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Dunstall mufflers

jensen
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Post by jensen » Wed Jul 07, 2010 1:02 pm

Hi Teazer,

I tested many combinations, and there was one after market pair with it, and that were the ones who were made in New Zealand. As these mufflers are a copy of the original, the curves looked the same.

I have a (Semi?) Dunstall set lying around, but I didn't tested that one because I think someone made them their selfs. It has aluminum cones at the back, and the pipes are extremely short too.

Jensen
assembly of Japanese motorcycles requires great peace of mind (Pirsig)

Vince Lupo
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Post by Vince Lupo » Thu Jul 08, 2010 3:44 am

cyclon36 wrote:Also, in regards to the weak mount point, I notice the mounting bracket is bolted to the rear of the channel on the muffler. Do you think shortening the bracket so it mounts in the center of the channel would do any good to even out the stress on the channel? Perhaps even do a double bracket with one attachment point on either side of the channel? Not sure if that would help or make it crack twice as fast.
From what I experienced (three time's a charm!), it breaks right at the edge where the 'face' of the channel and the horizontal angle meet (not at the weld where it attaches to the muffler). The only solution that I could see would be to weld a thicker piece of metal to that channel, or make a whole new channel that's more robust (then of course rechrome the muffler!). Unfortunately, the vibration that these bikes generate tends to want to break things, and the way that these mufflers mount makes them a bit more 'vulnerable' than the stock setup. And I don't think that moving the bracket to the center would make much difference -- I think mine was about 1/3 of the way in from the end, and it still broke.

Of course, it also depends on how much you ride the bike. If it's once a week for 75 miles, I wouldn't worry about it too much.

On a somewhat related note, I had mounting brackets fracture, the mounting point on the aluminum plate that holds the footpegs break, as well as the three previous EMGO/Dunstall mufflers break. It's always something!

Hmm.....was just thinking: What if you got a C-shaped section of metal that would fit over top of the whole channel, drilled a hole where you needed it, and then re-attached the bracket? I think if you go to Home Depot or Lowe's in the section where they sell lengths of metal and aluminum, they do sell that shape. Might be worth a try???

Another alternative would be to find a set of real Dunstall Decibels....

Mike Mullins
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re:

Post by Mike Mullins » Thu Jul 08, 2010 6:53 pm

Cyclon: I am running a 3.00x18 Cheng Shin on the back and a 2.75x18 Cheng Shin on the front. This was as close to stock as I could get when I put the bike together. I too have noticed the apparent off sided appearance of the rear wheel, but dont know why. Everything measures up withing reasonable closeness to what I think is centered. I suspect that something got "whanged" sometime, but its not apparent exactly what. (Probably the rear fender, but a board down the top of the bike indicates the tail light is centered.)
Bike rides OK apparently. Next bike will have wider tires. These are just WAY too skinny. (going "darkside" on the goldwing has spoiled me.)
Mikeyrx
"a free motorcycle is a bottomless hole intended solely for money"
66 CB 77
76 BMW R75/6
99 GL 1500 trike
75 & 79 XS 650's

cyclon36
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Re: re:

Post by cyclon36 » Thu Jul 08, 2010 6:59 pm

Mike Mullins wrote:Cyclon: I am running a 3.00x18 Cheng Shin on the back and a 2.75x18 Cheng Shin on the front. This was as close to stock as I could get when I put the bike together. I too have noticed the apparent off sided appearance of the rear wheel, but dont know why. Everything measures up withing reasonable closeness to what I think is centered. I suspect that something got "whanged" sometime, but its not apparent exactly what. (Probably the rear fender, but a board down the top of the bike indicates the tail light is centered.)
Bike rides OK apparently. Next bike will have wider tires. These are just WAY too skinny. (going "darkside" on the goldwing has spoiled me.)
Mikeyrx
I guess the picture makes them look thinner. I'm running the same setup at the moment. I'll post up what I find when I take my rear end apart and compare my current setup with the one from the parts bike. I'm guessing either tweaked swing arm or a spacer either missing or placed on the wrong side of the hub. Hopefully it's just a spacer problem.

My goal is to get the vintage Firestones on there. They're pretty wide but I think with the right modifications, it could happen.

LOUD MOUSE
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Re: re:

Post by LOUD MOUSE » Thu Jul 08, 2010 7:59 pm

When ya installed the parts did ya need to spread the end of the SA or was there a void which caused the nut to pull one side in?
Looks as though there is a lot of thread to the left of the nut.
HONDA did make 2 different right side spacers which look the same however they are different lengths.
I think one is for the H/SH and the other may be for the CL bikes. ..............lm

cyclon36 wrote:
Mike Mullins wrote:Cyclon: I am running a 3.00x18 Cheng Shin on the back and a 2.75x18 Cheng Shin on the front. This was as close to stock as I could get when I put the bike together. I too have noticed the apparent off sided appearance of the rear wheel, but dont know why. Everything measures up withing reasonable closeness to what I think is centered. I suspect that something got "whanged" sometime, but its not apparent exactly what. (Probably the rear fender, but a board down the top of the bike indicates the tail light is centered.)
Bike rides OK apparently. Next bike will have wider tires. These are just WAY too skinny. (going "darkside" on the goldwing has spoiled me.)
Mikeyrx
I guess the picture makes them look thinner. I'm running the same setup at the moment. I'll post up what I find when I take my rear end apart and compare my current setup with the one from the parts bike. I'm guessing either tweaked swing arm or a spacer either missing or placed on the wrong side of the hub. Hopefully it's just a spacer problem.

My goal is to get the vintage Firestones on there. They're pretty wide but I think with the right modifications, it could happen.

teazer
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Post by teazer » Thu Jul 08, 2010 11:23 pm

Sharp eyes LM.

It looks almost as if the swingarm is tweaked but that could just be teh angle we're looking from. I'd remove the bottom bolt from the left shock and see if the shock mounting hole becomes above or below the matching hole in the swingarm.

If the swingarm is bent, one shock will be sitting shorter than the other and will be under higher tension.

Mike Mullins
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re: hmmm

Post by Mike Mullins » Fri Jul 09, 2010 5:57 am

Hmm this thread is getting interesting. Lots of good info here. I dont recall any difficulty in assembly of anything. The swingarm looked normal, and the wheel went in without any difficulty. Just for kicks, when I was checking the tire before my last post, I did some rough measuring, and the front edge of the rim is about the same from both sides of the swingarm. I relaced the wheel and I suppose I could have it off center, but the spokes are all the same depth on the nuts and inside the rim, so I dont think that could have been the problem.
A board laid lenthwise down the center ( approximate) of the frame is resting on the center of the tail light. I have just laid this off to the fender being tweaked at some time in its young life, but there may be something else here. Now is a good time to check. I have the engine out to replace the cam chain and cross the gears and replace the brass bushing.
Mikeyrx
"a free motorcycle is a bottomless hole intended solely for money"
66 CB 77
76 BMW R75/6
99 GL 1500 trike
75 & 79 XS 650's

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