Clinician
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Post by ron521 on May 11, 2010 17:41:20 GMT -6
What rpm are you turning at your cruising speed?
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Clinician
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Joined: Apr 25, 2010 16:43:09 GMT -6
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Post by ron521 on Apr 26, 2010 6:31:58 GMT -6
Returning to scooters after a 20+ absence, formerly owned an Allstate, and 2 Vespas. Got this last fall, very nice features, including 12 inch wheels and disc brakes as standard equipment. Originally 50cc, now upgraded to 72cc. Also replaced airbox with UNI filter, and changed 6.7 gram rollers for 5.0 gram rollers. Changing the rollers moved maximum rpm from 6500 to 8000, providing a bit more power and acceleration. Runs very well, top speed 47 mph indicated, 42 up a gentle grade, and 30 up a steep grade. At part throttle on level ground holds 40 mph at 7500 rpm. Almost zero vibration at any speed above idle. I performed the upgrades myself, and am very pleased with the build quality of the engine. Castings and machine work appear very good, comparable to Japanese motorcycles I used to work, as well as my old Italian scooters. Construction is similar to a classic Lambretta, with a tubular frame to which body panels are attached, and with a engine centrally located for better balance and handling. (The old Vespas had body panels all welded together for make a unibody, and the engine hung out on the right side). Frame tubes are huge for such a small machine, although welds are not the most beautiful I've ever seen, perhaps because they knew they would be concealed by bodywork. This was also something which was sometimes seen on Japanese motorcycles of the 70's. Have been trying to ride the scooter to work, weather permitting, looking forward to more fun with it. Attachments:
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Clinician
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Post by ron521 on Apr 26, 2010 6:03:06 GMT -6
I took advantage of the nice weather last weekend and installed my 72cc BBK purchased from Scrappydogscooters.com, an eBay vendor.
Installation was very straightforward, the engine came apart easily and went back together the same way. I didn't remove the engine from the frame, merely removed the seat and storage tub, and a rectangular access panel on the "front" of the body, near the riders heels.
I kept thinking how much easier the install would have been if I were doing the same work on one of the old Honda 50, 70, or 90cc motorcycles, whose engines just stuck out into the air, with no body panels in the way. But if I were, the information wouldn't really be relevant on this forum.
I will mention that I already owned a UNI filter, but was not using it. I had tried it with the 50cc engine, and found no difference, even when changing jets. Apparently, the stock airbox can keep up with the airflow generated by 50cc. This is not the case when the engine is 72cc, more on that in a moment.
So I took the now 72cc scooter out for a ride (still with the stock airbox), and was impressed with the acceleration, and some increase in speed. I had the distinct impression that the engine was running a little bit rich now.
I removed the stock airbox, and installed the UNI filter which I had tried before, and found that the performance was very much better indeed, and the perceived richness disappeared. I ended up riding nearly 20 miles just enjoying the scooter on a nice day.
Previously, I could reach 36 mph on level ground, now I can reach that speed with part throttle, and 44-45 mph wide open.
On a long four-lane road with a gentle downgrade, where 50cc would take me to 42 mph, I could now reach 47 mph.
Going UPHILL, where 50cc would struggle along at 29 mph, I now sail up the gradient at 42 mph.
Put another way, I can now go as fast UPHILL as I could previously go DOWNHILL on the same road, with a significantly increased speed downhill and on level ground.
I am completely satisfied with the results of this BBK, and with the transaction from eBay seller scrappydogscooters.com.
In the ad for this particular kit, he was very upfront about the wrist pin being slightly too long (hence the very favorable price). Addressing the issue turned out to be very easy, took maybe 5 minutes to make it fit properly.
He also shipped my order very quickly, I placed my order on Friday, and received the box of parts on Monday. All the parts appeared to be very high quality, at least equal to those which I removed.
And the results are everything I could have hoped for. I'm still running stock jets in the carb (31 pilot and 88 main), and have changed out the variator rollers (originally 6.7 grams, now 5.0 grams).
I will probably experiment with the main jet, and possibly the rollers again, to see if I can break the magic 50 mph barrier.
If so, fantastic, if not, I'm still very happy.
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