Topic: Kerker Meg series on a 76 CB750k - I destroyed my head

[michrobi]

Wow, did I ever screw up big time. I just tried to replace my Kerker headers with a Kerker header from Dynoman.net. The design on the header has been.... What's the opposite of improved? Whatever it is, that has been done. These things come with a big ol bracket 1.5 inches from the end of the header, that's already machined on each header pipe and has 1.5 inch bolts included to connect them to the head (about 2-3 threads too short - maybe they forgot the space for the header gasket). The pipes aren't the correct angle and getting the threads started on the head was unreasonably difficult. Three of the 8 bolts ate a good amount of threads from the head, and now my 750 is going to sit till I can get a head installed. I couldn't be more disgusted with myself. Those headers weren't cheap and neither is a replacement head =(

[kghost]

Hi,

Welcome to the board.

Could you post pictures?

I'm not getting what the problems was......

[michrobi]

Here are some shots I just took. I got the pry bar out and managed to get three out of four pipes to thread up. On the last pipe, I think I just need bolts that are 1/8" longer to get it. If so, I might have a chance to get by until the 836 is finished. The last shot is of the old Kerker Meg header that came off the bike. I just put new batteries in my camera so the date is at default.

I'll keep you guys posted.

[754]

Do you by chance, have several exhaust gaskets in there?
 what do you mean by, "Wrecked the head"  ?

[michrobi]

The other headers were clamped around the outside of the port adapters in that last shot. Those get bolted into the head and the header slips on. The port end of those port adapters are rounded like a gasket and there weren't any gaskets in the ports.

I got cross threaded trying to start three of those bolts and tore some threads out. They're just too short to get a good start, and are easily cross threaded. On one of the bolt holes on the last remaining pipe, it's pretty stripped out... Maybe 3 or 4 threads.

[Jerry Rxman Griffin aka MuthaF'er]

Your head is not wrecked. Helicoils will work wonders. Studs might have been the better solution.

You're not trying to tell us that you attempted to use the spigots from your old header are you?! Hope not because that isn't how they work.

[michrobi]

Nothing there from the old headers except the head.

[Jerry Rxman Griffin aka MuthaF'er]

Make sure you have each individual pipe lined up where it fits into the exhaust port properly. Pop it in with the heal of your hand. Do a dry run first without the copper oring gasket to determine spacing. The bolts should be long enough to easily grab some threads with a fresh copper oring gasket in place.

Otherwise..............  You may be able to get some longer bolts or, like I suggested, the actual studs that the later heads use and screw them into the head then attach the header with flange nuts. The studs are 50mm long with threads of 19mm on one end and 15mm on the other. If you've totally stripped the threads I'm sure a helicoil can be inserted then you're good to go. Give Buzz a call at Dynoman and see what suggestions he has. He knows these bikes. I'm sure you're not the first to have this problem.

[cafeconleche]

I had this same problem.

I smacked the pipes into place with a rubber mallet. I've had them off and on a few times since then and it seems they go on easier every time.

[MCRider]

I had this same problem.

I smacked the pipes into place with a rubber mallet. I've had them off and on a few times since then and it seems they go on easier every time.

I think its a matter of technique. Sounds like you've got it!   

[michrobi]

I've beat the hell out of these things with my mallet, and pry bared them all over the place. I found some 1/4 inch longer bolts, so we'll see how it goes. I figure once their on, the heat from running them will make them true up some.

Thanks for all the input guys, I appreciate it.

[michrobi]

Does anyone know offhand what the header bolts are supposed to be torqued at? I can't find it in the Honda service manual or Clymer.

[Jerry Rxman Griffin aka MuthaF'er]

Evenly snugged   Just remember the exhaust seals are not flat washers but are intended to crush down some but not necessarily all the way.

[MCRider]

Does anyone know offhand what the header bolts are supposed to be torqued at? I can't find it in the Honda service manual or Clymer.

Others may disagree and I'll entertain such, but I would tighten them only as much as necessary to do the job which is to seal the exhaust gasses. Kinda like a spark plug. Run it down to where you feel resistance then 1/4 turn.

YOurs will be harder to do that way since the pipes are giving you resistance from the get go. Still my principle applies. Tighten to where everything is firm and you've caught roughly the same number of threads on each bolt, assuming they are all the same length.

Start it up, listen for a leak. If you find one, tighten it up a bit. Also use anti seize on the bolts as they are steel and the head is aluminum.

But I see no reason to wind them down real hard.  Just makes it hard to take them out later.

Now if it were the stock spigots I'd likely look for a shop manual entry for guidance.

