Poor performance

Had a 1985 Vespa PX150E engine with Polini 177 Cylinder cases Matches, Malossi Reed valve matched, HP4 Flywheel, Zirri exhaust, 60 long stroke crankshaft, T5 short fourth gear, reinforced clutch Malossi 4 plates 21 cogs, timing set 18 grades, but not going that fast. What I can do? Any tuning expert can make suggestions?

Should be doing that in third! sorry to sound stupid but is the speedo correct?
dose it run normaly or misfire?
are the brakes rubbing[:D]
dose it smoke ?
did it get slower as you put things on,or 1 item seemend to slow it?
what carb?
anything else you can tell us
what youve got should go well so might be able to help[H]

I will try and help Viperboy. What sort of performance, top end are you getting?

I’m doing about 55 mph. Very low start.

Can anyone had a suggestion?[:shoot2:]

Agree with slidingdog: The parts should all work when put together tight and set-up OK. Check everything is mechanically and electrically OK first…then start on the tuning it in bit:

Delorto Carb? what jetting?

I suspect you are missing the powerband in 4th? is that the case?

  • The Zirri pipe (tho I never owned one) is reknowned for being a high revver.
  • Did you open out the inlet inside over the crank towards the piston as well as down onto the top?
  • Though the short 4th is a bit shorter it isnt that much difference. Is the primary ratio afected by the 21 cog clutch? (what was P150 standard?)
    Where did you place the packing plate on the cylinder (base or head) to run the stroker crank (this can affect port timings and compression ratio).

Let me know the jetting (Im running simlarish capacity and set-up so should be able to tell if your’s is way off the mark)