change the gasket.
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Old December 5th, 2017, 07:19 AM   #13
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The factory "base manual" has a nice step-by-step procedure for removing the head on page 4-12. Not the supplement, the base manual. If the engine is otherwise symptom free, there's no need to remove it or get into the bottom end, just to change the gasket.
Yeah, THAT'S the ticket T.J.!

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Old December 5th, 2017, 07:37 AM   #14
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It's like I said in post #5 above, if it's a fairly easy fix, do it. If its not, like a cracked block or something, swap engines.
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Old December 5th, 2017, 08:01 AM   #15
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We blew a head gasket on our Ninja 500 a while ago, but the symptoms were different.

Depending on where the leak is, a blown head gasket may not allow coolant into the oil.

In our case, combustion pressure leaked into the cooling system - over-pressurizing it. The coolant then filled and overflowed the reservoir bottle as soon as the engine warmed-up.

As suggested - I would try the compression test first, just to get more info before pulling things apart. I wouldn't disassemble any more than necessary to cure the problem if everything else has been working properly.

If you do pull the head and cylinder, I suggest being prepared to lap them both before reassembly. I would also get your hands on a service manual of some kind to help you through the process if you are not familiar. We purchased an online Service Manual from Cyclepedia for the 500 that was pretty good.
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Old December 5th, 2017, 10:21 AM   #16
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Quote:
Originally Posted by MrAtom View Post
I was under the impression that this was, for sure, a head gasket issue if there was coolant in the oil. Where else would it be coming from?

Compression test is a good idea, though.
I've seen cracked heads leak coolant into oil also. Compression test would show that as well. If you don't find a compromized headgasket, look for cracks in head.
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Old December 5th, 2017, 11:46 AM   #17
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a leak down test beats a compression test, if possible, but both are helpful for different things.

In any case, if it is just a leaky head gasket, if you can do valve clearances, you can do a head gasket swap.

side note: I had the same problem as Jay + others. My "leak" was a sunken cylinder that allowed both coolant into the cylinder AND for excess pressure to go into the cooling system over pressurizing it.
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Old December 5th, 2017, 03:37 PM   #18
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My suggestion: swap & seal water pumps. Diagnose/tear apart and inspect the head gasket. Both are cheap.

If those don't fix it, here's a useful link:
http://www.rcramer.com/bikes/ex250/rebuild_notes.html

A complete rebuild is both more time consuming and expensive than you can wrap your head around if you have to ask, no offense. I did a bunch of work on mine and it was entirely too much effort for what it was. Then I swapped a built newgen engine in. Besides a few small details, that was very easy.
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Old December 5th, 2017, 05:43 PM   #19
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Originally Posted by choneofakind View Post
My suggestion: swap & seal water pumps. Diagnose/tear apart and inspect the head gasket. Both are cheap.

If those don't fix it, here's a useful link:
http://www.rcramer.com/bikes/ex250/rebuild_notes.html

A complete rebuild is both more time consuming and expensive than you can wrap your head around if you have to ask, no offense. I did a bunch of work on mine and it was entirely too much effort for what it was. Then I swapped a built newgen engine in. Besides a few small details, that was very easy.
What I'd learn in the process is worth my time. Y'know, getting out of your comfort zone and all that crap that keeps us all from killing ourselves. But, as this is my only motorized vehicle, I'll try to not bite off more than I can chew for now. At least until I get my hands on a Craigslist Virago that doesn't suck ****.
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Old December 5th, 2017, 06:09 PM   #20
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My suggestion: swap & seal water pumps. Diagnose/tear apart and inspect the head gasket. Both are cheap.

If those don't fix it, here's a useful link:
http://www.rcramer.com/bikes/ex250/rebuild_notes.html

A complete rebuild is both more time consuming and expensive than you can wrap your head around if you have to ask, no offense. I did a bunch of work on mine and it was entirely too much effort for what it was. Then I swapped a built newgen engine in. Besides a few small details, that was very easy.
It's difficult to take this guy too seriously with the Barbie doll and grammar. Two things I wish to point out regarding the valve adjustment procedure. Remove the two tear drop shaped rubber cam cover gaskets. If you don't you might lose one down your cam chain tower (ask me how I know). You must drain ALL the coolant out of your system or the engine will "burp" coolant into your crankcase via the vertical tube to the rear of the cam cover (ask me How I know). You do not need to remove the radiator completely. remove the attachment bolts and hang the radiator with a nylon zip tie or a piece of mechanics wire.

I spite of my somewhat snide comments an interesting read.

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Old December 8th, 2017, 03:42 PM   #21
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What I'd learn in the process is worth my time. Y'know, getting out of your comfort zone and all that crap that keeps us all from killing ourselves.
I get that 100% and that's likely the best reason to get into it for someone like us.

But... again... been there done that on this engine. I was literally in your shoes with your thoughts before I tore into it. I got and ignored the same advice I'm now giving to you. ...and they were right. It was a great learning opportunity but it wasn't worth it.

If you want to pull apart, repair, and rebuild an engine, go trash pick a lawn mower and make it run.

Quote:
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You do not need to remove the radiator completely. remove the attachment bolts and hang the radiator with a nylon zip tie or a piece of mechanics wire.
Even better, drill out the spot welds that attach the coil pack bracket to the engine mount. Then you can get the valve cover off and make a little space for yourself without having to take radiator off or dangle it to make space. A little touch up paint to keep the drilled section from rusting and no one will ever notice that you've drilled anything unless they look closely.
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Old December 8th, 2017, 03:58 PM   #22
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Actually, trash-picked small engine repair was what I did to make money in high school.
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Old December 8th, 2017, 05:30 PM   #23
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I get that 100% and that's likely the best reason to get into it for someone like us.

But... again... been there done that on this engine. I was literally in your shoes with your thoughts before I tore into it. I got and ignored the same advice I'm now giving to you. ...and they were right. It was a great learning opportunity but it wasn't worth it.

If you want to pull apart, repair, and rebuild an engine, go trash pick a lawn mower and make it run.



Even better, drill out the spot welds that attach the coil pack bracket to the engine mount. Then you can get the valve cover off and make a little space for yourself without having to take radiator off or dangle it to make space. A little touch up paint to keep the drilled section from rusting and no one will ever notice that you've drilled anything unless they look closely.
Good advice Chris. Especially if you plan on adjusting the valve lash more than once in your life.

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Old December 8th, 2017, 05:54 PM   #24
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I have completely taken mine apart 5 times....it gets easy around #3.
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Old December 9th, 2017, 12:59 AM   #25
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I'm an idiot. The only time I'd been riding is when I was going to work because I injured my knee and bicycling wasn't good for it. It's a short distance, so it's just water that didn't evaporate. Explains why my compression is still good. Thanks, everybody. False alarm.
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Old December 9th, 2017, 02:34 AM   #26
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I'm an idiot. The only time I'd been riding is when I was going to work because I injured my knee and bicycling wasn't good for it. It's a short distance, so it's just water that didn't evaporate. Explains why my compression is still good. Thanks, everybody. False alarm.
Good to hear your engine's OK. Better safe than sorry. I bet you learned a-lot too. Like, never do an engine rebuild.

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Old December 20th, 2017, 02:25 PM   #27
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glad to hear you didn't have to rebuild!
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Old December 21st, 2017, 07:10 PM   #28
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I kinda hoped for a cuss an thrown wrench filled build thread
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