Single sided exhaust project on the move!
 

So I emailed Bob Hayashida a few times regarding a mid-pipe for this Moriwaki can I have. The can was bought several years ago off ebay for $50. It's off the left side of an RC51. So it seems that the project isn't going to be as easy as I thought since Mori never made a slip-on system for the Superhawk. I was hoping to get by with just buying replacement parts, but that's not possible. So since I'm on vacation for a week I thought I'd have a go at it.

I had an extra stock right side can that I used for the connection to the header (bottom 5" or so) and the upper part of the Mori mid since that is a special fitted piece. Seems all I need to do now is to find a decent welder in the area who can do nice welds on stainless tubing. Some pics are attached.

Other than the exhaust hanger which I will fix with a small homemade Al bracket to the subframe and the spring tangs being...oh...about 90° off :oops: I think it will turn out okay. The Mori can has the quality and build to hold up to the exhaust pulses I hope.

Will post more pics when welding and polishing is done.

It looks like you're pretty close all the way around. Did you hold it up to the header to see what it would sound like once mounted? Are these cans larger in diameter because they're single sided installs? The outlet doen't look any larger than a regular D&D.

Nice! I think that's going to look real sharp.

Yeah, I have the hanger just a hair less than a 1/4" from the fairing. I tried to get the angle of the can so that it followed the lines of the bodywork and as high as possible with the hanger and pipe configurations that I have to work with. I guess it's 2-1/2 or 3" away. Not real close but it looks a helluva lot better than it did with low mounts.

No, didn't hold it up to the header because the left side pipe is still there. I have an extra header I got from an ex-lister a long time ago. Some of you may recognize the name: Doreen Yeager? There's a blast from the past there! Crazy chick on a Superhawk. Got pregnant with twins and was still riding up to about 5 months I think. Never met her in person but she was cool as hell. Anybody remember Geolinda?

Anyway, about the header, the left side pipe will get hacked off and patched with the material from the chop. I think I've found a local welder that's good. He's a rider and has been welding for 20 years. Will probably be a quick side job for him. I'm going to smooth all the welds and probably get the thing ceramic coated, though not sure what color yet. I have extra fork lowers and engine cases that I'm going to have powdercoated black. Maybe I'll do the exhaust black too. Or maybe I'll just smooth the welds and polish the whole thing....dunno yet.

What do you guys think would look better???

Oh, and the can is a hair over 2" dia OD. It should be pretty loud. I expect the same sound as the RC51 Jardine 2-1. I may actually get a before and after dyno as well if I can find a local dyno that's reasonable.

Here's a couple of pics of the mid pipes I made for my bike. I'm 150 miles away though. Do you still have the gap between the connector pipes or have you fit them together better? If you can't find anyone local I'ld be willing to help you out if you shipped the pipes to me or took a road trip and dropped them off. It could be welded together in less than a hour if everything is fit together properly.

I've always wondered what the negatives would be on a single muffler system on the Superhawk. If the abundant mid-range weren't negatively impacted I'd be interested in a single muffler set-up. The one major positive for me would be easier chain maintenance- cleaning with kero and lubing has been a hassle over the last nine years with the left Yosh RS-3 blocking easy access to the lower run of the chain. I'll keep an eye on this one Greg.

Two into one?
 

There is a long term test on a RC 51 in Motorcyclist..back a bit. They switched a Sato slip twin can system for a Jardine 2 into 1...They lost about 6-8 horsepower..they were dissappointed..could not get the fuel injection to map right..they decided to switch back..Performance after "mods" is very subjective..unless on a dyno with a follow up honest, drivablity test. If I remember the article...they RC 51..was too lean..could not map it rich enough. Tricky stuff.

Like the look and idea..following with interest...Did a two into one for a CXE 650 years ago...lucked out...worked really well..

Take Care
Dave...:-D

I had the '02 RC51 with Harris Ti highmount slip-ons. Stock was 115, after PCIIIr, rev limiter mod, and cans I was making 125.0. These were different days, same dyno, different miles.

