Finding carnage and replacing cam chain.

[AFazakerley]

As some of you might have read in my other thread, my bike was having bad idle problems and then all of a sudden the timing chain broke. I started to tear the bike apart and got the engine out. Surprisingly it only took me a bit over an hour to get the engine out and onto my work bench!







After removing the engine I started poking around and found some carnage!











Looks to me as if one of the rocker arm somehow came free and then cause havoc. I’m just guessing, I don’t really know. Could this be a result of us doing a poor valve job?
I’ll be removing the head soon as I do a bit of HW on how to do it without screwing anything else up.
I know the head will need a decent amount of work but can anyone tell me from the pictures if the bottom end looks like it’s going to be junk?
Should i also be looking into breaking the bottom end down even more?
Thanks for any input.

[FvnnyL3tt3r1ng]

No idea how your rocker arm broke loose other than maybe your cams were getting really close. The rocker arms dont screw into anything one half just sits inside a depression so maybe the bike fell over on its side and had enough force to dislodge the rocker. If you had it running before I don't think you need to go further than taking the caps and cams out of the head and replacing that rocker arm and chain.

[Motofool]

Originally Posted by AFazakerley

.........Could this be a result of us doing a poor valve job?
I’ll be removing the head soon as I do a bit of HW on how to do it without screwing anything else up.
I know the head will need a decent amount of work but can anyone tell me from the pictures if the bottom end looks like it’s going to be junk?
Should i also be looking into breaking the bottom end down even more?

The rockers are designed to be the weakest link and break first, avoiding further damage.

As explained by @alex.s in your other thread, it could be that the pistons hit the valves, after the CCT allowed the chain jump the timing.
Check if you can push your CCT backwards as it is now.

It could also be that the improper torque was used on the adjusting bolts of the rockers, making them loose after some miles; then the rockers get among the chain and sprocket, breaking the chain.
In that case, the head needs no work.
A leak down test may tell you if all the valves are undamaged.

As for the debris, everything should be at top and by the clutch cavity.
Inspect the teeth of the three sprockets.
If they are all good, and the broken chain is within specs, there is no need to replace those either.

The broken aluminum tab by the bottom sprocket may allow you to replace the chain without pulling the top apart (I am not sure).

I wouldn't pull the bottom apart.

Sorry that your friend and you could only enjoy the new bike for such short period of time.

[bdavison]

Originally Posted by Motofool

As for the debris, everything should be at top and by the clutch cavity.
Inspect the teeth of the three sprockets.
If they are all good, and the broken chain is within specs, there is no need to replace those either.

Unless trash went down the cam chain tunnel and into the bottom end....which is potentially likely.

[alex.s]

Originally Posted by bdavison

Unless trash went down the cam chain tunnel and into the bottom end....which is potentially likely.

it wouldn't get into the bottom end, it would stay in the clutch tunnel

only very fine shavings would be able to make their way into the bottom end

[AFazakerley]

Well i found one of the rocker arm down by the crank gear. I also still havent found half of one of the rocker arms.
Am i correct that i need to pull the head to make sure the valves are good and still seat properly?

@Motofool Thanks, my budy could care less since he has no idea. I havent talked to him in over a month now, sure hes having fun at basic trainning. I personaly could care less apart from the $$ its gona cost since riding season is over. Im starting to really like working on bikes ccompared to cars since everything is easily accesible and come apart quite easily.

Purchase List:
-Atleast 3 new rocker arms
-Timming chain

[alex.s]

you will need to completely disassemble the engine before you can make a full prognosis

take the bottom crank case off, take the head and cylinders off. once everything is apart carefully inspect and clean then relube each and every part looking for any debris or damaged parts.

since its an older engine you might as well do a full rebuild and replace all the gaskets. check the clearance on the piston rings, check the entire transmission for bite marks, check all the bearings and bearing surfaces. you broke the chain gaurd off the bottom case so you probably want to replace the bottom case.

if you go this route, might i make a suggestion; carefully bag and label parts with their fasteners and keep everything very organized. if you aren't comfortable with the entire workings of the engine, keep a master list of the order that you removed parts. write everything down. you WILL forget it. and if you don't, great. you have backup.

TL;DR: just buy a new engine and save yourself the hassle

[FvnnyL3tt3r1ng]

Originally Posted by alex.s

you will need to completely disassemble the engine before you can make a full prognosis

take the bottom crank case off, take the head and cylinders off. once everything is apart carefully inspect and clean then relube each and every part looking for any debris or damaged parts.

since its an older engine you might as well do a full rebuild and replace all the gaskets. check the clearance on the piston rings, check the entire transmission for bite marks, check all the bearings and bearing surfaces. you broke the chain gaurd off the bottom case so you probably want to replace the bottom case.

if you go this route, might i make a suggestion; carefully bag and label parts with their fasteners and keep everything very organized. if you aren't comfortable with the entire workings of the engine, keep a master list of the order that you removed parts. write everything down. you WILL forget it. and if you don't, great. you have backup.

