Topic: cb400f header source

[BobW]

Looks like I need a header (hole in the collector part of the header - bummer) for my 77 cb400f.  My bike it super original and looks like new so will probably go for a repro.  A NOS (with muffler) is on ebay right now for $2499 (not doing that).  I see David Silver Spares has one for $355 and 4into1 has one listed for $465 (what's the $110 difference?).  Any opinions or thoughts on these two or suggestions for other sources?  My muffler is in good condition so ok there.  What other parts should/need to be replaced at he same time?  I'll also place a note on the Wanted to buy board.  Thanks!   

[Bristledisk]

I just fitted a new header from Dave Silver USA. I'm really pleased with it.

This is what I ordered:

1 Exhaust downpipes and collector assembly
2 Exhaust port gasket
1 Exhaust No. 1 down pipe to collector box clamp
1 Exhaust No. 3 down pipe to collector box clamp 
1 Exhaust silencer to collector box gasket

[MoMo]

i bought the muffler from DSS and was quite happy with it. 

[caretta]

I bought the DSS header for my 400F and had put about 1000 miles on it before selling the bike. The header appeared to be a good reproduction of the original factory header. The chrome appeared to be good but not as deep as the factory chrome. The fit was just the same as the 40 year old factory header. It is built the same, with two welded pipes and two loose pipes to the collector. The collector is slightly different in the bends for the pipe fittings. Overall a good reproduction of the factory pipe but not identical in all aspects.

I used T style clamps for the pipe to collector joints instead of the cheap Honda clamps. You need two graphite seals for the two loose pipes joints and one for the collector to muffler joint. DSS had all the correct pieces.

Couple of side by side comparison photos attached.

[BobW]

Super helpful.  Thanks.  Are there gaskets for where the 4 pipes meet/attach to the heads?

[Flyin900]

Yes there are gaskets for the head to collector and be aware that the sandwich type gaskets which are thin metal on each side with a material in the middle like an Oreo cookie and can present problems in getting the headers into the head and getting the nuts on the studs.

I didn't find any of the copper donuts for the CB 400F that I am more familiar with for exhaust sealing from the header to the head.

Once you put the thicker seals as noted above and the header and the exhaust flanges on the head, I found I could not get any of the nuts over the studs as there was no room left for any exposed threads off the studs.

I ended up grinding the exhaust two piece metal flanges down about 1/8" on all eight pieces to allow me enough extra room to get the exhaust collars started on the studs.

I used the exhaust gaskets from 4into1 and found these to create the issue noted above. Maybe other have used a different gasket and not run into the same problem. There weren't any old gaskets left in there either; yet it is good to check as they are usually pretty flattened and with carbon build up can be easily hidden.

PS: The David Silver Spares product is first class in IMO for the money you spend ...  it is well made product and a good reproduction. I used the muffler and was very happy with the quality and price.

[carnivorous chicken]

I've ordered DSS stuff in the past and been happy, but haven't ordered 400F exhaust. They are still pretty widely available and as far as I can tell the prices for good condition ones (not NOS) have come down a little in the past few years (perhaps with the realization they're not the unobtanium that people thought they were). Depending on where you are, finding pipes or a muffler and getting them brazed if need be and chromed might wind up the cheapest option. I can get exhaust chromed where I am for about $150-200 (or at least the last time I did it). Jus' sayin' there might be another option.

[BobW]

That's a good thought.  The pipes and collector seem to be in great condition except for the one hole in the collector.  I guess others could be lurking under the chrome too.

[BobW]

I haven't done this before so another question.  As I detach the pipes from the heads will I disrupt the 4 gaskets?  Wondering if I necessarily need to replace those or if I just take off the old pipes and put on the new ones all should be good?

btordxe, you didn't list the four gaskets (pipe to head) in your order list to DSS.  Did you not replace them?

Caretta - same question.  You didn't list them either. 

Many thanks for all the great info!!!!!

[caretta]

I replaced my four head to pipe gaskets. I would not reuse the old gaskets but you probably can if they look to be in good shape. The gaskets compress when the header is first installed to make a leak proof seal. Reusing the old gaskets could result in some small leaks. It can be hard to tell if the old gaskets are viable. It also can be difficult to get the old gaskets out of the head but a pick and some gentle probing with the pick will get them out. Clean up the head surface and install new gaskets with a smear of anti seize. The anti seize might make it easier to remove them next time and it also holds them in place when you are messing with pipe alignment.

The collector is the low point of the exhaust and any water (condensation) will collect in the collector causing the bottom to corrode out from the inside out. My old collector had corroded out at some point in it's life and a PO had the bottom replated with some type of mild steel and it also corroded thru. The way to forestall this in the future is to make sure to get the engine completely warmed up so that any water boils off. When cooling off the humidity in the air will condensate again starting the corrosion process again. The solution is to not let the bike sit for long periods. Ride it often and get it hot!!

[BobW]

That helps.  Thanks  Pictures are very helpful

This forum is great!