Suzuki 2 Strokes

1973 t500. this may be silly but just want to be sure...The choke / starter lever on the left side carb..

If the lever is up = choke is off --------- bike idles great also adjusted idle to stay at 1500 rpm
if the lever is down = choke is on ---------- bike will immediately die out..is this normal ? or do i have to adjust..

Please correct if wrong.

freedom0226 wrote:1973 t500. this may be silly but just want to be sure...The choke / starter lever on the left side carb..

If the lever is up = choke is off --------- bike idles great also adjusted idle to stay at 1500 rpm
if the lever is down = choke is on ---------- bike will immediately die out..is this normal ? or do i have to adjust..

Please correct if wrong.

Bike may be running slightly lean or your idle adjustment is way off. An indication of that would be. When you're riding down the road and you turn the choke on and it noticeably runs better at that moment in time. Once the bike is warmed up to approximately 180 degrees. The bike shouldn't shut off if you turn the choke on. Regardless, you have to let the bike warm up. Read and compare your plugs. An easy way to determine if a bikes choke is open or closed. Is looking at the plunger that the lever is attached to. When the plunger rod is extended the most, the choke is open or on. As the bike warms up slowly. Slowly, close the choke until the bike is at operating temperature. At this time, the motor should run properly with the choke completely shut. But, will not greatly effect running conditions if it remains open for a short period of time other than idle increasing at a stand still. Because the carbs are getting too much air. Which is not needed, beyond initial start up.

But, will not greatly effect running conditions if it remains open for a short period of time other than idle increasing at a stand still. Because the carbs are getting too much air. Which is not needed, beyond initial start up.

Excuse me? And here all my life I thought a choke (enriching device) added additional fuel. Once warmed up, flipping on the choke makes the motor blubber horribly because it's basically flooding. I guess I need to go back to school

This video is the best I have ever seen as far as motorcycle chokes go. Presented in a way that anybody can understand. A definite 'must view'.

https://www.youtube.com/watch?v=Di-v06bnXYU" onclick="window.open(this.href);return false;

You are correct. On a T500 the lever is Up for OFF and Down for ON. As the lever is pushed down, it lifts the choke plunger and allows extra fuel to flow.

If it dies when the motor is warmed up, that's probably because its too rich as Coyote mentioned. But if starter jet is blocked it is also possible that the motor is dying because it is getting extra air without the extra fuel.

The fuel jet is pressed in to a drilling in the float bowl and sediment builds up and blocks it off. http://pinkpossum.com/GT750/carb/BS40carbs.htm has a nice picture of the enrichment (aka choke) system for BS40 carbs. Your carbs are different, but the starting circuit is the same.

It would be a good idea to pop off the carbs and clean them thoroughly. That jet is only 0.6mm diameter and clogs easily.

Coyote wrote:

But, will not greatly effect running conditions if it remains open for a short period of time other than idle increasing at a stand still. Because the carbs are getting too much air. Which is not needed, beyond initial start up.

Excuse me? And here all my life I thought a choke (enriching device) added additional fuel. Once warmed up, flipping on the choke makes the motor blubber horribly because it's basically flooding. I guess I need to go back to school

No need to be a totally ignorant asshole. I was just helping the guy. For now on, don't comment on my comments. I'll do the same to yours. Watch and listen to 7:18 to 8:10 of your video. It clearly states, how a choke plunger works. You introduce more air, in return more fuel is supplied. Call it what ever you would like. An "enrichening device, a choke, etc." Any time you induce more air, you induce more fuel into a mixture. A motorcycle will idle faster if the choke remains open past initial start up. Because, the motor is now efficiently burning off any fuel droplets because the motor is now warm. At this moment in time the motor is receiving too much air if the choke remains open.. Anytime a motor increases in idle is because of a leaner running condition. Not a rich one. The choke being open regulates vacuum, which pulls more fuel which is needed at initial start up. Once the motor is warm, there is no need of regulated air due to fuel burning efficiently.

It's probably semantics, but the enrichment circuit on a Mikuni is richer than the normal pilot circuit, and leaving it partially or completely open makes the mixture richer. The extra air part of the equation is the same effect as cracking open the throttle and that raises the idle speed.

As you mention PJ, s the engine warms up it vaporizes the fuel droplets better and that allows more of the fuel to burn. Liquid fuel is not burning, it's the fuel vapor on the surface of the droplet that burns and the better the fuel is turned into a vapor the more of it can burn. That's also why any carb that breaks fuel into smaller droplets will burn more efficiently and will make more power and use less fuel. And that's why 4 strokes use a Bleed type needle jet to get the air in to break up fuel droplets. The smaller the fuel droplets, the greater the surface area for a given mass or volume of fuel. More surface area makes for faster and more complete burning.

A CHOKE is so called because it chokes off the air supply and that creates a larger pressure differential across the pilot jet and pulls more fuel in.

In this case the question is whether the bike dies because of too much fuel or too much air. If the starter (enrichment) jet is blocked the outcome is likely to be a lean mixture at cold idle. If those jets are clear it is more likley to be an over rich fueling problem.

it's the fuel vapor on the surface of the droplet that burns and the better the fuel is turned into a vapor the more of it can burn.

And for that very reason, you should never polish intake ports. It might look neat, but you're actually shooting yourself in the foot as the roughness of the port helps to atomize the fuel.
Sorry I was off base PJ. I just woke up and was very pressed for time.

thanks for all the info...i turned both idle screws all the way in and turned both back out 2.5 times exact. then played with each equally until it sat at 1500 . but all this info cleared it up for me. thanx again.

The ideal setting is 1.5 turns for the Idle Air screw. The farther screwed out, the more air / leaner the mixture is. My personal preference is to adjust them to the smallest amount open, that the idle speed no longer shows any increase. You'll find that too lean (screwed out too much) increases the popping/surging at low speed, and causes the revs to take longer to drop when letting off the throttle.

The spec is typically 1.5 +/- 1 turn. Another danger of having the screw out too far is that the spring puts less tension on the screw, and it may, over time, become even further unscrewed.

That you need to lean the mixture out this much may mean that your choke plungers are a bit worn (allowing some additional fuel mixture past), or the pilot jet needs to come down one size (not common, of all other is stock).