Home made single carb manifold

[harold]

After hours of reading this forum on the subject of using a single carb, and with some advice from Bill J., I made my ownn since you can't apparently buy these anymore. To start with, I had a HSR 42 Mikuni that came off a 88 CI Buell. If figured it should be big enough for a 41 CI Baghira. I saw where the suggested jets were a 22.5 pilot, 147.5 main, and a 96 needle. It had in it a 28, 160, and 97 needle, so I ordered new ones.
Here is what it costs:
Used Grizzly manifold. shipped $20.
Raptor manifold spacer plate, shipped $40.
4 main Jets, 2 pilot, and needle, shipped $47.
Grizzly manifold, O rings, carb boot, shipped $42.
Pod type foam air filter. shipped $27.

Total cost with carb already...................$176
I have seen these carbs going new for $3-400. Of course you could use any type that the rubber boot would fit, or bolt a spigot mount directly to the new manifold instead.

The Grizzly as I should have known but it had escaped me, has the same size ports, but they are 1/2" closer together. So I made out of 3/16" aluminum a plate that would bolt to the manifold. Here is the hardest part, and you just about need a milling machine or you would spend quite a while with the die grinder. Even with a mill, I used my die grinder with a 2 flute carbide router bit, as grinding stones pack up with aluminum pretty quick, for the final fitment.

To join this plate that now fits the Grizzly manifold to the raptor 1/2" alumium spacer I welded mitered aluminum sch 40 pipe. As it turns out, 1" pipe ID matches the small port, and 1-1/4" slightly flattened into an oval shape fits the larger port. Not perfect, but close enough I think after some grinding on it. I spaced them at 1" in length. The manifold Bikeworks was making looked like their tubes were 3-4 inches long, but I was advised to keep the overall length at 2" to 2-1/2", and with the Grizzly manifold I am still longer than that. Any shorter would make it a bitch to work with. It will be longer than stock in any case, which should increase mid range torque all by itself.

You can't weld all the way around the tubes, at least I couldn't, so I covered the outside with silicone to seal it. I had to grind some of the ports again after welding as the aluminum has a tendency to bulge in from the heat. My boot, air filter, and O rings are supposed to arrive this week, and I will report again after installation as to the increase-it better be an increase- this modification will make. At least now jetting changes will be a snap, and any jet you need is available pretty much anywhere. Mikuni makes 5 different size needles, and Dynojet makes some too. Having an adjustable accelerator pump should give the snap I need to stand it up in 2nd. If nothing else, I got to play with my toys again.

Anyone need a stock carb setup?

[billr]

Good job. Thanks for the write up and pics.
Projects, projects...Here I go again...
And I'll probably wind up leaving it stock...
Bill R

[Bill Jurgenson]

it depends heavily on the end can, i. e. on its backpressure.
I am pretty sure you'll find that the accelerator pump will have to be heavuly curbed or disabled entirely.
With little or no backpressure (=LOUD) the TM 42 is easy to set up but with civilized cans nearly impossible.
It works best with large Ø absorber cans you can look thru.

[basser23]

I supoose you could use those 1/2 Raptor spacers and carb mounts to fit the Raptor carbs on a Skorpion. The biggest problem there apparently is the fit under the tank due to the
fuel spigot being blocked by the carb location for and aft...that is if for some reason raptor
carbs want to be used.....
Moridelli 17 had a manifold adapter made for an FCR41/Grizzly combo.....would be about $250..he said it works a treat...