I'm going to bite the bullet and buy the triangular ones.. They look way nicer in my opinion and beefier too. Plus they look like an original Honda (CT70) part. A bit more expensive obviously. The crappy holder will arrive first as it's coming from Australia, I'll use it in the meantime or return it, depending on whether I can be arsed sending it back. I tried to cancel the order before they shipped it, but they ignored that and sent it anyway... That annoyed me but it's my fault for rushing into it (and buying it, duh).
New to Honda Z50... Engine dead. Help!
- Thread starter QRSamuel
- Start date
Righto, bikes running great. BUT... it's smoking like a bastard. Oil smoke. Saw some oil drip from the exhaust too. Is it possible for that much oil to get past the rings, to where it's dripping (even just a little) from the exhaust? The other things it could be are the seal on the exhaust valve which I replaced or the copper head gasket isn't seating properly. I can drive it up and down or driveway just fine but it's really smoky. I also used the rings from the 12v china piston on the 6v one, but fitment looked almost identical other than some oil passages. I think the 6v piston had some extra. I did also put a fair amount of oil in the cylinder as I was concerned an oil passage might have blocked up and prevented oil from getting the head, but I figured out I'm a dumbass because the piston is splash lubricated. Anyway, that was the issue I found after I removed the cylinder when I began rebuilding after my parts arrived. It was very neglected. I did clean the mesh filter and centrifuge. I have no idea how long oil takes to burn off but I've been running it for a while now. I'll post more pics and describe what I did later, but for now I just want to get it to not smoke. If I need new rings, so be it. I was going to record a video but the smoke doesn't really show on my phone camera, sorry. Edit: It was just residual oil. a few more laps around the driveway and it doesn't smoke anymore. Yay! I so thought I had done something wrong. Double edit: Smoke is back. Oil is black (It's brown really, but that rhymes.) Ideas welcomes, thanks.
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https://photos.app.goo.gl/mEQXmw3FV7o4KyCD8 - video of smoke
I followed this guide (
) on how to install the rings. It didn't mention checking the ring gap, and I didn't have the right feeler gauges for it so I skipped over it. My bad if that's the cause. Double and triple checked against the video so they're in right. Valve stem seal was replaced with a new part. I didn't check valve seating but If I have to disassemble the top end I will lap them, just gave a cursory glance at exhaust valve contact surface when I replaced the seal and it looked good. When you mean check valves do you mean that or if there is oil getting down the valve stem? Thanks. Edit: D'oh, yes valves are adjusted to either 0.04 or 0.03 (mm) both valves. Can't remember which feeler I used but I did adjust them. I think the manual specified between 0.05 and 0.02.
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@OLD CT unfortunately the honda piston didn't come with rings so I had to use the ones in the cylinder kit. @-Nate The piston rings are new and I oiled the piston, rings and cylinder prior to installing them. Perhaps it's just that the rings or cross hatching on the cylinder are poor quality. Would the best course of action to be to get new rings and hone the bore? I will check over the head again if I do that too.
OLD CT
Well-Known Member
Best course of action is order the correct rings for the piston, dingle ball hone it. Very important, tiny numbers face up on the rings. Ring spacing. Read up on dratvs website, he has a lot of tips on installing the rings etc and a bunch of useful info.. ''What fits what'' is the section to read on his site.
I only have a rigid hone, will that work? And yes I did have the numbers facing up. Rings were spaced correctly. I followed that guide to the letter and it went over everything except for ring gaps. I think this piston is meant to go with the older one piece style oil ring, and the one in the kit was a three piece, though I don't get how that would affect sealing. Again though, It could be poor quality. After all, this was the cheapest cylinder kit I could find on ebay, though I think I got a steal because the seller jacked up the price after I purchased it.
Okay ;
assembling the piston wet is the problem here, coupled with (I'm certain) the wrong initial breakin regimine is what's causing this .
My self I'd take it apart, clean the piston, rings and cylinder bore HOSPITAL CLEAN AND DRY then reassemble it, make darn sure the timing is dead nuts to the "T" mark, fire it up and hold the throttle so 3,000 RPM as you watch the second hand of any analog watch / timer / etc. actually SLOW DOWN (yes, it seems this way as you newly rebuilt (!$!) engine is howling away) for SIXTY SECONDS NO LESS , then shut it down and take a break, it'll be hot as blazes so DO NOT re start it until the next day, it should fire right up, clean out some smoke then run as clean as it did when new .
I am fully aware this takes a HUGE LEAP OF FAITH so don't do it is you know beyond belief I'm crazy .
