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84 Engine Rebuild

10K views 50 replies 7 participants last post by  mattyo 
#1 ·
Hey everyone,
I've recently removed my 1984 VT700c's engine and it's sitting in my living room. I'm attempting to diagnose a seized engine, but wanted to ask if there is anything I should replace/clean/repair while I've got it off the frame (granted I can fix the original problem:) ) I'm planning on starting with the top covers and working my way down till I find the break. Thanks!
 
#2 ·
might be a good time to rebuild the starter and maybe replace the clutch plates

and honestly it's one of those situations that where your that deep in you may as well replace the rings and cam chain and all the gaskets

depends if your going to keep the bike for a long time - if so do it ... if not let the next guy worry about it!

If you do replace the rings you will have to break the engine in again
 
#3 · (Edited)
oh btw - a tip from a been there done that ....

The hydroloic tappets can be a total p.i.t.a if you don't do this ..

first be real careful taking the top part of the head, I STRONGLY suggest that the second you get about 1/2 -1in of daylight inbetween there try to stuff a rag or shop towel into the hole where the camchain is as the tappets which each have a couple of spacers on them can lift up with the head and drop right into the bottom of the crankcase

I was DAMN lucky and was able to fish out the spacer that dropped with a magnet as it had not gone all the way but that was blind luck

Also it is REAL important you record which tappet goes where and how many spacers it had ... DONT BLOW THIS OFF other wise you will have to do a valve adjustment - use a notepad and small baggies and mark whats what - they go back in the same way your golden

Also unless you have another pair of hands only do one cylinder at a time as there will be several times you will need to turn both camchains at the same time which is pretty much impossible to do on your own

gl
 
#4 ·
Thanks for all the insight! I bought this bike as a basket case (the tappets were handed to me with no labels in a plastic bag) and I plan to keep this bike as long as I can. Is a valve adjustment difficult? I look around a bit, probably something I should have done the first time I was putting it together.
 
#5 ·
Am I hearing you correctly? When you got the engine it was already partially disassembled and you built it back up and had to randomly reinsert the tappets (and shims) because they weren't labeled? I must have missed that point in your other threads, sorry.

If that's true, then that's probably the source of your problems. I don't know enough to explain how incorrectly set tappets would lead to an engine seize, but I do know it's pretty critical to get those set just right. Kudos to you, I'm surprised the engine would even turn over.

Please explain in more detail what you did to piece the engine back together.
 
#6 ·
Haha thanks! Basically yes to Mattyo's question above. I got the bike with the engine out of the frame, tappets and shims in a ziplock bag tagged "Misc." This was about 3 or 4 years ago, and the bike was running up until this past fall. I followed the clymer manual as best as I could, bled the tappets in a mason jar of kerosene, then reinstalled. Most of the engine work was on the head covers, so I was able to stay clear of the pistons, cam chain and transmission. I was going to prepare for a work meeting I have in the morning, but now I think I'm going to start disassembling instead:) wish me luck, I'll post pictures soon.
 
#7 ·
Okay so I've taken both head covers off and every thing looks good (not smashed, crackled or popped). I took a look at the cam tensioners and noticed that the top piece (see pics) of the front tensioner was free to be pushed in and then spring loaded back to normal. The rear however, was locked up and only after some "persuasion" was I able to get it to move up and down. But it sticks on its way back up like the metal to metal surface has worn a grove that prevents easy sliding. So, I'm trying to remove the chain on the rear side, I've removed the tensioner, but since I can't turn the engine, the second bold holding the cam in is so far inaccessible. Any hints? I was thinking I'll have to take the cylinder off to get to it, but would like to avoid it if possible. Ohh and I took the timing gear off (maybe a mistake, but I wanted to check this) so that I could isolate where the problem was. Since the clutch and transmission were no longer connected to the cylinders I thought if I can spin the clutch basket, while in gear, then the problem isn't in the transmission, and likely in the cylinder heads. Any thoughts? Thanks!
 

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#8 ·
Had to cut the cam chains in order to get them out:( But at least I can get to the pistons now. I removed the cylinder heads and cylinders exposing both front and rear piston. Aside from some expected soot, they look okay. Although the piston rings on the rear seem loose. Not sure how to explain it, but they can sort of hula hoop inside their grooves, unlike the front where they are essentially locked into place. Is this normal? But, I still can't turn the engine over, so my idea of locked up pistons causing the seize is false. Must be some sort of bearing between the primary drive gear and the alternator. I'm thinking that I'll have to split the case, which I've never done before, any suggestions? It will take me a while since I can't get the nut holding the clutch basket without an impact hammer...anybody in CT have one to borrow:) Throwing up some pictures to show the "progress", appreciate the suggestions.
 

