Carb Jetting in Stock Sprees

[GlynnC]

Just finished (almost) bringing '86 & '87 Sprees out of years of hibernation. Both start and run great, no mods. However, the '87 has obvious better & smoother acceleration from start to top end, no apparent dead zones. Top speed is about the same. The '86 has a slight dead zone at mid point. Both mufflers have been decarboned by heating in the gas grill. Air filters are new and air holes is air boxes are clean. Carbs have been cleaned, cleaned, and cleaned--they seem to be running too good for carb problems. The only known diff is the main jet--the better running one has a 65, the other a 68. The 68 jet is new--prior owner apparently tried to modify original with a BIG drill.

Could the slightly bigger jet be causing a rich fuel mix, and thus a little slugish in acceleration?

[ANDREW]

yes and no if the crab jet is SLIGHTLY bigger it can give you a higher topend speed and more power but if it is too big it could be bogging out and runing rich because of too much fule. i would put a smaller jet in it.

[Wheelman-111]

Greetings:

GlynnC axes:

Could the slightly bigger jet be causing a rich fuel mix, and thus a little slugish in acceleration

Certainly.

But so can slight differences in dozens of other components. Compression comes to mind. Might be worth procuring another 65 or just swapping carbs to test the theory.

[Kenny_McCormic]

Mid range is controlled by the needle clip setting, play around with that.

You can get a very noticeable boost by smoothing out the transition in the intake manifold. Look from the carb end, if you have the slightest grasp on flow you will know what to do.

[GlynnC]

Thanks for the responses, although I'm a new member, I've read many of the posts, and have been impressed with the combined knowledge and experience represented by the members of this forum.

It'll be a couple of weeks before I can get back to the Sprees, but will probably do the carb swap to test the results--will post outcome.

These 2 Sprees are running almost too good to believe to have been asleep as long as they've been--and probably not cared for as well by previous owners as the TLC they'll get under my ownership. I would like them to remain dependable for many years to come.

However, Kenny you bring up an interesting point of looking at the intake. The intakes do very obviously have a rough transition as discussed many times in the forum. I would like to clean this restriction up a little, but don't want to do anything to mess up these little scooters apparent toughness. How much, if any, derestricting can be done without losing the reliability?