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Gangsta gear up mod 49ccScoot.com Scooter Forums

27 Feb 2015 | Author: | Comments Off on Gangsta gear up mod 49ccScoot.com Scooter Forums

Gangsta gear up mod

Post by Benelli Pepe 50 LX on Feb 26, 2011 4:33:33 GMT -5

Hi Guys,

Just an update and a tale of caution.


One of the mods carried out on the Benelli pepe was the install of a gear up kit from malossi which dropped the final drive ratio to 3:1 this was to take advantage of the power up provided by the 70cc big bore kit and increase top end speed.

The kit arrived and all dimensions were correct except the length of the splined shaft that supports the clutch.

Talking with the supplier identified Benelli was sold to a chinese manufacturer in 2009 and the 2010 model underwent some subtle engine changes that broke the compatibility with previous models in some areas.

The Mallossi parts people have not updated the parts list to show the change.

The end game was no one was sure what gear up kit was compatible.

the engine type number is QJ1E40QMB-4

The shaft length of the new gear was too short and the gear size of the old part was not compatible with the new press fit gear.

Having access to lathes, mills and other toy’s I thought I could merge the 2 into 1 ( my bag is electronics so mechanical stuff is easy right?)

I used a thin cut off disk in a 4 inch grinder with the part spinning in the lathe to cut off the 2 gears. The shaft is surface hardened but is really crap metal once you get through the treated layer.

Once the gear was parted I bored out the centre of the new gear and the old shaft and joined them with a 16.5 mm press fit section that was full length of the gear and 20mm into the splined shaft. I used 0.1mm interference fit which took around 3ton to push together.

On the advice of others I drilled and inserted a small roll pin through the splined shaft interface and turned it back to the correct diameter.

got the scoot back together and it went like a scolded cat for a month, then disaster the shaft failed. Luckily it didn’t take out the gear box

I then got the shaft welded up and machined. Went like a scolded cat for a month then it failed again. ( what is it with the month thing )

So where to from here?

I went back to Mallosi site and know I can order a kit for a yamaha jog which should be at least the same dimensions as the original wrong kit and i have grabbed an old original shaft from a bike wrecker.

Benelli Pepe 50

The new kit will increase the top end further as its 2.47:1 ( the pepe wheels are 16 inch dia). I think I will just press fit the insert shaft this time with super glue.

Questions as follows;

1) Any comments on the new ratio do you think it will bog down too much on take off?

2) Does any one know of any other scooters that use the QJ1E40QMB-4 engine so I can check for an off the shelf gear up kit?

3) Any mechanical dudes have comment on the press only approach?

I am a bit worried the parts might rotate over time with the take off torque.

4) Should I just order up a 90cc engine and stop the mess around.

At the top of the thread I said a tale of caution. The caution is for those of you that recon mechanical stuff is easy. it’s not.

Cheers

your Aussie scooter mate

Benelli Pepe 50
Benelli Pepe 50
Benelli Pepe 50

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