Yamaha TRX850 Enthusiasts Forum

Ok guys (and gals) ... while I have the tank off and still have an electric drill in my hand , is there any advantage in drilling extra holes in the standard air box ?? I have a full set of drills and hole saws so anything from 0.5mm up to about 150mm is possible .
I also have a sheet of woven stainless steel I could fit to stop bugs and small children being sucked in if necessary.
I'm running a standard carbs & air filter with de-baffled stock silencers.
(All I'm looking for is a bit of induction roar really so any comments or advice would be welcome)

Take it off and fit pods? Now I may be interested in that thought!

Dave E

My bike has two holes cut into the airbox on the front as well as the snorkal facing forwaed. Bike has K & N airfilter and carbon cans. Induction roar is very nice but not sure if it is an improvement as bike was like this when I got it. I have turned the snorkal back round as I couldn't see what gain it made as it just faced the inside front of the tank. (the snorkal had been chopped in half to allow it to be turned)
I hope this helps
Heath

Red Rex wrote:Ok guys (and gals) ... while I have the tank off and still have an electric drill in my hand , is there any advantage in drilling extra holes in the standard air box ?? I have a full set of drills and hole saws so anything from 0.5mm up to about 150mm is possible .
I also have a sheet of woven stainless steel I could fit to stop bugs and small children being sucked in if necessary.
I'm running a standard carbs & air filter with de-baffled stock silencers.
(All I'm looking for is a bit of induction roar really so any comments or advice would be welcome)

I cut the snorkel back on my airbox and smoothed the edges where it had been cut. I don't know if it made more power but it sounded a bit faster

Kayla wrote:I cut the snorkel back on my airbox and smoothed the edges where it had been cut. I don't know if it made more power but it sounded a bit faster

... that's the answer I was looking for

Individual pods make slow speed running rough

dandywarhol wrote:Individual pods make slow speed running rough

No that's not. I also have individual pods and it runs verry good on low speed.

Maybe, but it'll run better with one box - cylinder robbing loses low speed torque - but if you're happy with what you've got - fair 'nuf

cv carbs like still air to feed themselves with.
so the std box over your pods would give you the best of both worlds.
alternative is a K&N to replace the std filter and a jet/needle/emulsion tube kit from FactoryPro.
then take it to someone who will spend time sorting it out for you.
cheers
fung

start fishin for some FCR's

dandywarhol wrote:Individual pods make slow speed running rough

Not if you spend ALOT of time on the dyno - this set up actually works way better than stock airbox if done properly. Both power & torque curve (at all engine speeds) are massively improved. I'll post dyno results to demonstrate all options when i get time. TRX's are notoriously buggers to set up so most tuners settle for a decent compromise i.e: they don't bother going outside what's supplied in a Dynojet kit to see what else will work.

Should also point out that this also makes the induction noise a little 'mechanical' which isn't to everyones liking.

NWS870R wrote:

dandywarhol wrote:Individual pods make slow speed running rough

Not if you spend ALOT of time on the dyno - this set up actually works way better than stock airbox if done properly. Both power & torque curve (at all engine speeds) are massively improved. I'll post dyno results to demonstrate all options when i get time. TRX's are notoriously buggers to set up so most tuners settle for a decent compromise i.e: they don't bother going outside what's supplied in a Dynojet kit to see what else will work.

Should also point out that this also makes the induction noise a little 'mechanical' which isn't to everyones liking.

It's what I've been bleating on about for some time NWS - a lot longer than the average Joe will spend and afford.

IMO the TRX/TDM setup is a notorious bugger of an engine to set up (with C.V.carbs without an airbox) due to its design and to get through noise regs when new.
It's my belief that the shock wave produced when the inlet valves snap shut actually helps the neighbouring cylinder fuel during it's induction stroke and helps low speed torque with the single airbox, especially with the uneven firing pulses of the 270 engine. I reckon some of the induction racket will actually be the slides rattling up and down without the assistance of the common airbox and will be knocking hell out of the emulsion tubes in the process.

There again, I could be completely blowing out of my arse..................................

It does indeed reduce the life of the emulsion tubes & they should be checked approx every 5k miles with this set up. Expect to change them around 12k miles or so - any later & they'll be proper stuffed

Anyone wanting to completely ditch an airbox would do well to look up "Plenum chamber, the need for" in any serious work of reference on the internal combustion engine before doing so.

Works best on injected motors, and adds weight with all the added gubbins! Also with the low state of tune of the TRX motor would it make much difference on a standard set up? Quantime ?

Dave E