Change Carbs or not?

The Carbs on my 1970 750 S model are shot. I keep going back and fourth on should I replace them with new Amals or go with a single Mikuni.
There are plus and minus to both. Any thoughts from some of you out there who have been where I am?

First thing I did with my bike was junk the Amals and put on 35mm Keihin flatslides (FCRs). I swear by these carbs; have 'em on my Ducati too. They positively TRANSFORM a bike - oodles more power, easier starting (including cold starting, which I've heard people complain about with these carbs - go figure), on the fly idle adjustment (via a small dialable control on a short cable), infinite adjustability.

Nope, it ain't stock, it ain't traditional, I am missing all that authentic fun of diddling with Amals. Okay by me!

I should mention, though, one particular downside - the FCRs are flipping expensive. I think they're worth it, but YMMV.

boz said:

The Carbs on my 1970 750 S model are shot. I keep going back and fourth on should I replace them with new Amals or go with a single Mikuni.
There are plus and minus to both. Any thoughts from some of you out there who have been where I am?

Click to expand...

When you say they are "shot", what do you mean? That the slides are worn? Most of the internal parts of the Amal can be renewed and the slides can be sleeved. Personally, I would not run ANY Amal carb that has not been sleeved. Improves idling by an order of magnitude. I would say that if you like fiddling with twin carbs and want to stay original, sleeve the Amals and replace the internal parts (needle, needle jet etc). If you want an easier carb to deal with, and don't care about originality, go with the Mikuni. Some folks have said the single Mikuni gives you a bit of a hit in terms of performance. Whether this is important to you will depend on your riding style etc. I switched my Amals out for a 36mm Mikuni on my 850 two years ago and the bike runs great. I could never get the Amals to idle properly but they were not sleeved and one slide turned out to be quite worn. I am thinking about going back to the Amals but will definitely sleeve them first! Sleeving two Concentrics will cost you about 150 bucks.

Boz

It took me seven years of fidgetting with Amals to realize that the Mikuni was the way to go. I put a 36 mm on my MK III two years ago and not looked back since . It starts better then my new bike , idles perfectly ,gets me going fast enough to be stopped by the police and all this coming right out of the box. As for worrying about it looking original .... you'll forget all that next time you're on the side of the road trying to get the damn thing running. Believe me ... been there .. done that.

I've been looking at the same question. Recently got a '71 that needs carbs rebuilt or replaced. I'm inclined to try and get the Amals working first. Where do you get them resleeved?

google "lunds machine" and see what comes up...

Alternative Motorcycle Repair of Tuscon, Arizona can bore the body of the carburetor oversize and supply a chrome plated brass slide. The larger bore provides for a slightly greater wear area and the chrome finish on the new slide tends to "glide" over the pot-metal surface of the carb body. These two features will increase the longivity of the AMAL carburetor at least twofold over the stock setup.

Hey Chap said:

I've been looking at the same question. Recently got a '71 that needs carbs rebuilt or replaced. I'm inclined to try and get the Amals working first. Where do you get them resleeved?

Click to expand...

I have had several done by Andy Hardan who now runs Lund Machine in Snohomish WA. He does a great job and his communication and turnaround time are superb.

Well, my .02.

The Amals are so simple and work just fine for these old motors.

I'm fortunate that my bike only had 4k miles on it so my Amals are still stock but it will start first kick, idle just fine, will sure as hell go fast enough, and still get at least 50 mpg it seems. When my Amals get worn I'll sleeve them as I tend to want to keep the bike original. I really like the process of tickle and kick, It just always works so well.

But, your bike, do what you wish.

MY 1970 750 S has been giving me grief Amal wise for 4 months, i would tinker with this ,adjust that, swear at it and start over, ever since taking great advice and making absultley sure the primaries and jets and needles ,float heights are correct and clean it now starts,idles,runs, powers great, plus it retains its original look which is just my opinion and taste but important to me. My 2.003 cents, ( taking into account the exchange rate) ,they are simple pieces of equipment ,even i can pull them apart and fix them now blindfolded so stick with the original

But i,m also the one that pulled the points first week and replaced them with EI , who knows one day i may even put a disc on the front and a belt on the primary

Hey Chap said:

I've been looking at the same question. Recently got a '71 that needs carbs rebuilt or replaced. I'm inclined to try and get the Amals working first. Where do you get them resleeved?

Click to expand...

Bruce Chessell in Canada has been re-sleeving Amals in brass for over 20 years:


http://www.nithburgcycle.com/



.