Bike bogs at full throttle.

shinyside · July 23, 2003, 02:47:18 PM

Riding on the freeway with my girl the otherday about 85mph on an incline and needed WOT, seemed howeverm that it would climb better at 3/4 than at full turn. The bike didn't choke and fall on its face, but it was a noticable decrease in power and sounded boggy. I am guessing this is a overly rich main jet... just wanted to bounce it off your heads before I start throwing down 5$'s at the dealership.

Uni pods, no restrictors, sv650 pipe, 40 pilot, 1 shim on the needle, 140 mains. Maybe 135's...

Thanks,
SS

KevinC · July 23, 2003, 03:02:54 PM

The main jet is too big. Unless you have pretty extensive engine work, and depending somewhat on altitude, humidity, and temperature, the GS needs a 132.5 or 135 main jet maximum.

With just pods and an exhaust, I'd try 135's at sea level, and 132.5's at anything over about 2,500'.

The Buddha · July 24, 2003, 08:49:05 AM

UNI pods...OK you must be the guy I suggested last week to try 140 mains. OK now the bike runs better if you gas it gently but misbehaves if you open fast then block off 1 hole on the slide.
Is it a feeling like its running out of gas or does it feel more like it was losing spark. Running out of gas is lean, feeling like its losing spark is rich. Its not actually lost spark just feels like it due to the incomplete combustion.
Cool.
Srinath.

shinyside · July 24, 2003, 03:45:04 PM

Hmmm... naw, must of been a different person.

The slide is plugged, sorry. The bike bogs(loses spark) from 3/4 to WOT, no matter if I yank it or if I turn slowly. In the back of my mind, I'm wondering if the mains are the problem; they have "RD" printed on them instead of the mikuni emblem. They seem to be cut deeper than the mukuni's.... dealer assured me it was ok....

SS

The Buddha · July 25, 2003, 07:53:58 AM

OK mains too big. Drop to ~135 as Kevin says. RD or is that RO...is for round and if the mains are about the same size as the ones you took out - you are fine...You have mikunis there. The big round ones are mikuni only, no one else makes similar ones. the little round ones however are keihein and minuni and you can fit one in the other by mistake but I believe the difference is under 1 size. Meaning 140 mikuni and 140 keihein are very very close. I believe 140 mikuni is about 137.5 keihein.
Cool.
Srinath.

Kerry · July 29, 2003, 10:56:45 AM

Quote from: shinysideRiding on the freeway [...] the otherday about 85mph on an incline and needed WOT, seemed however that it would climb better at 3/4 than at full turn.

Hmmm. I have a similar problem on my all-stock GS500E's ('96 and '99). It seems more like the last 1/8 throttle to me, but it could be as much as 1/4.

Could it be because I ride at elevations of 4000+ feet?

shinyside · July 30, 2003, 02:42:13 PM

Couldn't help you there; I'm in Nashville which is flat and low

zOU · January 18, 2007, 02:29:30 PM

"Warning: this topic has not been posted in for at least 120 days.
Unless you're sure you want to reply, please consider starting a new topic."

Should I really start a new topic as this one matchews perfectly my issue ?

Well.

I've got a race exhaust system (laser Pro D'Or)
Main jets were 132.5 and bike was way too lean
Main jets are now...err... 137.5 I think.

Since I've had the bike I've never been able to use the last 1/4-1/8 of the throttle. (even when jets were 132.5)

Any other idea than the main jets ?

News:

Bike bogs at full throttle.