Suzuki 2 Strokes

Can anyone help with the following - my 72 T500 motorcycle has been fitted with a new T350 speedo in kph. While they look the same, the T350 speed reads approx 10 kph lower at 100 kph. The T500 drive gear in the front wheel is # 54621-15000 and my question is - would changing this over for a T350 drive gear solve the problem? The speedo cable # 54611-11000 is used on both the T350 and T500. So, do the T350 and T500 drive gears have the same dimensions to retrofit over? If they are, what is the part number for a T350 drive gear?

Thanks - Syd

Back in the 1970s, motorcycle speedos weren’t particularly accurate. On top of that, the speedo is now about 40 years old.

The stock tire diameters are:
T350 with 3.00-18: 628mm (for IRC GS-11 tires )
T500 with 3.25-18: 660mm
The T500 tire is 5% larger. When stock, for a given wheel rpm the T500 is going 5% further & 5% faster.

Using the T350 speedo drive on a T500 would cause the speedo to read 5% slow.

I do not know if the speedo drives are interchangeable.
Perhaps one of the forum experts or mechanical engineers could answer that.

I would not be surprised if your 40-year-old speedo reads 10% slow,
or if a PO changed the speedo drive & the speedo reads 5% slow.

Thanks for the info..

Looks like speedo pinion gear same both bikes. But, the 500 has a 19 inch tire and 350 has 18 inch tire. So suspect speedo itself different between bikes. The t350 speedo expects more turns of wheel for same speed and since its is getting less due to taller it reads slower. 18"+6"(tire thickness summed twice) / 19"+6" is about 4-5% less of what it should be me thinks

Usually OEM usually reads faster. Say about 8 kmph at 100kph (see period magazine test to see what they found. T500 may have been more accurate than others). So if you got T500 speedo error would shift the other way anyways

Great, thanks for the info..

The T350 & T500 use the same speedo — the part #s are the same. (Sorry, I knew this but left it out of my earlier post.)

As Vintageman said, they use the same speedo pinion gear — the part #s are the same.
The speedo drive gears are different and have different parts #s.

Thanks, while the part numbers are not the same and the gear pattern will be different, it would be great if someone has a drive gear from a T350 and T500 to see if they physically have the same dimensions?