Honda Express Cylinder Jug Removal

Adam Kollipara /

Hi everyone,

I tried removing the cylinder jug from my 1981 Honda NC50 and it's not budging. I used a rubber mallet, but it seems the mallet will get torn up before the jug comes off. Would carb cleaner cut through some of the crap holding the jug on? I don't really want to take the engine off the frame. What else would work? The rings on the piston are worn, causing a loss in power and eventually making the engine die. It's making the engine run rich and I don't want to seize the engine, so anyone know some other ways to get it off? And where to get some new piston rings that aren't expensive?

Thanks in advance!

~Adam

Re: Honda Express Cylinder Jug Removal

Hey Adam,

I had troubles getting a cylinder off of my honda. My mechanic friend had me tap it with a hammer on the side with the fins with some wood and after so many POOF the cylinder slid straight off and over the piston. On another case I had laying around I had trouble getting the piston through the cylinder, hopefully you don't have trouble with that.

As for shops, I have not used either but according to this - you can use any honda 50cc rings ["Hobbit, NC50, NA50, NU50, NX50, etc."]

$10 + Shipping honda hobbit stock chromed piston rings set - 40mm x 1.5mm

The other moped shop 1977 Mopeds does not have any stock rings for some reason but a good shop to know about nonetheless

Hopefully that helps. You should order up a set of new gaskets -- Base and head -- too I guess since they are reasonably priced.

Be sure to make sure the cylinder looks clean also. Otherwise you may want to order a Piston + Rings $30 - If it is scored get the 44mm and get it bored haha

How many edits can I do! (edited)

Re: Honda Express Cylinder Jug Removal

Hey Adam, I am in almost the same spot as you, but my Express is a 78. I just yesterday removed the head and cylinder. I did use the rubber mallet, and was sorta surprised how hard I had to whack it. Try whacking on one side of the bike, and then the other, hitting the cylinder around the bottom. Don't forget to be ready to catch it when it breaks free. I am now trying to find a good way to clean the head because mine has all kinds of baked on dirt. I'm sure it will dissipate heat better with the dirt off! I ordered the 70 cc DR kit for mine, which comes with all the rings and gaskets, plus cylinder, clips, piston, etc. Looks like Bike Bandit has rings and gaskets for the 81 for about $41. plus shipping. Here's a LINK . Also found a cool section in the shop manual on how to check your rings with a feeler gauge. You take them off the piston and slide them into the cylinder (after you get it off), then measure the gap. Mine were way off. Here's ANOTHER LINK . My basic approach to working on my bike is, "If it ain't broke, don't fix it. But if it is broke, upgrade it!" Best of luck to you!

Re: Honda Express Cylinder Jug Removal

You might also try saturating that gasket with brake cleaner. Don't get any on you -- it's nasty! Spray it again tonight and let it sit overnight. Try whacking it again in the morning.

Re: Honda Express Cylinder Jug Removal

Easy-off oven cleaner works real good for cleaning the head and cylinder, get the spray not the liquid, and use gloves, mask and eye protection its pretty nasty if you get it in the eye or skin. Also dont let it sitt on the aluminum head for to long, 5 min tops, it will start to eat the aluminum.

Re: Honda Express Cylinder Jug Removal

Cliffs:

make sure the head is off

Hit the cylinder with a hammer

Don't break a fin, BUT hit it hard on the sides so you contact multiple fins in a rocking motion

buy a kit

profit???

to check ring endgap you can just throw a ring in the cylinder and measure it like that with feeler gauges

As for cleaning a head; I just scrape the inside of the fins with a screwdriver. On the outside of the head, I hit it with a brass 6" wire wheel on a bench grinder. The brass doesn't scratch the gasket mating surfaces, it only cleans them up so you dont have to be gentle, just dont really go into the cylinder I guess.

Otherwise the other option would be sandblasting I guess. I would like to clean mine up better but I wanted to make sure it was clear for airflow too.

Re: Honda Express Cylinder Jug Removal

Adam Kollipara /

Adam K. Wrote:

-------------------------------------------------------

> It's making the engine run rich and I don't

> want to seize the engine,

Woops! Rich should be lean.

I'll try tapping with the wood and hammer and see if I breaks it loose. Are new original gaskets better, or is it better to buy some gasket material and make my own? If the gasket material is better, which kind? I try to buy some piston rings soon.

Thanks for all the help!

~Adam

Re: Honda Express Cylinder Jug Removal

If you want to clean it, put it in the dishwasher. Make sure you give yourself ample time to clean up the dishwasher!

Re: Honda Express Cylinder Jug Removal

^haha yeah, dishwasher.

