Triumphrat

modre · 01-09-2009, 06:22 AM

I spotted cracked intake boots on a 2 yo bike and grumbled because my experience has been longer rubber life expectation in the past, so my reaction was to eliminate the offending weak link like so many others have done with those reported jubilant performance results.

so I took the air box out and opened it up out of curiosity before fabbing up the replacement parts...the more I studied it the more I come to appreciate what the design is.

I like the battery box, I like the utilization of the space, I like the wire chase on the frame spine, and I especially like the way they handle the breather huff and puff as well as the oil migration. the breather is wide open into a volume and uses the entire air filter as a breather element minus what the engine sucks. the drain tube is a sight glass to alert as to service attention needs.

eliminating the air box means a breather filter...that oil is going to migrate, so I had visions of a breather filter getting contaminated with oil within the first 5 miles, higher crankcase pressures, and breather efficiency compromised as the new norm.

I also saw the restrictor plate cross section is about equal to the air filter inlet cross section, so the stock filter inlet ID is what determines air volume...ahead of that is the snorkle that is the real restriction meter.

the purpose of the box is to scrub the intake air so grit doesn't score the cylinders and crap doesn't wedge under the valve seats...and then there's water. since I'm in SW Pa. conditions are not always perfect...I tend to be out early in the spring, late into the fall, and find iffy conditions in between...we don't get thin clean desert air here...we get mud, water, and salt on the roads, so the priority is similar to dirt bike requirements a certain part of the year.

I don't need big hp...my main concern is always getting back home, so I look at this system as a hip happenin' club called the Compression Chamber and the carbs and intake are the bouncer at the door. pods let just about anyone in, but the air box is the satin rope where some are turned away for being too ugly and un-hip for entry.

all the direction changes encourage the water to fling like a centrifuge and the restrictions act like an expansion valve on a refrigeration system with pressure differences to stretch and massage the processed air...I'm thinking that may further separate water.

so unlike many/most I ordered new rubbers and am going to put the box back in and study on it for another 2 years until the rubbers demand attention again...and I'm also leaving the snorkle and restrictor plate in place. the purpose is much like the long intake on the VW Bug engines...protect the engine from over revving...and yes there's a rev limiter to do that same job.

'70 1600 single port VW Bug was the last good one.
71 went to the dual port for higher revs/performance and began the downfall that went thru 75 FI and death throes.
the new Bug doesn't even count.

I'm good with 60hp...I don't need 75.
what I specifically don't want to do is pay $4/gal thru 145 jet orifices...yes, I know prices are currently back more reasonable, but those bastages will squeeze it up again with not much provocation, so I'm not fooling myself...the further I can separate myself from that game the better.

Say man!
I saw your wife the other day!
Yeah?
Yeah, an' she's ug-leeee!
Yeah, she's ugly, but she sure can cook!

If you wanna be happy for the rest of your life
Never make a pretty woman your wife
So for my personal point of view
Get an ugly girl to marry you

Haggis · 01-09-2009, 07:22 AM

A well reasoned response: just shows the wisdom of the saying, "horses for courses."

Sal Paradise · 01-09-2009, 07:42 AM

Hi Haggis,

I still have my airbox too, without restrictor plate and snorkel. Obviously I have looked inside th airbox . I agree with you that the airbox does a lot to protect the motor. However it is designed for very lean jets for EPA. I think they needed a lot of vacum in the box to make those very lean jets work, especially at low rpms. Have you ridden an old carb bike runing very lean? Tons of hesitation.

I am not an engineer, but I have done some piping and air duct design. From my training I know that each direction change in the airflow and each restriction adds to the static pressure or friction and hence decreases flow. People frequently talk about things like the snorkle as if any one restriction in the system can define the entire static pressure. Thats not correct. Its the cumulative static pressure that matters.For example, an engineer could tell you the equivalent length of pipe that would give the sme friction as your air box. The trick is to make the equivalent pipe length as short as possible and reduce the friction while keeping the benefits.