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#9 ·
Although the piston rings on the rear seem loose. Not sure how to explain it, but they can sort of hula hoop inside their grooves, unlike the front where they are essentially locked into place. Is this normal?
Well, all I can say if based off what I've come across in the two engines I'm still in the process of rebuilding. Also my first rebuild. WEE! http://www.hondashadow.net/forum/72-technical-discussion/120530-engine-rebuild-more.html

All my piston rings (in both engines) were loose and could do the hula-hoop thing you described. I would think that's the way it's supposed to be so the piston has some room to flex while the rings still keep a seal on the chamber. Take this with a grain of salt but I'm guessing your engine seize was from the locked rings. The rings could have dug into the chamber just enough to seize it up but with a little hands-on persuasion you were able to get it moving again? Not sure.

Let us know what you find.
 
#10 ·
Your thread is great! Exactly what I needed to start my own rebuild, so thank you very much. Looks like I have a long road ahead of me...are you close to finishing? Now that the pistons are out of the cylinders, I would think that I could turn the primary gear clockwise (if in fact, the cylinders were causing the problem), but it still won't budge. Do you think it could be a bearing? I'm 90% sure that I want to split the case so I can see what's inside, but right now I'm having trouble getting that dang nut off the clutch basket. I'll keep trying and let you know how it goes.
 
#12 ·
After reading Mattyo's thread I decided that I too should venture into the unknown and split the case. After a lot of pulling and swearing I finally got it split. And I you're right about the front piston causing the seize Mattyo. The front piston arm does not spin on the crankshaft like the rear piston arm does. It was literally locked into place, not until I unbolted it from the crankshaft was I able to get it moving. Even then, it took a lot of work to get it free. So, I'm wondering....what would cause this to seize and what should I replace? If I can find them, I'd like to replace the crankshaft main bearing plus all the others (anyone have a link plus a link to a bearing puller?).

Also, there was a lot of metal shavings in the case and stuck to the oil pump's filter. When I was first putting this bike together, I installed the clutch bearing backwards and burned through two sets of plates before figuring it out, so I'm guessing that's where the metals from. Does it seem possible that the large amount of metal caused a block in an oil pass and the piston wasn't getting its share? Also, the front (presumed faulty) piston seems to have some rust where the rings are, which I think it what it preventing them from moving. Well, a lot of work for one day, I'm going to let it sit and "cool off" for a while and enjoy the rest of the day, hope to hear some comments soon! Thanks!
 

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#13 ·
I'm making a list of the essential parts I'd like to replace and piston rings and piston rod bearings is on the top. But, I can't seem to find a vendor anywhere. Does anyone have any suggestions on where to find these things, again I've got an 84 VT700. Thanks!
 
#16 ·
Here's a few links for the 84 vt700 crankcase:
1984 Honda Shadow 700 VT700C Parts, 1984 Honda Shadow 700 VT700C OEM Parts - BikeBandit.com
OEM Parts Honda SHADOW (VT700C) 1984 CRANKCASE - Cheap Cycle Parts
Huntington Beach, California, Honda, Police, ATV, GL1800, Motorcycle, Watercraft, Dealer, Used, Parts, Accessories, Apparel, Service, ST1300PA,
1984 Honda SHADOW - VT700C OEM Crankcase Parts | MotoSport

You can find the fiche of the piston assemblies there too. They should sell the piston rings? I didn't check. :( Anyway, hopefully that will help.

And if you're going to pull the bearings, I have the "special" honda tool for getting those nasty trany shaft pilot bearings out that I can send your way. I bought 3 previous bearing pullers and none of them would fit around that protruding shaft seat thing (I don't know what it's called, I'm still a n00b). You saw the thread. :) Anyway, give me a shout if you want to barrow it! Hopefully I'll only need to use it ONCE! :-D
 
#17 · (Edited)
Okay so a little progress made so far. I threw the front cylinder with the locked up rings into the ultrasonic cleaner, and made it shine. The rings loosened right up, I'll check their dimensions tomorrow, if they're within spec should I even worry about replacing them?

Also, I'm beginning to think there was an oil blockage preventing flow to the front piston rod bearing. When I took it off the crank the two halves were nearly fused together. Definitely going to have to get new ones (if I can find them) Another little clue was a gouge made in the right crankcase outside the main bearing by the timing chain (I'm guessing). This was the same side that had the stuck timing chain tensioner. I'm going to put on my detective hat and take a guess, please feel free to call me crazy:)

1)Had previously burned and cracked friction plates and was unable to clean all fillings out of crankcase.
2)While riding, felt the engine seize and then took a short flight through time and space to meet my friend the ground.
3)After removing the front cylinder head, noticed cam chain tensioner was stuck
4)After removing front cylinder noticed piston rings were also stuck.
5)After splitting case and removing crankshaft and front piston rod noticed the piston rod bearings were piled on top of each other. This was the actual cause of the seize.
6)Cam chain wore into the right side crankcase.

