Topic: Intake Flange

[bunghole]

How hard is it to remove an intake flange from the cylinder head of a CB750?  It looks like a big wrench would do the trick, but I'm worried about the threads on the head.

[WHALEMAN]

Please do not try this. I learned the hard way. They are threaded in but sealed with a thick glue. You will not remove it undamaged.

[azuredesign]

I was asking Mike Rieck about that last weekend. Apparently, heating the area sufficiently will allow the intake component to be unscrewed. Mike suggested MAP gas, or was it napalm, darned mind is going on me...

[MRieck]

I was asking Mike Rieck about that last weekend. Apparently, heating the area sufficiently will allow the intake component to be unscrewed. Mike suggested MAP gas, or was it napalm, darned mind is going on me...

They come out with heat. Thick glue.......it's Gasachinch. Just heat it.

[mystic_1]

Is there an advantage to removing these?  Makes porting easier, maybe?  But then you'd still need to reinstall them in order to blend the intake spigots into the intake tract, yes?

Was just looking at a spare head last night in fact and wondering at the epoxy-like substance I spotted around two of the spigots.  I always assumed they were welded in or something.

mystic_1

[MRieck]

Is there an advantage to removing these?  Makes porting easier, maybe?  But then you'd still need to reinstall them in order to blend the intake spigots into the intake tract, yes?

Was just looking at a spare head last night in fact and wondering at the epoxy-like substance I spotted around two of the spigots.  I always assumed they were welded in or something.

mystic_1

I don't take them out for porting. I've replaced damaged ones with flanges from junk heads. the ones on my bike are welded in.

[bunghole]

The issue is that I have one with a big chip in it and want to replace it with one from a donor head.  I've been trying for an hour.  I sprayed some PB Blaster around all four flanges.  Tried the MAPP torch all around.  Got it nice and hot and still nothing.  I even went and bought a 35mm socket to fit it and used an impact driver and still nothing.  Any tips?  How did you guys do it?  The more details the better.  Did you use a socket or a wrench?  Impact Driver?  Penetrant?  Special Dance?  I'll try anything!

Thanks for all the help!  I need a beer break!!

[MRieck]

The issue is that I have one with a big chip in it and want to replace it with one from a donor head.  I've been trying for an hour.  I sprayed some PB Blaster around all four flanges.  Tried the MAPP torch all around.  Got it nice and hot and still nothing.  I even went and bought a 35mm socket to fit it and used an impact driver and still nothing.  Any tips?  How did you guys do it?  The more details the better.  Did you use a socket or a wrench?  Impact Driver?  Penetrant?  Special Dance?  I'll try anything!

Thanks for all the help!  I need a beer break!!

A 3/4" socket, long breaker bar and heat. A 6 point socket would be best but I only have a 12 in that size. I clamp the head to a bench. Spray penetrant doesn't do much becaused of the sealer. Let it rest and hit it tomorrow. It will probably spin right out.

[MRieck]

 Christ an impact ( with a 6 point) should do it. I can pull a donor off a head I have and then you can concentrate on getting the bad one off the good head.
  Mike

[bunghole]

Christ an impact ( with a 6 point) should do it. I can pull a donor off a head I have and then you can concentrate on getting the bad one off the good head.
  Mike

Right?

Thanks!  I'll try again.  One of the problems is getting the 6 point over the lip of the flange.  It sort of has to be pounded down as it is a tight fit.  I got the head hot enough to be too hot to handle (Black Crows) and it still didn't spin off.  The clamping head to the workbench idea might be the ticket.  I'll give that a try too.

Friggin' old Jap bikes.  I love them!

[MRieck]

Christ an impact ( with a 6 point) should do it. I can pull a donor off a head I have and then you can concentrate on getting the bad one off the good head.
  Mike

Right?

Thanks!  I'll try again.  One of the problems is getting the 6 point over the lip of the flange.  It sort of has to be pounded down as it is a tight fit.  I got the head hot enough to be too hot to handle (Black Crows) and it still didn't spin off.  The clamping head to the workbench idea might be the ticket.  I'll give that a try too.