propforward · 01-09-2009, 08:02 AM

Just a couple of quite minor points - 1) many folks have reported just as good mileage with airbox off as with it on, so I'm not convinced fuel consumption is a problem, 2) it seems from research I have done that Triumph had some bad rubber on some 07 bikes. If you still have warranty left Modre you can get your intake rubbers replaced under that, and it seems that they sorted the rubber issue out - so once replaced you should be good to go.\

Nice post. I have to say I've never been that interested in replacing the airbox before, but having found cracked inlet rubbers on mine I felt like giving it a go as it were.

dkreidel · 01-09-2009, 09:26 AM

The W650 crowd went through the airbox removal process a number of years ago, and I was one who modified the airbox on my W650 and eventually removed it completely as many have done to their Triumphs. I eventually went back to an airbox on the little Kwak and never looked back. I have kept the airbox intact on all of my T100s, only replacing the snorkels with NH bellmouth inlets and K&N filters for exactly the reasons Modre mentions - and the lessons learned from the W650 community. The airbox on the Kwak is almost identical to the Bonnevilles.

Dick

faltzgraph · 01-09-2009, 09:53 AM

I have been having this arguement for a couple of weeks...K&N filter, stock airbox, D&D race pipes that go under the frame. I live in Central Pennsylvania...so I need to keep my filter protected. My argument has been air injection removal due to my black pipes getting messed up like stock would and possibly putting vent holes in the air box. Thoughts???

InkSlinger · 01-09-2009, 11:04 AM

If transportation was the primary purpose of my bike I would keep the airbox and maybe add a K&N filter , a bellmouth, and rejet . However , I bought my bike to have fun and ride like a hooligan so the airbox had to go!! As far as gas mileage goes , when I ride like a sane person ,it's just as good if not better than it was with the airbox.

Geimer · 01-09-2009, 11:48 AM

Modre's observations regarding the airbox sound well reasoned to me. We have made design improvements on our gas valves to add chambers on the inlet side which trap moisture and sediments to keep them from contaminating the valve seats. So Modre's observations seems well reasoned to me.
But mainly I'm chiming in regarding the rubber boots. I do not know enough about rubber to add proper scientific information but I've been close enough to the manufacturing processes here at work to maybe know more than most. And here is all I am going to say:
The ingredients, molding, curing and finishing processes have everything in the world to do with the longevity of rubber products similar to those boots. From my observation point it really only looks like a case of a bad batch or maybe several bad batches. I say that because after seeing photos of some of the boots they look like they have been setting out in the sun for the past 15 years yet they are two years old or less. It seems to mostly affect the 2007 model year (I could be wrong about that). But I can see from my son's 2007 T100 that it does not affect ALL of the 2007 model year. His will be 2 years old in April and the boots look like they are brand new. My 2005 T100's boots look fairly new still too. I think there is every chance in the world that when you replace your crappy boots with new boots that they will last much longer than two years.

mikeinva · 01-09-2009, 12:47 PM

I ride my bike in all kinds of weather doing away with the air box does not make the filters get wet or dirty .What you are not looking at is with 2 filters there is 2x the filter area so the air going in is just as clean maybe cleaner.The next thing is the breather if its in the air box and you get oil in the line it puts it your motor thats not good for anything.If you have much blow by to the point your dripping oil you got something wrong any way.If your motor is right about all you get is water out of the breather.The air box is not doing you any favors.You can get as good or better mpg with out it.The truth is the stock carbs wont flow what the stock head will and the air box wont even flow what the stock carbs will.
When you do the air box kit its not like the filters are out in the open they are behind the side covers they dont get as wet as you might think.I look at it this way ether leave the bike stock and ride it or pull the air box and be done with it,dont waste work or money changeing the air box its a waste of time.

MONTTU · 01-09-2009, 06:45 PM

If one does not like to tinker with bike and power is not a factor in riding pleasure let it be as engineers planned it to be.

Some of us are anyhow different, we cannot leave it like it is but to try to make it run better, faster, louder...because the pleasure is there.

I have thought to run the bike in future without filters, only nice looking and sounding trumpets on carbs. I know that engine will eat dirt but who really cares? Bike was made to give pleasure, not to last forever!
My next engine tuning idea makes me to open it anyhow long before it has worn out and propably I will change the parts long before they are worn out even without filters.