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I just bought a rebuilt MC-91, sans carb. Since I've never been thrilled with the Mac/duckbill carb, I'd like to know what Tillotson options I have (running gas, with original manifold and reed cage). I'd prefer recommendations on a new, current Tilly but any info on the older models would also be appreciated. What are the differences between all the different models of HL and HR? Which are most adaptable to the Mac 91? THX...............

Matt:

An HR181 Tilly carb works great on 91's, I run them on my engines. If you look on this REAR site you will see how to make the change over to the Tilly carb.

Ernie

If you want to run a HL series (smaller, maybe for a youngster or very early kart) carb on the engine you can get a different manifold & reed cage and use that also. Over the years there is a variety of sizes available that should suit your needs.

The HR series works great. Lots of HR181 & HR191 carbs from the controlled reed engines around.

Matt, I have had good luck with the Mikuni 34 mm and it's an ezee mod to use it on the big Mac flatback intake set up. I do beleive the HR 181 needs the same mods to manifold. Tom L

Tom Luttenbacher wrote:Matt, I have had good luck with the Mikuni 34 mm....

Does the Mikuni actually pass the vintage sniff test?

I have often thought about using a Mikuni or Keihin carb (Even asked about it once or twice) but was unable to find any info on the subject. I'm surprised that you recommend a carb as large as 34mm.

I would really like to learn more about this subject. Please feel free to send a PM if you prefer.

Thanks

Harold Member I thought you were going to leave. Don't let the door hit ya on your way out.

I run the 34mm Mikunis on everything. They require a strong pulse, preferably 1/4 fuel hose with a spring inside to prevent collapse. You can get the pulse plate modified for a 1/4" external pulse by Dave Bonbright. Ask him to use the 45 degree brass elbow on the pulse inlet. They also require a non-restrictive fuel delivery. Mikunis were available by the '72 cutoff date. Mod your reed for a 91 according to thr REAR tech article. Ted

As a side note, does anyone know when HR178's came out or what they were used on? I have a couple and they are alky carbs and work well.