The valve lash on my 20hp on one bank got so bad both pushrods came out of their seats and got bent. No damage was done to the head thank god. I had to bend the pushrods back into shape just to get by until I can get new rods & the exhaust valve guide. It backed out and I think caused the intake pushrod to jump out of the rocker. I'm just limping it along, adjusting that cylinder every time before I mow before I get it repaired. It's pretty costly to have a shop do it as I'm an automotive mechanic and dont have the tools to do it myself. I can rent what I need perhaps but i dont want the headache. Rather just bring the head to a shop.
You need to turn the motor just over TDC to get past the compression release, if you turn it over while using the feeler gauges you will feel the right spot. Thanks for the video.
Failed to mention, four strokes have 2 TDC , compression and exhaust. Get this wrong you got a problem. Adjust valves on compression, when rockers will be a little loose,
1/4" past TDC as well. You can hear/feel this. Correction. You hear the lobe just before TDC then feel it 1/4" past TDC. Compression release is the theory behind this. I've always done it.
It wouldn't crank when the flywheel/perforated wheel was in a certain position. If I moved it by hand, it would start. After I adjusted the vslves. It starts without issues.
great video... how did I never learn about this until today??? BTW - I appreciate all the background noise and times when you blocked the camera... that stuff happens to me all the time
@@alan93 sure there is, both valves should have a gap on that stroke, hence them not being open and allowing the combustion chamber to be sealed to compress gasses. If either valve is open while at tdc you need to rotate the motor to the next stroke.
@@marksalamack6133 it wasn't meant for people that don't understand how engines work, there is a fair bit of people that should stay out of an engine. Myself may be included in that category lol
Very good video! I/we just discovered out of the blue my g/f's Craftsman with a V twin that will only crank up to compression and then stops turning. Brand new StrongBox battery. Cables and connections pristine. Got to be those clearances.
Good video, but.... next time use a straw instead of a screw driver to check for TDC. Once you find TDC, rotate the engine until the straw goes back in 1/4". This is because the valves should be adjusted just a tad bit below TDC. Once you have the piston (and the valves) at the correct position, make a mark on the flywheel relative to the plastic cover to mark TDC. After you adjust one side, rotate the engine 1 full revolution, that should get you VERY CLOSE to the TDC for the OTHER cylinder. Use your straw to check for the correct position of the cylinder/valves.
I'm trying to figure out how you did a piston ring replacement job and put the engine back together WITHOUT adjusting the valves and it still ran!!! wtf?
Real simple. I've done it too. When you're putting the heads back on and reassembling the valve parts, you start it out at 'yeah, that kinda sorta feels right enough to hold stuff together while I finish the rest of the reassembly' with the intent to go back later after rotating the engine a few times revisiting that with feeler gauges. Sometimes it happens.
If the valves are tight TDC, doesnt that indicate you are TDC on the exhaust stroke? I was under the impression on the compression stroke at TDC the valves are not tight and adjustment should be made on compression stroke.
Yes, he is at the wrong TDC in this video....valves are tight when they both should have some slack. So he's actually adjusting the rockers to DOUBLE the gap. Sure hope he didn't try to start the engine afterwards !
How to you know which valve is intake or exhaust.when you were showing how to find tdc on of the rockers was still tight and about to open so you turned it again to tdc till both rockers had slack. I'm guessing the valve that opened just past tdc was exhaust..is this right . I'm doing it tomorrow on a 23hp vaguard in my argo.. never did valves before.2 stroker here . Looks super easy though. But I'm hoping it's why it wont turn over at startup. To much compression.and I'm hoping it's just adjustment and not a blown up camshaft compression relief doohickey !!
So the valves became too tight? I would expect them to get loose over time. Mine is running fine for about 30 minutes then it immediately becomes rough with a loss of power. Would this be more likely a valve adjustment issue or sticky valve or bent rods?
Doesnt carbon build up between the valveseat and valve causing it to become farther from the rocker, thus causing a larger gap over time? Esp on the exhaust valve??
Opened the engine found the cam decompression valve failed. New cam on order....and it was not a V twin.. it was a single cyl. Housing cover is deceptive.
