Topic: Rebuild

[Phoenix]

Getting ready for my twelth top end job.  Oil leaks remind me of Harleys.  Been reading abunch of threads and try to put them all together.  I have a japanese 836 that I have about 10,000 miles on.  Also, heavy duty studs and decked head and jugs.  One thread said Athena head gaskets cause leaks.  Of course that's what I purchased for the build.  Mark talked about thicker o rings for the new head gaskets.  I am ordering some.  They said if you use an MLS gasket you don't need orings because they are built in.  Is this correct?  Also, does anyone remember the source Mark gave for the thicker pucks.  Any insight would be appreciated.  I'd like to make this the last trip into my engine.

[RAFster122s]

Wouldn't you need to know if you are picking up the MLS or using your Athena gasket and it's thickness to answer which thickness orings you need? Decking your head and jugs/cylinders depending upon how much you skimmed impacts any grooves that were designed for the orings. But the thicker gaskets do lead to leads as do not sealing and replacing the pucks with the correct thickness pucks, most of the kits and even the Honda current pucks are the wrong thickness. Parts N more I believe carries the correct pucks.
Drop HondaMan a PM and he can direct you to sources and probably already has either in memory the sizes you would need. Documenting that information in your thread would be helpful to others. I'm going to suggest to Mark to post a thread as a sticky to put in the FAQ about the gasket kits and their corresponding orings size required as he likely has already noted this in his files and mentioned it in various threads across the forum.

Read Brandon's Leak Free Head Guide thread, pretty sure it is a sticky topic in the FAQ.

HondaMan's CB750 book available on Lulu is very helpful and he goes over many of these topics and more. Lulu discount codes can save you a little, generally 10-15% are frequently ran and certain times of the year 20-25% codes are available.
David

[ekpent]

If skimmed also make sure any locating dowels aren't too long now also.

[MauiK3]

I'm thinking that if it's skimmed too much would there be any piston/valve clearance issues?

[PeWe]

If skimmed also make sure any locating dowels aren't too long now also.

All dowels a very good idea to measure before assembly.
Case-Cylinder block-head.
I measure the holes and compare with lenght of dowels. They have changed during the years. Easy to mix them up too.

If the total depth of case-cylinder is as deep as the dowel is long (shorter OK) it will be good, base gasket as extra clearance. Same at top.
If dowels are just too long, it will not seal.
There are several dowel lenghts. 22, 18, 15 something and the special ones for oil return on later cylinders around 14mm .

My rather much milled 970cc build use the special ones between cylinder and head.

The dowels must have a few mm into both sides to ensure parts to be correct located and keep it that way.

EDIT:
I commented different models of head gaskets today. Also came in to the o-rings and how to measure for right choice.
http://forums.sohc4.net/index.php/topic,189544.msg2231097.html#msg2231097

[Phoenix]

I have used the mls gaskets in the past and also Marks orings.  My current leak is weeping under a couple of the exhaust spigots.  If you look at the cyclex website, they argue with a need for oversized orings.  Some say the orings are built in to the mls gasket.  My question is, what is the safest way to go.  Athena with Marks orings, something else with Marks orings, MLS with Marks.......

My dowels are ok since they have worked over the last couple of builds.  You might ask why so many builds.  I burned ap piston on two different trips to Sprinfield for a race.  Within 25 miles of each other.  I go a different way now.  Just trying to put this to bed so I can get on the road again.
Thanks.

[PeWe]

O-rings must be fine if size is correct for where used as I wrote with reference to an o-ring supplier, compression OK.  Make your own calculation will show if using correct o-ring.

This is what Hondaman made us to observe.
Stock o-rings originally made for stock head gaskets that were 0.8mm thick.
Later headgaskets 1.0-1.2 mm thick need thicker o-rings.

I have always used 2 o-rings (stock size) for oil feed as extra safety on MLS. 836, 900, 970 and 1005cc.
There are people that say that o-rings are not needed. They are probably right. I have never tested.
The MLS is designed for no o-rings.

[HondaMan]

Things to directly measure so you know for sure if the O-rings are the source of the trouble are:
1. Lay your new head gasket onto the [decked] surface of the cylinders, then measure how deep the oil holes are to the top of the gasket. Your new O-ring must be at least [0.1mm taller than the unused gasket + hole depth], and I never go less than 0.15mm myself. If the head gasket is Vesrah (because I detest Athena head gaskets, and even NE brand have leaked on me before, but in different places) then it will need to be 0.15 mm taller, and will work 100%.
2. I don't use MLS gaskets. They are the most-common leaking gasket found in these forums. There's a lot of hype and 'mystique' applied to them: but even at 12:1 compression ratio, running roadrace speed profiles, Vesrah's head gaskets don't leak. MLS do, often.

[PeWe]

Head can also leak via the rubber pucks under cam towers and via cam studs.
Oil visible in the spark plug compartments.
Remove plug and feel inside with finger if oily wet on the ceiling.

MLS rivets can be a reason if they are located between head and cylinder mating surfaces.
I have drilled dimples where the 4 rivets hit the head vs cylinder mating surfaces. 10mm drill ca a mm.