This is how Bell Textron breaks in is new helicopter engines, BMW breaks in their new car engines with fully synthetic oils and also how HONDA breaks in their C.A.R.T. racing engines, a friend of mine used to build those Honda engines in California .
It took me several years and many engines before I decided to try this and I was certain I'd fry the new pistons, rings and cylinder wall but it didn't s I've been a fan of this method ever since . no need to hone it either ~ I typically have an old cylinder that's within spec. but is glossy like a mirror, the rings bed in in that initial 60 seconds and I've never had a comeback yet .
This is a true "HAIL - MARY" only to be tried if you're willing to gamble making it worse .
Just a thought from some random guy on the internet you don't know for what that's worth .
Gotta follow the steps *EXACTLY* tho' or it won't work .
assembling the piston wet is the problem here, coupled with (I'm certain) the wrong initial breakin regimine is what's causing this .
My self I'd take it apart, clean the piston, rings and cylinder bore HOSPITAL CLEAN AND DRY then reassemble it, make darn sure the timing is dead nuts to the "T" mark, fire it up and hold the throttle so 3,000 RPM as you watch the second hand of any analog watch / timer / etc. actually SLOW DOWN (yes, it seems this way as you newly rebuilt (!$!) engine is howling away) for SIXTY SECONDS NO LESS , then shut it down and take a break, it'll be hot as blazes so DO NOT re start it until the next day, it should fire right up, clean out some smoke then run as clean as it did when new .
I am fully aware this takes a HUGE LEAP OF FAITH so don't do it is you know beyond belief I'm crazy .
This is how Bell Textron breaks in is new helicopter engines, BMW breaks in their new car engines with fully synthetic oils and also how HONDA breaks in their C.A.R.T. racing engines, a friend of mine used to build those Honda engines in California .
It took me several years and many engines before I decided to try this and I was certain I'd fry the new pistons, rings and cylinder wall but it didn't s I've been a fan of this method ever since . no need to hone it either ~ I typically have an old cylinder that's within spec. but is glossy like a mirror, the rings bed in in that initial 60 seconds and I've never had a comeback yet .
This is a true "HAIL - MARY" only to be tried if you're willing to gamble making it worse .
Just a thought from some random guy on the internet you don't know for what that's worth .
Gotta follow the steps *EXACTLY* tho' or it won't work .
I've been doing a bit of research and a few places have been saying to drive it like you stole it for the run in... I'm honestly tempted to go for a blast up the hill. It could be expensive but it would be expensive fun. I rebuilt the thing and I'll damn well do what I want with it, right? 
Maybe... I might try your method first @-Nate but 3K RPM is nothing for these engines. I probably wont destroy anything except the rings by running it hard since I have good oil flow, I checked. In which case I will buy a new set that I know are correct. The only reason I'm going to try those methods is because I am going to get new rings, but if there could be awful side effects let me know and I'll do things properly. Before doing any of this I will flush the oil and refill. If I have any misconceptions about this you have a day to warn me, I'm not going to do anything until tomorrow afternoon which is over 20 hours away from now. Until now I haven't really run it super hard, I've driven down the driveway, around the cul-de-sac, never going above second gear, up the driveway again, down again while engine braking and repeating that a few times.
Maybe... I might try your method first @-Nate but 3K RPM is nothing for these engines. I probably wont destroy anything except the rings by running it hard since I have good oil flow, I checked. In which case I will buy a new set that I know are correct. The only reason I'm going to try those methods is because I am going to get new rings, but if there could be awful side effects let me know and I'll do things properly. Before doing any of this I will flush the oil and refill. If I have any misconceptions about this you have a day to warn me, I'm not going to do anything until tomorrow afternoon which is over 20 hours away from now. Until now I haven't really run it super hard, I've driven down the driveway, around the cul-de-sac, never going above second gear, up the driveway again, down again while engine braking and repeating that a few times.
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OLD CT
Well-Known Member
Not a steal, if it's not a one and done. Never hurts to ask about products as we have a lot of members that know thier parts and vendors. Ebay and Amazon only have fluff. I loved that stuff as a kid. Fluffernutter.
I was shocked in 1964 when mom brought home a jar of fluffernutter ! . we weren't allowed soda, chips and so on but those tasty (to children anyway) sandwiches remain fond memories .
What to do is a tough call .
Once I'd tries this and learned it works I was hooked .
I once bought a dead 1968 VW Beetle where it had expired just off the freeway, the fan belt had broken and by the time he got off the engine had badly over heated, collapsing the piston rings but it hadn't bound up nor seized so I decided this $25 junker was good to take a "Flier" on and Lo ! . it worked like a charm .