TL;DR: just buy a new engine and save yourself the hassle

A spare engine would be nice as you could work on the broken one in the meantime with no rush

[n4mwd]

Originally Posted by AFazakerley

Looks to me as if one of the rocker arm somehow came free and then cause havoc. I’m just guessing, I don’t really know. Could this be a result of us doing a poor valve job?

Yes. Overtorquing the nuts on the rocker arms during a valve adjustment starts a chain reaction that results in what you have.

As long as nothing is cracked or broken, you can usually salvage the top end with new rocker arms. Its possible the valves could be bent, but in most of these cases, they were OK.

As long as the case isn't damaged beyond the broken tab, you can probably just leave the lower end alone. However, normally, you have to split the case in order to get the cam chain installed, but because of your broken tab, you might be able to squeeze it in there without splitting it. If you can, and as long as the crankshaft turns freely, and all the gear teeth look good, I wouldn't split the case.

[AFazakerley]

Alright. So i am currently searching for another engine, but till then ill rebuild this one for obvious reasons and just to learn.

If i don’t crack the case open is there any sure way to get all the debris out?
Does cracking open the case greatly increase the work load?

@alex.s I’ve already started organizing all the bolts in jars and what not. I have learned this lesson the hard way many times when doing car work. Either end up with extra bolts and nuts not enough

@n4mwd It’s very possible we over torqued one, especially since my buddy was there for that job and he’s a bit of a brute. Didn’t help that i didn’t have a proper torque wrench either. Won’t make that mistake twice.

[Motofool]

Originally Posted by Motofool

........The broken aluminum tab by the bottom sprocket may allow you to replace the chain without pulling the top apart (I am not sure).

I wouldn't pull the bottom apart.

Check this video about replacing the chain with minimal taking apart work:

Link to original page on YouTube.

[n4mwd]

I warn people all the time about overtorquing those adjuster nuts. Some believe me and some don't. I suppose its a bit hard to swallow because it seems so trivial, but its basically the trigger to a hand grenade.

Most of the debris should be in the clutch area and easy to pull out. Anything in the engine itself is going to be hard to get at. You might be able to fish it out with a grappler or magnetic screwdriver for steel parts.

Its not a big deal to split the case. The hardest part is making a secure stand to support it. You'll need to be able to flip it over to get to all the bolts that there are. I used an automotive engine stand with a bit of angle iron to make it fit. See attached photo.

You'll need to order the gaskets for the two side covers, the oil screen and the valve head. I am not convinced that you need a new cylinder head gasket (bottom one) unless it is damaged. The cases are put together with Hondabond, so you'll need a tube of that.

The bearings in the engine are very expensive so I don't recommend changing them unless they are bad. A new set, not including the rod bearings, will run you about $100-$125.

But before you do anything, I recommend the following test....

1. Remove the clutch basket. The big nut has 100# of torque on it. You do not need to remove the flywheel on the other side.
2. Remove the plugs.
3. Rotate the cams so that none of the valves are engaged.
4. Turn the engine over using the nut on the flywheel.
5. The crank should turn over freely and without binding. Make sure you are turning it in the correct direction or else you'll also be turning the starter motor over.

With this type of catastrophic failure, a bent crank is very possible. By turning it like this, you should be able to tell if its bent by feeling for binding. The crank is ultra high tolerance so any warpage is going to be noticed. The tolerance is measured in 1/1000th of a MM - not inch.

If you believe your crank is bent, don't try to rebuild it. Just get a new engine.

[alex.s]

have i mentioned how much i'm in love with your engine stand, D?

[alex.s]

also a note about replacing crank bearings. like D said they are very specifically sized and the size varys from case to case and crank to crank, so you need to do an ink crush measure stick thing otherwise you'll risk blowing your brand new bearings in a few hundred miles. of course this is assuming the crank is straight

[n4mwd]

Originally Posted by alex.s

have i mentioned how much i'm in love with your engine stand, D?

It was $19.95 at Harbor Freight a few years ago, but I just checked and they've gone up a bit.

The thing about the bearings is that if you don't change or move them, you can reuse them as long as they are good. No need to plastigauge since you already know they work. But if you put in new bearings, you have to plastigauge everything. And to make matters worse, if you pick the wrong sized bearings, the dealer wont take them back.

