New Carb Set-up

I am seeking tips to help me. I installed a brand new aftermarket carb and the carb is installed and throttle cable is on and routed fine. All seems ok. When I start the bike I am seeming to get full wide open throttle without turning the grip at all. The mixture and air screws have not been touched yet.

How would I go about solving this issue? There are only two screws for adjustment on the carb. One air and one throttle stop. Here is the new carb. My bike is 1970 ST70, any and all tips would be very helpful.

It sounds like a stuck float to me after thinking about it. How would you fix or check that?

See if the slide isn't installed wrong.
When it's turned, it won't go all the way to the bottom.
Also, check the needle and fitment of all pieces.
If it would be the floater, it should leak fuel.

Try unscrewing(anticlockwise) the throttle stop screw, also make sure you have some slack on the cable, or as waynus said slide incorrectly fitted,does the throttle feel like it has full movement(twist),and not just slack play.
A very weak fuel mixture will also cause engine to race to an extent.

Chief wrote:Try unscrewing(anticlockwise) the throttle stop screw, also make sure you have some slack on the cable, or as waynus said slide incorrectly fitted,does the throttle feel like it has full movement(twist),and not just slack play.
A very weak fuel mixture will also cause engine to race to an extent.

I took out the slide twice and made sure it is in properly and goes to the bottom. The throttle feels like it is slack for 1/2 turn of the throttle and then picks up the slack and has tension. Still racing at full bore. I turned out the idle screw all the way, a few turns in and by increments but there was no difference.

There is something wrong here, probably simple again, as is in most cases. I kick her over and she races all out.

Try looking into carb from inlet manifold side(remove it first)dont remove slide and look for slide to be completely closing hole,dont forget cutaway in slide always faces airfilter.operate the throttle and observe slide for correct movement up and fully down. If this checks out OK I would suspect major air leak at manifold/head or to carb

Chief wrote:Try looking into carb from inlet manifold side(remove it first)dont remove slide and look for slide to be completely closing hole,dont forget cutaway in slide always faces airfilter.operate the throttle and observe slide for correct movement up and fully down. If this checks out OK I would suspect major air leak at manifold/head or to carb

Chief..... I took off the carb, left it connected. I look in there and see the jet. I turn the throttle and nothing is moving. I do not see the slide at all in there and the jet looks like it is just down and not moving when I turn the throttle. All I see in there is the jet. Does that mean the slide if not working?

In other words I dont see the slide at all just the jet when looking into the carb from the front of the bike to the back.

DaxST70 wrote:

Chief wrote:Try looking into carb from inlet manifold side(remove it first)dont remove slide and look for slide to be completely closing hole,dont forget cutaway in slide always faces airfilter.operate the throttle and observe slide for correct movement up and fully down. If this checks out OK I would suspect major air leak at manifold/head or to carb

Chief..... I took off the carb, left it connected. I look in there and see the jet. I turn the throttle and nothing is moving. I do not see the slide at all in there and the jet looks like it is just down and not moving when I turn the throttle. All I see in there is the jet. Does that mean the slide if not working?

In other words I dont see the slide at all just the jet when looking into the carb from the front of the bike to the back.

Thru the tips on this issue I concentrated on the slide. Removed and reinstalled 4 or five times to no avail. Then I turned it 180 degrees no difference. I turned it back and it dropped all the way down. Maybe something was sticking like the cutaway had a bur? Now the carb is running great. I had to adjust the idle and air so I kicked it over.... no start.... after 2 minutes of kicking I turned the ignition key on and it started up. Duh! Always simple things that make seemingly simple jobs difficult.

The slide was the correct area to concentrate on. Thanks for all the tips. I dont know what we did to eventually fix it but it now works fine although there is absolutely no throttle return unless I bring it back with my wrist. Thats a separate and bothersome issue.

Glad to read you sorted it Dax,must of been quite alarming when starting and stuck on full bore!
Do be carefull though that problem is resolved as the consequences can be dire if occurring while your wizzing about!
Happy riding,Chief.

Chief wrote:Glad to read you sorted it Dax,must of been quite alarming when starting and stuck on full bore!
Do be carefull though that problem is resolved as the consequences can be dire if occurring while your wizzing about!
Happy riding,Chief.

Thats good advice Chief, will keep my eyes on it.