Topic: Wiseco 836 and oil leaks!

[dakeddie]

Hi all,

I've read that a lot people have oil leaks with their wiseco bigbores... the topic has been brought up many times.  I've made a discovery that I haven't read in anyones posts yet and I'm sure some of you must have discovered this too.  It has to do with the differences in the wiseco head gasket from the stock one (besides the obvious).

I've attached two pictures.  The first one shows the rubber inserts that are used in my K3, but are not apparently used in all K bikes.  The second shows the stock head gasket.  It appears that the holes in the gasket (circled) are too small on the wiseco gasket and don't allow proper seating of the rubber inserts.  This is where I believe my oil leak was originating.

Unfortunately, I've already replaced my wiseco gasket with a new one.  I actually thought I forgot to put the two o-rings (item 10 of the first picture), but they were in there so I just reassembled the motor with a new gasket and orings.  It wasn't until the next day when I was toiling over why my engine leaked when I thought of these rubber inserts.  The I compared the old wiseco gasket with a stock one and sure enough, the holes were small.  I'm going to take the head off my bike today and punch out those holes.

Has anyone else done this?  I want to make sure I'm doing the right thing.  I might try adding a little 3bond 1104 around the holes I punch out.  Is that a bad idea?

[754]

Is that oil smoke in your avatar??

Because if thats a burnout , you are missing 90% of the smoke!!

[dakeddie]

i think it's a combination of burnout and oil smoke... but that was a long time ago now, i think i was nervous of using up my tire.

[eurban]

I installed the Cometic brand gasket that came with my Wiseco 836 kit on my 78K. This was about 7 years ago.   I did expand the holes for the rubbers and put things together without any special sealers.  I have yet to have any oil leaks however the engine has done only 3K since I have had the bike offline a good bit for other mods.  It is possible that Cometic may offer a head gasket for the later engines requiring the larger holes and it is also possible that Cyclex's 850 gasket will work and has the larger holes.  I am sure someone like MRieck can tell you for sure.  If I had it to do over again I would probably find a correct fitting gasket as I have always wondered what I was thinking when I simply cut the gasket I had to fit. I would also definitely not omit the rubbers.  . . . Most of the oil leak issues I hear about with the 836 kits are related to supposedly excessive crankcase pressures causing areas like the valve cover seal to leak.  I do have a tiny bit of seapage in this area.   

[CB750F2]

G'Day. I am in a similar situation to you. I am using the 836 kit with the Cometic head gasket. Dynoman tells me that there is no need to enlarge the cutouts for the oil return holes because they are not the source of any oil leaks. I my case the oil leak was coming from one of the two "O" rings that are fitted around the stud holes that form the supply oil passages to the head - make sure you replace these. I suggest that you make sure that the gasket surfaces of the head and cylinders are flat. I aso suggest that you check the "O" rings that fit over the bottom of the cylinder sleeves. These "O" rings need to be in good condition and seated properly otherwise oil can work its way up the sleeve and out through the head gasket. I hope that you receive a few more replies. Pat

[scondon]

  I've been checking in to possibilities as to why my 836 engine finally gave in to the leaks and lost compression on two cylinders after 18,000 miles over two years. Too much oil everywhere to find a "smoking gun" so I'm covering all the bases before reassembly.

     I've talked to Buzz and Mrieck about those rubber inserts in the return passages being bigger than the Cometic holes and neither one of them seemed overly concerned although Mrieck pointed out that the metal dowels that the oil actually flows through are the same size as the gasket holes and that I might be fine just to leave the rubber inserts out(he had filled the gaps where the rubber goes with aluminum,I think, on one engine. Mike?). I think I am going to cut a bit of material from the ends of the rubber inserts to make them a bit shorter,enough to fill the hole/gap between dowel and cylinder but just come flush with the cylinder deck(or just a hair over). Then slather the inner/outer surfaces of the rubber with 1104 before inserting. May not be necessary at all, just figure I'd try it.

