Steve Saunders Goldwing Forums - View Single Post - 1997 Goldwing GL1500 Jerks under 2,000 RPM

View Single Post
post #5 of (permalink) Old 06-09-2018, 05:24 AM
DaveO430's Avatar
Join Date: Nov 2007
Location: Amity, Arkansas, USA
Model: 2010 GL1800
Posts: 24,013
Originally Posted by GoldwingA1500 View Post

Here is another symptom I've noticed. When I replaced the IASA valve, there are three hoses attached to it; one side has a large vacuum hose with plenty of pull; the other large hose pulses. The 3rd hose is a very small vacuum hose. I believe constant vacuum from the small hose is applied to the valve keeping it closed. But when you snap the throttle closed, the momentary drop in vacuum pressure moves the switch in the open position, thereby allowing exhaust gases to temporarily flow back into the left and right intake manifolds; this allows for a reduction of fuel delivery from the carbs to high RPM deceleration, and also reduces the chances of rear wheel lockup. Once you come to an idle or stop, the IASA valve closes and the engine then receives fuel from the carbs.

You're close but off the mark. What that valve does is allow extra air into the intake on high vacuum situations, i.e. deceleration to keep deceleration from being too harsh. If it wasn't closing it just wouldn't idle and if it didn't open you would probably learn to refrain from closing the throttle too quickly.

With no God over the state, the state then becomes not the defender of liberty but the definer of liberty.

NRA endowment life member
Wild Rhino Arkansas chapter
2010 1800 pearl yellow

If I disagree with you it's simply because you're wrong.
DaveO430 is offline  
For the best viewing experience please update your browser to Google Chrome