[kghost]

The other headers were clamped around the outside of the port adapters in that last shot. Those get bolted into the head and the header slips on. The port end of those port adapters are rounded like a gasket and there weren't any gaskets in the ports.

Even those spigots in the last shot use the copper gaskets

Make sure you got the old ones out.....

[MCRider]

The other headers were clamped around the outside of the port adapters in that last shot. Those get bolted into the head and the header slips on. The port end of those port adapters are rounded like a gasket and there weren't any gaskets in the ports.

Even those spigots in the last shot use the copper gaskets

Make sure you got the old ones out.....

Ditto to that. Manys the time someone here has said "there weren't any gaskets below the spigots" only to go back and pick at them with a small screwdriver or such and sure enough there is a nasty flattened copper oring gasket stuck in there, hidden by a lot of exhaust crud.

[kghost]

The other headers were clamped around the outside of the port adapters in that last shot. Those get bolted into the head and the header slips on. The port end of those port adapters are rounded like a gasket and there weren't any gaskets in the ports.

Even those spigots in the last shot use the copper gaskets

Make sure you got the old ones out.....

Ditto to that. Manys the time someone here has said "there weren't any gaskets below the spigots" only to go back and pick at them with a small screwdriver or such and sure enough there is a nasty flattened copper oring gasket stuck in there, hidden by a lot of exhaust crud.

After years of crud they match the rest of the port 

[MCRider]

The other headers were clamped around the outside of the port adapters in that last shot. Those get bolted into the head and the header slips on. The port end of those port adapters are rounded like a gasket and there weren't any gaskets in the ports.

Even those spigots in the last shot use the copper gaskets

Make sure you got the old ones out.....

Ditto to that. Manys the time someone here has said "there weren't any gaskets below the spigots" only to go back and pick at them with a small screwdriver or such and sure enough there is a nasty flattened copper oring gasket stuck in there, hidden by a lot of exhaust crud.

After years of crud they match the rest of the port 

Yes they really do.

[Alan F.]

Have you tried threading your bolts into the head just to verify that they are the correct thread?
-A

[michrobi]

The other headers were clamped around the outside of the port adapters in that last shot. Those get bolted into the head and the header slips on. The port end of those port adapters are rounded like a gasket and there weren't any gaskets in the ports.

Even those spigots in the last shot use the copper gaskets

Make sure you got the old ones out.....

Ditto to that. Manys the time someone here has said "there weren't any gaskets below the spigots" only to go back and pick at them with a small screwdriver or such and sure enough there is a nasty flattened copper oring gasket stuck in there, hidden by a lot of exhaust crud.

After years of crud they match the rest of the port 

Yes they really do.

Yep, and I did, and they were there! As it turns out, I haven't even gotten one header into the head far enough for those hidden gaskets to have be a problem. I had new ones on top of those and I still haven't even touched them with a header. I have tried to connect, and removed the headers maybe 7 times now, with no success. They simply will not go into the head ports, and the sides of the outside of the ports are all scratched up from trying. I've had this bike and kept it on the road for 15 years, and worked at an automotive shop for 4 years. I don't think I'm going to get them to line up without removing the forks and using a portapower. That seems like too much labor for a set of pipes intended for my bike. Maybe I got a bad header, who knows...

*sulk*

[MCRider]

Man that's too bad. A struggle is not uncommon, but they should go on with some sweat but no blood and tears.

Ah feel yore pain.   

[Alan F.]

I just reread your first post to be sure, you're replacing an older Kerker pipe with a newer Kerker pipe, do the bends on the new pipe follow the lines of the old pipe?  Maybe something is out of place? Maybe it's simply the wrong pipe?
-A

[michrobi]

Yeah, it's identical to the one that came off, except for the head connections and the Kerker name badge on the muffler is bigger.

I put some grease around the head ports and little bit on the rim of the header pipes. while I was pushing the biggest problem pipe of the 4 with my left hand, I jostled the muffler end under the bike violently with my right hand. The pipe actually popped in for a split second, then right back out when I took either hand off to pickup a bolt. What a bastard.

[754]

Line up the port ends of the pipe against a flat piece of wood or wharever, it may show which pipe is out.
 then put that one in 1st.

 they could been dropped, if the port end hits the ground, it may be hard to tell.

 peel the old gasket out or re-use it (but dont run both), as the deeper into the head the pipes go, the looser  they get..ie 3/4 inch away from seating, the would have to hang up.

[michrobi]

I removed the old gaskets, and the ports are pretty deep. About half an inch or so I would say.