Street Twin Hi Flow Air Filter

The unvarnished truth?

K&N are very successful at profitably marketing a product that filters air. Plenty other brands do it just as well (the filtering) and with marginal differences in flow rates. Some better, some worse.......

Sometimes engines are best thought of as air pumps. Their total flow is a function of everything between inlet and tail pipe; fuelling, inlet tract, valves, camshaft, exhaust port, exhaust.....

By all means fit a K&N but on its own but you will not notice a blind bit of difference. And don’t assume the stock filter is more restrictive. Marketing remember........

 

Syd
I changed my 59 Bonneville and it didn't need any maps. I also removed the snorkel it was fine.
Ride Free
Joe.

 

I put a K&N air filter on my street twin. The K&N is oiled which will filter much better than the paper stock filter. I don't really notice a performance improvement but I just want the cleanest air possible to my engine. Possibly overkill but I always treat my bikes with ultimate respect !!

It was not hard to install. I actually found a utube video which helped.

 

And no remapping is necessary.

 

BigClm
I did the same and like you always do all my bike to the best. I took the snorkel out and it give it a nice deep rumble deep down. You do lose most of the overrun popping but it sounds good.
Ride free
Joe.

 

The thing is.......

Dry paper filter elements generally filter more particles out than oiled filters. The difference is marginal (of the order of 99% v 98%) just as the claimed increased in airflow is highly marginal.

The real advantage is cost if you religiously changes air filters every year. A K&N will pay back in year 4. How long did you say you kept your bikes?

Then again, if you over oil your filter as many do (just to be sure!) then you lose all its supposed benefits .......

I am NOT rubbishing K&N (I have used them on side draught Webers). I am merely reminding folk that like angling gear a LOT of stuff catches more anglers than fish.........

 

the biggest downside to an oiled air filter is that some of the oil from the filter will find it’s way into the throttle bodies- not good, and turn to gum. This I know from personal experience on several cars and bikes. if you dont oil it then why change from filter is the first place? like others have said, they have great marketing hype. Save your $ and just take off the snorkle.

 

Have to agree with Callumity here. On it's own, a K&N or any other free-flow oiled filter will not make any difference at all.

I did the Triumph Twin Power (TTP) Stage 1 Induction mod on my 865 EFI air cooled Bonnie, which includes a DNA Filter and velocity bell-mouth intake in place of the snorkel. You then need to remove the air box baffle, the secondary air injection system and the O2 sensors and fit some improved flow exhausts (I already had TORS fitted) and get the remap from TTP and install it via your laptop using TUNE ECU.

According to TTP:

The Bonneville/T100 and Thruxton benefit greatly from stage 1 mods. The mid range has not only been boosted by just under 9%, but the torque hole between 3500rpm and 5500rpm of the standard model has been filled to give virtually flat torque between 3400rpm to 5800rpm. Peak power has moved up to around 8400rpm.

Conclusion

Per Model Power & Torque Figures

Model Induction Exhaust Peak Power (BHP) Peak Torque (ftlb) Max Torque Increase

Bonnie & Thruxton OEM OEM +0.0% (60.64) +0.0% (46.84) +0.0%


Bonnie & Thruxton Stage 1 TORS +5.6% (64.06) +8.4% (50.78) +15.9% @ 4,200 rpm







Well worth doing as it transforms the bike

 

I am not particularly familiar with the Street Twin and later water cooled motors but the biggest simple ‘bang for buck’ performance improvement (if that is what you are looking for) seems to come from replacing the restrictive catalytic converter with an x pipe like this
https://www.squaredeals-ltd.co.uk/t...thruxton-1200-bonneville-t100t120-39301-p.asp

Subject to NZ legislation it’s about 190 dollars plus shipping.

 

How much oil did you put on the filter?
I’ve used oiled filters for donkeys years, a mild spray on the outside of the filter, not the induction side will never pass through.

I’m not saying they’re any better than a standard filter but if looked after correctly, they will last many years