YOU DONT KNOW WHAT YOUR TALKING ABOUT THATS NOT THE OILPUMP THATS THE FUEL PUMP AND WHY YOU NEVER ADJUST VALVES WHEN YOU TOOK APART ENGINE THINGS CHANGE WHEN YOU TAKE STUFF APART CAN SEE YOUR NOT THAT EXPERIENCED
I got confused. You said .004” on the intake, and .006” on the exhaust. Then you set both at .006”
The valve lash on my 20hp on one bank got so bad both pushrods came out of their seats and got bent. No damage was done to the head thank god. I had to bend the pushrods back into shape just to get by until I can get new rods & the exhaust valve guide. It backed out and I think caused the intake pushrod to jump out of the rocker. I'm just limping it along, adjusting that cylinder every time before I mow before I get it repaired. It's pretty costly to have a shop do it as I'm an automotive mechanic and dont have the tools to do it myself. I can rent what I need perhaps but i dont want the headache. Rather just bring the head to a shop.
You need to turn the motor just over TDC to get past the compression release,
if you turn it over while using the feeler gauges you will feel the right spot. Thanks for the video.
Biggs & Stratton recommends a 1/4 inch piston travel
I feel its trivial but I've always abided.
Failed to mention, four strokes have 2 TDC , compression and exhaust. Get this wrong you got a problem. Adjust valves on compression, when rockers will be a little loose,
1/4" past TDC as well. You can hear/feel this. Correction. You hear the lobe just before TDC then feel it 1/4" past TDC. Compression release is the theory behind this. I've always done it.
Thanks for posting this. Cured my hard to start mower!
Was your motor hard to start cause it didn't turn over. .or turned over but wouldn't fire?
It wouldn't crank when the flywheel/perforated wheel was in a certain position. If I moved it by hand, it would start. After I adjusted the vslves. It starts without issues.
@@glennmilles341 ok,good to hear..I'm having the same troubles. Going to check valves tomorrow. 23hp vanguard in an argo 6x6
Great camera work. 👍
Thanks for the video my zero turn runs like a top now 👍
great video... how did I never learn about this until today??? BTW - I appreciate all the background noise and times when you blocked the camera... that stuff happens to me all the time
Thanks Bro, very helpful
Thanks for the info. Going to do this for the first time in my life.
You just adjusted both valves at the same time at TDC on compression stroke I believe ! Both valves should be fully closed at that point !
Briggs actually says that piston should continue past tdc down 1/4 inch .this ensures intake is past the compression release position.
Correct, 1/4" past to dead center on the compression stroke.
It would seem there is no way to determine this for a novice.
@@alan93 sure there is, both valves should have a gap on that stroke, hence them not being open and allowing the combustion chamber to be sealed to compress gasses. If either valve is open while at tdc you need to rotate the motor to the next stroke.
@@lundyracing That is a concise, yet thorough explanation...thank you
@@marksalamack6133 it wasn't meant for people that don't understand how engines work, there is a fair bit of people that should stay out of an engine. Myself may be included in that category lol
If you rotate the motor CCW, you defeat the compression release and when you get to TDC back it off 1/4 inch. Always do the intake first
I noticed that the 16HP Vanguard service manual said to adjust at 1/4 past TDC. Does that mean that the piston travel (i.e. piston drops 1/4")?
@@mkshffr4936 you just go to TDC and then 1/4 below TDC
If you’re lucky, a valve adjustment is all you need. My B&S camshaft with compression release broke, making it very tough to start.
Valve adjustment fixed mine.
Thanks for the instructions, that is a fuel pump not oil pump. The hose you disconnected is a breather hose.
No it’s not a breather hose it’s a vacuum hose to operate the Fuel pump
Thank you for this video! I always wondered how to turn the crankshaft without running into all the interlocks for the blade (power take off).
MRI DYI do you have a video on valve service/ adjust on the Briggs flat head Quantam L heads?
Very good video! I/we just discovered out of the blue my g/f's Craftsman with a V twin that will only crank up to compression and then stops turning. Brand new StrongBox battery. Cables and connections pristine. Got to be those clearances.
I could be compression relief went kaput like they are famous for. And that's a complete engine teardown
Thanks
@@jamiehalifax4954
Thanks
Or the compression release lobe on the camshaft.
Or the valve guide backed itself out of the head and it bent your pushrod.
The decompression mechanism failure is common on the single cylinder engine, but the twins need valve adjustment. (so I am told)
The valve adjustments are often overlooked.
Thanks brother! Quick and easy....Great video...