I installed the Cometic brand gasket that came with my Wiseco 836 kit on my 78K. This was about 7 years ago.   I did expand the holes for the rubbers and put things together without any special sealers.  I have yet to have any oil leaks however the engine has done only 3K since I have had the bike offline a good bit for other mods.  It is possible that Cometic may offer a head gasket for the later engines requiring the larger holes and it is also possible that Cyclex's 850 gasket will work and has the larger holes.  I am sure someone like MRieck can tell you for sure.  If I had it to do over again I would probably find a correct fitting gasket as I have always wondered what I was thinking when I simply cut the gasket I had to fit. I would also definitely not omit the rubbers.  . . . Most of the oil leak issues I hear about with the 836 kits are related to supposedly excessive crankcase pressures causing areas like the valve cover seal to leak.  I do have a tiny bit of seapage in this area.   

  eurban, what cutting tool did you use to enlarge the holes on your Cometic gasket? I have one of Cycle-X's 850 gaskets that came with the jugs and pistons I ordered and yes, the return cutouts are larger to accommodate the rubber inserts. Material does not seem to be up to Cometic standards but I'll know more when I put that engine together. I haven't measured the fire rings to compare size to the 836 gasket but will do so eventually.



dakeddie, how did that Webcam work out for you? (or did I already ask you that )  I've put 7k miles on mine and it's working out well

[eurban]

If I recall correctly, I used a combination of a small razor knife and snips.  I remember using the stock gasket as a guide for the hole size.  The Cometic gasket was metal reinforced so thats where the snips got involved.  They make hole punches of various sizes for gasket making but I didn't have any and I don't know how they would handle the metal reinforcement.  Got to wonder why Cometic can't make and Wiseco can't supply a gasket that actually fits?  Wiseco still makes the kit, they obviously sell a number of them and this is not a inexpensive product! I originally thought that it was only the very late engines (like the 77/78s) that had this issue but apparently it goes a good ways back.  Kind of ridiculous if you ask me! BTW, what year did Honda start using the rubber inserts?

[scondon]

 I've just been guessing that they started using them around K4, but dakeddie has them in his K3. I've got cylinders from a modified K2 engine that doesn't use them, but can't be certain that they are the original set. A quick look through some online parts fiche should settle it. Feeling too lazy today though

[CB750F2]

G'Day. Honda Service Bulletin #42 which came out in 1975 describes the modification. Knock pins and sealing washers were used from engine number 2352923. Prior to that number "O" rings can be used. Dakeddie, you may also consider installing a set of heavy duty studs which can be torgued higher - a number of the experienced members of this site have made this recommendation. Pat

[dakeddie]

well, I did it.  pulled the gasket out and punched out the holes to match the stock ones.  I really think this is the problem.  After looking closely at the gasket I took out, I could see the dowel had been biting into the gasket material.  I wonder if the head was fully tighten down because of it.  On one side, the holes were off centre by about a millimeter!  I know it doesn't sound like much, but it really made the dowels bite in.  I put 1104 on both sides of the gasket just around the oil ports.

And yup, I got the heavy duty studs... i spared no expense I tell you.  Well, that's a lie.

And Scondon, the webcam is working out fine.  I did a couple big trips last year, and the bike was a rocket on the open roads.  I'm not sure how many miles I put on it, but the plugs just started to burn tan as I took it off the road, so I'll assume the rings are close to fully broken in.  Apparently it takes awhile.  I wonder if people at my honda shop wonder where I've gone, I haven't been in for parts since I finished the rebuild.  The bike's been totally reliable... only thing is the oil leak, which appears to be mostly cosmetic.

[CB750F2]

Dakeddie, I am not sure exactly what you have done. My understanding is that when you first fitted the Wiseco gasket you fitted the gasket with the small holes around the dowels on the return oil passages - item 3 in your first picture but not item 2. Now you have removed the head, obtained another gasket and after enlarging the holes for the oil return passages fitted this gasket together with the dowels and rubbers - items 2 and 3 of the first picture. You also put some 1104 around the edges of the enlarged holes. Have I got it right? Pat

[Sweep]

I simply tightened everything down with the Cometic gasket over the dowels and donuts.  Once I had oil come out of someplace near the valve cover but that was only once and I had timing and carb problems so I discounted it.  As of now no leaks but I have yet to put any serious miles on it.  It would make sense to me that enlarging the holes would help.

[754]

FWIW.. make sure everything is flat.. and this does not alway mean a trip to the machine shop.

Type of gasket and what you smear on it.. makes a difference.

