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Old August 1st, 2020, 07:33 PM   #1
Kawinoob217
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Yet Another Engine Rebuild

Hi Everyone!

This marks the start of what I hope to be an active thread concerning the engine rebuild of my 98 Ninja (see my profile pic for the bike in question). When I got the bike, I also got a box of assorted parts, as the bike was not running. Due to the unknown history of the bike and possibly the mods that I had to do to get it running, I may have been damaging the engine. I'll start with a breakdown of the bike.

Mods:
  1. Yoshimura slip on exhaust.
  2. K&N pod filters.
  3. Slightly larger than stock jets with adjustable mid range needles.

Like I said, not the best list of parts to just get the bike running, but it's what I had at the time (as a poor college kid I was not going to go out and buy all new parts .

Known Problems:
  1. I know that I'm definitely burning oil. When I go to change the oil as well, I smell a good bit of gas with it.
  2. If I leave the bike alone for about a week and then go to start it, it can take an obscenely long time to start (40 seconds). When doing so it steps through three stages of starting.
    1. Starter running with no combustion.
    2. Starter running with some combustion that will not sustain if you let go of starter.
    3. Bike actually starting.
  3. Large throttle blips from idle after the bike has warmed up can use it to lug and kill the engine.
  4. Overall slower than expected RPM climb when revving.

I've been dealing with these issues for some time, but due to some life changes, I'll be moving across the country soon. I'd love to be able to get the bike mechanically sound and rely on it as a form of transportation for once I get there. Knowing that I'm burning oil, my intuition tells me that my rings may be fried. This should show up in a compression test right? Today I took a trip and went down to my local AutoZone and picked up a tester. Here's cylinder 1...

And cylinder 2...


If you can't see the pics I've attached them below as well because I haven't completely figured out this forum posting business works yet.

Now, this isn't as bad as I though it was going to be but I've been told that a difference of 30 psi between cylinders isn't good. Also, the low end limit for cylinder compression according to the EX250F service manual is 142psi. I'm a little close for comfort in my opinion. The next step for me is going to be draining fluids so I can pull the engine out and put it on a table. I'm by no means a mechanic, but if I can get this running a bit better than what it is currently I'll call it a win. Please feel free to leave suggestions and comments as I'm completely new to this kind of work and will be asking many questions in the first place. Whelp, here's goes nothing...
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Old August 2nd, 2020, 07:45 AM   #2
csmith12
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Old August 2nd, 2020, 12:27 PM   #3
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Hi Ethan, I don't think you want to rebuild... Compression readings are good for gauge with bleed-valve at gauge-end.

Quote:
Originally Posted by Kawinoob217 View Post
  • I know that I'm definitely burning oil. When I go to change the oil as well, I smell a good bit of gas with it.
Gas in crankcase has nothing to do with burning oil. First gas-smell is due to leaking petcock that drips petrol when bike is stationary. And non-sealing float-valves allow bowls to fill up and drip petrol down carb-throats into engine. Which then seeps into crankcase.

Actual oil-burning would result in acrid exhaust smell and blue-smoke out tail-pipe. And oil-levels dropping quickly over time with constant topping-up needed.

Quote:
  • If I leave the bike alone for about a week and then go to start it, it can take an obscenely long time to start (40 seconds). When doing so it steps through three stages of starting.
    1. Starter running with no combustion.
    2. Starter running with some combustion that will not sustain if you let go of starter.
    3. Bike actually starting.
  • Large throttle blips from idle after the bike has warmed up can use it to lug and kill the engine.
  • Overall slower than expected RPM climb when revving.
Again, completely full float bowls overfilled with petrol will meter out too much fuel and prevent starting. Liquid petrol does not burn, it needs to be vapourised. You have way too much darn fuel in cylinders and it takes A LOT of cranking and engine-revolutions to blow it all out until mixtures are more optimal. That's also why you have disparity between cylinders on compression-test, one of them has more liquid petrol in it than other. Would be better to do compression-test after completely warming-up engine.