Good video, but.... next time use a straw instead of a screw driver to check for TDC. Once you find TDC, rotate the engine until the straw goes back in 1/4". This is because the valves should be adjusted just a tad bit below TDC. Once you have the piston (and the valves) at the correct position, make a mark on the flywheel relative to the plastic cover to mark TDC. After you adjust one side, rotate the engine 1 full revolution, that should get you VERY CLOSE to the TDC for the OTHER cylinder. Use your straw to check for the correct position of the cylinder/valves.
I'm trying to figure out how you did a piston ring replacement job and put the engine back together WITHOUT adjusting the valves and it still ran!!! wtf?
Real simple. I've done it too. When you're putting the heads back on and reassembling the valve parts, you start it out at 'yeah, that kinda sorta feels right enough to hold stuff together while I finish the rest of the reassembly' with the intent to go back later after rotating the engine a few times revisiting that with feeler gauges. Sometimes it happens.
the intake is top.. right ?! He pointed to bottom one and said "intake"
Do you do that on cylinder 2 as well
I liked the video. You said you like intake at .004, then you adjust to .006 in the video.
Maybe rewatch as he explains that.
What you are working on would help.
Is is possible to turn the output pulley instead of removing the top cover
.
Yeah
If the valves are tight TDC, doesnt that indicate you are TDC on the exhaust stroke? I was under the impression on the compression stroke at TDC the valves are not tight and adjustment should be made on compression stroke.
Correct
TDC compression. some make mistake of TDC exhaust.
That's why you finger cap the spark plug hole, turn the motor till compression blows your finger off the hole then use screwdriver to achieve TDC.
Yes, he is at the wrong TDC in this video....valves are tight when they both should have some slack.
So he's actually adjusting the rockers to DOUBLE the gap. Sure hope he didn't try to start the engine afterwards !
Is there a way to provide a picture of this decompression mech? I took a couple of pics and can share these; not sure how here.
How to you know which valve is intake or exhaust.when you were showing how to find tdc on of the rockers was still tight and about to open so you turned it again to tdc till both rockers had slack. I'm guessing the valve that opened just past tdc was exhaust..is this right . I'm doing it tomorrow on a 23hp vaguard in my argo.. never did valves before.2 stroker here . Looks super easy though. But I'm hoping it's why it wont turn over at startup. To much compression.and I'm hoping it's just adjustment and not a blown up camshaft compression relief doohickey !!
exhaust is nearest where exhaust pipe comes out of head. intake is near carb.
So the valves became too tight? I would expect them to get loose over time. Mine is running fine for about 30 minutes then it immediately becomes rough with a loss of power. Would this be more likely a valve adjustment issue or sticky valve or bent rods?
Nope, valve clearance always gets tighter over time. Has to do with the valves hitting the seat and them getting pushed out over time.
@@lundyracing I found out mine had a left side coil go bad. Repaired. Runs great now.
Doesnt carbon build up between the valveseat and valve causing it to become farther from the rocker, thus causing a larger gap over time? Esp on the exhaust valve??
They wear looser but valves sometimes sink in cylinder head making them tighter. Then they could have been adjusted wrong.I never knew what to expect.
Valves will tighten up as the metal gets hot and expands losing the clearance
Thanks for the video very well explained !
Where can I get a fuel pump exactly like that one for cheap
I just purchased one from Ebay, $7.60 total. My old one was leaking fuel.
Is there going to be oil in that area
Usually is
👍
set them both on 4 thousands
is that what manual says ?
@@jamesweigand7524 .004-.006
Opened the engine found the cam decompression valve failed. New cam on order....and it was not a V twin.. it was a single cyl. Housing cover is deceptive.
The decompression mechanism failure is common on the single cylinder engine, but the twins need valve adjustment. (so I am told)
Could not see what you was doing
00:57 the oil pump... Uh, yeah....the oil pump that sucks gas into the carburetor.
Obviously a misspeak. Feel special?
Oil pump???? petrol/gas pump..
It's a fuel pump not a oil pump
YOU DONT KNOW WHAT YOUR TALKING ABOUT THATS NOT THE OILPUMP THATS THE FUEL PUMP AND WHY YOU NEVER ADJUST VALVES WHEN YOU TOOK APART ENGINE THINGS CHANGE WHEN YOU TAKE STUFF APART CAN SEE YOUR NOT THAT EXPERIENCED