Honda Twins banner
1 - 11 of 11 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
I'm more than slightly out of my depth, so any suggestions and or critiques (phrased gently, if you are able) would be greatly appreciated.

Background, briefly: I was looking for something small for some novice riders in my acquaintance, and found a 75 CB200T for sale on Craigslist. It wasn't running, but the kid who owned it assured me that it *had* been, only the previous summer (and there was a parking permit for the previous year on the bike), but wouldn't now start. The battery was fried (I found a dead cell in it later) and when I touched the carbs my hands came away with sticky, gross fuel. Cosmetically the bike was grand -- tiny seat tear and some rock dings in the tank, but otherwise very nice.

I diagnosed a thorough cleaning, paid the kid a pittance and we pushed the bike into the back of my truck.

I spent the next several evenings after work cleaning things up: carbs off and soaked and cleaned out, tank drained and flushed (not rusty inside at all!), oil change (the tabs on the oil pump cap were destroyed, so I couldn't get inside that, but everything else in there was in really nice shape so I ignored that for the moment), new spark plugs and a new battery. Got everything put back together and went to start it and...

Well, it cranked nice, but wasn't getting going. I leaned over to work the choke and that's when I saw oil simply OOZING from the cylinder base.

I cursed, and then I sulked for a day. Then I decided I was up to the task and I took the engine out of the frame and put it on my shop bench for a disassembly. I had a Clymer manual and, later, a PDF of the shop manual to guide me, but I've hit a snag.

I'm down to removing the cylinders, to assess if my leak is due to a failed gasket (I hope) or some more critical failure. But the damn things won't come off!

The shop manual says, simply, "Remove the 6mm cylinder hold-down bolt and take out the cylinder." The Clymer manual says much the same thing, though also adding that a "tap" from a rubber mallet may be required to loosen the cylinder first.

It's a no go. I've beat on that damn thing, had it on the floor of my garage and me on top of it straining with all my might, and it hasn't even *budged*.

My suspicion is that there isn't a traditional gasket there at all, but some sort of gasket compound/cement that has hardened. It may have finally developed a fault that allows the oil to leak, but the rest seems more the adequate to the task of keeping it on the crankcase. I think this because the engine has obviously been broken down before -- the signs were everywhere as I worked on it. Further this is not the original engine! The VIN on the engine and the bike frame don't match. (I feel a bit of a fool for not checking that before.)

So. Suggestions? I'd love to pry at it, but I know as soon as I do I'll start breaking off fins. Did I miss something, is my guess reasonable?

If I can get it off, I'm going to need a gasket, and I understand that they are no longer being manufactured by Honda. I'd like a whole set -- the head gasket has a worrisome crack in it, and it would appear that the breather cover gasket has been hand fashioned (a guess, as it is relatively raggedly cut on some corners). Any suggestions on where to get such items?

Thanks in advance -- this is my first Honda (only a Yamaha rider before this, please don't hold it against me) and while this project is a much bigger one that I had anticipated (or desired), I have great hopes!

Here is a picture of the bike before I started the engine removal -- the side covers are not on, but I do have them and they are in nice shape as well:

 

·
Sensei
Joined
·
27,183 Posts
First, ...relax,... the engine serials RARELY match the frames on the older Hondas, as long as it's a similar sequence it's probably the original....(Like CB200-2004XXX on frame and CB200E-2004YZZ on engine)

The stock gaskets are a real pain to "break loose" as well, but, DO NOT PRY....A rubber mallet and repeated blows around the perimeter will eventually break it loose IF you have all the bolts/studs loosed......Strike directly at the fins (parallel to them ) to rock the cylinder.........
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #3 ·
Thanks for the reply!

I am happy to hear that the engine and frame may indeed be a matched pair despite the VIN difference. (I don't know why it really matters, but...)

I will resume beating on the cylinders tomorrow in hopes that you are correct and they are simply being difficult. My poor rubber mallet is likely going to need replacing after this ordeal.

Any suggestions on hunting down a gasket set?

...anyone?

-b
 

·
Registered
Joined
·
703 Posts
What I did, although it may not be right is get a blow torch and throw some heat around the base. Not too much though. Then beat the **** out of it with a rubber mallet. Even if you have to do this over several days. It'll come off.

