Author Topic: Rejetting the ST1100  (Read 4112 times)

Offline Bikebear

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Rejetting the ST1100
« on: May 02, 2012, 07:03:25 PM »
Has anyone done any rejetting on the ST1100?
I see that jet kits are available for about $50 from the States and since I have STaintunes and a K&N filter I was thinking that now it breathes a little better I may be able to extract a little more from the motor by upping the main jet to a 135 and the pilot jet to a 40 and shimming the needle. I'm thinking it may improve the throttle response and give a little more for towing the trailer. I've done it before on the Shadow and it made a massive difference to that bikes performance.

Craig..
STOC #8215
UC #42145
SCA#2478

Gold '99 ST1100A (Golden Brown), Black '04 VT750, Red '15 1800 Valkyrie (Hildr), Black '08 DN01



"Golden Brown finer temptress, Never a frown with Golden Brown"
 

Offline Greencan

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Re: Rejetting the ST1100
« Reply #1 on: May 03, 2012, 10:44:51 AM »
Mornin' BB et al...

Many years ago a Chap form the US posted a thread on the STOC site on a modification he did along these lines, where he drilled a series of 25mm holes around the outside wall of the air box...then proceeded to re-jet it so that it ran properly...I can't recall the full outcome....but it did increase power, but from memory I think the claims made were a bit subjective...no dyno stats to back it up.

You can replicate this mod by simply removing the top lid from the air box and running the engine...it'll 'bog' down (starve for fuel), as soon as you open throttle...this is because the rubber torque tubes (mid range), require patency of air box in it's present setting to work.

However, John B (JZR 'pilot'), may be able to help you...I believe John just drilled out the main jets using a series of number drills until he got it right...he had to do this as he had to remove the OEM air box and the rubber torque tubes within...and substitute his cleverly patterned plastic cake holder...and having been in this 3-wheeler, it certainly gets up a boggies :thumb, considering it's got an additional 90kg penalty before you shoe-horn yourself into it :eek.

So whatever you have in mind with altering the air / fuel mix you will need to alter the airflow to within the air-box (eg holes), before undertaking any alterations within the carburetors themselves as the replacement air filter alone isn't enough to warrant any carburetor modifications.

I guess if different 'internals' are being offered for 1100 carburetors then this modifications can work...but I think a visit to your friendly motorcycle shop who has a dyno to begin with would be in order...interested to hear how you get on :wink1

Ciao, the can :)
 

Offline royst1100

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Re: Rejetting the ST1100
« Reply #2 on: May 03, 2012, 05:08:41 PM »
i did the holes in airbox after easter and made a huge differance. so thats K&N filter, new delkevic pipes and 4 (only)holes around the sides only1 not front as i didnt want to drive air into airbox. re post "black smoke" i cleaned K&N and all those problems have gone. throttle response brilliant power hase improved single and 2up. as we are not small specimens of the human?? race the improvement was noticable even to her. may rejet oneday

regards royce
regards
           Royce