Triumphrat

setts · 07-26-2006

Okay, so I have the off road exhaust, rejetted with 138 mains, drilled slider to 3mm, 1 shim under the needle, mixture fine, UniFilter, snorkel removed and NH Belmouth fitted. Big improvement especially mid range torque and power. But power flattens out at the top.... So I'm going to remove the airbox. Question is which kit to use. It's an expensive mod and shipping costs to South Africa are killing so I don't want to make a mistake. All advice appreciated. Thanks

Thrux-ton-up · 07-26-2006

Setts rather than remove the airbox - get the K&N filter for the stock airbox, then remove air restrictor/noise plate and snorkle - you can then also take a hole saw and cut a few well placeed air intake openings as well - I belive this is the route I would take - cheaper for sure and likely as effective. Others have cut away enough of the stock air box to fit K&N pod filters and then also have a nice tool storage area in whats left of the air box. I believe T1 may have done this - check his album. I have the Brish Customs kit and love it - fit and quality are excellent. JCW

ThruxACT · 07-26-2006

Setts, your setup is very similar to mine.

Staintune mufflers, stock airbox, DNA free flow filter (similar/same characteristics as K&N and Unifilter), no snorkel - NH bell-mouth fitted, slider not drilled, no shims, mixture screws 3 turns. However, main jet size is 128. This accords fairly well with the tuning recommendations in the Jenks Bolts tuning notes for the Triumph Bonneville family of motorcycles. (They recommend 125 mains for this type of setup.)

Could you be a bit on the rich side? This will have the effect of flattening out the top end (leaner = more power [within limits]).

CYNCRZR · 07-26-2006

Setts,

I agree, that with your setup, 138 mains sound way too big. I'm running D&D pipes, K&N pods & 140 mains, 42 pilots, extra vacuum hole in the slide. I think I'm running a wee bit rich on top and may go down to 138 mains.

I gotta figgure I'm flowin way more air than you are.

Cuttin up the stock airbox is a fine way to put pods on, ThruxtoneOne did it and has pictures in his member album to inspire ya.

SBTThruxton · 07-27-2006

Quote:

On 2006-07-26 05:12, Thrux-ton-up wrote:
Setts rather than remove the airbox - get the K&N filter for the stock airbox, then remove air restrictor/noise plate and snorkle - you can then also take a hole saw and cut a few well placeed air intake openings as well - I belive this is the route I would take - cheaper for sure and likely as effective. Others have cut away enough of the stock air box to fit K&N pod filters and then also have a nice tool storage area in whats left of the air box. I believe T1 may have done this - check his album. I have the Brish Customs kit and love it - fit and quality are excellent. JCW

This seems like the way I'd like to go for now - at least removing the sorkel right away and cutting holes later. The previous owner had Staintunes installed at the original purchase and it was re-jetted then. Would I need to re-jet if I just pulled off the snorkel? :???:

setts · 07-27-2006

On the possibility of running too rich.... Firstly thanks for all the input. I too thought I may be running too rich and jetted down. The dyno showed a big loss in mid range power and torque and it still flattened off at the top!!!! Bigger mains were far better. Could it be a fuel thing? We run 95 RON petrol in South Africa. I seem to recall that in the US it's different??? The other suggestion I've heard is ignition timing? Too much science for me!