Prima Stage 1 kit installation and review.
The Prima Stage 1 Kit comes with:
Prima exhaust & all necessary hardware including gasket
6.5G Prima Rollers
1000 rpm torque spring
3 jets 85 - 90 - 95
As you can see the pipe has a nice overall fit and finish to it.
Compared to stock
The installation was super easy and came with very good instructions.
Remove the two exhaust header nuts.
The two hanger bolts
Remove the emissions tube, effectively making this a "off road only" race scooter.
Installation only took about 15 min's to complete even with the pictures and removal of the seat bucket. So far this buddy has been very easy to work on.
Looks and sounds great.
We decided to take it on a test run "as-is" without any jetting changes or spring installation.
(Remember we already have 6.5G rollers installed)
Results were what we expected. Loss of bottom end performance but we had a top speed increase of over 5 mph and much better midrange performance.
Plug chop at this point was reading lean.
Now we break out the handy ZTR tool and install the 1000 spring.
Done deal
After the clutch was re-installed I took it on another test ride. Top speed of 45 mph (GPS) was still there but the acceleration was very much improved and overall we were very satisfied with this part of the upgrade. However the plug chop still showed lean.
Now time to tune the carburetor.
We went ahead and removed the carb and installed the 95 main straight off because its better to tune rich and work down to lean. We found with the stock air box this was the perfect combo for our setup. At this point the restriction was still in the airbox.
Test ride and the top speed remained unchanged.
From there I installed a free flow air filter as a experiment.
Although it looked cool the plug chop read very lean with this setup and the noise was unbearable for most people. The intake was by far louder than the exhaust. Not only that but we found the intake runner and carb to be to small to handle this type of intake no matter what the jetting change. Not only that but there was very little performance increase over the stock airbox.
(Wish I had took more pictures at this point sorry guys)
Next we installed the modified airbox (removed intake tube) and it ran about the same with a bit more bottom end pull. Nothing to write home about but at least we were no longer running lean and the throttle response was a bit better also.
Overall results:
Stage 1 kit w/ 95 main jet, Prima exhaust, 1000 rpm spring, 6.5G rollers, and modified air box.
Better acceleration
Better midrange acceleration
5 mph top speed increase to 45 mph on flat ground (270# rider)
Hill climbing performance increased a bit but not a whole bunch.
We will be playing with lighter rollers at the track and will keep you posted of the results.
Next round 70cc Prima Big Bore Kit.
Amerivespa Indy 2015.
Scooterists start your engines!
#AVINDY15