You could easily re-use the stock metal head gasket if you clean it up well with carb cleaner and put a little oil on it before you put it back on, that seems to work fine.

However the stock base gaskets stick to the cylinder too well and I have a feeling yours will get wrecked taking off the cylinder ( Nothing you can do about it because they are likely old since they are stuck on so well )

Gasket sets are cheap from treatland or 1977.

Here is a few, I dont think the 70cc gasket sets make any difference

honda hobbit 70cc gasket set

honda hobbit 50cc complete gasket set

Honda Hobbit Moped Gasket Kit

And for cleaning again, maybe little scraper/putty knife may work to get in between the fins, and some cheap wire brushes if you dont have a bench grinder. Tape off the mating surfaces with some masking tape if you use a rough wire brush.

Either that or just leave it, Its probably fine. (edited)

Re: Honda Express Top End Assembly

Adam Kollipara /

Now that I ordered and received piston rings and gaskets, I finally was able to get the jug removed. But now my next problem is getting the cylinder over the rings. It's quite difficult and I'm just getting frustrated with it. Any tips? Thank you.

~Adam

Re: Honda Express Top End Assembly

Noah Reinhart /

cut a peice of rubber sheeting or whatever will work, cover the inside with oil, wrap the piston with the rubber and some hose clamps to compress the rings, slide the cyl down a bit then take the clamps and rubber off. hope tat makes sense.

Re: Honda Express Cylinder Jug Removal

Rubber sheeting? What?

Use two fingers.

Position the rings on their notches. Now when you take your two fingers and squeeze, you will see the ring ends move. You want them to stay within those notches in the ringland.

Anyway, if you know the proper ring placement

Squeeze the rings with two fingers pretty hard, and rotate the cylinder left and right.

The thing to look out for is that you dont want to catch a ring end on a boost port, so get the first ring on and squeeze the second ring, and slowly push it through.

Haha dont forget your gaskets

Then you can throw a stud in if you need a brake, If you just want to get it done keep going.

make sure you oil your gaskets lightly with 2stroke.

Put the cylinder on then - while your holding that with your left hand - slide 1 stud through the head, put the head gasket on the head, then throw that on the cylinder and put the rest of the studs on.

Make sure the gaskets are on the right way.

You dont need anything special.

Re: Honda Express Cylinder Jug Removal

Adam Kollipara /

Okay, thanks a lot!

Gonna work on it right now.

~Adam

Re: Honda Express Cylinder Jug Removal

minor carnage, for your viewing pleasure

top end removed

piston

did the teardown to replace sloppy bearings and seals for a friend, should of expected this from the airleaks.

Re: Honda Express Cylinder Jug Removal

Hey Adam, congrats on getting the jug off! That must have been a huge relief! I just took mine off again yesterday to check rings and reinstalled. What I do to put it back together is:

-Clean gasket surfaces. I use WD40 and a razor blade. Clean off oil.

-Attach gaskets in place with 4 tiny dabs of silicon on outside edge of bolt holes. This will keep them from sliding around when you are trying to line up and install everything later.

-Lube inside of cylinder and outside of piston and rings with 2-stroke oil.

-Make sure all surfaces are clean

-Insert piston into cylinder carefully, one ring at a time. I just use my thumbnails to press the ring into its slot so I can slide piston into cylinder. The piston only needs to go into the cylinder about half way.

-Hold cylinder up to the connecting rod with one hand, lining up holes in piston with hole in connecting rod.

-Insert wrist pin through cylinder and connecting rod with your 'free hand' (ha-ha! Got a match?)

-Once the wrist pin is in, I put a block of wood under the cylinder to support it so I can center the wrist pin and put the clips on the ends of the wrist pin that hold it in place.

-Put top two bolts through head, gasket, cylinder, gasket and finger tighten.

-Put in bottom two bolts and torque all four bolts working in an 'X' pattern.

Good luck to you!

Re: Honda Express Cylinder Jug Removal

Adam Kollipara /

Sorry for the very late posting, but I got the rings and everything on and it runs great (about 1.5 months ago)! It's quieter than before (loud popping noise is gone). Thanks for all the help. Now there's no more overheating and white smoke, except for the disgusting smell of built up carbon during the time it wasn't running.

I ended up having to take the piston off the crank, slide it in the cylinder, and then reinstall. All the seals are working good, no leaks so far. Runs and accelerates smoother than before, but I can't really see a different in speed, but that's okay, just as long as it runs.

Thanks again!

~Adam

Re: Honda Express Cylinder Jug Removal

How do you know if the bearings are shot without breaking it open?

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