Single Mikuni on Baghira

Black Panther/Street Moto, Baghira, Enduro, Mastiff, Skorpion Traveller and Tour.

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Single Mikuni on Baghira

Postby harold » Tue Aug 30, 2011 7:35 pm

1st off, this is not for someone that doesn't already have the 42 HSR, and also wants to get the bike to wheelie. I have been told not to do this, especially when it comes to removing frame parts. I don't jump this bike off tall buildings, or off anything, so the weakening of the frame I am not worried about. Your results may vary.

The Baghira is different from a Scorpion, and this may be the only single carb Baghira ever. I obviously have too much time on my hands, but also have the machine shop to do this, and I love a challenge-and to be able to wheelie.

Stock, the bike wouldn't pull the front in 1st, without clutching it-which I don't do. Power wheelies are a good indication of power, much cheaper than a dyno. After mods to the stock carbs and exhaust pipe welds, shown on another thread, it would pull the front wheel in 1st, but wasn't going to flip unless you really tried.

After finally getting this Mikuni on the bike, it would pull it up a little and hold it through the RPM range in 2nd. I am going to play with the main jet and needle setting to see if this can be improved, but it will flip in 1st now if you are ham fisted. Big difference.
High speed response I think is a little down from the twin carbs, and that is either from the longer manifold, not perfect jetting yet, or just having one carb with less diameter than the stock carbs were combined. A Harley Sportster does just fine with one 42 Mikuni, but the racer version has 2, one on each cylinder. Of course it is designed to run flat out, which is not what I do on the street.

The Baghira has a frame that not only makes it hard getting the stock carbs off, but prevents you putting a single carb on, since it has a vertical 1/4" by 1" flat stock steel member running right down the middle of the frame.
I cut it out, made a manifold to go from the Grizzly port spacing to the Raptor port spacing, and found there still wasn't room to get the Mikuni on without putting it on the other side of the frame. This requires a 5" of so spacing between the carb and the Grizzly manifold. It also required a beveled spacer to get the carb level, and beveled both ways. To make a leak free connection required milling the input of the Grizzly manifold to accept a 2" aluminum tube. with it also turned down. A 2" plumbing rubber union hooked it all together, but the gas vapors only go through the aluminum pipe.

Pictures follow. After it was all over, I probably should have taken Bill J's advice, but the Mikuni gives a jolt I never got with the twin stock carbs, and as I said in the beginning I already had the Mikuni. Before I spent $1,000 on new twin carbs, I would spend that money on a big bore kit, cam, and head work. This doesn't require removing or disassembly of the motor, just part of the frame.
strut interference 1.jpg
Strut
milling grizzly.jpg
Milling the Grizzly manifold
manifold and spacer.jpg
Milled manifold and double beveled spacer


Three pictures appear to be the max on this forum. If anyone is interested in the final assembley, let me know.
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Re: Single Mikuni on Baghira

Postby edec » Wed Aug 31, 2011 12:12 am

Thanks for sharing harold. Keep up the hard work and the updates coming.
Good luck, Ed
01 Baghira
01 Moto Guzzi California Jackal 1100
99 Ducati SS750
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Re: Single Mikuni on Baghira

Postby harold » Wed Aug 31, 2011 5:13 am

Here is a picture of the final installation. I put a K&N filter on the crankcase breather tube that used to go to the airbox.
Attachments
final install.jpg
top view.jpg
Top view
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Re: Single Mikuni on Baghira

Postby basser23 » Wed Aug 31, 2011 1:25 pm

very interesting,but I wonder why you wouldn't have first changed the rear sprocket to a 45 or 47 tooth?
Chip
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Re: Single Mikuni on Baghira

Postby harold » Thu Sep 01, 2011 4:49 am

The rear is a 45, apparently stock. The bike only had 1,500 miles on it, and the chain and sprockets all looked like new. I would put a 47 on, but it looks like I would have to replace the chain also, as it would be too short. The axle is almost all the way forward.
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Re: Single Mikuni on Baghira

Postby cat » Thu Oct 27, 2011 3:52 pm

edec wrote:Thanks for sharing harold. Keep up the hard work and the updates coming.
Good luck, Ed

+1 Thanks! :)
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Re: Single Mikuni on Baghira

Postby harold » Sat Oct 29, 2011 7:47 am

Update on the jetting. I have had things I thought were right a few times already, only to ride the bike again on another day and feel something that wasn't quite right. Having a dyno with an O2 sensor would have made this a piece of cake, but I don't.

My current setup, which seems pretty close to perfect is:
147.5 main.
27.5 pilot at 7/8 turn out. Screw position is very important to smooth idle to 1/8th throttle transition.
97 needle, with clip at the top- the leanest position.

Stock, the bike wouldn't get the front end off the ground no matter what you did in 1st. Now, 1st gear wheelies are just a flip of the throttle, and if you hit it right in 2nd you can stand it straight up. It accelerates from any throttle position with just a touch more. In order to get the jetting right, I have marked my 1/4, 1/2, 3/4, and full throttle positions. At most jet settings, I would get 60 MPH at 1/4 throttle. Now I am getting 70 MPH at 1/4 throttle. It accelerates hard to 80, and then slows a little while it keeps climbing. Chopping the throttle on or off at any position or speed causes no popping, missing, or anything else bad. It is a hoot to ride now. It is not as quick as my 88 CI Buell, but is just as much fun to ride.

I never would have been able to get the stock carbs to perform like this, as just the hassle of getting them on and off to change something would have prevented me from doing it, IF you could get the jets, WHICH you can't. It was a lot of work, but at least for me it has been worth it. Now when I get the cam and piston put in, re-jetting for those changs will be easy. Plus the shop that is going to do the work has the dyno, so I will be able to show before and after charts.
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Re: Single Mikuni on Baghira

Postby cat » Sat Oct 29, 2011 11:28 am

This is all good, but what we need is to get someone to make manifolds for us. :D

Yes, one carb...easier access and easy to get jets, not the Teikei crap.

It sounds like you got the performance good. Who needs modified engine and dual flat slides.
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Re: Single Mikuni on Baghira

Postby basser23 » Sat Oct 29, 2011 12:28 pm

EDELBROCK MAKES A KIT FOR THE RAPTOR THAT WILL WORK....BUT IT HAS THEIR CARB
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Re: Single Mikuni on Baghira

Postby chisleu » Sat Oct 29, 2011 5:24 pm

Why hasn't anyone put a Megasquirt on this guy yet? Unless you have a flair for fabrication and free parts laying about. Not that MS would be better than a good carb setup. I've just had a bit of experience with it. Thinking about putting an MS2 I have laying around (or maybe building an MS3). Plus with a wideband, you can auto-tune the bike and do altitude adjustments automatically. nice if you do mountains and such.
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