Recently put my 1988 T5 on the road. But having problems with the tuning. I have never set up a carb before and also had issues with setting the timing. Any help would be much appreciated as now confused as to the next steps.
The bit below are what I have done and the basic set up.
Fast flow fuel tap.
Original CDI unit (Have tried a different one no change).
New plug HT lead and spark plug cap (Tried alternatives and no change).
Original stator plate.
R9357 Dellorto VHST 28BS carb with the following standard jetting.
- 55 Slide
- D41 Needle
- 269 HE Atomiser
- 142 Main jet
- 35 S Idle jet
- 60 Choke jet
- 270 Float valve
- 15760.5 floats – 3.6 grams
The scooter starts fine and idles ok although a bit lumpy. Changing the mixture setting seems to make very little difference unless two or more turns are done. Acceleration is good but does misfires a little. Decelerations is a big problem as it backfires and also looses power until at a slower speed and revs are back up. I can lessen the problems by keeping up the revs slightly when slowing but never had this issue with any other scooter i have had.
I attempted to set the timing today but not sure I have it right. I tried to used a stop screw to get a reference point either side of top dead centre. I then halved the measurement and measured out 16 Deg. Used a strobe but the markings were way off (stator was aligned to markings at this point. I then used a Vernier to get top dead centre and marked out 16 Deg. Checked with the strobe again markings still out and to get them aligned i had to move the stator ten millimeters advanced past the casing/stator markings.
Tried a run with the new timing setting and found the back firing was worse than ever. The fuel consumptions seems exsesive but a long time since i have been on the road also not sure i can trust the gauge yet.
It feels like a carb issue but don't know where to start with the jetting (the jets arE standard when i bought it from SIP).
Sorry for the long winded post but thought i would get every thing down.
Appreciate any help Mark