Topic: Strange loud crack coming from engine - If your cases are split, a MUST read.

[MRieck]

I have seen the C clip problem before in several of the ZX-11's I rebuilt that had had the transmissions rebuilt by the dealer.
 The manual is very specific in regard to C clip position/thrust direction.

[Terry in Australia]

Well Scott posted a link to this thread, as this might be the reason for my massive skid mark on New Years Eve when my gearbox locked up the rear wheel at (luckily only) 40 MPH. I won't pull my engine down for a few weeks as I'm starting another project today, but this thread has got me wondering if my K6 or F0 transmission has suffered a similar failure? So much for Honda's reputation for quality control!

New Years Eve Bitsa disaster 2019 by Terry Prendergast, on Flickr

[PeWe]

I guess the Honda warranty is max one year after delivery to first owner, not 40+ 
I wonder how many that has died due to this? The reason by media is usually that motorcyclists drives like crazy!  Maybe something like ... "he crashed after trying to brake for something, an animal, drunk, hallucination etc...". The drunk or stoned rider got the blame for the factory assembly

Very important point to investigate. I hope both my bikes are correct. "Never had trans apart" will not ensure a correct assembled c clip/snap ring as witnessed here.
I usually let my bikes idle on side stand. One has undercutted gears by professionals and most likely correct assembled after that.
My K6 has irritating rattling clutch discs when leaning it to the left and sliding on the clutch when doing a sharp u-turn on a street. Not a distinct "clonk".  (I'll throw in a later clutch (F2))

- Interesting to see what Terry will find when taking his engine apart. Important to be aware of the various threats that can end the bike, not only cars with their drivers except for self inflicted too inspired riding. 
- Terry, please keep this thread in mind when opening the cases.

I have not fully understood this until now when its clear that the pressure of the gear must be applied on the "rounded" side of the clip so the sharp edge will sit in the groove and keep it there. If flipped, the rounded edge will not be able to keep up the pressure in the shafts groove, it will slide over the groove.
I have 2 trans in a box to check. Low mile 1975F and my old K6-76 with 100.000km

This must cover all CB's and other bikes too like Mike has seen, right?

[bryanj]

I distinctly remember a warning in the official Honda workshop manual about correct positioning and orientation of circlips but as these manuals were very expensive only dealers had them.
I suspect that those with moved circlips have be dissasembled outside of official dealerships and reassembled incorrectly AND with reused circlips.

Do you really think that with the legally oriented US market that Honda could have got away with a dangerous fault without a class action?

[Terry in Australia]

Good question Bryan, but it happens. My Triumph Rocket III's output shaft bearing collapsed after 8000 Km (around 5000 miles) and lucky for me it didn't hand grenade like at least one other guy I spoke to who blew his bike up spectacularly crossing the Nullarbor Plain on a ride from Adelaide to Perth.

Triumph didn't do a recall, they came up with a "Revision kit" that included a new bearing, revised sump, lots of other parts I've forgotten, and even new coils and a few other bits that took it to the same spec as the 2011 model. Each major dealer had one or two of these kits under the counter to install in a customers bike if they experienced a bearing failure, as long as it wasn't a catastrophic destruction. It wasn't free, it cost me $2290 (AUD, around $1600 USD) because technically my bike was out of warranty. (it was 2 years old when I bought it from my brother with 20 miles on the odometer, and 4 years old when it blew)

It wasn't a design fault, it was a manufacturing error, apparently it's a sealed bearing like a wheel bearing, and has a seal that should be facing out on installation, so that oil splashed up from the sump/transmission lubricates it. Only problem is, now and then the person installing the bearing would forget which way to install it, and put it in the wrong way around, so the only lube it had was the manufacturing grease. They must have been pretty good bearings to last as long as they did, so once my bike was fixed I was pretty confident that it wouldn't happen again, but I wasn't happy that I had to pay for it.

[Geoff Hastings]

Thanks for all the responses, I really thought this problem was going to be a mystery but it would appear to be a straight forward solution. It’s just a shame that it will involve another engine out and strip down to cure, still, no harm done, and I did get to ride it so I know what a nice bike it is to ride.

[Don R]

 My brother and I repaired a K7 trans with a broken thrust washer. It had shifting issues and pieces of it in the sump. I don't remember any snap ring issues but that was a while back. 

[Terry in Australia]

Well now that I'm waiting for my Kawasaki Z1 cases to arrive from the US before I can slot the hotrod 1100cc engine into my new (to me) Z1B build, I might pull the engine out of my K2 bitsa to see what caused the gearbox to lock up. I'm not sure if it is a circlup issue, or if one of the gears has shattered. What's weird is that I can still select gears (not sure if I've still got all of them though) and neutral, and the engine runs fine. I'll take the exhaust off and drop the sump pan and pump, and if lots of chunks of metal fall out, I'm guessing it'll be a busted gear.

[HondaMan]

Well Scott posted a link to this thread, as this might be the reason for my massive skid mark on New Years Eve when my gearbox locked up the rear wheel at (luckily only) 40 MPH. I won't pull my engine down for a few weeks as I'm starting another project today, but this thread has got me wondering if my K6 or F0 transmission has suffered a similar failure? So much for Honda's reputation for quality control!

New Years Eve Bitsa disaster 2019 by Terry Prendergast, on Flickr

Yeah, that's just what it looks like!
The rounded side of the circlips go toward the moving parts, if they are in between 2 gears. This moves the tips of the spreaders away from the moving part.

The problem appears to be most common in the [later] K5/6F0 bikes, from what I've seen and heard of it. This makes sense to me, as this was when Honda started making the CX500 and Goldwing designs, and they probably took their experienced people away from Production to do it. They started making the Honda cars then, too, with the famous CVCC engines. Sochiro lost control of his company in 1973 and was working himself on the production lines in 74-77, according to my friend Axel here, who was born in Japan, worked on the Honda lines (CX500 and CB350F/400F bikes) and came to the USA as a teen.

[scottly]

Well now that I'm waiting for my Kawasaki Z1 cases to arrive from the US before I can slot the hotrod 1100cc engine into my new (to me) Z1B build, I might pull the engine out of my K2 bitsa to see what caused the gearbox to lock up. I'm not sure if it is a circlup issue, or if one of the gears has shattered. What's weird is that I can still select gears (not sure if I've still got all of them though) and neutral, and the engine runs fine. I'll take the exhaust off and drop the sump pan and pump, and if lots of chunks of metal fall out, I'm guessing it'll be a busted gear.

Terry, didn't you find a broken off gear tooth behind the shifter cover on that motor?? My C200 trans locked up once, but after rocking it back an forth it freed up, so I went merrily on my way. Later, I found a single tooth, that had evidently jammed the gears, then fallen free. Never did replace the gear.

[Terry in Australia]

Well now that I'm waiting for my Kawasaki Z1 cases to arrive from the US before I can slot the hotrod 1100cc engine into my new (to me) Z1B build, I might pull the engine out of my K2 bitsa to see what caused the gearbox to lock up. I'm not sure if it is a circlup issue, or if one of the gears has shattered. What's weird is that I can still select gears (not sure if I've still got all of them though) and neutral, and the engine runs fine. I'll take the exhaust off and drop the sump pan and pump, and if lots of chunks of metal fall out, I'm guessing it'll be a busted gear.

Terry, didn't you find a broken off gear tooth behind the shifter cover on that motor?? My C200 trans locked up once, but after rocking it back an forth it freed up, so I went merrily on my way. Later, I found a single tooth, that had evidently jammed the gears, then fallen free. Never did replace the gear.

Yeah mate, I found the broken off tooth a couple of years before the gearbox locked up, and I did a lot of miles in between, so really not sure what happened, but what worried me was when it locked up I pulled the clutch in, and it made absolutely no difference, and I just had to ride it out s I was skidding up the road.

I can't just forget about it and ride it again until I pull the engine this time, because had the gearbox locked up a minute earlier when I was doing 70 MPH on the freeway, I probably wouldn't be here to talk about it. You're right though, even with a tooth missing, it didn't make any funny noises etc while riding along. Weird.

[PeWe]

Terry, please open that engine so we all will know!

If this is a Honda production issue, we all might need to open our engines to have a look at our circlips on trans.
Alternative a crash.

I have many memories leaning the bike in a nice long curve in +100 MPH, metal barriar rather close or just meeting trucks or narrow roads with very dense forests. Thick timber....

Time for a ride.

[Terry in Australia]

Terry, please open that engine so we all will know!

If this is a Honda production issue, we all might need to open our engines to have a look at our circlips on trans.
Alternative a crash.

I have many memories leaning the bike in a nice long curve in +100 MPH, metal barriar rather close or just meeting trucks or narrow roads with very dense forests. Thick timber....

Time for a ride.

No worries Per, when I do, I'll take lots of pics. I still think it's a busted gear, but I guess I'll find out soon.........

[Alan F.]

Is this something that we all should set eyes on if we get the chance regardless of 750 model or year?

New circlips are required? 5 total?
CIRCLIP (OUTER) (25MM)
90601-300-000 
$2.81 at Partzilla, $3.02 at Bikebandit


I've got a K8 that looks like the cases have never been split, it'll need at least a primary chain tensioner while I'm in there.
I've never split cases before so I've got some reading to do.
Any pointers are appreciated, build thread link in my signature, thanks.

