86 spree w/ 85 nb50 swap. throttle sticks on startup

[sully865]

Hey guys, been here for about a year, and i've usaully found all the info i need from other posts but i'm stumped. It started revving to the sky immidiatly after i switched the throttle assembly to stock. Before, it was the spree throttle, and it seemed to work alright, it functioned at least. I figured it would run better on the aero throttle so i swapped it, however i didn't swap the entire cable just the part that goes into the carb. i cleaned the carb out, tried w/o the bystarter, tried with no throttle installed, thought extra air might have been getting in so i choke it hard with my hand and it does the same thing. i've examined that throttle moving in the carb, and it seats properly and slides perfectly. im stumped anyone have any ideas?

[motormike]

It seems you have a Spree with an Aero motor...is that right ?
Your description leads me to believe your were using the Spree carburetor "slide" in the Aero carburetor...and it worked fine.
Then, You switched to the Aero OEM slide in the Aero carburetor...and it revved uncontrollably.
Is that also true ? . . .

[sully865]

yes. sorry if i was confusing

[sully865]

cleaned the carb good. seems to be fine. Just curious as to if anyone here could tell me what couldve been not working in the carb. pretty dirty under the float, think that may be it

[motormike]

Sounds like you have it sorted after cleaning...

[sully865]

air filter fell off for about 20 feet. having the same problem again. dont know why a dirty carb would make it rev out of control. could an air leak cause this to happen? my carb screws to the manifold dont get very tight at all. They seem to "slip" when i tighten them maybe a a turn after is on the mani.

[Wheelman-111]

Greetings:

Quoth SullyCCMLXV:

my carb screws to the manifold dont get very tight at all. They seem to "slip" when i tighten them maybe a a turn after is on the mani.

You've just found your problem. It is not a trivial one. Loose carb lets in air, diluting your fuel mixture to dangerously lean levels. If that burns for a while, it WILL overheat and seize.

Those bolts can strip the aluminum carb threads with frightening ease. The fix can be as simple as getting a standard 1/4" SAE tap. and a 17/64 drill bit. Run the tap through the threads on the carb flange, then drill out the manifold and that brown plastic insulator. Use the correct length of SAE 7/16 hex bolts, being careful not to pop a hole in the carb bowl. Trim the bolt to the right length, which I think is a 1" on the outside and 1.5" - trimmed to suit - on the inside. Then go easy on the Wheaties when you remount the carb securely. Consider using a torque wrench set to no more than 6 ft.-lbs.

[sully865]

didnt want to tap it but it seems the best option. thanks for the help guys.

[Wheelman-111]

Greetings:

You can consider installing a thread repair insert, but it's a lot of trouble for an iffy fix. The bigger bolt will be more tolerant of ham-fisted tightening, and the carb threads are already toast.

[sully865]

carb is on tight, and set right. still having the same problem. I've tried using the oem slide, and the spree slide with no luck. I believe I forgot to change the spring from the aero cable, as I am using the spree throttle cable with the aero slide.everything I've Checked is sealed. maybe the reeds are stuck open? I'm yet to Check later on tonight.

[patthesoundguy]

Stuck reeds will be hard to start and bog in the bottom end. If you are not running the stock airbox and air filter it will be very lean and can rev a little funny. Or if the the idle speed screw is in too far or the idle ait mixture is all messed up. or the slide could be not lining up with the guide pin and it will rev like that.

[Kevinstonge]

Any results on this issue. Having a similar issue now. Swapped an 84 spree engine into an 86. Revved like crazy on start up. Swapped the 84 needle assembly to the 86( noticed the needles are different diameters) and no help. When riding while holding the brakes I can crack the throttle a notice a difference in rpms. This us leading me to believe it's either a massive air Leak even though everything seems tight..