Twin carbs or not. (2011)

Status
Not open for further replies.
A

AussieCombat

Joined
Jan 20, 2011
Messages
893
Hey guys, and gals, I've just put gasket sets through my 932's and notticed they are starting to show a bit of wear. Soo I'm thinking about that pair of 32 Mikunis' I'v got in the cupboard which came off a warm XS650. Being a Combat I'd really like to give them a go, and have had resonable experience with mikuni set ups before. Or... I've got a pair of good Mk2 Amals there as well. I know most people will say put the two into one mikuni conversion on, but I like the idea of twin carbs. Any body out there,... " been there done that" ?
 
Sure, a pair of 32 Mikunis have the potential to run very well. More power than Amals. The biggest problem is the carbs are too wide to be mounted parallel like the Amals were. They need to angle out at the back and this presents a big problem with getting a good air filter to clear the frame tubes. Certainly has been done many times however usually with foam socks for air filters. Jim
 
Thanks for that Jim, We dont need air filter problems. I'm a mug, I just had the damn carbies off and was going to sit the Mikunis in there to have a look, but must have got too excited, and didn't! Any other suggestions, I dont want to loose any power.
 
Well you can do twin Keihin flatslides for a small fortune. They run very well and fit fair.
Jim Schmidt has the twin PWK carbs that reportedly work well although I have not personally had my hands on a set.
You could also do the Amal mk2 carbs. They are a bit better than the concentrics if you buy the chrome slides that are available for them. Jim
 
Allens Performance in the UK can supply inlet manifolds to allow very neat fitting of VM Mikuni to Norton motors. In the US JRC can supply flat slide carb kits to fit the Norton, and these are likely to work better than the old style round slide VM's.

Sure you can pay to have old zinc-lead Amals sleeved in order to avoid problems related to very rapid wear. However their basic design is 40 years or more out of date, and performance, reliability and fuel economy are not comparable to more modern Japanese made carburetion.
 
Your Mk2 amals will do a great job, the pair on my 850 have done 45000 miles+. I changed the slides last year only because I found a pair of new old stock at half the price. The old ones had a few wear marks but were performing perfectly. I've only had to use a chrome slide on a single Mk2 to prevent it sticking never on a twin set up.

Cash
 
AussieCombat said:
Hey guys, and gals, I've just put gasket sets through my 932's and notticed they are starting to show a bit of wear. Soo I'm thinking about that pair of 32 Mikunis' I'v got in the cupboard which came off a warm XS650. Being a Combat I'd really like to give them a go, and have had resonable experience with mikuni set ups before. Or... I've got a pair of good Mk2 Amals there as well. I know most people will say put the two into one mikuni conversion on, but I like the idea of twin carbs. Any body out there,... " been there done that" ?
Click to expand...
If you already have them then for goodness sake, give them a try. The angle adapters and cabling should be the main issue.

Be forewarned, many have tried before and have retreated to the funny farm trying to get these to sync and idle. I believe the venturi on these are demanding. As a single carb they are proven to function all the way to 38mm but as a twin set up there just isn't enough draw to make them work well, even with a combat. Twin MK2's are a great way to go. I tried a 34mk2 as a single and it just did not have it.

Flat sides, on the other hand, have really come into their own. Single or twin setup are fantastic. I run a 34mm TM after running a 36mm VM for 2 seasons, and they come to as close to twim carb performance as I can imagine. Oh, I still have a good set of 32mm Amals and i have it down to be able to switch in 30 Minutes. I have a new stage one cam kit that may push the 34mm TM and the Amals may return as the winner. Twin Flatsides may be the utimate solution. We'll see in the spring.

Again, if you got them try them. Please pass on the findings.
 
For what it's worth:

JRC is the importer / distributor of the "Superior" flat slides; they DO NOT sell to end-users.

Jim Shmidt and I resell the little flat slides; Jim''s got them more dialed in and turn-key than I do (I have only set them up on Triumphs).

I've not read a negative report on them, but the float bowls are a bit of a fiddle on an old pre-unit Triumph with no room to work above the magneto!
 
grandpaul said:
For what it's worth:

JRC is the importer / distributor of the "Superior" flat slides; they DO NOT sell to end-users.

Comnoz and I resell the little flat slides; Jim''s got them more dialed in and turn-key than I do (I have only set them up on Triumphs).

I've not read a negative report on them, but the float bowls are a bit of a fiddle on an old pre-unit Triumph with no room to work above the magneto!
Click to expand...

Comnoz has no carbs. Jim Schmidt has flatslides. Jim Comstock -Comnoz
 
pvisseriii said:
AussieCombat said:
Hey guys, and gals, I've just put gasket sets through my 932's and notticed they are starting to show a bit of wear. Soo I'm thinking about that pair of 32 Mikunis' I'v got in the cupboard which came off a warm XS650. Being a Combat I'd really like to give them a go, and have had resonable experience with mikuni set ups before. Or... I've got a pair of good Mk2 Amals there as well. I know most people will say put the two into one mikuni conversion on, but I like the idea of twin carbs. Any body out there,... " been there done that" ?
Click to expand...
If you already have them then for goodness sake, give them a try.
Click to expand...

truer words cannot be said

by all means run the two VMs - i'd get the victory library mikuni VM tuning manual (ebay search) - i'd think you'll not have a hard time if your familiar with mik's getting it to run right - that being said i also have switched over the mik TM flatslides - while i love the VM i like the TM's even more

the TMs utilize the same flange adapters/manifolds as the VMs so if you decide to go that route somewhere down the road its no big deal

remember carbys are fun!
 