I think, the fillings clogged the oil jet, and both the piston bearing and the piston rings continued to move dry and then seized up. The cam chain may or may not have been involved, but regardless the tensioner was stuck and allowed the loose chain to come in contact with the metal and shave some off. That or Professor Plum did it with the candle stick:)
 

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#44 · (Edited)
You mean YOU'RE the reason I can't find piston rings in my home town!!!! http://www.hondashadow.net/forum/72...tinued-gaskets-1984-vt700c-necessary-amp.html. Ugh I should have bought them 6 months ago when I had the chance.

^^^^That's hysterical!

Bad news, just got the email (that I was sort of expecting) from HB honda saying the piston rings and piston rod bearings are discontinued. Back to square one. I'm thinking that I might have to change pistons? I can't imagine doing all this work and then not replacing the rings. Errrr. Any suggestions?
Oh wait I should have read further. I take back all those nasty things I thought about you. They did have it in stock awhile back... maybe it was closer to two years ago... hbhonda is the cheapest by far for dealer parts, but shhhh, that's my secret.
 
#20 · (Edited)
Not to pick apart your diagnosis in anyway but just curious.
When you say the cam chain tensioner was stuck, do you mean it was difficult to pull the tensioning wedge up thereby loosening the tension or did you mean it wouldn't move at all? In my tremendous experience (sarcasm) with the two engines I pulled apart, all the cam tensioner wedges were a bit stuck and took a little force to get them to pop free. Saying that to say, I think being a bit stuck is normal? but if you couldn't budge it at all, well that's a different story.

Glad to hear you found the parts you needed. It's pricey but it's still cheaper than the local mechanic!

And it looks like I'll need to buy an ultrasonic cleaner! My wife will be so pleased! LOL!
 
#21 ·
Not to pick apart your diagnosis in anyway but just curious.
When you say the cam chain tensioner was stuck, do you mean it was difficult to pull the tensioning wedge up thereby loosening the tension or did you mean it wouldn't move at all? In my tremendous experience (sarcasm) with the two engines I pulled apart, all the cam tensioner wedges were a bit stuck and took a little force to get them to pop free. Saying that to say, I think being a bit stuck is normal? but if you couldn't budge it at all, well that's a different story.
No, I welcome the opinion. Just because I've convinced myself doesn't mean the bike will run when I put it all together. The more questions the better! The wedge was pretty much locked into place and I was only able to move it after a few (somewhat gentle) whacks with the buttend of my socket wrench:) Their are two wedges really, one that rides up and down against the other, but the wedge that moves wore a groove into the other and on its return (after pressing it down) it also gets stuck. I found a used pair on ebay for like $30, not perfect but I think it will be better than what I have.

Glad to hear you found the parts you needed. It's pricey but it's still cheaper than the local mechanic!

And it looks like I'll need to buy an ultrasonic cleaner! My wife will be so pleased! LOL!
Yeah it was a little expensive, but I'm gaining a ton of knowledge and tools (though my bank account isn't so happy:) ). All in all this has been a fun project so far. And just tell your wife the ultrasonic cleaner is for her jewelry!;)
 
#29 ·
That I do not know, I would naively think you'd take the measurement as is, ie not forcing the gap closed but I don't know. I haven't measured my rings yet (sheepish grin). Maybe I'll do that quick. You should be able to tell from the listed spec and your measurement. If the measurement is way off from the spec then it's probably because the measurement was done incorrectly. An open gap to closed gap measurement compared to spec "should" be a good indication.

Just a thought, but the 85 vt700 might have the same dimension rings as the 84 vt700. I know parts-wise, the 84 and 85 vt700 are pretty similar. I would be surprised if Honda changed the fundamental engine dimensions in those two years. Someone on this forum might know, or go to local bike mech and ask but I'm betting it's the same engine.
 
#31 ·
#32 ·
I'd be worried about the width and thickness of the ring. Don't know if those are standardized parameters but I'd guess not. You could get them and measure them and send them back if they're incompatible? Also the material the rings are made out of might not be to spec for the vt700? Just throwing some idea's out there. I don't know enough about motorcycles yet.

could be genius!
 
#33 ·
Those are all really good points, and I guess I'll keep my old rings and just hone the cylinders lightly. Also, since I won't be able to rebuild this thing without new piston rod bearings I'm a little stuck and need some opinions. This item (hopefully no one buys it from under me:) ) is listed for 80, but he'll take 70 (plus 31 for shipping :mad:). Worth it? It's a lot of money (at least 100 Ramen Noodles) so I'm hesitant, but without it I'm stuck. And I guess I could always sell what I don't use.

http://www.ebay.com/itm/1984-Honda-...Parts_Accessories&vxp=mtr&hash=item3cc155fc98
 
#34 ·
This item (hopefully no one buys it from under me:) ) is listed for 80, but he'll take 70 (plus 31 for shipping :mad:). Worth it?
I just bought it. I'll sell it to you for $90, plus $30 for shipping. :D

If you can't find the rod bearings anywhere, then I'm thinking that's your best option. $70 is pretty good considering if you could buy the whole crank shaft assembly from Honda it would probably cost around 200-300 raman noodles.

