G1 exhaust throttle plate, remove?

[taylorward5]

Is it worth removing?

[twobore]

Hi taylorward5;

If you are using the original G1 oil injection system I would leave it in place and make sure the linkeage is adjusted as described in the repair manual (it should start to open as the throttle begins to open, and be wide open when the throttle is wide open). It's purpose is to modulate the intensity of the exhaust "puffs" from the muffler to the oil pump diaphragm via the flexible rubber hose. It's the reason the G1 oil/gas ratios vary from 150:1 at full throttle to 300:1 at low speed with the built in oil pump system.

If you are not using the Yamaha oil system, and are instead pre mixing your gas and oil, it serves no purpose and can be removed or just fixed in open position. But even then you might want to leave it in place as long as it's opening fully. Two cycle engines are strange creatures and depend on a certain amount of back pressure to function properly. That's why the muffler has a large inlet pipe and a much smaller outlet (exhaust) pipe and that exhaust butterfly valve could play a back pressure role as well.

[taylorward5]

awesome thanks! I am still using the stock oil injection and I replaced the oil line from the pump to the carb boy did that take a long time to prime, I shut it down multiple times to dump a little oil down the cylinder, But it is working the line I replaced it with is clear and I could see it pump!!

the plate seems to be working correctly as well. I just ordered the repair manual so I could understand the motor a little better. I adjusted the linkage a little so it would fully open and it stays open a little on close throttle. I couldn't get full open without doing so. seems to run good.

[sho305]

Yamaha always said it quieted the cart down and made more power/efficient at low speeds. Having worked on them a lot it didn't ever seem to be adjusted properly, it did make it quieter a little but some later G1 didn't even have them for some reason and yamaha didn't say why lol. It does not hurt the cart and you can't really gain any advantage getting rid of it, so its pointless to do so far as power output. They seem to run fine with them fixed open. Make sure its open or nearly so at full throttle and you are good to go.