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Scooters - 50cc => Agility 50 => Topic started by: scooterman11 on July 09, 2012, 05:17:45 PM

Title: What are the Symptoms of a slightly bent valve
Post by: scooterman11 on July 09, 2012, 05:17:45 PM

I am pretty sure i have a bent valve on my intake
i need to know what the symptoms are

Title: Re: What are the Symptoms of a slightly bent valve
Post by: wordslinger on July 09, 2012, 06:20:17 PM

..Check compression for verification...

..why do you think you have a bent valve?

..i ask, because i have never known one of these engines to have one...

Title: Re: What are the Symptoms of a slightly bent valve
Post by: scooterman11 on July 09, 2012, 06:24:51 PM

I recently installed a 70 cc airsal bigborekit to replace my stock setup, before i did this it acted like it was getting to much gas
it seemed to me that the intake valve wass sticking open, i noticed some pitting on the valve seat on the head
How ever I am running my stock valvetrain with the big bore kit
the more help the marrier

Title: Re: What are the Symptoms of a slightly bent valve
Post by: scooterman11 on July 09, 2012, 09:56:43 PM

the valve stem doesnt look to be bent, i think the valve seat on the head isnt seating properly
with the 70cc airsal kit i have 190 psi of compression with a high dome piston
with the stock setup i was only getting 150
Is it Possible my timming could be 180 degrees off
She has Bright Blue spark,perfect compression she just doesnt seem to want to wake up and go take me for a ride

Title: Re: What are the Symptoms of a slightly bent valve
Post by: streido on July 09, 2012, 10:23:09 PM

Have you got the jetting right?

Title: Re: What are the Symptoms of a slightly bent valve
Post by: zombie on July 10, 2012, 12:11:56 AM

If you had a leaking valve it would show brite clean metal in the area of the leak, and you would never get 190 psi.

Title: Re: What are the Symptoms of a slightly bent valve
Post by: wordslinger on July 10, 2012, 01:17:18 AM

...150??...190??...

..holy fuk!!!

Title: Re: What are the Symptoms of a slightly bent valve
Post by: zombie on July 10, 2012, 04:18:26 AM

They use a hi dome/hi compression piston.
Did you hit the valve? Is that why the post? The aluminum is so soft that the chances of bending a steel valve is pretty slim. If it did hit it was open. That would bend the stem and the valve could not seat. Therefore very low compression.
To test it just put the end of the stem in a drill, and check for runout.

Title: Re: What are the Symptoms of a slightly bent valve
Post by: scooterman11 on July 11, 2012, 05:28:31 PM

I have 190 pounds of compression, great blue spark, just doesnt want to seem to run or even fire up

Title: Re: What are the Symptoms of a slightly bent valve
Post by: zombie on July 12, 2012, 01:33:16 AM

The obvious answer is no fuel. Have you tried either, or manually adding fuel to the Cyl.? The only other reason is 180* out on the crank. Align the tdc marks on the flywheel/engine, and check the cam. The Big hole should be on top/center.

Title: Re: What are the Symptoms of a slightly bent valve
Post by: wordslinger on July 13, 2012, 02:35:04 AM

..yup..tdc ...


..spray a SPRITZ! starting fluid into the carb intake...

..if it fires, STOP!!  immediately, as that stuff burns lean!!...

..but it will tell you if you have a fuel delivery issue...

Title: Re: What are the Symptoms of a slightly bent valve
Post by: zombie on July 13, 2012, 05:58:03 AM

"..spray a SPRITZ! starting fluid into the carb intake..."

That is missing from my post as well. When my AV updates it cuts off my keyboard. Slinger gots it!

Title: Re: What are the Symptoms of a slightly bent valve
Post by: kanbisk on July 13, 2012, 09:32:04 AM

Quote from: wordslinger on July 09, 2012, 06:20:17 PM

..Check compression for verification...

..why do you think you have a bent valve?

..i ask, because i have never known one of these engines to have one...

4t have valve's

Title: Re: What are the Symptoms of a slightly bent valve
Post by: wordslinger on August 13, 2012, 12:06:26 PM

4t have valve's


..really??...woww....    :o

Title: Re: What are the Symptoms of a slightly bent valve
Post by: The Rookie on August 17, 2012, 10:36:11 AM

Kanbisk, you donut, he meant never known the engine to to have BENT valve!