[Terry in Australia]

Is this something that we all should set eyes on if we get the chance regardless of 750 model or year?

New circlips are required? 5 total?
CIRCLIP (OUTER) (25MM)
90601-300-000 
$2.81 at Partzilla, $3.02 at Bikebandit


I've got a K8 that looks like the cases have never been split, it'll need at least a primary chain tensioner while I'm in there.
I've never split cases before so I've got some reading to do.
Any pointers are appreciated, build thread link in my signature, thanks.

You can pull your engine, tip it upside down and just unbolt the lower case (there are some thru-bolts on the top case that will need removing as well) but if you don't have any top end issues, it'll save having to pull the head and cylinder block. Just be super careful reassembling it, make sure both case half mating surfaces are perfectly clean and free of old sealant and just use the absolute minimum of sealant. Finally, make sure you use a good torque wrench to torque all those bolts correctly, and in the right sequence.

[Alan F.]

It's a new to me K8 bought for peanuts, compression was about the only thing it had going for it. I'll have to check ring gap before reassembling, but top end is all off, A.P.E studs will be going in. It won't get any easier than it is now I guess.

I'll order a primary tensioner and some Threebond then.
Thanks!

[scottly]

Is this something that we all should set eyes on if we get the chance regardless of 750 model or year?

New circlips are required? 5 total?
CIRCLIP (OUTER) (25MM)
90601-300-000 
$2.81 at Partzilla, $3.02 at Bikebandit


I've got a K8 that looks like the cases have never been split, it'll need at least a primary chain tensioner while I'm in there.
I've never split cases before so I've got some reading to do.
Any pointers are appreciated, build thread link in my signature, thanks.

No need to replace the clips if they aren't damaged or worn. Yes, it's definitely worth a look while the cases are apart, and judging from the blue goo, you need to split them anyway.
Per, when the clips are installed incorrectly, it doesn't take much to dislodge them. If you have a large number of miles without any problems, you are probably safe.

[Terry in Australia]

Is this something that we all should set eyes on if we get the chance regardless of 750 model or year?

New circlips are required? 5 total?
CIRCLIP (OUTER) (25MM)
90601-300-000 
$2.81 at Partzilla, $3.02 at Bikebandit


I've got a K8 that looks like the cases have never been split, it'll need at least a primary chain tensioner while I'm in there.
I've never split cases before so I've got some reading to do.
Any pointers are appreciated, build thread link in my signature, thanks.

No need to replace the clips if they aren't damaged or worn. Yes, it's definitely worth a look while the cases are apart, and judging from the blue goo, you need to split them anyway.
Per, when the clips are installed incorrectly, it doesn't take much to dislodge them. If you have a large number of miles without any problems, you are probably safe.

+1 on what Scott said, looks like someone's been in there before and was using way too much sealant, you need to strip it right down and clean all that sh1t out, and check your oil pump and oilways (especially in the head under the cam towers) to make sure little globules of sealant haven't been floating around with the oil and gumming everything up. A Triumph "Mechanic" did it to my first K1 in 1981 and it destroyed my whole top end. A little sealant is good, a lot is terminal.

[Alan F.]

It hasn't been run since those gaskets were torqued, hasn't even been oiled, rest of the bike is in boxes. PO says he got it this way. I dont expect to find a mess but I agree on the need to get in there. I'll get the studs out and split cases this week. I'll get some photos of those clips posted ASAP.

Thank you Gents.

[PeWe]

OK, good news Terry and Scottly.
No need of open my engines then.

I'm still curious

Alan.F: Head gasket lubed?
A fiber gasket should not have any extra sealer. No gasket need that.
(MLS can be reused with special gasket spray to repair flaking Viton after brushed clean)

Your pics show how a future cam and total top-end oil starving catastrophe started.

Remove all that blue junk if those are photos of assembly, not what found when got the parts.

[Alan F.]

Received it that way. I'll get that all get cleaned out and new gaskets in, no worries.

[bryanj]

Now Blue silicone is different, ive had clear, white, silver, black and orange before but not blue and he was obviously dertermined not to waste any by leaving it in the tube!!

[Terry in Australia]

Now Blue silicone is different, ive had clear, white, silver, black and orange before but not blue and he was obviously dertermined not to waste any by leaving it in the tube!!

I had a tube of Selley's blue silicon sealant once Bryan, was great stuff, fuel proof when when cured, I had a leaking fuel tap on a Suzuki GS1000 and it was the only stuff that the fuel wouldn't weep past. Also brilliant on car water pumps. I've never tried it on engine cases, but I'm sure that if used sparingly, it'd work fine. Sadly, like all my adhesives, it dried up in the tube long before I used the last of it.