Velocity stack/ham can

Thanks John, great info!!! No need to take pics, your description was excellent! I'll do the JB Weld process on the stacks/carbs.

Mike, note that the top edge of the end of the stacks’ bells may touch the underside/inside of the top of the filter element. I once found chafing through there which I resolved by pushing the filter element and screen as high up as possible. Gravity, of course, tends to allow the screen/filter to settle down onto the tips of the stacks.

Also, IIRC, I had to trim the the top edge of the holes in the front plate so the bellows werent pinched between the OD of the stacks and the ID of the plate

Gotcha, thanks! I am still considering NOT running the filter at all even though my long-time experience/common sense argues strongly against it. As I said in my first post, one of the reasons I want the stacks is for "the look." If most of the stack is in the can, then the "look" is gone.

However I suspect that my inherent dislike of non-filtered air will...(NPI)...triumph!

When I do it again, I will use a gasoline resistant glue that is less durable than JB Weld so that the bells, if necessary, can be removed from the carbs.

These suckers were developed , as the full diameter screw on ones , when your ' topped out '
On the Daytona Speed Bowl , Auto Bahn , or Aucland Harbour Bridge , can go lean .

the RAM AIR ( on the cheap ones ) can ram up the vents , presurise the float chamber , or the opposite ,
so the mixtures off . The Factory ( Hele etc ) found .

THATs why they should be vented to atmosphere . Similar if carbs in cold air pressure box intake set up .

A trick to be wary of , if anyones ' flat in top ' for any length of time .

As for filters , the shelas nylons & a rubber band , over the intake , work wonders .
Or real very fliter foam , if your decadent .

Wire Gauze , is for a Flame Trap . Anyone experincing beating out a intake fire ,
under the nylon fuel lines , from a backfire on a cold ( flooded ) start up ,
may consider this .
Smothering ( He relaced the jacket ) or throwing it in the lake , is the sure option . Otherwise .

BRAIDED ( Marine 0 fuel line is less problematic , in that circumstance , ordinarilly .

Bits of fuel which hang-up on the gauze can cause the motor to run rich and become sluggish. But if you don't have the gauze and there is a gap under the seat, you can suck-in a stone. I had one at a race meeting. I only found it because the bike was difficult to start with the stone holding the throttle slide up off the stop. I was then aware I had a problem, the bike usually starts instantly.

If the fuel catches fire, it is not as difficult to extinguish as when the oil lines burn through. In any case, my tank is held by a strap with a quick release catch.

Well, I've finished the work on the Commando and ended up NOT using the stacks with the new Premiers for a couple of reasons. I just couldn't deal with the thought of unfiltered air - it's quite dusty here - AND more importantly, with the side covers on, you can't see the stacks at all and since one of the reasons I was doing it was for the look, there is no look! I had ordered a KN filter, originally thinking I might adapt it to fit the stacks but that wouldn't fit properly the way I wanted it due to the oil tank/battery box. So I'm using the Premiers with, at the moment, the KN filter. Not sure I'll keep that configuration. I like the look of the OEM ham and it's a better filter than the KN anyway can so we'll see about that.

I currently have stacks inside foam filter socks and honestly I can tell no difference from the conical screened-paper filters I had on there previously. Stacks with no filters may yield some bhp, but having seen the inside of a Triumph ran with no filtration keeps me from doing that.

I remember reading a story about some guys racing a Norton at Daytona and the engine would fall on it's face on the banking and never pick up full revs before having to close the throttle. Leo Goff advised they get some stacks and that would cure the midrange flat spot holding them back. After looking at every shop in the area, they gave up and cut some aluminum beer cans to fit and the midrange came back. I actually tried this and it actually worked, yielding a significant bump in the middle of the powerband.

Of course, if you're going for looks, you can always get a modern Triumph twin with the phony monoblocs.