Friggin' old Jap bikes.  I love them!

I see the problem....you own a Yamaha 550.

[bunghole]

Mmmmmkaaaayyy...

I used lots of penetrating oil...lots of heat...and all the strength I could muster with a breaker bar.  Results below:

[754]

Why oh why did you not just weld up your old one??

 I took a set out to port a head, 1/2 of them stripped. If I use that head, I will machine new ones and weld them in. Shold raise the ports while I am at it..

 Be careful porting, I have heard measurements of ports on here that are leaving less than 1/16 of an inch per side.. less if they are not centered. Be a shame if one cracked..

[mystic_1]

Zounds!  Did someone JB-Weld them into place or something?  The epoxy I observed on my spare head (73 I think) was a whitish substance, yours looks dark in color, but maybe that was from the heating.

Guess you could get the stub out by grinding out a line down the inside with a dremel or some such, allowing you to crush the remains and pull it out, kinda like you would on a stuck cush drive bearing retainer but on a larger scale.  Whether this would work for you depends on why the thing is so stuck to begin with.

mystic_1

[bunghole]

This was a donor head, so I'm not so worried about the head itself.  I actually was just looking to salvage a flange for a head that I bought on Ebay that had a cracked flange.  I've got one more flange that looks pretty good on the donor, but I'm not holding out much hope considering what happened on my first attempt.  Whatever adhesive was used was brownish in color even before I applied any heat.  Maybe I should "remove the head from the flange".

I think the real problem here was just my brute strength.  I work out a bit.  A little bit.  Sometimes.  But I've been compared to a pissed off Bruce Banner.  Only with less green and about 180 pounds of flab and not much muscle.  But the flab gets irritated sometimes.

Stupid Honda!  I love it!

[mystic_1]

This was a donor head, so I'm not so worried about the head itself.

Whew!  I was feeling really bad for you when you posted that pic.

I think the real problem here was just my brute strength.

In which case, just threaten and glower at the three remaining ones, you should be able to just scare them out at this point. 

cheers
mystic_1

[754]

So try welding the other, nothing to lose..

It could come out (of the good head) like that one, if you get a spare.. then you will still end up welding..

[bunghole]

So try weling the other, nothing to lose..

It could come out (of the good head) like that one, if you get a spare.. then you will still end up welding..

Not a bad idea.  I have a stick welder, but I'm a real novice.  What kind of metal am I dealing with and would you recommend bringing it to a specialist?

Thanks for all the help everyone!

[bunghole]

I finally beat the #$%*er and on my last try got one out that looks useable.



What the hell kind of metal is this?  It seems like pot metal or something.  Weighs about as much as a fart.

[754]

die cast alloy

[mystic_1]

I finally beat the #$%*er and on my last try got one out that looks useable.

Of course it was on your last try, once you succeeded you stopped trying, right? 

J/K well done.  I dread ever having to tackle something like that.

mystic_1

[754]

TIG weld would work real good.

[WHALEMAN]

Clean both threads very carefully. Hand start and run in a few times before glueing in for good. The threads are very fine.

[bunghole]

Clean both threads very carefully. Hand start and run in a few times before glueing in for good. The threads are very fine.

The threads on the flange I removed look a little buggered, so unless I can find a die that will fit them, I might be in trouble.  I don't have the new head yet to evaluate its threads.  If all else fails, is it possible to just glue the flange into the head without the use of the threads?

[birdcatcher]

The guy working on my head broke one of the intake flanges.  What's frustrating is that I didn't ask him to work on this part of the head at all.  He was supposed to be doing a valve job.  Nevertheless, I now have three good flanges and one broken one.

I've tried searching ebay, online stores (dynoman, cmsnl), and parts yards here in So Cal, but I haven't found a replacement flange.  Any advice on where to find one?  Does anyone one have an extra one they'd be willing to sell.  If so, name your price.  Once I can get this piece, I have everything to put the engine back together.

Thanks guys.

Randall