Man up and keep the Amals on there! Next thing you know you'll be thinking about electric start. ;)
 
Thanks for all that, Now its up to me to get the digit out. I'm leaning towards the Mk2s' simply because they are pommy (British) and max h.p. is not the issue here. Will let you all know in due time.
 
I'll be interested in the outcome of this one, A.C. I've always run the stock Amals on my English bikes and they've been ok for what I've needed. But the talk of flatslides ?? I'm unfamiliar. Are these anything like the old Lake Injectors? Does anyone remember them ? That was the supposed hot set-up in my circle in the mid-seventies but I have no first hand experience with them.
 
Carbonfibre said:
Sure you can pay to have old zinc-lead Amals sleeved in order to avoid problems related to very rapid wear. However their basic design is 40 years or more out of date, and performance, reliability and fuel economy are not comparable to more modern Japanese made carburetion.
Click to expand...

The design of the Commando engine is 60 years out of date! Arguing about which carb(s) is most appropriate for these bikes becomes like an oil thread. Some folks like the original appearance of the Amals and would never put Japanese carb on a Commando, some of us got fed up dicking around with Amals and replaced with a single Mikuni. Others want to mortgage their house and run dual Keihins. To each his own.
 
I've the whole series of evolutions from Lake Injector, just an upright tube and flat slide with a shaved nail raised in tube with slide lift. Kick ass for un-blown applications, but sticks open when sucked to hard again its slides. The it became Lectron flat slides that kicked ass for racers, had bowel but no idle circuit and tended to stick just enough it was dicy on powered leans. The final version QuikSilver, flat slide with dual push/pull cable cam operation, bowel, idle circuit and accel pump. My blown special will use the Lake Caveman injector with the addition of a positive dual cable pull shut throttle adaptation. I've a pair of 30 or 32 mm Lectrons I'm not going to use. Love dual 32 Amals on my factory Combat
for the crisp response even if not the most top end feeding set up.


This sweetie pie BSA runs a Lake.
http://www.jockeyjournal.com/forum/show ... hp?t=16479
Twin carbs or not. (2011)


Twin carbs or not. (2011)


http://www.lectronfuelsystems.com/
http://www.htgracing.com/lectrons.php
Twin carbs or not. (2011)


http://www.650motorcycles.com/QwikSilver.html
Twin carbs or not. (2011)
 
mike996 said:
Man up and keep the Amals on there! Next thing you know you'll be thinking about electric start. ;)
Click to expand...
Man up? Really? Right off the Palin campaign trail.
That's kinda like saying "Man up and surf the Internet with a 2400 baud fax modem".
Anyone who wants to try to make 2 32mm vm's work is definitely not looking for the easy way out. This is both ambitious and manly.
Now if you're just a purist or are warning the guy to save him some frustration,.....well that I can sort of understand.
 
Tried them from single Mikuni to twin Amals and then tried the two 32mm Mikuni set up.

Forget it. Stop screwing around.

$435 for PWK 32mm flatslides from Jim Schmidt who posts on this site. They come COMPLETE, already jetted, and they start one kick, idle like a rock, and flow like hell, much better than any other set up I have tried.


32mm flat side Keihin/PWK Twin Carb Kit, complete with lower cables, airfilters, curved manifolds with rubber mounts and clamps, Customized and tuned for Nortons. No modifications necessary (more info).

Price: $435
An unbeatable deal for a superior twin carb kit.

click here and scroll halfway down to see the carbs. And NO, I have no financial interest in this recommendation. These carbs ROCK
http://www.jsmotorsport.com/products.asp
 
1up3down said:
Tried them from single Mikuni to twin Amals and then tried the two 32mm Mikuni set up.

Forget it. Stop screwing around.

$435 for PWK 32mm flatslides from Jim Schmidt who posts on this site. They come COMPLETE, already jetted, and they start one kick, idle like a rock, and flow like hell, much better than any other set up I have tried.


32mm flat side Keihin/PWK Twin Carb Kit, complete with lower cables, airfilters, curved manifolds with rubber mounts and clamps, Customized and tuned for Nortons. No modifications necessary (more info).

Price: $435
An unbeatable deal for a superior twin carb kit.

click here and scroll halfway down to see the carbs. And NO, I have no financial interest in this recommendation. These carbs ROCK
http://www.jsmotorsport.com/products.asp
Click to expand...
But he already has the carbs in his hands. And besides, I really want to see what he comes up with. If I had them in hand I would do it and report my success or failure.

Again, Aussie, concentrate on needle and needle jet combinations, your guess is as good as any. Mains around 210 and pilot at 35ish. Sudco has a downloadable catalog and tuning guide. Parts (jetting) from Pat's Small Engine(google it).
 
Status
Not open for further replies.

Similar threads

Reggie
  • Locked
23t gearbox sprocket. Problems or not. (2013)
2 3
Replies
56
Views
6,989
crusadersports
C
B
  • Locked
Change Carbs or not?
Replies
11
Views
1,663
Nithburg
N
Back
Top