Do you have a local mech you can talk to? Sometimes they have a whole load of used parts that they're happy to part with at a very reasonable price. It's always worth just stopping by and having a chat with them anyway. Knowledge is priceless, so I've been told.
 
#35 ·
Good news! In regards to the cylinder gasket you can't find. If you take a look at the fiche for my 83 750 (Ronayers.com Microfiche Honda>Motorcycle>1983>VT750C>CYLINDER @ REAR CYLINDER HEAD) you will see #2 and #8 gaskets you can buy. I bought them both but then they said #2 wasn't available anymore. So I got my #8's and didn't really take a close look at them because I'm not at the point where I need to install them yet but at first glance I noticed there were 2 gaskets in the package, but didn't think much of it. So I took a closer look tonight to see what the deal was. And it appears that when buying #8, you actually get #2 and #8 in the same package, which I guess is why they say #2 isn't sold anymore, but it would be nice if they'd also say that #2 now comes with #8. The assumed #2 gasket did fit perfectly for the surface between the crankcase and cylinder so I'm pretty sure that what I've said is true.

Ronayers doesn't have a fiche for the 84 700 but they do have a fiche for the 85 700 and the gasket part numbers are the same as the 83 750. So I'm guessing the 84 700 will also have the same #2,#8 gaskets being sold as the #8. I guess one clue is that they call #8 a gasket "set" which I didn't notice before.

I think your ebay link had them listed at a lower cost, I can't remember, but if you feel safer with honda direct, I'm pretty confident that ordering the #8 gasket "set" will get you both gaskets you need. Here's what I got when I ordered the #8 "set".

 
#36 ·
rings for cars we normally insert into the cylinder and push down about 1/2 inch with the piston. then measure the end gap. the shop manual should have specs for that. what kind of bearings do the rods use. I was expecting ball bearings like my old honda had. those required the crank to be pressed apart to change. if plain bearings bad enough to stop the motor what do the journals look like?
 
#37 ·
Okay I'll try that, makes a lot of sense actually, thanks! The bearings are more like shims than anything else. They're two halves of a cylinder that rotate on the journal (which I think is in good shape). But you do bring up a good point which makes me think I should just suck it up and drop the $100 on the crankshaft. Good thing I'm single :)

To Mattyo, that must have been a pleasant surprise! I just ordered two sets, so thanks for finding them. I impulsively bought a pair of cylinder head gaskets yesterday for 25 on ebay...so if anyone needs them let me know cause I should have spares!
 
#38 ·
Interesting twist to this engine rebuild. Taking Mattyo's advice I called my local mech to see if he could find the parts. After I told him how the bike seized and that I'm doing an entire rebuild he basically said...

"Don't rebuild that motor, you don't know why that bearing seized and it could be pretty dangerous to have it happen again while on the highway"

Now I rarely listen to people, especially when I'm already so deep into this motor. But he then said he has a shadow same year and model sitting in his shop that he's selling for parts and it has a working motor that he would sell me for $300. This is very tempting, though it's more than what I originally paid for the bike, I'm already shelling out a ton for all these parts I've had to buy (Which I would return unless someone here needs them:) ) So, what do you all think?
 
#39 ·
Jumpin Jehosaphat! Well on the one hand if you're replacing your rings and bearings and if you buy that crankshaft assembly off ebay, I don't think another engine seize is a concern. But $300 for a working engine is probably comparable in price to the all the parts you're buying right now. And a parts bike comes in very handy for all the little crap that breaks down, and for trouble shooting. If you suspect a faulty part, you can swap it with the parts bike's and quickly check if that's in fact the problem.

You can probably return most the parts you've bought so far. So assuming you can recoup most of your expenses so far, I'd personally take up the offer on the parts bike. My parts bike has saved me quite a bit of money in the long run. Just my opinion on the matter. And you could probably talk him down to $250. He's had that thing taking up space for who knows how many years. He just wants to get rid of it.
 
#40 ·
Very sound advice, I'm going to call him tomorrow. I've learned a ton from just ripping the bike apart, but it will be nice to actually be able to ride this summer:) I'm going to offer him $300 for the motor, the clutch master cylinder, tach/speed assembly, and battery cover (all things either broken or missing from the early crash). I can't wait! Just hope that summer funding is all set!
 
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