Your main issue is most common ailment that inflicts these bikes: dirty carbs and petcock needing completely rebuild and restoration. Takes only one week and couple hundred bucks to send to ducatiman for expert refurb service. Do search here for "ducatiman clean carbs" to see tonnes of others with similar symptoms. And notice before and after reviews.
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Old August 2nd, 2020, 03:06 PM   #4
Kawinoob217
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Thanks for the DannoXYZ for the suggestions, however I'm not inclined to believe this to be true. A couple of points to make about the bike that I failed to mention in the first post.
  1. I did end up replacing the fuel petcock for a new one after about 6 months of having the bike. I doubt It's gone bad after just a year or two. I pulled the oil out of the bike today in preparation to take the engine out, and it was definitely not as viscous as it should have been (also reeked of gas).
  2. The carb is a newly refurbished one that I went through myself with a fine tooth comb, including setting the float levels.
  3. I'm not sure if I mentioned it or not in my first post, but I took the bike for a ride before doing the compression test yesterday. Those results are after about a 30 minute ride, and then letting the bike sit for maybe 10 minutes (just enough time to drain carb bowls, remove gas tank, etc.)

On a side note, can someone tell me how to add pictures in line with the text? I tried using the insert image button with links to some pics that I have in google drive and that didn't seem to work. Again, thank you DannoXYZ for the suggestions! Any help with this project is really appreciated.
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Old August 2nd, 2020, 04:14 PM   #5
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Quote:
Originally Posted by Kawinoob217 View Post
On a side note, can someone tell me how to add pictures in line with the text? I tried using the insert image button with links to some pics that I have in google drive and that didn't seem to work. Again, thank you DannoXYZ for the suggestions! Any help with this project is really appreciated.
How do I load pictures on to this site?
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Old August 2nd, 2020, 07:37 PM   #6
Kawinoob217
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Whelp today concludes day one of work on my engine rebuild project! I went as far as to set up a work space for myself, drain the oil and coolant, and remove the engine from the bike. While not as hard as I imagine it could be for other motorcycles / cars, I did learn quite a bit about the bike.

Hot Takes:
  1. Wear clothes you don't care about when draining coolant. There's no way to do it nicely and you will get some on you.
  2. Remove the bottom radiator bracket BEFORE you decide to try and take the exhaust off.
  3. Find a friend to help when it comes time to actually drop the engine out from the frame.
  4. Engines have a lot of gravity in them (at least I think that's how it works).
  5. Keep extra 10mm everything around for when you inevitably loose your wrench / socket.
  6. Next time don't be so quick to delete your center stand, as it may come in handy.
  7. Take pictures of all your electrical connections and their routing for when you have to put things back together.
  8. Hydraulic jacks are great for lowering the engine once the mounting bolts are out.

Things started off with the easy tasks. First up, draining the oil. Upon doing so it was evident that less oil came out than I put in during an oil change. Also, the consistency was way less viscous than what I'm used to from fresh 5W-40 (yes the bike was completely cold). Also, it reeked of gas. There's definitely some mixing going on.

From there I drained coolant, which went as well as I could have hoped...and by that I mean I dumped half of it on me and half into the tub I had set up. In the half that made it into the tub ,there were some black flecks, telling me I'm about due for a coolant flush anyway. Next I traced all electrical connections going to the block and disconnected them, making sure to document along the way. Then it was just exhaust, carburetor, sprocket + chain, and the engine bolts themselves. I did have to massage the back of the block with a crowbar to push it forward a bit but besides that all went smoothly. I quickly found out how much I'm been neglecting my upper body workouts when I had to lift the block to the table about 10 meters away . I stopped by my local AutoZone, recycled my gas infused oil, and picked up a few cans of gunk with some rags. Later this week, I'll work on shining up this block a bit!



When going to remove the cover for the sprocket I noticed a crack in it.



I'll definitely have to add that to my growing list of parts.





