I'm trying to rebuild a tatty VFR750FL (RC36 circa 1990 )
I have so far replaced the headers/collectors with a direct replacement from SandyBike Spares...I dont believe this system gives any better exhausting gas dynamics over the original ( funny, I couldnt find a TwoBros Racing exhuaust for love nor money !) but the silencer might.
[image: vfr750.jpg]
Having modified my airbox, I have approached Sigma for a jetting kit to suit the bikes configuration.
Can anyone speak of their experience with Sigma, and perhaps to efficacy of the "custom" jet kits they put together...?
Grtzzz...
Do a dyno run. Then you know what changes in jetting are nessesary.
750s are jetted rich from factory, I wouldn't change a thing until you've got the bike up and running.
I like the radiator set-up!
More pics!! What front end is that, I spy 4 pot pistons. Also, loving the radiators and coolant bottle...we need a full build thread matey :)
uuummm forget the jets. go for custom ear plugs!!! :blink:
then get a k&n jet kit it should / will have every thing you need.. :fing02:
except the earplugs you need to stop yourself from joining me at deaf happy hour... :laugh2:
Why modify the airbox?
Removing the snorkel at the front (for more induction noise) ok, but what else?
More air per cubic inch? Jet to suit and surely it'll add some mid range
Modding the airbox still keeps the velocity stacks inside a box, albeit below the filter - modern bikes ( yes, even a 1990-1 VFR ! ) tend to use the airboxes as a sort of plenum chamber...This will still be the case with this
However, I intend tio use the newly found space to hide the electrics. To make it look right, Im gonna have to work hard to keep it clean !
The silencer is rated at 101dB....track days here are of a similar , if not greater noise level. My local ( Snetterton) is 101dB. I think it'll be fine ...but what do I know !?! :tongue:
For the sake of a few quid, I am all for jetting the bike to match induction and exhaust changes. Especially as the carbs are an unknown and are on the bench, in need of a service...
The question is, how effective am I likely to find Sigma rated kits...?( http://carbjetkits.com/jet-kit-calculator-how.html ) Is this the same crew making clutches...? If so, their reputation preceeds them...!
Having had some email contact with them, they seem to require specific details, to recommend a kit.
If K&N gear goes straight in with a choice of jet sizes, Im guessing it's not viewed as that hard a task to get them set up...? Id rather eliminate the guess work from the start, where possible ! :lobby:
cHeers
PS- Forks are a straight swap with VTR forks...resprung for my weight, and a bike dry weight of @ 200kgs. They have been treated to RaceTech Gold valves ( comp & rebnd) The shocker is a Jamie Daugherty special....modded to increase ride hide by 25-30mm, valved and sprung accordingly.
The calipers are Tokico 4 pots ( from a GSX-R750)..well spotted- they bolt straight on too.....
Glad you like ! :smile2:
Yeah it's looking food. Regarding the jets, I don't think it'll be as simple as dropping them in, I'm no expert so stand to be corected - but the A/F ratio needs adjusting (the scews are blocked off with blanking plates) which requires a rolling road set up. Steve Jordan near me can do this for about £250 as it's a 4-5 hour job (rolling road to see current a/f mixture > carbs off > new jets in > RR again to see if it's right > possibly take them off again if they're not)
actually they are just drop ins.. aka screw the old out . screw in the new..
replaces the jets, needles and springs :beer:
the airful mix screws are NOT blocked off. . not in the USA anyway..
even if they are , its not brain surgery to remove the plugs, and the kit would come with instructions to remove them.
as for noise.... like i care :tongue: :musik20: :wheel: