Topic: worst nightmare--need cb400f cylinders! Help!

[jessezm]

Well D#$@#%@#%@!!!

I pulled my top end today to send the heads to MReick for some head work.  My newly built motor has been smoking but really mostly only one really warm, so I was thinking valve guides or stems (or both) may have been worn since I didn't replace them during the rebuild.

Inspection of the head and valve area didn't show any obvious leaking, but the #1 chamber and plug looked oil fouled.  I rotated to the motor to have a look at the bore on #1 and YIKES!  There was about a 1" wide gouge running the length of the stroke which I could feel quite easily with my finger.  Probably about .002-.003" deep at the deepest point.  I pulled the jugs and found the culprit--the bottom piece of the oil scraper ring was out of its groove and crushed between the piston and cylinder wall.

So that explains the smoking and lower compression reading on cylinder 1...  Now I'm screwed because it was already bored to the limit at 466cc.    Soooooooo, does anybody, please, please, please, have a 400f cylinder in decent shape that they'll sell me?  Bores don't matter, as I'll have it bored out, but no broken fins would be nice... I'll post over in WTB also.  There was a good one on Ebay that disappeared today, dangit!   

I'll try to put up some pictures tomorrow to show the damage.  I also found some funkyness all around the oil galleries which explains the head weep.  It looks like the oil jet O-rings didn't seat all the way and smashed and spread out against the heads, preventing it from sealing.  What a mess!  Oh and this head gasket that comes with the 466cc kit from japan is kind of lame.  Think I'll spring for a Yosh gasket next time...  I am so bummed.  It's primo riding season and my bike is out of commission, and we're looking at major cash to get her right again.  And me and my girlfriend split today for good.  It's just been a #$%*ty day altogether.   

[tweakin]

Not mine.
http://cgi.ebay.com/ebaymotors/HONDA-CB400F-CB400-CB-400-FOUR-CYLINDERS-SUPER-SPORT-/200564523863?pt=Motorcycles_Parts_Accessories&hash=item2eb293c357#ht_500wt_1182

Not to pretty but you could swap the sleeves from this set into yours and then have them bored out. 

[Steve_K]

I know some bikes can have new cylinder sleeves installed. (I did it to a cb350 twin).  Would need to bore to size.  But, used may be cheaper, no boring etc.
Good luck Steve

[jessezm]

Not mine.
http://cgi.ebay.com/ebaymotors/HONDA-CB400F-CB400-CB-400-FOUR-CYLINDERS-SUPER-SPORT-/200564523863?pt=Motorcycles_Parts_Accessories&hash=item2eb293c357#ht_500wt_1182

Not to pretty but you could swap the sleeves from this set into yours and then have them bored out. 

Yeah I saw those--a bit too ugly for this bike...  There was a nice set on Ebay until this morning but I didn't discover this till tonight...  There is someone on the selling forum that has some cool 400 stuff so I just sent him a message...

[scunny]

as tweakin said, don't worrt about the block, the sleeves are easy to change over.

[jessezm]

Where do I get sleeves, though?  Oh, do you mean just have them pressed out of another block, then into mine and bored? 

[scunny]

yes, you can do it yourself, they come out if you remove the o-rings round the sleeve and place the block upside down in your pre heated to 200c oven, with a couple of spacers to lift the block about 40mm above the oven rack. open beer and wait for them to drop, it doesn't take long. replace in reverse.

[MoMo]

Where do I get sleeves, though?  Oh, do you mean just have them pressed out of another block, then into mine and bored? 

Did that happen to the cylinders you got from me?  I do not know if it can be done with a 400 four but we used to replace liners in most 2 strokes when the bore was past the limit. Check with a machine shop, hopefully someone with that experience here will respond if your local machine shop does not know.  You've had a run of bad luck with your project, hope all turns out well...Larry

Looks like you have an answer

[crazypj]

I've got a block with sleeves removed (have sleeves, can re-fit them pretty easy)
 I was going to do a 500 conversion but everything fell through after I started getting stuff together
 As far as I remember, one fin has a chip about half inch wide, 2~3mm deep.
I'll dig them out and get some pics if your interested?
 You don't need to fit spacers when removing sleeves, just stand cylinder on spigots and wait for block to drop
I use about 325F 

[jessezm]

Cool, thanks--I'll see if I can get them out easy.  Yeah, would definitely love to see pick of what you've got.  Actually, what if I just got the sleeves from you and put them in my block?  That would be the cheapest/easiest I presume...

[fmctm1sw]

hmmm. I never would have thought removing those sleeves would be "easy."  Kind of makes me wonder f I threw away a usable jug a few months ago...

[JBMorse]

Since you're re-boring and maybe re-sleeving, could you also use a 350f cylinder?  That might make it easier to find.

[jessezm]

Well, the 350 cylinder is slightly different.  I think there is an extra bolt hole for the heads, and I believe the liners are not as thick as the 400.

I'm looking into the possibility of just changing out the one bad sleeve and having it rebored, rather than all of them.

[Greggo]

Any idea what caused the ring to unseat?

[MCRider]

Where do I get sleeves, though?  Oh, do you mean just have them pressed out of another block, then into mine and bored?

new sleeves should be no problem. These guys probably have them on their shelf, collecting dust.
http://www.lasleeve.com/

[MCRider]

hmmm. I never would have thought removing those sleeves would be "easy."  Kind of makes me wonder f I threw away a usable jug a few months ago...

Yes swapping sleeves is "easy". Relatively.

[MCRider]

Any idea what caused the ring to unseat?

If i may...ring problems like that usually occur at the time they are installed. Cylinder dropping over rings catches one and pulls, pinches, breaks, it.

[jessezm]

Any idea what caused the ring to unseat?

If i may...ring problems like that usually occur at the time they are installed. Cylinder dropping over rings catches one and pulls, pinches, breaks, it.

Yep, that was exactly what must have happened.  That was only my second time installing pistons/rings.  The first time I snapped a ring.  With the 466cc kit on the 400, there is very little taper, if any, left in the bottom of the sleeve to aid in compressing the rings.  I used hose clamps to compress them, as there is very little room to work.  Installation went well until I got to the the last oil ring on 1 and 4.  It must have caught an edge going in.

[jessezm]

Well, the cylinder sleeves came out easy enough, just like y'all said!

[scunny]

Well, the cylinder sleeves came out easy enough, just like y'all said!

you can't beat home cooking. 

[jessezm]

Well, the cylinder sleeves came out easy enough, just like y'all said!

you can't beat home cooking. 

I even used a cookie sheet!

[crazypj]

Re-fitting is almost as easy.
 Biggest problem is different expansion rates.
 Sleeves will stick up about 0.010" when cold.
 I made a set of clamps to hold top flange in place then cool top with water so it grips sleeve as rest of block cools down
I didn't on a XS 650 Yam several years ago and sleeve 'dropped' causing major oil leak when combustion pressure got into oil-way (the 800cc conversion didn't help

[MCRider]

For install, a machinists press may be in order. Make sure the sleeve gets where it needs to go and stays there.

[jessezm]

For install, a machinists press may be in order. Make sure the sleeve gets where it needs to go and stays there.

I think that's advice I'm gonna take!

[Really?]

I was going recommend Advanced Sleeve.  I just got a sleeve made by them for the YZ. Excellent!