Looking Forward:

This week, I'm hoping to get the exterior of the engine cleaned up as well as crack the valve cover. Just thinking forward about what I'm going to want to remove and do to the engine, I've got a couple of questions.
  1. How do people recommend I clean carbon off of things like valves and piston heads? I've got a crappy harbor freight ultrasonic parts cleaner, but as for solvents I've got no idea what to use.
  2. Are the cylinder head bolts torque to yield / should I replace them when I reassemble?
  3. While I'm in here is there anything I should replace just for preventative maintenance (I'm thinking things like cam chain, valves, etc...)?
  4. How should I go about taking the valve springs out? I don't expect valves to be the problem but I'd like to clean them and lap them while I'm doing rings.

Thank you all for going on this journey with me and I appreciate any help / info you can lend!
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Old August 3rd, 2020, 12:23 AM   #7
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Ok, maybe do one more final confirmation before tearing it apart. Get borescope and take look down spark-plug hole.

What's it look like on piston tops?
What's faces of valves look like?

Maybe take some photos and post them. Just don't want to see you spend extreme effort when there may be an easier solution.

Last futzed with by DannoXYZ; August 3rd, 2020 at 11:44 AM.
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Old August 10th, 2020, 01:28 PM   #8
Kawinoob217
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So far I'm making good progress on getting everything torn down. My apologies for the lapse in posts, as I had to completely replace the AC system on my car!

Hot Takes:
  1. Removing cylinder head bolts is a lot easier with a breaker bar if you can't mount the engine correctly to something.
  2. Gunk is awesome for cleaning off engines.
  3. Sometimes things need massaging with a rubber mallet to come loose.
  4. No matter how much you think you've emptied fluids out of the engine, there will always be more and you will always dump it on yourself.

My first order of business was to clean the engine up a bit. There was quite a ton of grease buildup around where the chain attached to the sprocket (I blame me and my overuse of chain lube for that one), but it was nothing a can of Gunk couldn't fix. Also, I never got a front faring piece for my bike, so my front tire has been kicking up road debris and sticking it to the exhaust side of my engine for a couple of years now. I made quick work of that by stuffing the exhaust with some shop towel and blowing out the area with some compressed air.

Here's before cleaning...


And, here's after...


After cleaning I took the valve cover bolts off and got a look at the cam lobes. Everything looks good so far, but it would appear that the back of my cam lobes are as shiny as the fronts are, indicating possible bad valve adjustment? If you've got insight about this, please let me know whether these parts should show that kind of wear.



After this I removed the brackets holding the cams in, timing chain cover, and the chain itself. Pro Tip: make sure you remove the timing chain tensioner before you try to take the cam shafts off. It's impossible otherwise .

Finally I took out the head studs and lifted up the head....or at least tried to. Upon lifting up on the engine, the cylinder block stayed attached to the head and lifted up off the rest of the assembly. Did I do this right? It looks as if when you take out all the head studs and the one upside bolt, there's nothing holding the block and head assembly to the crank case and rest of the transmission. Anyway, after a few hits of the mallet I was able to pull the head off the block.





Now, I'm no expert, so the extent of my "engine palm reading" goes as far as looking at the color and condition of spark plugs. If anyone could tell me if anything looks out of sorts with my head or block and pistons, I'd be really grateful! Upon feeling the cylinder bores themselves, I don't feel any ridges and all scoring looks minimal at best. I can't speak for the pistons on overal condition, but upon an initial inspection, I don't see anything majorly wrong with them. Inspecting my head gasket too, I don't believe I see any signs of blow through. Again, if anyone notices anything different please let me know!



Looking Forward:
This week I want to focus on taking a closer look at the pistons, the bore, and the valves. Upon trying to lift the block up, the sleeves started pulling out of the block as the pistons were gripping on them. Is there a proper way to pull the block from the pistons without touching the bottom end of the engine?
  1. Find a way to compress valve springs so I can inspect valves.
  2. Decide whether to clean up valves or get new ones based on condition.
  3. Inspect piston health and bore diameter, look into honing if needed.
  4. Measure piston ring gaps and decide on new size of rings if needed.

