Hi, I've been reviewing these interesting documents
"In order to meet the EURO 1 limit values, Sachs has incomprehensibly shortened the carburetor springs in addition to the SLS; an uneven throttle response is the result. With the optimized carburetor modification, there is torque without dips over the entire speed range up to In addition, ..."
My questions are
1) Regarding "torque without dips over the entire speed range". Are we sure the carb is the cause? Apparently there is a microswitch on the front carb which alters ignition timing. Evidence from here http://vx-faq.thevuelta.com/. pasted below (I have since just disabled the switch)
2) Regarding being bad to shorten the carb piston spring. This being done together makes me think that Sachs wanted to
a) reduce engine braking effect by making slide return down at a slightly slower rate (the Sachs doesn't have the VX800's slipper clutch)
i.e. smaller hole in slide piston
b) not be detrimental to quick throttle response, ie shorter spring, less preload resisting vacuum
c) for emission purposes, produce more torque lower down the rpm range.
Furthermore, I think this is why the prototype Sachs went from 160/60 rear tire to a 160/70 rear tyre, to reduce the RPM and therefore emissions when being tested
I have no proof of these carb considerations, but will add them to the questions I give to former Sachs R&D Director Mr Huhn
What do you think?
- "6.6 OddSwitch
- Recent European models (definitely the German models, perhaps others)
- have an unusual switch on one of the carburetors that closes when the
- throttle is fully open. Harald Bilke made some inquiries, and found
- that it's part of a system to reduce noise emissions!
- "The switch is necessary to keep the noise emissions just below the
- threshold. It engages only in the 3rd and 4th gear when turning the
- Throttle fast to "full open" and between 40 and 60 km/h. (This is
- the setup how the measurement is done - hint, hint ;-)) The
- ignition timing is being changed - so full power is released a
- little bit later. This is enough to pass the microphone and having
- a little more distance between it and the engine the dbs are lower.
- As I recall now I could feel the "hickup" myself. But you have to
- turn the throttle really fast."