Airbox flow testing

[Speed3Chris]

There are a couple of techniques as Aussie suggested you can try to remove the restriction plate. You can unbolt the airbox from the frame...there are four bolts up top that secure the box to the frame...and remove the boot clamps and then push the box rearward for better access to the two side panel rear screws...and/or you can try to remove these two screws behind the rear frame rail with a pair of needle nose vise grips....a great tool that comes in handy in tight spots where std. vice grips with wider jaw are too clumsy. Ventura taught us that how opening the airbox does change the jetting which agrees with not only Aussie's testing but Pieman's dyno testing as well. Best tip I can give is when you replace the right side cover of the airbox after pulling out the restrictor plate, don't use two of the screws that were hard to remove. Replace them with hex head screws so if you want to take the side cover off again...say to put a hole in it or reinstate the restrictor, you won't have to unbolt the airbox from the frame...just use a 8mm box end wrench on those hard to access screws.
Be patient with removing the right side cover...it comes off without too much trouble but you have to remove the fuse box and some stuff on the right hand side...I believe I removed the drive sprocket cover for best access as well....you will see when you get there.
HTH.

 

[ivar]

Another factor to be considered is that the actual intake airflow in an operating engine is a pulsating airflow not a smooth constant airflow. Intake cam timing plays a part here, if you consider a camshaft with an intake duration of 242 degrees air is flowing into each cylinder for only 33% of the time (720 degrees divided by 242 degrees) so for the other 66% of the time no air is flowing in that intake tract.

This means that, with our 2 cylinder engine, there is no flow through the airbox for 33% of the time - in theory at least. To compensate for this in a steady flow testing scenario flow rate should be increased by 33% in my opinion.

Very good point - with those pulses , I'd think peak flow will be much higher than if it would be a smooth air flow.

On one of my snowmobiles, a 2000 Polaris XCR 800, a 2-stroke triple producing 150HP at 8200 rpm. It gets enough air for this using this airbox:

#2 is the "polaris rubber bellmouth" that was a popular mod for the Bonnies a couple years ago. Later XCR models had 2 of those bellmouths, and then allowed 180HP with porting/pipes etc.

IMO, would be interesting to apply loudspeaker design tools / principles to these airboxes - to get a good and consistant flow over the whole RPM range.

 

[Texas94fs]

Wow, thanks for the write up. And for doing all the leg work, I'm glad I already did my homeade dremel to the airbox and fitting of uni filters!

 

[outwestrider]

How to responses

Aussie T and Chris thanks so much - I'll give it a go on pulling the restrictor plate, then get in to the carbs to see what's up with my jetting. Greatly appreciate the help!

 

[outwestrider]

Done

Pulled the plate - seat of the pants is it's better on the top end, seems about the same every where else. No carb adjustment was necessary? Bought the bike in Denver - 5280' above sea level - live in western Colorado at 4600' above sea level - might be the reason ... volume is about the same, but I wear ear plugs when riding so it's hard to really tell. Thanks again ya'll.

 

[Speed3Chris]

Pulled the plate - seat of the pants is it's better on the top end, seems about the same every where else. No carb adjustment was necessary? Bought the bike in Denver - 5280' above sea level - live in western Colorado at 4600' above sea level - might be the reason ... volume is about the same, but I wear ear plugs when riding so it's hard to really tell. Thanks again ya'll.

Restrictor removal may warrant 1 jet size but all depends where you currently are at with respect to fueling. Your observations are the same as mine which are supported by Pieman's dynotesting. Removing the restrictor helps breathing above 4500 RPM or so and doesn't detract from low end performance which frankly was my biggest reservation to doing it earlier...affect to lower RPM intake velocity.

 

[outwestrider]

1 jet size

The verdict will be this weekend as to the rejet. Many routes to choose from around here - the ones for this weekend will be averaging 6-8k with a few passes over 10k so we'll see how she runs - been fine in the past before I pulled the plate so I have a reference to start from.

 

[Speed3Chris]

There is a knowledgable tuner by the name of Ventura that has posted a correlation between jet size and motor de-restrictions...varying degrees of airbox modification and pipes compared to jet size. If you can find it on the web, worth a download as he is meticulous and respected for his work. A note on jet size and change to pipes. Opening up the airbox completely generally increases air flow and affects jet size more than changing pipes.
HTH.

 

[outwestrider]

Thanks - I'll look for it.

 

[Jimbon]

Good, practical, inventive, Factual information we've been looking for, Aussie T. You're a genius mate!

As I've pulled the snorkel, any chance of chucking some water at this and telling me whether I'm going to break down with a soggy paper filter on the way to holiday Cornwall in the predicted poring rain this Friday?

I wonder why pulling the snorkel should mean a soggy filter (as I've been told) when the snorkel opening points forward towards any wind blown rain.

 

[cynr1023]

I've got just a set of uni pod filters on mine, I got caught in a torrential downpour (cars were pulling off the road) and didn't stop, I know it was stupid but hey, no one has ever accused me of being the smartest guy in the world. I started to have some issues with it but it really took a fuck ton of water to do it and as long as I didn't crank on the throttle it was fine. Short of driving into a lake I think you'd be hard pressed to get more water into that thing than I have.

 

[Jimbon]

If I'm sensible and slow down in pouring rain I should be alright.

So that's me standing by the bike kicking it somewhere in Wiltshire.

 

[HiVel]

just wondering where the spun aluminum intakes are from? Cat number or vendor would help-I like those.

Good info from the tester and the other comentators -all good stuff. Thanks Who sells DNA filters in ht USA?

 

[Aussie_T100]

just wondering where the spun aluminum intakes are from? Cat number or vendor would help-I like those.

Good info from the tester and the other comentators -all good stuff. Thanks Who sells DNA filters in ht USA?

The spun aluminum velocity stacks are a Mikuni part available from Sudco:-

http://www.sudco.com/CatalogJPG/088.jpg

50mm - Mikuni part No. KRS-003, Sudco order No. 005-251.

They are sold only as a set of 4, I paid AU$130 for a set from a retailer here in OZ so you are probably looking at under US$100 direct from Sudco.

DNA filters are available from Twinpower:-

http://www.triumphtwinpower.com/dna-pod-filters---54mm.php

Not sure of any USA suppliers of DNA filters, sorry.

 

[Aussie_T100]

Good, practical, inventive, Factual information we've been looking for, Aussie T. You're a genius mate!

As I've pulled the snorkel, any chance of chucking some water at this and telling me whether I'm going to break down with a soggy paper filter on the way to holiday Cornwall in the predicted poring rain this Friday?

I wonder why pulling the snorkel should mean a soggy filter (as I've been told) when the snorkel opening points forward towards any wind blown rain.

I've run my bike for 20,000Klm's with no snorkle and a Triumph OEM paper filter, only ever saw occasional light rain during that time but the filter never got wet even when I washed the bike with a garden hose. Easy to switch to a UNI filter oiled foam filter which will handle water intrusion better than a paper filter anyway if it became a concern.

Here in Australia a UNI filter for a Bonny is half the price of a genuine OEM filter and it's reusable. Pretty good value I think.

 

[Jimbon]

You're right: I've washed my de-snorkeled bike with a highish pressure hose without any problems. I'll give it a go and get a Uni-filter for the next service.

I'm chuffed that your experiment shows the biggest jump in airflow comes from pulling the superfluous snorkel, without having to spend money or cut up parts.

Did you fit a bell mouth? I can't see the point of fitting one as I don't think it would do much and they're inordinately expensive for what they are.

 

[Speed3Chris]

I will look for your help post if you continue to wash your bike with a high pressure hose...and it won't be related to the airbox...but rather the electronics.

I would never take a garden hose to a motorcycle either but thats what makes the world go round...like washing a car engine with a garden hose...same lottery if it will start...starters corrode faster etc. Relays are sensitive to water ingress and many have trouble even after riding through a rain storm.

As to snorkel being superfluous...Triumph really doesn't put superfluous parts on these bikes...although the restrictor plate is close. The snorkel keeps sound down and helps keep water out...it may fractionally increase air velocity as well.

You are right about bellmouths...a waste of money.

 

[Aussie_T100]

Did you fit a bell mouth? I can't see the point of fitting one as I don't think it would do much and they're inordinately expensive for what they are.

No I didn't fit a bell mouth, expense and limited improvement reported by others ruled that out even before I got to the dual entry stage. It would have been interesting to include one in my testing although I suspect that the increase in airflow gained from the bell mouth would be no greater than that gained by enlarging the primary inlet, possibly even less.

 

[Aussie_T100]

I would never take a garden hose to a motorcycle either but thats what makes the world go round.....

Funny, "washing", to me at least, suggests the use of water, soap and mechanical action to remove/dissolve dirt and grime followed by a rinsing process with clean water to wash off the dissolved grime and leftover soap suds. The method I choose to apply the rinsing water is to use a soft spray from a garden hose which, to me at least, seems to be a better proposition than just chucking buckets of water at the bike. I don't think using a garden hose on the bike in this way is anymore detrimental to the bikes longevity than riding it in the rain occasionally would be, particularly as it is dried off immediately after rinsing anyway.

I do use "waterless" wash on most occasions but sometimes the bike is just too dirty to use that process and that's when I hit it with the hose. How do you wash your bike Speed3Chris or don't you ever get it dirty enough to require a water wash? :chin:

The snorkel keeps sound down and helps keep water out...it may fractionally increase air velocity as well.

Removing the snorkel doesn't seem to cause any problem with water intrusion from my experience and any increase in sound is marginal and probably only audible to those with stock pipes or TORs anyway. :shrug:

Also, I fail to see how any increase in velocity from the snorkel could be of any benefit considering that the airflow is aimed directly at the blind bottom of the filter. I find your fascination with retaining the snorkel, even after removing the baffle plate, to be rather - well, unfathomable really. :d

Take a deep breath before responding now, it's your bike and you can mod it any way you like. You can even wash it with water if you want. :lol2:

Just havin' a dig at ya mate.:australia:

 

[fender]

Aussie - like you I also use a garden hose on it. I use the wifes sprinker head for watering flowers. Gives a nice soft spray pattern. My bike only gets washed about 3 times a year. It does get waterless washed several other times thought the riding season.

I can't imagine that water would get anywhere else that it wouldn't by riding in the rain.