Topic: brandEn's leak free top end thread = Tips, Tricks and Suggestion encouraged

[Nuffsa Fugginnuff]

Subscribed (again)

This site is an excellent source of 'stuff'. Especially when one is on the process of a project bike. Gone so far as to buy the My CB750 Book by Mark Paris.

[DWS]

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[edwardmorris]

Adding this here as it's relevant and sorta critical info about the dpwel pins for the top end and wrong parts diagrams

Beware, for a 750 engine the 12 x 22 pin is incorrect.  The parts manuals say 12 x 22 but they would be too long not allowing the head to be flat on the cylinder.  What was actually used is part number 94301-12180, 12 x 18.  Every engine I have had apart (at least five) had the 12 x 18 pins.

[PeWe]

My engine had the 22mm dowels between case and cylinder.
I see that Yamiya750 must have mixed up case-cylinder with cylinder-head.  The other way will work in my engine (K6) I think it had 12x18mm cylinder-head earlier. I have 15mm now.

12x15mm
http://www.yamiya750.com/index.php?main_page=product_info&cPath=246_21_249_54&products_id=1715

12x22mm
http://www.yamiya750.com/index.php?main_page=product_info&cPath=246_21_249_54&products_id=1716

[01Thomas]

Bump so I can find this thread again

[MCRider]

Bump so I can find this thread again

You can save the thread as a favorite place. That's what I do, using a folder aptly named.

PS this is a good one to save.   

[01Thomas]

Thanks good idea but that'll only work until ones' PC bombs out and one gets a new one and then the favourites are all gone with it.

Bump so I can find this thread again

You can save the thread as a favorite place. That's what I do, using a folder aptly named.

PS this is a good one to save.   

[oldhatt45]

01Thomas,

Your Favorites are only gone if you Don't back up things like your email, favorites, and personal documents.

Back up can be done by copying your favorites, etc. to a Flash Drive, the Cloud, etc.
There should never be a case where you lose everything.

That's just my 2 cents so please don't take offense.

Charlie

[flybox1]

Bummer...this is a thread has been totally derailed 

[oldhatt45]

I apologize.

Maybe we can get one of the moderators to remove the last few off topic posts.

Charlie

[lucky]

A few comments.

Good write up and good photos Branden.

Those part#3's are locating dowels not "knock pins".
And they will all need to be measured now on every engine, since 40 years have gone by.
The cylinder heads have been through a lot of rebuilds possibly. Height has to be checked or the cylinder head may not tighten down.
You need those locating pins.
You cannot get rid of all of them. They align the cylinder head with the cylinders.

If the locating dowels are too long you WILL have problems.

Never "grind" Honda Valves!! Period.
Just install new valves. It is not like old cars used to be.

You can re cut the seats though (if there is enough material left), after all of these years.

[AintNoEasyWay]

I made some shims out of tongue depressors. BRILLIANT! Made installing the cylinders easy.

BrandEn, thanks again for such documentation. I've been using it all to get my top end rebuild finished. I'd like to use your method for installing the cylinders onto the piiston, & I'm wondering what you did for the clamps you used as compressors for the rings.

What size clamps do you recommend? What method did you use to keep the rings compressed as you put the cylinders on & then remove the clamps? Does the fastener on the clamp make it difficult?

[MCRider]

Some of my observations using hose clamps. USe the size that is closest to the size of your piston. This keeps the clamp as round as possible, so compresses the rings evenly.

Don't put the buckle of the clamp over a ring end gap. the gap wont close and may hangup when you drop the cyls.

Tighten the clamp slowly making sure it pushes the rings into the grooves. Then back it off just enough that you can rotate it with the rings. Just a tad. You'll want the cyls to push the clamp down the skirt of the piston, rings going into the cyl. When the cyls are first resting on the clamps, squirt some oil onto the cyl walls where the rings are, to help the cyls drop down.

[flybox1]

...to add to what MC was advising, also position your clamp screws in an accessible manner. 
I had to stop and rotate a few once my cyls were on....
I used a 15-20mm wide strip of .5mm sheet plastic kitchen cutting board around the rings underneath the clamps. 
this made sliding the clamps downward quite easy, and ring ends did not catch anywhere on the clamp cutout holes.

[edwardmorris]

Just FYI, the OE ring compressor tools are still available for around $50 shipped from partzilla. Well worth the investment even if its just rebuilding one motor. They'll sell themselves when you're done.

[brandEn]

Those last 3 posts are all GREAT advice

[AintNoEasyWay]

Agreed. Thanks guys & thanks again brandEn!

[AintNoEasyWay]

...to add to what MC was advising, also position your clamp screws in an accessible manner. 
I had to stop and rotate a few once my cyls were on....
I used a 15-20mm wide strip of .5mm sheet plastic kitchen cutting board around the rings underneath the clamps. 
this made sliding the clamps downward quite easy, and ring ends did not catch anywhere on the clamp cutout holes.

Is there some sort of plastic that fits over cutting boards that you're referring to, flybox1? Not sure if I've seen it around before.

[evanphi]

ALSO smooth out the inside of the hose clamp bands with some sand paper to make sure no gouges are put in the rings.

[flybox1]

...to add to what MC was advising, also position your clamp screws in an accessible manner. 
I had to stop and rotate a few once my cyls were on....
I used a 15-20mm wide strip of .5mm sheet plastic kitchen cutting board around the rings underneath the clamps. 
this made sliding the clamps downward quite easy, and ring ends did not catch anywhere on the clamp cutout holes.

Is there some sort of plastic that fits over cutting boards that you're referring to, flybox1? Not sure if I've seen it around before.

I just grabbed what I had in the house.  Any thin flexible plastic will do. 
Cut a ring out of the lid of a rattle can, tennis ball can, the flat of a 2litre soda bottle....etc   

If you go the clamp route, set your upper edge of the clamp right on top of the upper ring. no big overlap here.
When you set your cylinders down on the pistons, it will take very little downward movement to get the first ring in the bore, and you're off.....  Do #2&3 first....then 1&4

[MCRider]

The Flybox idea of plastic sleeve is great! I never liked the feel of the steel clamp against the steel rings.

But, it does work as well, without the plastic.

[koendd]

so, I'm close to finishing my engine build (F2).
But I have a question about the o-rings on the cylinder base.

you mention four smaller o-rings and two bigger.
I get the bigger ones go on the recessed area on the crankcase where the oil feeds up but what about the 4 smaller ones?

I don't see them in the parts fiche?



any idea what size they should be?
Cause I have some small ones that fit but the base gasket doesn't clear them...

[bytio]

No 6, there are 4 of these but if you have the HD studs these are a bit fat, so I used slightly thinner ones,

[bytio]

These go on the studs that have the dome/acorn nuts on the F2, you will see on the bottom of the F2  cylinder the 3rd stud hole in from outside has a slight cut out for this o ring. No oil should come down this hole, it keeps dirt etc out the crankcase

[koendd]

aha, so I use four on the studs with dome nuts and 2 on the middle ones where oil feeds up, right?