My buddy had an 02 as well and he had the Jardine 2-1 system. We did a dyno day for charity one fall day and his pull was 1hp less than mine on top but he gained midrange by about 2-3hp over me. I was at 129.5. This was same dyno, same day. Same mods except for the exhaust.

The Satos made about 3hp more than the Harris. YHPMV :)

MrBillet, could you please make your pics a little bigger. Thanks.

If you check out my profile you can see the posts I started. Look for "check out my new exhaust" and there is better pics in that post.

Ah, yes. Now I remember. I needed a magnifying glass for the other ones. Thanks.

The junction where the stock header pipes come together measures at
1.930" on my bike so I think running a 2" mid pipe from here to a single can should work very well. Lucky you have an extra header to work with as you can cut it about 2" past the junction and work from there. That way there is no messing with capping off the left side after the split. The Two Brothers cans on my bike I found to be overkill with the stock jetting and by putting backpressure into the system I picked up midrange so a single 2" I.D. can will be interesting. The stock pipes are very restrictive so a single 2" can should flow a little better than that. If you have a jet kit and air filter you might find yourself too rich though. I think the scavenging takes place right afte the junction so there is no reason why it wouldn't work.

It looks like the hardest part is finding a good tubing bender to make the mid pipe. I would practice the look of the mid pipe with regular exhaust tubing then once you have it just the way you want it, duplicate the bends with stainless tubing that you might be able to find at Summit racing.

Let us know how the finished looks and performs.

Have you thought about one of those short GP looking cans like I have seen on some of the new bikes? That way you could make a really short mid pipe and have the short can right behind the peg.

Yuck! I don't want it to look like a Gixxer!

On the ZRX owners assosciation web site they did a shortened muffler mod to some of their bikes and it looked pretty cool. That was before this GP look even came out but to each his own.

Why would I even attempt trying to dissect such a beautiful can though? The pipes went to my welder buddy yesterday. He called today and is also taking care of the spring tab issue. Getting the old ones off will not be easy without messing up the pipe.

I would make sure you have 2 1/4" minimum bottlenecks throughout the whole system. I ran a single can on the left side for the street but when it came to racing the bike ran like someone stepped on its nuts. I would open the right side and the power would come back. It probably accounted for 7mph in the 1/4 mile. You can do single sided but I would modify the header. Cut the header leaving only the inputs in the four way connection and run a 2 1/4 or bigger pipe to the can. Just my .02.

I'm coming out the right side. Unfortunately I do have a bottleneck where the two pipes come together, but it will be no worse than stock, as it is still the stock header, just modified. After that the exhaust quickly opens up to 2". We'll see how it goes. If anything else it'll look cool! :)

Okay, she's done! I spent many hours last night polishing the crap metal Honda advertises as "stainless" steel. They turned out quite nice. After about 5 minutes of running the bike they turned golden and purple color. I think I'm just going to get them coated...

Anyway, the welder did a great job. His welds were damn near perfect where they needed to be. As you can see the capped off left header welds are a bit larger but still better than stock, and can't be seen anyway.

The stock header has such crappy welds I just had to do something about them while I had the header off so I hit them with the grinder and a Dremel. Cleaned them up pretty good, at least where they can be seen. The restriction in the right header is essentially gone. The welder removed it when he sliced off the left outlet pipe since it was then easy access. I did my best to clean up the other internal welds. The stock header where the flanges meet the head have an internal weld bead that reduces the diameter by at least 1/4". They are 1/8" weld beads all the way around the ID. I cleaned those up too.

I just happened to have a high mount bracket off a TBR. Don't remember where I got it but it sure came in handy. The last step will be to relocate the tubing to my Scottoiler, which will now have to be run forward and down near the front sprocket, then back to the rear sprocket via the underside of the swingarm. Need tubing and some time.

