New Member!!

Hi All!,

My name is Scott, I live in Owosso, Michigan, U.S.A., I've been riding and wrenching on motorcycles my whole life. I have a small collection of bikes. They're mostly Japanese 3 cyl. 2 stroke of 70's to 80's vintage. Every once in awhile I find that I'm working on something that's new to me, such is my case at present. I've recently embarked on a restoration of a 1975 Commando 850, It's a 19,000 mile original. I was even afforded a good set of wrenches and sockets to go along with the restoration. I have it on the lift now, fortunately it was stored properly and covered. I have the tank and side covers and seat removed as well as the carbs and K&N air filter. I got the digital 35 out and started taking pictures at the start of the teardown too.
The exhaust needs to come off next, but I'm unfamiliar with how to take the pipes off the head. I have 2 manuals but they are vague about this. I could use some direction... I can't wait to see this bike finished and I think with this forum and all the knowledge about this brand of bike, It can be a "winner" I'll try to post some pics as I become more familiar with this forum.

Thanks, Scott.

Hi Scott and Welcome.

You might do best to post questions in the Commando Section, that is where most of the eyeballs are.
For the headers, use a peg wrench to unthread the exhaust nuts at the head, (right hand thread, nothing tricky and off they come, provided you have removed the mufflers already.

Glen

chainsaw77 said:

Hi All!,

My name is Scott, I live in Owosso, Michigan, U.S.A., I've been riding and wrenching on motorcycles my whole life. I have a small collection of bikes. They're mostly Japanese 3 cyl. 2 stroke of 70's to 80's vintage. Every once in awhile I find that I'm working on something that's new to me, such is my case at present. I've recently embarked on a restoration of a 1975 Commando 850, It's a 19,000 mile original. I was even afforded a good set of wrenches and sockets to go along with the restoration. I have it on the lift now, fortunately it was stored properly and covered. I have the tank and side covers and seat removed as well as the carbs and K&N air filter. I got the digital 35 out and started taking pictures at the start of the teardown too.
The exhaust needs to come off next, but I'm unfamiliar with how to take the pipes off the head. I have 2 manuals but they are vague about this. I could use some direction... I can't wait to see this bike finished and I think with this forum and all the knowledge about this brand of bike, It can be a "winner" I'll try to post some pics as I become more familiar with this forum.

Thanks, Scott.

Click to expand...

Hi, welcome. The finned nut unscrews from the head. A special spanner is needed, unless it was loose, in which case you have bigger fish to fry. http://www.oldbritts.com/19_063968.html
Lots to read... use the search and get comfortable :mrgreen:

Owosso? That as close a Norton to me as heard of in a long long time. Welcome neighbor, sort of.

Anyhow,
If an 850, then you probably have those big steel collars. If so tight that they will not move then heat around them with heat gun. The softer alloy of the head is vulnerable to damage so take care.

I have put a big pipe wrench on those concentrating on the larger lugs of the exhaust nut. If pristine then special care can be taken. If sort of crapped out then don't worry about them so much.

Loosen them a bit, then remove the bolt from the mounts on the back side. Then unscrew the exhaust nuts by hand and remove the entire system as a whole assembly.

Just to add norbsa48503 is right over there in Flint.

Hi Scott. Welcome.

Do you have a Widow Maker

Ciao Scott, welcome to the forum

Hi Scott, Check my web site out and contact me using that I can help with a fly wrench and what ever there is I am doing up a 75 right now and I am in Flint ...Greg

As with the others, welcome !!! I'll be following your thread and looking forward to pictures as well ... cheers

Welcome and give us plenty of pictures!

Welcome Scott, The exhaust nuts, or hollow bolts as some like to call them can be removed with judicious use of a brass punch, but not recommended. The special Norton exhaust nut tool is better. I noticed the Bike is a '75 so if the exhaust is the original with the connecter pipe up near the head, the system will not come off in one piece. You must loosen the clamp bolts on the center section and slide it one way or another (whichever way it wants to move, if it will move at all) until it is free of the adjacent pipe, then the exhaust system can be removed from the head. I personally like to take the whole thing down in parts rather than deal with both pipes and mufflers as a unit. That center piece may not want to budge so you may just need to cut it and replace it.

I should edit my method here. When I said "as a unit" I meant one side with the muffler as a unit, not actually the whole thing. Sorry.

To get head free of headers it kinda of depends on the condition of the muffler/pipe fit, if loose then I leave mufflers on their hangers and pipes come off easy, if too snug then off with mullfers first. It helps to heat the head at the hollow ring bolts, exhaust rose's etc, guite a bit for a few minutes to let alloy expand some before attacking the likely almost fused blended threads by now. A shock absorber wrench sometimes fits the fins and lugs but may need a helper to coutner balance undoing LH as generally needs long enough lever and force to lift the bike over onto RH side. I long ago gave up on the long lever method for the proper tool w/o is rubber hand grip so 4ft pipe fits over or 3# sledge not to strain me no more. Really tough fused threads can fold over-break off a thin fin and the thick lugs may not give good angle for the initial drift-hammer method to break free, though the hammering shock goes a long ways to break free similar to air impact vs same constant torque that can twist bolt nut right off. I've tried off the shelf anti-seize but they tend to melt out so I've gone with Milk of Magnesia and rather pleased it acts like loctite formulas that harden to a crust locking up but unlike loctie that can't take exht heat, MoM turns to a powder that lubes the threads for un abrasive thread removal after the inital first sucessful break free. There's a number of reasons/occasions to remove headers now and then so best to bite new tools bullet. Here's image that conveys control by brute force message.

I grew up there in the '60's. Lots of brit and Jap bikes around then

If you have exhaust headers with the crossover pipe, then it is best to remove the mufflers, before trying to remove the headers. Same for the crossover, too.

The heads in the thread, if they are original, are aluminum and vulnerable to damage from the end of the exhaust pipe if you don't have everything free before trying to remove them. It is very easy to cause damage if you try to remove the center portion of the crossover tube with the large exhaust nuts loosened.

For exhaust headers with or without the crossover, remove the mufflers first. This will protect the exhaust nut threads in the head from damage, as the header(s) will not be moving in contact with the head if the large exhaust nuts have not been loosened.

Then attempt to loosen the clamps holding the crossover assembly. I would use an appropriately sized flat screwdriver, or something that is equivalent. With heat, oil, and prying, you may be able to loosen the two clamps.

If you are unable to dismantle the crossover in place, or get everything very loose, then it is difficult to remove the headers without causing damage to the threads of the exhaust ports.

It's been a long time since I've removed a set of headers, with or without the crossover, but I'm pretty sure the whole unit cannot be removed without the crossover being loosened.


The least desirable situation you want to be in is having the crossover inadequately loosened, trying to work the exhaust off by fiddling the header pipes back and forth with the crossover section fighting you the whole way.



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