Replacing mufflers on my 1978 kz650B2

Anyone know what the OD of the exhaust pipe is, that the factory mufflers on these bikes clamp over, or are welded too ??

My left side muffler, has a big hole in it from rust that needs attention. I've decided to just remove the factory mufflers, and install some slip on / weld on mufflers in there place.

Edit to anyone who reads this: he still doesn't have the measurement. I goofed. :blush:

Thanks for your reply martin_csr !!

I'm going to use the factory header pipes just the way they are. I needed to know what that header pipe's collector piece, right before the mufflers, has for openings, going to the mufflers. So I can get the closest fit, aftermarket mufflers for the bike. I figure I will have to cut off the factory mufflers, then clamp / weld on the replacement mufflers

Is there any demand here, for the factory mufflers on the 1978 kz650's ?? If memory serves me right (which it seldom does), the right side factory muffler on my bike is in good, to great condition, and I won't have any use for it.

Thanks......

My mistake. I only read as far as the "big hole". hee.
You could remove the muffler cover & measure it.

Replacement mufflers.
HELIX RACING UNIVERSAL MEGAPHONE MUFFLER

HELIX RACING UNIVERSAL DUNSTALL TYPE EXHAUST MUFFLER

EMGO UNIVERSAL DUNSTALL STYLE MEGAPHONE MUFFLER
(apparently, nla at jcwhitney. Not sure if JPCycles or etc would carry them or what).

Verner-650's bike w Dunstall Replicas --- I'm not sure exactly which ones he installed.

I wonder if these mufflers will fit my 77' KZ1000A? Has anyone tried these on a 1000 ???

They're listed as universal fit. The JCWhitney info indicates that the Dunstall type has a packable silence. If need be, muffler baffles are available. Search baffle at JCW --- they have various sizes... might take some work to fit 'em right, though ???

The Helix Racing website doesn't have much info, but you could give them a call.

That 650 in the picture is almost exactly like mine. It's a nice looking bike !!

My problem lies with the fact that, my kz650 is stored 25 miles away. So it makes it hard to get specific info about it in a short amount of time. Which is why I ask a lot of, "I should be able to get this info myself questions"....LOL

I got a 24 hour 20% discount offer from JC Whitney, and thought about getting similar tail pipes like you've posted for my bike. I would prefer to keep this bike completely stock, as it's all original with extremely low miles, but I'm not a big fan of the stock mufflers, and it annoys me that they interfere with the removal of the rear axel.

Since those aftermarket mufflers are universal fit, you can probably make them work --- one of them says they fit up to 1-3/4". If the diameter is too great, I guess you could get some kind of donut spacers from a muffler shop to make up the difference . ???

The mufflers shouldn't have anything to do with removing the rear axle (except for shaft drive models).
Instead of trying to remove the axle, remove the whole rear wheel & axle n stuff as an assembly. Disconnect the brake stuff. Loosen the axle nut, loosen the chain adjusters & swing them out of the way, then remove the chain adjuster blocks, kick the wheel forward, then lift the chain off the sprocket & roll the wheel assy away from the bike. I've never looked in the manual to see how to remove the rear wheel, but that's the way I've always done it. I put a foam pad behind/under the wheel to have something to roll the wheel onto instead of having it drop off the swing arm --- makes the job easy.

Take a look at the picture of the 650 posted earlier in this thread. What I'm talking about, is to be able to remove the rear wheel assy, you have to get the axel pulled out of the way, before you can pull the rear wheel off the bike. Looking at the picture posted, you can see the mufflers are covering both sides of the axel. So the muffler on one side needs to be loosened, and pulled out of the way, to be able to pull the axel out, so the rear wheel can be removed.

The axel goes through the swing arm, and then the wheel assy. The axel has a washer built into one side of it, that keeps it from being able to be pulled through the swing arm. Which requires the muffler on one side to be pulled out of the way to remove the axel. The axel has to be completely removed before the rear wheel can come off the bike.

The only way around it would to be to pull the swing arm off with the rear wheel assy, then you wouldn't have to mess with the mufflers....But then that's even more work......

Take a look at the picture, and you will see what I'm talking about....

With the aftermarket mufflers, they should be able to be set up so they don't block the axel, which will make it easier / less work, to remove the rear wheel assy.

I think you are mistaken about the axle. From the diagrams your swing arm & chain adjuster stuff looks about the same as on my 81 KZ650-H1 CSR. You can probably remove the rear wheel & axle as an assembly without removing the mufflers & without removing the axle first.

Here's a question: does it make sense that you'd have to remove the entire exhaust system to change a tire or patch a tube? That would be a nightmare roadside repair.

MAC makes some slip on muffler options as well. I will try to scare up a link
themallshop.worldofpowersports.com/MAC-4...uctId=7855381&ez=Mac Mufflers&pos=17

Thanks for the link HBKwaka !!

Martin_csr, You CAN "teach an old dog new tricks" after all !! I wasn't aware that the end of the swing arm had a removable part like that !! Yes that makes sense, as it does create a ----load of extra work to drop one side of the exhaust, as I did on my 1980 kz750 when working on it not long ago..... I bet it has the same setup ???? If only I'd have known, it would have made that repair a whole lot more enjoyable !!

Old age, tired muscles, bad eyesight, arthritis, these are all my excuses for not seeing the obvious !!!! LOL

Thanks for the education !!!!! I will not be making that mistake again !!

I just checked my service manual for my kz750, and it has the same removable block, as the 650's do, to be able to remove the rear wheel assy without having to mess with the exhaust !!! Sometimes I feel like a nut !! At my age, I should know to read up on any work I plan to do to my bikes, but I seem to always overlook that important step ??