Twin Amals or Single Mikuni?

Hobot · Feb 6, 2013

Ugh to implement a MicroSpirt means implementing both its spark and fuel functions which requires about a shoe box volume of components to inter connect all the sensors and outputs.

pviserillii I might have something that won't bog with that big ole 40mm pumper inhaling slug. We owe it to our short lived selved to go for the biggest grin.

pete.v · Feb 6, 2013

hobot said:
Ugh to implement a MicroSpirt means implementing both its spark and fuel functions which requires about a shoe box volume of components to inter connect all the sensors and outputs.

pviserillii I might have something that won't bog with that big ole 40mm pumper inhaling slug. We owe it to our short lived selved to go for the biggest grin.

I can swap out a system now in about 40 minutes. An EFI might be a little radical and not so easy to reverse, but I won't rule it out. Right now I am mentally limited to normally aspirated situation, which is more than enough to keep me busy and grinnin.

Hobot · Feb 6, 2013

Ugh copy and paste pvisseriii, last post took 3-4x's double checking your handle, so focused/blurred on all them upright letter counts and heights I left out one of the run together sssssss's, ugh. A n/a aspired engine can ripe right out from under in lower gears and pull your ears back in top. Comstock via CNW has off the shelf EFI that can supply 175 hp for most of $3000 investment. I've had such surprise improvements on twin engines with a single carb I don't know what might work best for anyone. One of Peel configurations must not have anything excessive so no water tank nor air station or blower or cage just a 'paired' down big single carb on charger-less small battery ignition power.

hobelliirrrellliissis

beefco · Feb 6, 2013

Just to throw in an oddball carb to the discussion. I had a 1984 EI Magnum Flatslide that was a one kick wonder cold or hot until ethanol ate the float last summer. I put on a VM34 Mikuni from Fred. It runs really nice when warm but takes the usual 1 kick to prime w/o ign and at least two with ign when cold.
I picked up a NIB EI but am afraid to use it with ethanol. And I had already made up new Bing fuel lines for the Mik. Besides, the Mikuni really does work well when warm and that doesn't take that long. And you can get parts anywhere for them.

mike996 · Feb 6, 2013

As noted, it's all about what you like. I would only offer that if you like the look of the Amals and want them on the bike, don't be concerned about them causing all sorts of problems. They really don't once they are set up properly; admittedly "properly, IMO includes sleeved slides or perhaps the new Amal slides. I did a lot of work on mine a couple of years ago to get them into good shape but they have been completely trouble free since then and will idle smoothly at 500 RPM. When I got the bike the carbs had sleeves but were warped everywhere they could be. the needles/needle jets were badly worn and they didn't work worth a darn. But again, I haven't touched them since I overhauled them. I like the original look of the Amals/oem air box so I would not personally consider different carbs. But beauty is, as they say, in the eye of the beholder.

donmeek · Feb 7, 2013

Yes, there is no clear-cut answer for the original post which was "which is better?' Everyone has their own personal reasons for setting up their Norton the way they do. A better question would have been: which is better for me ? and then go on to describe riding style, mechanical abilities, etc.

mike996 · Feb 7, 2013

I don't know...that's an awfully logical approach; seems totally out of place here.

Unclviny · Feb 7, 2013

donmeek said:
Yes, there is no clear-cut answer for the original post which was "which is better?' Everyone has their own personal reasons for setting up their Norton the way they do. A better question would have been: which is better for me ? and then go on to describe riding style, mechanical abilities, etc.

Who do you think you are to be bringing logic and calm into this?!

Now let me get this thread back on track: "anybody who runs anything other than dual Concentrics is a fool" (that should do it).

Vince

72westie · Feb 7, 2013

Not the best of pictures, but here are some twin Mikuni's on my '74 850 Hi Rider

Yellow_Cad · Feb 9, 2013

I like them both but a few things to think about:

Amals are as good as their slides.

Gas mileage (range) is an issue considering that the single does pretty good performancewise.

cmessenk · Feb 17, 2013

Apologies in advance, because I know we're all tired of this subject....but...had to bump this thread to tell you how proud I am of my 40-year old girl. Chilly here in FL today @ 48 degrees on the Gulf Coast. Hadn't had the Combat out in 2 months...put her on trickle charge at 11:00 am and drained the sump...oil tank echoed like an empty house. Decked out in all my leather gear, flipped up the enrichener of the TM34 flatslide, turned the key and one-kick start....God our bikes love flying in cold air! Not trying to "re-discount" Amals, but you can't beat a long-term sitting in the garage, cold weather start like that.

JRD · Feb 17, 2013

Cold weather ? really !

concours · Feb 17, 2013

JRD said:
Cold weather ? really !

