low speed stumble?

[SpeedTrippin]

First off just want to say hello everybody, just bought a black 99 S3 two weeks ago and i love it Had always admired the triples, now i own one.

Bike runs great except for when your riding around town at steady, traffic speeds (30 - 40mph, 3 - 4k rpm). Here it stumbles/stutters a bit, almost like its starving for fuel but more subtle. Accelerate, even a little bit, and it dissappears and runs beautiful.

I'm wondering if its the injection mapping? Someone suggested to me this was an early, known, issue with the mapping on these bikes. Also, orig owner said he had it mapped after adding the exhaust. Specs below, thanks for the help.

99 S3
30k mi
Triumph factory race exhaust (carbon can)
K&N
one tooth down on front sprocket

[British-Customs]

Hello,

This is Alex over at British-Customs. If the previous owner flashed the ecu, did he use a program or did he just get a TOR map or dealership reflash? I would reccom. looking into a tuneboy reflash system. You can pull codes(scan tool) data log you bike, make a custom map for your riding style(a/f tables) even be able to control fan cycle. That is what I would do to try and pinpoint your problem. Either something in the mapping or perhaps service? Let me know if there is anything I can help you with...contact me via 310 225 2570 or my e-mail alex@british-customs.com

Goodluck!

[ronin]

Sounds just like you said, air/fuel issue...it is low speed surging.

[SpeedTrippin]

i beleive it was a dealership reflash.

i have done some searches and have seen the tuneboy software/cable. looks very nice, but not sure if i want to drop $300-400 if i am not sure the mapping is the problem

[SpeedTrippin]

the local Triumph dealer will flash the bike for $50, so i am tempted to just try that.

honestly i have no real way of knowing where, how, or what tune the origonal owner had put in, but he did state it was always dealer serviced.

[British-Customs]

Fluids Changed/Vac Lines/Intake Box on even all around/Clean Filters...thats where I would start, let alone around 30k your bike might need it. Next I would try spark(plugs ect) I deal with both Tuneboy as well as Powercommander. I like Tuneboy for datalogging sake as well as not needing to plug in a box for a boost in perfomance, just a complete reflash is safer. Well you dont need to by the software as well, you can get a unlock ecu key code and find someone local enough to you to be able to use there program and tune your bike rather then getting the entire USB starter kit

[British-Customs]

For a reflash!? At a dealer? Take it!!!

[SpeedTrippin]

maybe i will for $50, couldn't hurt i suppose.

and i think i will go through 'all things intake' on the bike as well, seems like a good idea, saw a diffrent post where a vac line seemed to be the issue. runs so well otherwise tho..

thanks for the advice, do u have the tune boy software? where r u located?

[SpeedTrippin]

update:

I did get the dealer tune update. Cost $45 and it did make the bike run a little crisper, but didn't solve my issue.

Turns out, the whole "stumble" was due to a chain issue. Not something that initally occured to me, just something i came across because i was going over the whole bike. Info in this post:

http://www.triumphrat.net/speed-trip...ml#post1102761