The bike now sounds like a BIG SV650. I was really surprised the first time I started it up. It sounds like a different bike at idle. The idles is definitely quieter and deeper at idle than the low mount Hindles I had. But blip the throttle and she barks loudly. I think I'll like it. Unfortunately damp sandy roads, 40°F temps, and WOT testing don't mix so it'll have to wait for another day.

Here's some pics. Enjoy.

A few more...

That looks pretty sharp. Nice job. Yeah I did the same thing when I had my stock header-ground it down and wetsanded it and as soon as I started the bike it turned gold and purple. Actually I thought it looked pretty cool and since it was so much smoother than stock it was easy to polish with some Mothers. Let us know your seat of the pants impression once you get to open her up a little.

Yes, I definitely will document the jetting woes I know I will go through. Bah, that's okay. It's time to clean the K&N anyway. :)

Oh yes, I forgot to mention that Bob Hayashida and I had some correspondence just prior to this getting done. This is what he had to say:

"Glad that worked out for you...I have used this method before to make
exhaust mods to the VTR specifically for exhaust system development. We
experimented with 2-1 exhaust for the VTR but I was never happy with the
results, could not get good power without large holes in delivery. The same
was also true for the RC51, even the WSB folks and factory Honda dropped the
2-1 setup. If what you are after is something unique, should not be that big
a deal, and you save some weight too.

The header obstruction is a result of manufacturing simplicity to keep cost
down. Surprisingly, removal made no difference on the dyno, but that was
with 2-2 setup... Never tried it with a 2-1 setup. The stock header works
very well on stock or mild engines, only when adding much more cam and
compression did the good full exhausts make improvements.

I would not worry about trying to make up the difference in pipe diameters
you have as long as they joint is clean. The slight step in diameter is
insignificant structurally. I would actually recommend cutting the mid pipe
up another inch or two and using another section of pipe with a slight bend
in it to make the transition between the two sections. This would make the
bend easier to fit and probably look better as well."

Wow, that looks great! Your welder guy did a great job.

Well, have you had this bird out of the barn yet? I just looked at your weather. I don't see much that a Superhawk would like. The closeups really show what the mod is all about. Your welder is very good. I really would like to know what it sounds like on the road but that doesn't look like it's going to happen anytime soon. You're going to have to find something else to tear apart while you wait :mrgreen: We got a couple days of riding in here but the wind was howling. 24mph yesterday and after hopeing for better conditions today is 26mph. Really getting knocked around out there.

I rode about 300 miles today. Overall power impressions:

Off idle - a little lacking, but almost the same as dual Hindles
Mid - great midrange power. Probably equal or better then dual Hindles
Top end - falls on it's face. Exhaust tip was a bit sooty, but not terrible. Need smaller main jets. Currently 188r/185f.

Got back today around 5pm and tore into the carbs. Everything was really clean. Nothing gummed or clogged. Checked the needle guides and have ZERO elongation of the brass insert after 40000 miles (just turned over today). Switched to 185r/182f mains. Didn't change the needles - still at 4th notch down. Mixture screws were at 2 1/4 turns now at 2 1/8 out. Still stock pilots. Jet kit is Factory 1.1 Ti. K&N filter, elevation about 1000ft above sea level.

Went for a quick ride to dinner and it pulls better up top, maybe just a hair slower then the dual Hindles. Low and mid are still the same. I cleaned the exhaust outlet and will see how it looks after the ride tomorrow.

I'm still watching this thread for your final impressions. In my book enhanced mid-range and better chain access for cleaning and lubing are my two goals...

Well, it's hard to compare really. See, I went 6 months without riding at all (!) and I did this mod at the end of the riding season last year. It's hard to compare since I have no recent memory of how it feels with the dual cans. I'm just going by my feel at this point. I guess I'd have to put it on a dyno to be sure. That won't be anytime soon. Maybe in a month or so. What makes it even more difficult is that I switch off between the VTR and the 1000RR on a daily basis. The RR pulls like a fuggin freight train. The VTR seems downright slow in comparison.