& instead of fretting over the holes in the gaskets and wether they are or are not there.. consider this.. even if they were in there , it is no guarantee that they will all line up.. just a fact of life. if you want them in. put them in..

 nobody buids great engines by rushing thru assembly, so check fit, recheck & check again.. til its right, and only then put it together..


Oh and unless someone snuck another bike in here.. we are talking CB 750,s.. they may leak a bit on the head gasket.. and upping compression and going big-bore aint goona help it.. so suck it up or get a new bike..

[eurban]

Oh and unless someone snuck another bike in here.. we are talking CB 750,s.. they may leak a bit on the head gasket.. and upping compression and going big-bore aint goona help it.. so suck it up or get a new bike..

Big bore or not, no reason that 750 head gasket oil leaks can't be avoided.  Flat / clean surfaces, proper installation of all the bits and pieces (use quality bits and pieces), a quality properly fitting head gasket, heavy duty studs and proper torque.   The Cometic head gasket that comes with the Wiseco is graphite btw and other than its knock pin holes being too small should be a good piece.  If Honda can provide a gasket that fits, Cometic certainly could as well. Overall, no need to suck it up at all; striving for an oil tite sohc 750 engine, particularly at the head to cylinder joint is not a waste of time!

[dakeddie]

To recap, his is what I did:
1) The first time I built the engine, I just used the cometic gasket, no mods.  I kept both the dowel and the rubbers in the oil return.

2) Then I rode my bike like crazy all summer.  It was great, the engine was clean, no oil.  Then after a while, the head gasket started to sweat oil, and I thought exactly what 754 said above, these engines sweat.  But by the end of the summer and into fall, the sweat became excessive.  It was making a huge mess.  I said it was cosmetic, cause I don't believe it was seriously affecting my performance, but there was a light coat of oil on my float bowls, my dynamax bluebox, battery, etc, as the wind blew the droplets through as I rode.  As I tried to figure out what I could have done wrong (because this is definitely NOT normal for an 836cc, it was too much oil for me to 'suck up'), I feared that I had forgotten to put the two oil feed orings (item 10) in or maybe they got pinched when I assembled the head on the cylinders.

3)I ordered a new head gasket from wiseco and new orings for above and below the head.  When I took the engine apart, I was actually sad to see the two oil feed orings (items 10) in perfect condition.  I replaced the gasket and orings and reassembled the motor.  I again kept the dowels and rubbers.  It wasn't until the next day that I thought of these holes being too small.  So I compared the old gasket I just removed to a stock gasket that I had never used, and sure enough, the cometic gasket had small holes.

4) Finally, I removed the gasket I had just put in, punched out the holes, added a little 1104, and reassembled.

I know it's bad to reuse a head gasket that's been torqued down, but it actually looked very good.  I couldn't see any impressions of the small scratches like I could in the first cometic gasket I pulled out.  I'll find out in the spring if any of this helps.  If it's not this, then maybe it's the big orings between the cylinders and the case.

Btw, the shop that bored out my cylinders and did my valve seat touching made sure the surfaces were flat.  They didn't have to do any machining, but they did dress the surfaces.

[CB750F2]

Dakeddie, thanks for explaining what you have done. I hope that you have fixed your oil leak. Pat

[dakeddie]

I just wanted to report my findings.  No more oil leak!!!!!  If you have the 836 big bore kit and your engine has those dowel pins with the rubbers on the oil return lines, I highly recommend punching out the corresponding holes in the cometic head gasket.  I'm absolutely sure now that the problem lies in the dowel pins biting into the Cometic gasket.  Not only are these holes in the gasket the wrong size, they don't line up very well!

I was going to wait until the end of summer before declaring no oil leak, but I've put many miles on my bike since spring and there's not one iota of a sign of oil.  wooooot!

[scondon]

 Thanks for the update

[Gamma]

Yes, thanks for the update, as I cut out those holes to standard gasket size too.  Bit of a bugger to do, I made a rotary cutter and used the standard gasket as a guide for the cutter.

[Gamma]

When I used it it had a bolt and 2 nuts to fit it into my drill.http://i192.photobucket.com/albums/z293/galaxy8155/ElCheapogasketholecutter.jpg[/img]]

[dakeddie]

Very nice tool Gamma...

I used a standard gasket punch, and it took some whacking to get through the copper layer.  It made a bit of a flare, but nothing I was too alarmed about.