Tuning the HSP 94122 (Flying Fish), fixing errors

 Tuning the HSP 94122 (Flying Fish)

I found this car generally to be neat, however I found out that the stock parts of the sealings do not fit very well. If you happen that you find your engine is overheating, this is most likely due to that the fuel tank is not air tight. I'm using a fuel tank with the metal lid. All 3 that I have were not air tight. This is due to the O-Ring used or that the spring is not strong enough. The perfect size for the fuel tank O-Ring is

ID: 16 mm

CS: 2,65 mm

You can find out if the fuel tank is air tight by holding a finger on the exit to the carburetor and blow into the intake from the exhaust pipe and putting the fuel tank under water. There should be no bubbles coming out and the lid should not lift. If the lid lifts, than adjust the spring by bending it a little bit more.

** UPDATE ** 

I was curious about this issue and bought several fuel tanks. I found out that the fuel tanks with the plastic lid seal better and were air tight by default mostly and that the ones with the metal lid always have issues. The needed size of the O-Ring also varies, i got a second one sealed with an O-Ring of ID: 18 mm, CS: 2,65 mm. So you're better off buying a set of O-Rings in the Range: ID: 16 - 19 and CS: 3, 2,65, 2,6, 2,5. I think if you want to go for the metal lid, than it is a good advise to buy a fuel tank with plastic lid and buy the metal lids in bulk separately. 

O-Rings of the differential gears (front and rear). 

These are by default ID: 5 mm CS 2,5 mm, I exchanged these with NBR Rings as these are moving parts with 

ID: 5 mm

CS: 2,6 mm

this makes the drive shafts less loose and performs well.

O-Rings of the carburetor 

I found these also a little bit too loose, so for the high speed needle I use: 

ID: 3,5 mm

CS: 1,5 mm 

VMQ (Silicone)

normally ID: 3,7 mm and some other CS value maybe correct but I did not find something like ID: 3,7 CS: 1,4 or 1,3 mm easily online, so I stuck to the values above. For the low speed needle I did not find a perfect match yet, something like ID: 2 mm, CS: 1,25 or 1,3 mm may work maybe even CS: 1,2 mm.

The lower O-Ring of the shaft  is ID: 8 mm CS: 1 mm, for the upper O-Ring I exchanged the stock one with ID: 10 mm CS: 1,1 mm

Main Gear

I had huge problems with my 2nd gear shifting, as for now I compeletly shimmed the main gear that there is a slight tolerance. In the stock setup the tolerance is way too much and you can move the gears too much. For shimming I used washers with M5x8 mm.

Clutch Bell

The same as for the main gear also applies to the clutch bell, I shimmed it also with M5x8 mm washers.