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A A A A Author Topic: Stalling/plunging idle under hard braking  (Read 334 times)

cx_3121

Stalling/plunging idle under hard braking
« Started on: 25-Sep-21, 15:49 »
Hi. I know this has been discussed here before with no real results.

1981 cx500 stalls or experiences massive idle plunge under heavy braking.
I have replaced ignition (Ignitech) and traced and eliminated any electrical issues.


I have Murray’s round slides. Runs GREAT through the rev range, just this little annoying issue at idle/braking.
Idle is also fluctuating a bit and high after a nice long run at high speed.

Have checked for leaks and checked float levels.

Here’s me just pushing it across the lawn and grabbing the brake…..

https://drive.google.com/file/d/1QLyrb9WmAPOje2zHWe0QI7eGx-1_eilK/view?usp=sharing

Really pulling my hair out over this one.....

Seagrass

Re: Stalling/plunging idle under hard braking
« Reply #1 on: 25-Sep-21, 20:35 »
Your video requires a login to get to it.

I am going to suspect a vacuum leak is the cause but I have not been able to watch the video.

Seagrass

cx_3121

Re: Stalling/plunging idle under hard braking
« Reply #2 on: 26-Sep-21, 07:25 »
Sorry, all fixed. Please try the video again.

Seagrass

Re: Stalling/plunging idle under hard braking
« Reply #3 on: 26-Sep-21, 08:03 »
Thanks for fixing the video.

It appears that there might be a problem with your throttle cables. The CX has a push cable and a pull cable for the throttle and it appears this may be the cause of your problem (throttle is being forcibly pushed back to the off position too far).

@CX PHREAK may be able to offer more advice

Seagrass

cx_3121

Re: Stalling/plunging idle under hard braking
« Reply #4 on: 26-Sep-21, 09:05 »
The cv carbs are long gone. I have Mikuni slides so no return cable. I’ve even raised the tank mounts 10mm to make sure there’s definitely no cable pinching.

CX PHREAK

Re: Stalling/plunging idle under hard braking
« Reply #5 on: 26-Sep-21, 12:35 »
I have mikunis on one of my bikes.

A rich mixture can cause a plunging idle as can incorrect float levels.

This seems to cut out so quickly that it actually seems like the spark has been cut.

Brake lines aren't contacting a loose connector or anything like that? Will it stall with the brake if not moving?

On another note, where did you get that fork brace?

cx_3121

Re: Stalling/plunging idle under hard braking
« Reply #6 on: 26-Sep-21, 20:38 »
Fork brace was a CNC project my Dad and I made.

I can make it do it with the rear brake if I really stand on it. It’s definitely a momentum thing.

I think I might make up a tank from a sauce bottle, go for a ride and see if I can see what moves under the tank area when I brake.

What’s the standard mixture setting for the Miks? 1.5 turns out?



CX PHREAK

Re: Stalling/plunging idle under hard braking
« Reply #7 on: 26-Sep-21, 22:50 »
Starting position of 1.5 turns out. Maximum of 3 turns out or the pilot jet is wrong. Ditto going in.

This may help.

http://www.mikuni.com/pdf/vmmanual.pdf

Also, out is leaner with the miks as the screw is an airbleed.

 


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