Wide-open throttle! How common is it

Jetting, Reeds, Air Filters, etc.

Wide-open throttle! How common is it

Postby ctman » Wed Jul 13, 2022 7:32 pm

2022 Xtrainer went “Wide Open Throttle” the other day during a race.
Before I could figure out what happened a tree took me out.
I do know it had nothing to do with the throttle cable.
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Re: Wide-open throttle! How common is it

Postby F5 Dave » Thu Jul 14, 2022 3:33 am

Well it's a PWK carb. Most common fitment on 2 strokes for last 20 odd years. So very uncommon.

Yes the most likely cause is the cable being pulled out by a branch and hanging up on the adjuster. It won't be wide open but it will feel like it when you close the throttle and it is still 10mm open. And then can snap back into place. People wire them.

I have had this happen when messing around with the needle at the track. Some dirt must have dropped down and got caught in the needle jet and needle. Damaged the jet so it would stick and damage the next needle you put in there. Scary .

Check for scratches on needle if you have replaced it at any stage.

You could try look at throttle assembly for debris in there. I also had this happen on a road race bike where there had been some crash damage and it kept degrading. Should have replaced it, my own fault. 2 operations and plenty of time sleeping in a chair.
21 XTrainer
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Re: Wide-open throttle! How common is it

Postby pscook » Sun Jul 17, 2022 7:42 am

It's very common on bikes with the Domino throttle as the cable is not secured to the throttle housing. This allows the cable housing to be pulled out by a branch or by something simple as turning the bars lock to lock and the housing catches on something on the bike.

There is a cable for sale somewhere that has the secured end, maybe Motion Pro? But another easy fix is to safety wire the cable housing to the throttle housing to prevent it being pulled apart. Lots of results on the web if you search for "safety wire throttle cable to housing."
Here's a video showing the process: https://www.google.com/search?q=safety+ ... Oq0r_YBA34
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Re: Wide-open throttle! How common is it

Postby pscook » Sun Jul 17, 2022 7:45 am

pscook wrote:It's very common on bikes with the Domino throttle as the cable is not secured to the throttle housing. This allows the cable housing to be pulled out by a branch or by something simple as turning the bars lock to lock and the housing catches on something on the bike.

There is a cable for sale somewhere that has the secured end, maybe Motion Pro? But another easy fix is to safety wire the cable housing to the throttle housing to prevent it being pulled apart. Lots of results on the web if you search for "safety wire throttle cable to housing."
Here's a video showing the process: https://www.google.com/search?q=safety+ ... Oq0r_YBA34

Got it: Motion Pro T3 cables:
https://www.motionpro.com/c/t3-cables
Extended versions are available and recommended. I had them on my GasGas back in the day as I had a couple of moments where the cable was pulled free during lock-to-lock turning situations. Not great.
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Re: Wide-open throttle! How common is it

Postby ctman » Mon Jul 18, 2022 9:54 am

pscook wrote:It's very common on bikes with the Domino throttle as the cable is not secured to the throttle housing. This allows the cable housing to be pulled out by a branch or by something simple as turning the bars lock to lock and the housing catches on something on the bike.

There is a cable for sale somewhere that has the secured end, maybe Motion Pro? But another easy fix is to safety wire the cable housing to the throttle housing to prevent it being pulled apart. Lots of results on the web if you search for "safety wire throttle cable to housing."
Here's a video showing the process: https://www.google.com/search?q=safety+ ... Oq0r_YBA34


Thanks for the info I will check out the cable ties when I get the bike back from the dealership.

The first thing I thought was the cable had been pulled from the housing but I was on a straight stretch with no branches on limbs to pull the cable.
The bike over revved with out working the throttle.
I know I should have pulled the clutch but the first thing I thought was turn the throttle back and hit the breaks, it all happened too fast.
25’ later into a tree I’m left with with a pile of bike a broken thumb and bruised ribs.
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Re: Wide-open throttle! How common is it

Postby fenderworks » Mon Jul 18, 2022 3:43 pm

handguards? were the handguards attatched to the end of the handlebars? (like my enduro engineering handguards) were they binding up and causing the throttle to stick?

just thought i would ask.

hope you are feeling better.
fenderworks
pueblo, co
2020 Beta Xtrainer, Fmf turbinecore 2, AMP modded front suspension, TMD skid plate.
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Re: Wide-open throttle! How common is it

Postby F5 Dave » Thu Jul 21, 2022 12:48 am

ctman wrote:[
I know I should have pulled the clutch but the first thing I thought was turn the throttle back and hit the breaks, it all happened too fast.
25’ later into a tree I’m left with with a pile of bike a broken thumb and bruised ribs.

Ahh, good old hindsight. It catches you off guard when your mind is on riding, yet the action you took was to back off the throttle, but the carb didn't believe you.
It feels like betrayal and if you had a moment to reflect on the best course of action you might say, to heck with the racing engine, I'll pull the clutch.
But you don't. However this is good practice. Now you have another option in your brain stored if it happens again.
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