Stalling at idle after hot highway ride

[Bjorn]

Hey guys,

Question about some symptoms I just experienced. Its very hot today (32°C/90°F) I did a test ride with my new exhaust. First hour no issues with normal riding at B roads. On my way back I did some higher speed testing on the highway. Strong headwinds, riding 130kmh (80+ mph) for about 5-10 minutes.

Coming off the highway first traffic lights, bike stalls without warning. Bike did this before, so I just restart, stalls again even with some more gas. Starting again and taking off is troublesome, felt like riding on 1 cylinder and was way down on power. After some more throttle the bike picks up speed. Slowing down at the next stop, the bike stalls again.

Luckily I was home and I'm letting the bike cool down now.

What could these symptoms be?

 

[Bjorn]

Checked fuel, tank half full, on reserve.

Guessing overheating? Had the bike on the Dyno last week. A/F was hard to read with the probe hard to place inside the exhaust. Measurements did show lean spots. Not sure if this is the case, or the measurements are off. I'm planning on changing the exhaust to solve this in the near future.

But for now I just want to make sure I didn't damage anything...

Red line is the exhaust I'm running now.

 

[Bjorn]

Pulled the plugs, they look fine to me. Not ultra white, and no metal particles.

Borrowed a scope. Resolution is not great but I can clearly see the cross hatching (good), but also some faint vertical marks....

How bad is this? I have no experience or reference for this.

 

[Jan_P]

Typical symptoms for Not Charging the heat and high speed can have heated something. up
Not always permanent fault --- if not it will run fine on cold upstart.

I had one stock regulator overcharge warm days and at higher highway speeds I found it via having a Voltmeter installed
could se the overcharge over 15 V
New regulator and rectifier and no more problems the new wiring for them perhaps also helped

 

[Bjorn]

No voltage issues, according to the voltmeter i have on the bike. I'll try the bike to see how it goes.

 

[gggGary]

I'm guessing vapor lock, how is it running riding today?

 

[gggGary]

I went back and looked at some of your previous posts....

guessing STRONGLY suspect vapor lock.
Might want to think about a heat shield 'tween the inny and the outy.
Check that vinyl vent line for melting too.

 

[Bjorn]

Vapor lock? Are you refering to where the fuel tank creates a vacuum? Or something like overheating the float bowl of the carb?

 

[Bjorn]

I just did some more testing.

Oil level checked
Cold compression test WOT:
- LHS 150psi
- RHS 140psi

Bike started normal, I rode around the neighborhood no issues. But after like 10min of riding I noticed some weird things:

- Tachometer is fluttering
- bike does not feel "smooth" at constant throttle.
- noticing that the voltage meter is showing around 13,4v max. Normally it would be around 14,0-14,4.

Drove back, starting to mis a beat every now and then.

 

[gggGary]

overheating the float bowl of the carb?

This.

 

[Jan_P]

Dont remember your setup Possibly the alternator rotor gone bad
13.4 is about what a good battery can have ( almost )
If multiple fuses on a stock bike one can run on battery a while fuse removed Without charging circuit connected

Inspect brushes and try measure slip ring resistance other possibilities

 

[Bjorn]

thanks gary, ill look into this!

Im running a VAPE 270°system.

Im confused by the observations about the charging system. Maybe ill try to run the bike with a (new) battery from my other bike.

 

[Bjorn]

Pulled the alternator cover, smells incredible burnt! Looking through the holes in the rotor I can see Molten pieces of insulation.....

 

[Its been a long time]

Oh dear. That looks like expensive trouble.

 

[Jan_P]

Be sure to check the regulator .. also
It can have burnt first and then the alternator .. Replacing the alternator and not regulator can fry alternator again
VAPE can have support.

 

[Bjorn]

Normally om doing root cause analysis for my work as an engineer. Today in doing it at home.

I found the root cause of my problems. I would love to share it but I've contacted the seller (and in his turn the OEM) first.
The problem is very clear, but I want to give them a chance to respond first before I put it on the internet.

Hope you understand!

I'll definitely get back on this topic if I have news.

Just sucks it's this middle of the riding season

 

[Jan_P]

Sorry to hear about the setback.
Maybe you have the stock alternator and regulator still in house
We know you are skilled mechanic .If the TV program is bad it can be a 2 - 3 hours work
put in the old parts for now.
And the fried rotor and side cover needs to come off anyways.

 

[Bjorn]

Little update:

I found the root cause quite quickly. The two bolts holding the stator in place lost their torque and failed. One screw was completely out! Allowing rotation of the stator and loosening the second screw. This one was only in place due to a blob of molten plastic holding it in place.

It funny, I do root cause analysis as part of my engineering work in the automotive industry. Basically it comes down to:

- insufficient specified tightening torque for the bolts, resulting in the failing.
- tightening torque not reached in production, therefore failing.
- in addition no measures were taken to prevent the loosing the screws in the threads, like loctite.

 

[Bjorn]

So obviously I contacted VAPE, since this is a production related issue. These are not bolts that I or any end user needs to touch during installation.

Today I got the official response from VAPE, they will not accept the claim, because the production date of the parts > 2 years (according to them).

Funny that I bought this set 1 year ago. Apparently the shelf live is an issue for the end user. Nevertheless it's a ridiculous reaction, it's obvious that they don't really value the end user and just want to sell products.

 

[Bjorn]