GS300L 1982 mod and questions

[LHO39]

The GS300L for 1982 and I think onward have no tachometer. Annoying to me. The parts bike in my basement, a 1981 GS450, had instruments that looked temptingly similar. So I swapped them. The mounting was easy, two nuts off remove and replace, tighten the two nuts. There are two electrical connectors on the 300. One of them is exactly the same on the 450. It plugs in under the gas tank. The other connector of the 300 has three counterparts on the 450. I chose to modify the bike to fit the GS450 instruments. This involved connecting two power and grounds for dial lights. A bit of mix and match. Gray wires are lighting 12V and black/white are grounds. Now for the tricky part. I got a spare six pin connector from the 450 and removed the pins with a jeweler's screwdriver. Tedious. Then I removed a blue nine pin connector from the GS300 wiring harness in the headlight bucket by teasing out the pins the same way. The bike's pins insert into the six pin connector except for one yellow wire. That had to be inserted into a soldered in round type connector. I think it is for the oil pressure light.

Now for the tachometer. I thought the driven tach gear I took out of the 450 would work in the 300 (remove the plug on the upper right front of the 300 engine at the tachometer drive hole). But this did not insert. On the 450 the pin inserts below the camshaft while on the 300 it inserts above the camshaft. This means that the driven gear is left hand on one and right hand on the other. But the older GS250s had a tach. So I ordered a driven gear from a 250 and luckily it inserted easily, it fit and it turned. I connected the tachometer shaft from the 450 and it turned in the direction that made the 450's tach work correctly. A total success. Sorry no pictures.

But now I am irritated by how fast the engine is turning. So here is a question. Has anyone relpaced the stock 15T and 42T sprockets on the GS300L with say 17T and 39T? I will give up acceleration for quieter cruising. I can down shift when necessary.

And the final point is that I have FOR SALE an instrument cluster for a 1982 GS300L that works perfectly. The speedo says 6737 if that matters. I am thinking of $40 including shipping. Your read it here first. eBay may get it in couple weeks.

[mriddle]

So you used a GS250 driven gear in the GS300L and it worked perfectly ?

That is a big jump (like 18%) to make on the gearing .. I would think that 5th gear would be all but useless, but nothing ventured nothing gained

The GS300L for 1982 and I think onward have no tachometer. Annoying to me. The parts bike in my basement, a 1981 GS450, had instruments that looked temptingly similar. So I swapped them. The mounting was easy, two nuts off remove and replace, tighten the two nuts. There are two electrical connectors on the 300. One of them is exactly the same on the 450. It plugs in under the gas tank. The other connector of the 300 has three counterparts on the 450. I chose to modify the bike to fit the GS450 instruments. This involved connecting two power and grounds for dial lights. A bit of mix and match. Gray wires are lighting 12V and black/white are grounds. Now for the tricky part. I got a spare six pin connector from the 450 and removed the pins with a jeweler's screwdriver. Tedious. Then I removed a blue nine pin connector from the GS300 wiring harness in the headlight bucket by teasing out the pins the same way. The bike's pins insert into the six pin connector except for one yellow wire. That had to be inserted into a soldered in round type connector. I think it is for the oil pressure light.

Now for the tachometer. I thought the driven tach gear I took out of the 450 would work in the 300 (remove the plug on the upper right front of the 300 engine at the tachometer drive hole). But this did not insert. On the 450 the pin inserts below the camshaft while on the 300 it inserts above the camshaft. This means that the driven gear is left hand on one and right hand on the other. But the older GS250s had a tach. So I ordered a driven gear from a 250 and luckily it inserted easily, it fit and it turned. I connected the tachometer shaft from the 450 and it turned in the direction that made the 450's tach work correctly. A total success. Sorry no pictures.

But now I am irritated by how fast the engine is turning. So here is a question. Has anyone relpaced the stock 15T and 42T sprockets on the GS300L with say 17T and 39T? I will give up acceleration for quieter cruising. I can down shift when necessary.

And the final point is that I have FOR SALE an instrument cluster for a 1982 GS300L that works perfectly. The speedo says 6737 if that matters. I am thinking of $40 including shipping. Your read it here first. eBay may get it in couple weeks.

[LHO39]

GS250 driven tach gear in GS300LZ

Yes. The gear slid right into the hole, engaged the gear on the camshaft. Note that I used the retainer from the 1981 GS450 and set aside the plug that came on the 300. This also fit perfectly.

[duaneage]

A taller tire can reduce RPMs by 200-300 at 60 mph. 18% is a bit large, I would go 10%. I geared my Yamaha down 11% and found it a bit buzzy so I went back up to stock. I was tempted to go higher but the 38 HP engine might not be able to pull hills in the wind.

Your bike is a bit small, depending on rider weight, a fairing (or not) and bags it might struggle a bit at highway speed if you go 20% or so.

[doctorgonzo]

A 300 is very borderline for highway (70 mph) driving IMO. A 98 lb woman, probably ok, 1 220 lb man, I bet it would cry like a baby trying to hit 75 uphill.

[mriddle]

Level ground it will carry a big guy 70 all day .. (ask me how I know)

Doesn't do big hills well but that is what gearing down is for

[LHO39]

Highway?

As old farts we do not do highways on a GS300L. I agree about down shifting when necessary. Most of the time we are just keep on rolling along like the Mississippi River. We putt around the rural eastern Connecticut roads, maybe venturing as far as thirty miles.

We are breaking in a peppy 1980 Yamaha XS400 that might someday see a quiet interstate.

[Kitten Tooth]

I went all the way to sioux falls from sioux city on my GS300L.
70 MPH!!!!!