briggs timing

[fowler]

ok this is a bit differant as the engine is on a ride on lawn mower but u guys seem the best to turn to and this engine can be used on a kart

the engine is an 18hp briggs and straton Vanguard V2 which i assume means its a clone.

i was mowing this morning and somehow the spark timeing on one cylender has been thrown way out.
it is missfiring and back firing bad, it also has no power

so the question
how do i fix the timing on one of the cylenders (pics if possible).

oh yeah it is the left hand cylender from the poit of veiw of the driver.

thanks

 

[Russ2251]

the engine is an 18hp briggs and straton Vanguard V2 which i assume means its a clone.

Not a clone.
Sounds like a valve failure.

 

[Bluethunder3320]

yeah i think hes right. the timing cant really jump gears one day.

 

[fowler]

bugger
what makes u say that
i did think it would be odd because it happened during operation

 

[Bluethunder3320]

a bent valve wont seal all the way and whenever the gas comes in theres always a hole to blow all of the ignited gas out of

 

[fowler]

are yes
well i live 130 km out of town so it looks like im not mowing.
but just in case how would i ajust the spark timeing.

 

[Bluethunder3320]

i dont know if its possible. your flywheel is factory set with a keyway on the crank and the magneto cant be moved. its already set to blow just past TDC. i dont know what else to do than to take off the head and check the valve seats. usually you can bend a valve back with a hammer.

 

[fowler]

is there any way to see if there is a bent valve without takeing the head off

 

[fowler]

last question
should the rockers be parellel
because the good cylender is a little angled and the bad one looks like alot of angle

 

[sideways]

is there any way to see if there is a bent valve without takeing the head off

Do a compression test.

last question
should the rockers be parellel
because the good cylender is a little angled and the bad one looks like alot of angle

Pictures?

Thanks

Hayden

 

[fowler]

i have no compresion tester
ill go get the pics

 

[fowler]

sorry about the quality

 

[slideways]

Did you check the lash in this cylinder? You know how to do that right?

There is nothing that can create a timing problem on just one cylinder. The timing is the same for both and can not change unless the flywheel key shears.. then both cyls will not run well.

Check that and let us know. I have alot of experience with the Briggs Vanny motors. They are far from clones.. about the best thing you can get nowadays.

 

[Bluethunder3320]

just put ur finger overt the spark plug hole and you can tell if its low

 

[sideways]

usually you can bend a valve back with a hammer.

No, you can't, a hammer is no where near accurate enough, a valve can be bent by 10 thou and you'l loose compression, I'm sure you can't hammer some thing accurately to within a few thousands of an inch. Also hammering the head of the valve will deform it, make it mushroom out and so on. Sure, you could try it as a I'm to cheap to buy a new one, I'l see if I can fix this kinda thing but it extremely unlikely that it will work.

sorry about the quality

Check for a bent pushrod.

just put ur finger overt the spark plug hole and you can tell if its low

10 psi will blow you finger off the hole, I think 60 PSI would be low on an engine like this. Sure, you can use that method to check if it any compression but not to see if it has enough.

Thanks

Hayden

 

[metalthrashinman]

i was mowing this morning and somehow the spark timeing on one cylender has been thrown way out.
it is missfiring and back firing bad, it also has no power

How do you know the timing is off, let alone on one cylinder; and how are you sure that it is the left one? What tools are you using to determine this?

How old is the engine, and how many hours are on it (approximately)?

Have you considered the posibility of a wiring problem? A bad ground perhaps... Remember that the ignition is controlled with voltage and can cause exactly what you are describing.

 

[Bluethunder3320]

http://www.youtube.com/watch?v=rAU-omdBmI8&p=09AF7C41D27F360C&playnext=1&index=9

 

[fowler]

How do you know the timing is off, let alone on one cylinder; and how are you sure that it is the left one? What tools are you using to determine this?

How old is the engine, and how many hours are on it (approximately)?

Have you considered the posibility of a wiring problem? A bad ground perhaps... Remember that the ignition is controlled with voltage and can cause exactly what you are describing.

ok i know it is only on one cylender because i took turns runing one cylender without the spark lead connected when only the lead was connected it ran fine (appart from the niose of a non firing cylender).

the engine is about 4 years old and has done 5611 hours it gets the air filter cleaned and an oil change twice a year.

there is plenty of spark based on the fact that when my dad grabbed the spark lead it gave him one hell of a shock and made him jump back.

im tempted not to pull it apart based on the fact it is very fiddly and i dont like small engines. ill practice on our old mower and see if it is worth the trouble or just take it to the small engine shop and let them sort it out.

 

[DustinWolfe]

ohhhhh those poor valve seats..... screwdrivers are definetly the tool for that job

 

[Bluethunder3320]

yeah well the metal right under the valve is soft enough... and it re seats even if you dont bend it back perfectly. 4 years isnt alot of time..... fvckin briggs these days...