Bonneville America Forums Forums Technical Forums Performance Mods Snorkel and what it does

I have ran the snorkel for the first thirty one hundred miles of the bikes(BA)life,about three and a half months now.The point being that I am pretty familiar with the bikes character.Anyway I did a test late tonight with the snork in and with it out.Low rpm,mid rpm,and high speed roll on tests.I found that throttle responce was far softer at all speeds with the snork out.I am pretty sure that it is playing the role of an old fashion velocity tube/stack.I also believe that I may not have seen as much of a change if I still retained the original front sprocket gear.I will probably retest after replacing the original gearing.I think sometimes you have a better chance of seeing where you are by going back to where you have been.That seems to work in life,as well as performance tweaking. Al

dont forget you wont get the full effect unless you rejet

Frank

It seems to vary a lot for different bike/setups meaning bike model and what pipes, air mods, etc. I'm not exaggerating when i say that my 05' speedy with Tpipes, AI removed and other wise stock got what I consider a major boost in power by simply removing the snorkel. The Tbike guys showed a few HP increase on thier dyno after removing thiers. To me it felt literaaly like a good 3 or 4 HP increase. It actually fely like a bigger increase than the pipes themselves did. Why your's turned out different i don't know, but many speedy owners (mostly 790's) have seen the same results as i did. I don't know if there is a difference between the america 790 and the speedy 790, but i don't think so. However, you don't say whether you have stock pipes, and most or possibly all the guys i've read about having great results like i did have aftermarket pipes. As for the sprocket, if it's better now with bthe snorkel in going up or down in sprokcet size isn't going to change the relation between how it runs with and how it runs w/o the snork.

Frank,a rejet would mean that you increased the air flow by removing the Snorkle. I do not believe that that is the case,except at WOT.I believe that you have higher air flow/velocity,with the snorkle in place.For REAL world street performance,a small block Chevy always run better with a 650cfm carb that with the 750cfm carb.O yea,the bigger carb runs better at WOT,but most of the time you are not a WOT,and high air velocity will give you a crisper response and better torque.I would love to see the dyno chart with and without the Snorkle, anybody got one?I am pretty sure that the Triumph engineers put that little snorkle setup in to increase street performance by increasing the intake tracts air velocity,not to restrict the air flow so our engines would not run as well.JMHO.Dyno charts please? Al

That theory would make sense, if they didn't put the rubber down inside the air filter about a third of the way. That's why some guys just cut the the part that sits down inside the air filter. As the part is engineered, it sure looks like to me it's restricting air flow.

FWIW, when I took the snorkel off 2 years ago, and the dealer re-jetted with off-road pipes, they told me it was the biggest jet size increase(to 135 mains) they had done to that point on a Speedmaster or America. It wasn't dyoned, but they did tune with an air/fuel ratio tester.

I have to agree with SalMaglie. The velocity stack would be nice if it was ABOVE the air filter, but when I first looked at my snorkle/filter, that rubber thing goes in about 2/3 the way and the bottom 3rd of my filter was dirty, and the rest was clean. So that tells me the inner snorkle restricts the flow by reducing the usable air filter area. I honestly don't know why Triumph did it this way. Maybe they thought it would help? One of my riding buddies who has a S3 and I talked about air box theory once. Some bikes have VERY specifically designed air boxes, in which case I think they are a good thing, but our bikes air boxes are an after thought... They are the size and shape they are simply because of the surrounding frame, etc, not because of airflow.

Noise abatement. That's why Triumph put it there, in an effort to quite down the intake noise. Sound waves don't corner well, and with the bottom of the main snorkel below the opening of the forward snorkels the sound waves are pretty effectively blocked. Unforutnately, all of this turning and twisting also has a detrimental effect on airflow, so out they come!

Good point!! At least with mufflers, Triumph can sort of say "hey, we know the stock ones are quiet and restrictive, so here are some 'offroad only" pipes to keep you happy on the track." Like anyone takes their cruiser on the track?! They should offer an "offroad airbox" too!

Well, maybe Triumph knew the stock airbox sucked and made the snorkels easy to remove to effect a sort of "Off Road Use Only" airbox!

All I know is that pulling the snorkels gave me at least as much noise and probably more power that adding the "Off Road" pipes.

I had drilled my air filter and bottom of the air box back in June before my knee surgery, so did not get much test time immediately after - one ride, then 3 months layed up.

Now I've put another 2400 miles on. Shimmed the carb needles and pulled the snorkle last week, and the sound and HP both are definitely up, by the seat Dyno anyway. I like it alot, and wish I had pulled the top snorkle sooner. Mine was only about an inch and 1/4 down into the top of the filter, though. I like the sound of my stock SM pipes, and now with the intake "growl", I may never change pipes. It doesn't idle loud at a stop, but you sure hear it when I whack the throttle. Shimming those carb needles made a nice difference, too. Rare, occassional backfireing on decelleration, but I mean rare. It's not a worry.