Exactly... 15 degrees with winds gusting to 50 mph right now. Just wrenching today, no ridin'.

cmessenk · Feb 17, 2013

I can relate, Concours...I was in Denver last week fpr meetings...Tuesday morning @ 9 degrees F. Dry air and zero oxygen.....uhhhh! No wonder professional sports teams have such a hard time competing against Dever teams...baseball, hockey, basketball and hockey.

Back in Florida we had a "cold front" move through yesterday and "plunged" us down into the low 40's / upper 30's....downright cold for us "thin bloods". Since I knew 90% of us on this Forum simply can't get out this month, I thought I'd "Take one for the Gipper" and brave the 80+ mph / 47 degree wind chill factor (33 degrees F.).

worntorn · Feb 17, 2013

" Not trying to "re-discount" Amals, but you can't beat a long-term sitting in the garage, cold weather starting like that!"

How about a four year sit and three kick startup on four year old gas at about 35f with original twin Amals. Not a bad idle on the old fuel either, about 900- 1000 rpm seems to run OK

http://www.youtube.com/watch?v=7sSjSy_7 ... e=youtu.be

cmessenk · Feb 17, 2013

worntorn said:
" Not trying to "re-discount" Amals, but you can't beat a long-term sitting in the garage, cold weather starting like that!"

How about a four year sit and three kick startup on four year old gas at about 35f with original twin Amals. Not a bad idle on the old fuel either, about 900- 1000 rpm seems to run OK

http://www.youtube.com/watch?v=7sSjSy_7 ... e=youtu.be

That's fantastic, Worntorn! But I suspect your're in the minority. When my Combat was restored in 2008, I had brand-new Amals installed. I had GP, Windy, and the the "god father" of Nortons here in Florida, "Mike Carter" try and get my Amals simply "stabilized".... i.e. reliable idle. No dice. Again, not diminishing your experience, but I've moved on from having to sport the classic Amal "look".

concours · Feb 17, 2013

cmessenk said:
I can relate, Concours...I was in Denver last week fpr meetings...Tuesday morning @ 9 degrees F. Dry air and zero oxygen.....uhhhh! No wonder professional sports teams have such a hard time competing against Dever teams...baseball, hockey, basketball and hockey.

Back in Florida we had a "cold front" move through yesterday and "plunged" us down into the low 40's / upper 30's....downright cold for us "thin bloods". Since I knew 90% of us on this Forum simply can't get out this month, I thought I'd "Take one for the Gipper" and brave the 80+ mph / 47 degree wind chill factor (33 degrees F.).

Yup, I've seen it firsthand :roll: lower than 50F, the goose down jackets are out in FL. :mrgreen:

Reminds me of the snowmobile rides below 0F, the engines really pull hard, carburet cleanly because the jetting was set for -4F from the factory. ABOVE that they got progressively loagey, until downright soupy at 35F. A well tuned 2-stroke up on the pipe squeezing out 175hp is a feeling to behold!

worntorn · Feb 17, 2013

"When my Combat was restored in 2008, I had brand-new Amals installed. I had GP, Windy, and the the "god father" of Nortons here in Florida, "Mike Carter" try and get my Amals simply "stabilized".... i.e. reliable idle. No dice. Again, not diminishing your experience, but I've moved on from having to sport the classic Amal "look".[/quote]

That is strange, I find the twin Amals to be so easy to tune and to keep in tune. Others must have experienced the same problems you've had judging by the number of single Mikuni conversions out there. I did read somewhere that a number of the single Mikuni conversions are now going back to twin Amals, not sure what is driving that.

Glen

cmessenk · Feb 17, 2013

worntorn said:
"When my Combat was restored in 2008, I had brand-new Amals installed. I had GP, Windy, and the the "god father" of Nortons here in Florida, "Mike Carter" try and get my Amals simply "stabilized".... i.e. reliable idle. No dice. Again, not diminishing your experience, but I've moved on from having to sport the classic Amal "look".

That is strange, I find the twin Amals to be so easy to tune and to keep in tune. Others must have experienced the same problems you've had judging by the number of single Mikuni conversions out there. I did read somewhere that a number of the single Mikuni conversions are now going back to twin Amals, not sure what is driving that.

Glen[/quote]

Perhaps all the persistent claims of better "top end" w/ dual Amals? FWIW, my flatslide Mic delivers all my 58 year-old nerves are willing to take. Absolute 90+ mph / 3/4 WOT performance today keeps me from jumping on that band wagon.

Whitworth Ranch · Feb 17, 2013

I'm going triple carbs. Any recommendations?

Twin Amals or Single Mikuni?

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