UPDATE: Yesterday I installed velocity stacks - I decided to try them figuring I can take them off if I didn't like them. These: https://thebonnevilleshop.com/trium...32-billet-alloy-velocity-stacks-2-pn-928-076/

Well, I just got back from a ride - they are NEVER coming off! They made an instantly noticeable improvement in power, especially noticeable in the midrange and when shifting gears at max power - the bike "lunged" forward at the gear change as it never has before. Mighty impressive! They are unfiltered. Oh well, I know how to overhaul engines!

As John suggested earlier in this thread, I was going to epoxy the stacks onto the new Premiers but then decided for test purposes I would drill a couple of small holes in the edge of the flange where they fit on the carbs and safety-wire them onto the carbs. That way I could easily remove them. The holes are in the flanges, not in any part of the stack that see's the airflow. They are very firmly in place so I might just leave them safety-wired. But I have plenty of JB Weld!

I said I was doing it for the appearance but with the side covers in place you can't really see the stacks anyway. But they seriously improved power over:
1. The stock ham can/paper filter or
2. Dual inlet K&N that mounts directly to the carb OR
3. The Amals with no air filter at all.

FWIW, I couldn't tell any difference between 1, 2, or 3.

Don’t believe you...

Need pics to prove !!

They shouldn’t make that much difference to the mid range really. My guess is they’re correcting over richness of the needle.

But so what, they look cool and make it go better... what’s not to like !?!

You could be right re correcting richness in the mid range - needles are in the middle position but, OTOH, to me the bike acts lean on WOT throttle application from low RPM. I have a #3 slides and 105 needle jets if needed. The stacks definitely leaned out the top end based on plug appearance/the fact that at WOT if I reduced the throttle a little, the bike went a bit better. So I just got done changing from 240 mains (we are at 6400 feet here and I've been running 240's for years) to 260s as well as epoxying the stacks onto the carbs since I'm never taking them off. So the JB Weld is setting up as I type this. Tomorrow, after the JB Weld has cured, I'll put the carbs back on and do another test run with the 260 mains. I thought about making some other changes - slide/needle jet/needle position but one thing at a time.

Keep us posted and remember to post pictures !!

Watch out for a fuel tap leak and backfire through the carbies, don't take much to start a major fire on start up, ask me how I know

Ashley

Thanks! I'll be careful - I've always been very anal about fuel leaks but, as you pointed out, a leak plus a backfire would be more excitement than I care to deal with!

MexicoMike said:

Thanks! I'll be careful - I've always been very anal about fuel leaks but, as you pointed out, a leak plus a backfire would be more excitement than I care to deal with!

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It wasn't more or less not a leak but a sepage but the bike fired up and my mate was waving to me but me thinking he was saying bye was in realaity him telling me fire fire and I was sitting on the bike, found out when the flames shot up my left arm lucky I had my leathers on and soon leaped off the bike in a mad panic, lucky it was a top fire, damage was new paint job completely burned off, seat melted, wiring completely melted and damaged speedo, everything else servived, had it rewire and started next day but had to wait a week for the seat to be redone, went back to airfilters and a week later while a 100 miles from home the black box for the Boyar shit itself from the fire, my fuel tap only decided to leak that day and when I turned the tap on felt a bit of wetness on my fingers, it was also the first time it ever backfired so was a unlucky day for me, that will always be in my memory, my mate Kevin who was waving to me is no longer with us.
But it did run pretty good with the stacks on it I got to admit, the stacks I had were made for Amal carbies and screwed on and looked good, but that was way back in the early 80s when I first convered to the Featherbed frame, it was the cork seal that failed in the tap.

Ashley

The change from 240 to 260 mains did the job! The bike has never run so well; I'm very pleased! I didn't have the space to accelerate beyond a bit over 90MPH indicated on the calibrated E-Smiths speedo but it never felt that strong at WOT getting to that speed prior to the stacks, regardless of previous jetting.

Got to ask , how are your brakes , maybe a good time to have a look see .... glad to hear you tearing up the roads down south !