Join Date: Jun 2018
Location: Sumter, SC
Model: Goldwing GL1500 Aspencade
I haven't yet solved the problem, but I feel that I'm getting very close to identifying the issue. Today was 97 degrees and hot, and that's when the bike jerks and spark-knocks even worse, and that was with 93 Octane fuel. It does it even worse with 87 Octane fuel.
Anyways, the bike cruised beautifully at highways speeds at about 70mph to 85mph. Once I slowed to 45mph in OD, I decided to overload the engine and duplicate the issue. I would snap the throttle to 3/4 to full, and the left side of the engine popped and backfired I believe in the intake manifold. I was able to duplicate this over and over. It would jerk, pop, or spit on the left side of the engine. So let's review here.
What causes intake backfire? Feel free to add anything I've missed:
1. Vacuum leak
2. Sticking valves also leading to vacuum leak but is compensated at higher RPM's since the gases cannot escape fast enough
3. Improper ignition timing (Computer maybe?)
4. Lean fuel condition (accelerator pump or improper fuel metering)
My first guess is to check for leaky valves, so as soon as the bike cools down, I'm going to perform a compression test on the entire left side. I'm leaving out the right side since no popping originated from that area. Now since the left intake manifold is the only manifold with vacuum ports and lines, tell me if you think this might work. If I simply removed the forward and aft vacuum lines and plugged both ports, assuming that a leak is in the vacuum hose/tube system (in theory), wouldn't that eliminate the popping assuming that was the problem? Unless I am in error, the left intake manifold supplies vacuum to the following components: Let me know if I missed anything:
1. Cruise Control
2. PAIR Control
3. IASA Valve
4. Intake Heat Snorkel
Did I miss anything requiring vacuum which is supplied via the left intake manifold.
By God I'm going to solve this problem if it kills me. LOL I should go back to school and take a class strictly on the GL series engines; especially the older carburetor engines.
"Input! I need Input" Anyone remember what moves that was from? LOL