@DannoXYZ I'm sorry I didn't get around to bore scoping the cylinder and head. Due to the low amount of posts I have I'm still getting my posts checked by mods before they get posted. I had already removed my engine and taken some of it apart before I saw your post. I just didn't want to make it seem like I was ignoring you!

Again, thanks to anyone who has any insight as to how I should be going about this process. It's as much of a learning experience for me as it is a process to get my bike running right. All I've got is the shop manual and my hand tools, and some determination. Please post any tips you have about how I should be going about cleaning the head, block, pistons, valves, etc, and what I should be replacing in the mean time.
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Old September 1st, 2020, 11:02 AM   #9
Kawinoob217
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After a bit more investigation I believe I have finally figured out why I had low compression!

Hot Takes:
  1. Be careful when using solevents in an ultrasonic cleaner.
  2. Take your time when removing valve springs.
  3. Having an Ford Motor Company powertrain test engineer for a father can be really helpful.
  4. Carb cleaner can clean more than just carbs.

Removing the head it wasn't immediately obvious as to why I might be having compression issues. From the last post you can see that there was no damage to any of the valves, so I knew that timing was fine. The pistons, while dirty didn't seem too have anything inherently wrong with them either. After a bit more massaging with a rubber mallet, I was able to pop the block it self. Once I removed the block and inspected the pistons, I saw something quite peculiar. Upon inspecting the piston rings, I found that the openings in my top two rings were lined up, facing the front of the engine. Taking a look at the service manual they clearly indicate that the openings should be sitting opposite of each other.



Still, the gaps when the pistons are in the bore is fairly small, and lining them up wouldn't kill my compression that much. My dad suggested that I do a crude valve sealing check by back pressurizing the intake and exhaust sides of the valves. With a trip the the hardware store to get some adapters for my air compressor, I was ready. I mixed up a bit of snoop (water and dish soap) as a leak tester and got to work. I pushed a measly 10 psi into the intake sides and saw a bit of bubble growth. The important part was that the bubble growth was identical across all the intake valves. I then removed those valves and they sure were dirty!



The important part was that the wear patterns seemed alright. Everything looked uniform and the thickness of the wear surface was within spec according to the service manual. I decided to throw them in my harbor freight ultrasonic cleaner with a mix of water, Zep 505 degreaser, and some Dawn dish soap. While those were cleaning up I worked on the pistons. I started with some WD-40 and a nylon brush. This wasn't getting me anywhere fast so I tried some carb cleaner, and whoa....what a difference.



I tried a bit of carb cleaner on all the gasket surfaces and it gave me a mirror finish. At this point my intake valves were done in the cleaner and I pulled them out. This was my first major road block. I'm not sure whether it was the solution I had put together or something wrong with the valves themselves, but the cleaner had eaten away at the contact surface. It's hard to see in this picture, but there's a smooth surface to the right and then to the left you can see where the mating surface got eaten away.



This happened with all of my intake valves, so I added those to the list to buy for the rebuild. At this point it was time to pressure check the exhaust valves. I did the same as the intake side, and pressurized the exhaust through a spare manifold with 10 psi. I wish I could post a gif or video of this, but the picture will have to suffice. Cylinder #1 (the one that had 30 psi less of compression) looked like a bubble machine.



After taking the exhaust valves out, it was obvious that E1-1 (exhaust valve, cylinder 1, furthest from cam chain) had a wear pattern way larger than E2-2 (E1-1 on right side).



While my wallet is already yelling at me, I added exhaust valves to the buy list as well.

Looking Forward:
As of yesterday I just received all my valves, gaskets, and other pieces to reassemble my engine. Not wanting to devote too much time to figuring out how to compress valve springs, I broke down and bought a 20 dollar kit on amazon. With that, I also purchased some valve lapping compound and the suction cup tool to do so. From here on out it's putting things back together and hoping it all works!

I hope this thread can offer help to someone in the future who decides to rebuild their engine. I'll be sure to post progress on valve lapping and other reassembly steps!
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