I saw that first time I used an MLS head gasket, 836cc. Head did not seal to the cylinder, I saw a gap. Rivets on mating surfaces. The drilled dimples fixed it.

Interesting to know if leaking MLS used o-rings for oil feed or not. The mating surfaces need to be really flat with smooth surfaces.
Grit 400 smooth without scratches.

My 970cc build has done over 10.000 km plus 4 torturing dyno visits,  each can cause an oil leak, that's for sure!
I reused an MLS I had used earlier during 1500km thecyear before. I remembered the torque, I tightened head a little harder this time.

Only earlier oil leaks have been the reused RCS base gasket. Plus around oil filter.

Last time repaired RCS base gasket with a very thin coat of high temp silicone on both sides. Let it cure 2 hours before assembly.

I hope it will stay dry, no oil on its outside.

[jgger]

Pewe, didn't you have a recurring oil leak at one time that was related to a too deep hole for the cam towers, or something like that. IIRC whoever had that issue it was also leaking by the spark plug. Also IIRC you can only see that issue with the head off and upside down.  I think the fix was a spot of JB Weld........but then again I could be halustrabating.

[Phoenix]

How or where can I get a Vesrah 836 head gasket for my bike.  If Mark says they're safe, that's all I need.

[PeWe]

Pewe, didn't you have a recurring oil leak at one time that was related to a too deep hole for the cam towers, or something like that. IIRC whoever had that issue it was also leaking by the spark plug. Also IIRC you can only see that issue with the head off and upside down.  I think the fix was a spot of JB Weld........but then again I could be halustrabating.

I did not have a leak due to thread holes for cam towers. I repaired a heads threads where I found some threads to be drilled thru by a PO.
I restored the bottoms with JB Weld.
This to avoid leaks. I also covered the hole where cam studs end up in plug cavity with JB Weld.

A few oil weeps at valve cover. Tacho gear seal, tappet plug o-rings, bad valve cover gasket in combination with valve cover screws going thru. Yamiya kit has them with thread sealer.

*** I forgot to mention about MLS ****
Heavy duty studs + torque 28-29Nm.
I have read about 21-22 ft lbs on this forum. 22 ft lbs is almost 30Nm.
Stock studs and less torque will probably leak.
*****************************"

All my extra job with redo and upgrade my K6 during the last years have given me insights.
This in combination with this forum where much knowledge, experiences bad and good with inspiration are found.

My K6 had heavy oil consumption for a while I initially thought to be head gasket.
But it was the guides.
First the short lived 5mm stemmed bronze guides with a horrrible wear at their upper end. Must be the flexible weak stems.

Changed head.
This had lash cap issues on F2 in valves, 0.25mm dimples causing less lift. F2 valve stems mushroom very quick, caps a workaround.

Replacing lash caps every 5000 km is not ok for me. One cap needed removal of its rocker arm to come off.

Changed head again to a better looking and maybe better ported 392 head.
Guides not enough sunken in head. K valves have a very deep groove for keepers.
This groove entered the guide seal due to the cams lift, 9.8mm at running lash.
The stock iron guides had to get their groove for stopper washer recut a bit upper. Guide sunken more.

CycleX iron guides are made for deeper assembly and higher lifting cams.

Distance between guide seal upper part and keeper groove must be min cam's lift + 0.5mm.
The oil consumption started to happen after 5000 rpm. After a few thousands km it sucked oil constantly, lots of it.
I had to clean pistons and head that was fixed by the nearby shop.
I could at that time install another cylinder, 970cc when I found pistons and sleeves for good prices. Earlier billet block 1005cc that I did not want to abuse more with oil and wrong jetted carbs.

It can come back later. Its pistons will be gas ported forcing the upper ring outwards so a little bit more power might happen

I have been able to tune the parts better together and increase the power. Found correct cam timing and gasket thicknesses increasing the compression.
From 92 ---> 101.5 ---> 104.5 ---> 107.5 whp.

I have no idea where to find other  65mm fiber head gaskets than Yamiya, Cometic  Dynoman, CycleX), Cruzinimage low priced and stray gasket on eBay.

EDIT: All reworks and upgrades thanks to Franks (forum member 754) frame kit.
Test 3 different cams within a few days not possible if engine must be dragged out each time.

[Stev-o]

Getting ready for my twelth top end job. 

On the same motor?!  Have you read BranDen's thread?   

 http://forums.sohc4.net/index.php/topic,107040.0.html

[HondaMan]

How or where can I get a Vesrah 836 head gasket for my bike.  If Mark says they're safe, that's all I need.

I don't know that Vesrah makes one, but I have used the ones from CruisinImage with success. Check at their website, not thru eBay, for that part. I add some Permatex #2 all around the camchain tunnel opening and oil ports when using these.

And, I did forget to mention what someone else did note above: there are head puck seals out there that are thinner (for some of the superbikes around 1990-2000 era) that sometimes get mixed in with ours. Make sure your pucks are thicker than your holes are deep!