Its maddening.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #5 ·
Cylinders removed!

In the end, I had to get aggressive: I would place a piece of 2 x 4 against the spot I wanted to "tap" and beat it with a five pound mini-sledge. Much anxiety! But it broke loose and there are no damaged fins, so hooray.

New question! How best to remove all this old gasket material without scoring the surfaces it is adhered to? Because it is *really* stuck down.

Some crummy pictures to give you an idea:





I poked at it a bit with a flat bladed screwdriver, but it would seem too easy to dig furrows into the aluminum that way. Is there some kind of solvent I could try, or should I go with something like a plastic paint scraper?

-b
 

·
Premium Member
Joined
·
2,386 Posts
Good job getting the cylinder off. I've heard there is a chemical what will soften the gaskets off but I haven't found it. A razor knife is what I used but I've also used a wire wheel on a drill in the past as well.
 

·
Registered
Joined
·
54 Posts
Loctite 79040 chisel gasket romover. It can be found at any good harwear store.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #8 ·
Has it really been a month since I posted? My my. Work exploded and I had basically no free time -- my poor CB200 engine languished in pieces in my garage!

BUT, I have finally removed all the old gasket material from the cylinder and crankcase! I used a wire wheel on my drill for the actual cylinder side (thanks for that suggestion, MNellis) and ended up ordering some of that Loctite product online (could NOT find it anywhere in town) for the crankcase side, since I couldn't really get the wire wheel at all the surfaces I needed to clean and I was concerned about getting the resultant nasty dust down inside the engine. So thanks for the heads up on that stuff, JapJohn! It's nasty, but boy does it strip that gasket material (and paint, if you are unlucky enough to drip some on the starter) right off!

I am still without a gasket to replace the one I spent hours removing however! I am having ZERO luck finding any NOS gasket sets (I really, really want to replace the head gasket too -- it's torn almost all the way through on one corner, ugh). The gentleman in this thread (http://www.caferacer.net/forum/topic.asp?TOPIC_ID=9661&whichpage=1) rebuilt a 74 CB200T during his cafe racer mod and replaced his cylinder base gasket with a custom copper one from Copper Gaskets Unlimited. I like the idea! But I'd need to know the thickness. Any ideas on how to find that out? (I hate being a newbie.) And is it a mistake to go copper for a head gasket too?

Lots of other CB200s being worked on in the forum...haven't caught up with them all yet. Forgive if some of this stuff has been covered. And thanks for all the help!
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #10 ·
Well, as I said, I am having no luck finding any NOS anywhere. Not even ebay, though I continue to look.

Since I am impatient and could potentially be waiting months for someone to dust off a gasket kit and decide to auction it off, I've decided to order custom copper gaskets from Copper Gaskets Unlimited (http://www.coppergaskets.us/index.html). The guy who runs it is really nice and he has templates for the gaskets I need already -- he just wants to know the bore size and how thick I want them to be.

I put my calipers to my head gasket and came up with 2 5/16" for the bore size. Does this seem reasonable to you guys? I don't want to be off.

As for thickness, I am undecided. He can stamp them out in thicknesses of .016 to .125 (thousandths of a inch). I suppose I should try to figure out what the original gasket thicknesses were, but I simply don't know how to go about doing that for the base gasket, since it is well destroyed. Any advice would be greatly appreciated!
 

·
Premium Member
Joined
·
132 Posts
Hi, I'm in the middle of my first rebuild too. I ordered a NOS Honda top end gasket set for my '75 CB200T from Western Hills Honda (http://www.westernhillshondayamaha.com/) in Ohio. Just call them and ask for vintage parts. The guy there is great. The gasket kit cost a bit, but it's definitely the right stuff and it got here fast.

Or do a search for "cb200 gasket" on Ebay UK ( ebay.co.uk ) for other third party stuff. I would have bought there if I had more patience.

Good luck with your rebuild! Your thread here helped me get my cylinders off. Now if the machinist would just get my cylinder and valves finished...
 
1 - 11 of 11 Posts
Top