Of course I replaced all the rubber and paper seals and made sure it was properly assembled and timed etc. but it worked .
Maybe you can spray some brake cleaner or alcohol in the spark plug port to wash the piston and cylinder clean but I
d not expect that to be a full cleaning .
Let us know what you decided to do and how it turns out .
What to do is a tough call .
Once I'd tries this and learned it works I was hooked .
I once bought a dead 1968 VW Beetle where it had expired just off the freeway, the fan belt had broken and by the time he got off the engine had badly over heated, collapsing the piston rings but it hadn't bound up nor seized so I decided this $25 junker was good to take a "Flier" on and Lo ! . it worked like a charm .
Of course I replaced all the rubber and paper seals and made sure it was properly assembled and timed etc. but it worked .
Maybe you can spray some brake cleaner or alcohol in the spark plug port to wash the piston and cylinder clean but I
d not expect that to be a full cleaning .
Let us know what you decided to do and how it turns out .
I think I will firstly disassemble, check through the head, I want to grind the valves anyway, hone cylinder, clean rings coat with just a thin bit of oil this time, then try Nate's method for ring sealing. If that doesn't work I'll go for a rip, and if that doesn't work I'll get new (part number matching) rings. I'll post an update after with results.
Ok. Update. It wouldn't start with that method. So the rings are probably trash (No compression without oil). I tried bump starting it down the drive too. And I think somehow I managed to break the kickstart/clutch... Good grief. The engine isn't seized, I can turn the flywheel easily enough with my ratchet. When in Neutral there is next to no resistance on the kick lever and the flywheel does not spin. When in gear the bike rolls with resistance but the flywheel does not spin. After pulling the clutch lever in it does not spring all the way back out after I let it go, I have to push the arm coming out of the clutch with my fingers. I only ever tore the clutch down as far as the centrifuge, maybe I didn't torque the screws down enough? But I did give them a couple smacks with my impact screwdriver. I might leave the bike for a while, take a break, and tear the engine down again this weekend. I don't have that much time at the moment anyway and it's getting dark quickly after work now. Edit: Trying again after a little while, the kickstart magically works again now. Weird, but good! Perhaps something to do with the clutch lever not springing out... Anyway, still the same deal with starting. I thought I might have drowned the plug in Brakleen so I will leave it with the plug out overnight and try starting again tomorrow. If it still won't start I will do a compression test with a Brakleened combustion chamber and with an oiled one.
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KITACO : 75cc LIGHT Big Bore Kit [6V] [212-1013480]
Product Description: KITACO 75cc LIGHT Big Bore Kit [6V] [212-1013480] : Fits:HONDA SUPER CUB 50 C50-5200011- : HONDA SUPER CUB 50 C50-3000001-51... - Webike
japan.webike.net
Okay ;
You didn't follow my instructions to the letter, when making a 'Hail Mary Pass' the details are critical .
I don't want it not to work and then be blamed for your not following the directions .
The piston, cylinder and especially the rings deep to be bone dry, I use white paper towels to ensure there's not a trace of oil anywhere in the three .
That the engine failed to turn when pushed in second gear indicates the clutch is slipping, a rare thing indeed unless it's totally worn out, mis assembled or mis adjusted .
I had been thinking this was an AutoClutch bike..... apparently not .
If/when you remove the cylinder head, hold it with the open exhaust port facing up and dribble a little bit of gasoline IN the exhaust port whilst watching the valve proper .
If you see any droplets the valve isn't sealing and will need to be lapped, another simple thing that requires a valve spring compressor .
If it doesn't leak droplets of gasoline, drain it and and hold the head with the intake port facing up and repeat this test .
You're close, don't get upset, these things happen .
You didn't follow my instructions to the letter, when making a 'Hail Mary Pass' the details are critical .
I don't want it not to work and then be blamed for your not following the directions .
The piston, cylinder and especially the rings deep to be bone dry, I use white paper towels to ensure there's not a trace of oil anywhere in the three .
That the engine failed to turn when pushed in second gear indicates the clutch is slipping, a rare thing indeed unless it's totally worn out, mis assembled or mis adjusted .
I had been thinking this was an AutoClutch bike..... apparently not .
If/when you remove the cylinder head, hold it with the open exhaust port facing up and dribble a little bit of gasoline IN the exhaust port whilst watching the valve proper .
If you see any droplets the valve isn't sealing and will need to be lapped, another simple thing that requires a valve spring compressor .
If it doesn't leak droplets of gasoline, drain it and and hold the head with the intake port facing up and repeat this test .
You're close, don't get upset, these things happen .