[flynjay]

If you're interested, I have a (used) cam chain and rocker's that I could sell you. My previous engine has a bad crank bearing. PM if interested.

[AFazakerley]

Thanks for all the info guys!
I can’t watch the video till I’m out of work, but that should be very helpful.

I will try an locate all the debris and then test the crank. If the crank is bad i will call it a day and hunt for a new engine.

Sounds like I might be able to get away without splitting the case, which would be nice since it sounds like that complicates the task a bit.

I should be fine with the current bearing since they have less then 2k on them, right?

Now I just need some free time to get to work!

@flynjay how many miles on them?

[flynjay]

Originally Posted by AFazakerley

@flynjay how many miles on them?

12000 on the cam chain, 2000 on the rockers.

I would recommend getting a new chain. I will will do $50 for four rockers shipped CONUS.

I can throw in the cam chain for free but I would recommend getting a new one (that's not something you want to change twice). But if your engine is toast you don't want to spend $$ on it. I've been through this myself and after it all the new chain didn't solve the problem so ended up pitting a new (used) motor in.

[CZroe]

Originally Posted by AFazakerley

Thanks for all the info guys!
I can’t watch the video till I’m out of work, but that should be very helpful.

Not so much. Definitely watch it, but he was only able to do what he did because parts were destroyed and they didn't care if the engine blows up ("just a beer runner").

[AFazakerley]

Alright i went to work, took the head off and removed all the clutch parts. I rotated the crank witht the head off and everythnig was smooth! Then i put the head back on and did the same thing. Now i know having the rings against the walls adds friction but i found it fairly hard to turn the crank by turning the clutch plate with the gears. I could barely do it with one hand. Is this normal or could something be bent?

[alex.s]

kinda hard to tell when you do it by hand, i use a ratchet on the flywheel bolt

[AFazakerley]

Ok ill try that, maybe even use a torque wrench to see how many # it takes.

[n4mwd]

If the case halves were torqued together when you turned it (ie-not taken apart), and the crank turned easy, then the crank is probably not bent. The resistance with the heads on could be coming from a bunch of stuff including the cams.

Did you look at the teeth on both sides of the crank to make sure nothing chipped off? Especially the timing chain sprocket.

[Motofool]

Originally Posted by AFazakerley

......Then i put the head back on and did the same thing. Now i know having the rings against the walls adds friction but i found it fairly hard to turn the crank by turning the clutch plate with the gears.....

If you left the spark plugs in place, your hand was working against the compression of each cylinder.

Either way, the springs of the valves create an important resistance if the timing chain is installed.

[AFazakerley]

@namwd Case is still whole and crank does turn smooth when head is off.
I have not looked at the teeth of the cam chain sprocket, only the outter one.

@Motofool The plugs are out and the chain aswell, there is no compression just the friction of rings against side walls.

[Motofool]

Originally Posted by AFazakerley

The plugs are out and the chain aswell, there is no compression just the friction of rings against side walls.

Then, you meant that you turned the crankshaft without the cylinders, not only without the heads.

In that case, you may have one (or two) bent connecting rod.
If that is true, the pistons are crooked inside the cylinders, creating extra friction.

I believe that the repair manual shows a way to measure that.

[AFazakerley]

Originally Posted by Motofool

Then, you meant that you turned the crankshaft without the cylinders, not only without the heads.

Correct the head and sidewalls all came out as one.

Originally Posted by Motofool

In that case, you may have one (or two) bent connecting rod.
If that is true, the pistons are crooked inside the cylinders, creating extra friction.

I believe that the repair manual shows a way to measure that.

Ahaha that would make sence, ive had car engines turn over with less amount of force. Thought something might be up. Guess its time to buy a repair manual, even though looks like im looking for a new engine

[n4mwd]

The teeth on the crankshaft cam chain sprocket need to be checked. Nothing special, just look to make sure none of them are missing or chipped off.

Bent rods are certainly a possibility. But the only way to check them properly is to split the case and remove the rods from the crank. Then you need to replace the rod bolts which are expensive. I have seen these before, and bent rods, and even bent valves, are not common. The rockers are the weak link and help protect against that sort of thing.

I suggest before you do all that is to remove the cams and chain and plugs and see if that makes it easier to turn. The pistons will make it a little harder to turn, but you should be able to turn the crank easily with a torque wrench on the flywheel nut.

The clutch basket is going to be a lot harder to turn because its gearing it up. That is, you turn the clutch basket once and the crank turns 3 times. Therefore, its not a good place to judge the hand turning torque, because it take 3 times as much torque to turn the crank that way. So don't use the clutch basket to judge engine resistance.

[Motofool]

Good point about the torque amplification.

I fully agree with n4mwd.

[AFazakerley]

Alright cams and chains are removed. When i get home ill turn the crank by the flywheel and not the clutch basket and see how that goes. Sadly my torque wrench is a POS and i dont think it will pick up anything below 5#s.

Good to know about the clutch basket gearing up, gives me a little hope in this engine.

Painfull to see people riding these days, even though the weather and streets are far from perfect it still sucks knowing i cant ride even if i wanted to.

[AFazakerley]

After turning the crank with a 3/8in rachetin wrench i determined i need a new engine. As i turned it, i can feel irregular friction. I guess i bent something causing irregular friction.

Im going to start looking for an engine or a parts bike localy. Thanks everyone for all the advice.

[n4mwd]

In that case, I'm going with the bent rod theory.

I would rebuild it. The problem with new "used" engines is that you never really know what you are getting.

You can buy new rods for about $40 on ebay. However, if they are a different code than yours, you'll also need new bearings to match. Otherwise, you can use the same bearings. I suggest you split the case and fine out what your rod codes are and then try to get replacements with the same code so you don't have to get new bearings.


Either way, you'll still need new rod bolts.

PS: If you still want to get another engine and want to give away the old one, I'm available.

[AFazakerley]

Small update, i think i jumped to conclusions about feeling irregular friction. I believe it was just due to how i was rotating it. After i removed the stator/cover and was able to turn the flywheel by hand its not soo clear any more.

Any way to test? Are there torques wrenches that pick up low enough readings to tell if its to spec?

Haha no ideas if that amkes any sense

[n4mwd]

As the crank approaches TDC or BDC on either cylinder, the crank will be slightly easier to turn, but it shouldn't be a huge difference.

EDIT: Honestly, just put it back together and ride. If it blows up, you'll have spare parts to fix the next engine.

[AFazakerley]

Originally Posted by n4mwd

As the crank approaches TDC or BDC on either cylinder, the crank will be slightly easier to turn, but it shouldn't be a huge difference.

EDIT: Honestly, just put it back together and ride. If it blows up, you'll have spare parts to fix the next engine.

Alright! I like that kind of thinking

Ill order the parts, rebuild it and then will see what happens.

[n4mwd]

Originally Posted by AFazakerley

Alright! I like that kind of thinking

Ill order the parts, rebuild it and then will see what happens.

Are you planning to split the engine? Its a pain, but it isn't going to cost any extra. You'll need to buy a $20 tube of hondabond HT to put it back together. Most of the expense is normally in the side cover gaskets and the new head gaskets. The bottom cylinder gasket can be reused, but the top one should be replaced ($20). Another guy here just reused his so it is possible, but I personally wouldn't chance it. There are also aftermarket gasket sets, but I don't know anything about their quality.

If you find that the rods are bent, I don't see why a machine shop couldn't bend them back???? They might have to have them re-tempered, but it should be possible. I've never done that myself though.

[AFazakerley]

Originally Posted by n4mwd

Are you planning to split the engine? Its a pain, but it isn't going to cost any extra. You'll need to buy a $20 tube of hondabond HT to put it back together. Most of the expense is normally in the side cover gaskets and the new head gaskets. The bottom cylinder gasket can be reused, but the top one should be replaced ($20). Another guy here just reused his so it is possible, but I personally wouldn't chance it. There are also aftermarket gasket sets, but I don't know anything about their quality.

If you find that the rods are bent, I don't see why a machine shop couldn't bend them back???? They might have to have them re-tempered, but it should be possible. I've never done that myself though.

I was not planning on splitting the case. I think ill just throw it back together and see what happens. Its very likely that i will be picking up a parts bike localy anyways. That way i can work on repainting the good plastics from said bike and if the engine blows, then i have a spare anyways. I ordered all the parts today, hopefully ill wrap it up by next weekend.

[adamjenkum]

i tore a 250 apart once, looked up prices on gaskets and parts i would need and even with some parts used that i sourced it was too expensive to be worth it. got a used bike with a good engine for 300 at salvage yard and swapped the engine in a afternoon and was riding the next day.


you are lucky that gear isn't buggered on the crankshaft though, that was what turned me away from rebuilding , but in 15 years it might be harder to find engines and the prices on parts wont look so bad, but by then 2008 and up ninjas will be the old model.

[AFazakerley]

Update
I bought a parts bike for the engine but also plastics and any other pieces i might need.
Wicked cleana nd only 52 miles.

started swaping the engine.

Got it in and started! Still need to button a lot of stuff before i can ride it though.

Started rebuilding other engine aswell.

[n4mwd]

The RED one is the parts bike? Why not go the other way? The red one looks so nice.