Craftsman YS4500 Briggs and Stratton 21HP Intek Single Cylinder Problem

[MasonH]

Briggs & Stratton 331877 21HP Intek Single Cylinder

Hi all - I am new to this site because I need some help with getting my riding mower to start. Here is the situation:

I rebuilt the engine after the camshaft broke. New camshaft, new governor, new (uised) sump, new gasket, etc.

I followed all the correct procedure - including lining up the timing marks, and I also installed a new governor which had been destroyed.

I buttoned it all back up and put oil in it. I torqued down the cylinder head and adjusted the valves in accordance with the correct procedure.

When I first went to start it - it started right up and ran for a while - then got rough and died - since then it will not start.

I checked the valve clearances, cleaned out the carb thoroughly and checked for spark and compression pumped up to 90 psi and held. I clearly can see the pushrods working with the valve cover off and re-checked the clearances at least 5 time now.

I notice when I push the throttle lever forward nothing really happens to the throttle valve on the carb - it doesn't move at all, but the choke level opens and closes correctly.

When I move the governor lever back and forth it moves just a very small amount like 1/4" or less. I am wondering if this is the issue? How much movement should there be in the governor lever? I did try adjusting it by unloosening the clamp nut - turning the governor shaft towards the back and holding the lever towards the back all the way and then tightened it down - but this had no effect.

Could it be that the governor broke or went wonkie inside the sump? Before I take it down again I thought I might ask here and be sure?! Or is there a way to adjust the lever that I am not doing?

For reference I attached is a pic of the lever (this is before I did the rebuild and cleaned everything up.)

Thank you kindly for your replies - my wife will be overjoyed when and if I ever get the lawn mowed - its been 3-4 weeks now and the same amount of time of nagging and whining. ;-)

 

[Rivets]

Can you take a second picture where we can see the top of the carb. I think I see a problem, but don’t want to guess without more info.

 

[MasonH]

Hi - okay - I am attaching pics of the throttle and choke carb levers with throttle control lever pushed all the way forward (choke) and all the way back) - and also showing the governor lever (forward and back) - now that I look again I do see the governor lever moving forward and back and seeing more movement in the throttle valve lever - hopefully you can see the amount of movement - not sure what I did different - but I had the carb off and remounted it.
Forget to mention - new fuel filter. Also the start motor spins the engine quickly and easily - no compression stop - and I can clearly hear and feel the compression spring when turning my hand to adjust the valves.

Thanks!

 

[Rivets]

You first picture had the choke linkage in the wrong position, but you have changed its location to the right position. That is what was confusing me. Now my question is, after you Reassembled the engine did you do a static adjustment on the governor. This manual might help you out. https://docs.google.com/open?id=0B6NaqjIxWV1ybEN0LWo3azl6OUU

 

[bertsmobile1]

Did you remove the flywheel when you did the job ?
If so check that the key has not broken so the engine is electronically out of time.

 

[MasonH]

Yes I did remove the flywheel and I replaced the key. Rivets - thanks for the link to the manual - that is great to have.

Update: I finally got it to start again after removing the small black stopper on the carb solenoid plunger. I cleaned the plunger well with carb cleaner and can hear it clicking when connected but in the meantime I just removed the black plug piece. The engine started but didn't pick up speed - just ran doggy and loud at the valves - so I'll wait for it too cool down and check the valves again. At least it will fire up now - and hopefully I can get it running right. I had got inside the carb bowl to clean the float needle and the rest - it was very clean acutally - but I may have to re-check it and make sure everything is good inside there. I appreciate your inputs - I knew it had to be something "simple." and thank goodness I don't have to dig into the sump again.

 

[MasonH]

Update - one of my pet peeves on these forums is when people don't reply or update their questions so that others may profit from their findings and experience. So, I hope the hours of frustration I spent chasing down a rabbit hole will help somone else. I finally found the cause of the problem - after going through everything and even replacing the carb with a brand new Walbro - still motor would spin freely bit never fire up. Checked valve clearances multiple times, had spark, new carb with clear fuel hoses, good compression, no bent pushrods, no issues with the valves or cylinder head, new flywheel key....and there was the culprit! Because the remaining symptom was the carb bacfiring from the intake I had to conclude that the gas wasn't getting into the cylinder, i.e timing issue. Although I had looked at the flywheel alignment with the key several times it looked fine - however on closer inspection sure enough the key was sheared and the flywheel had moved 180 to the other side. Now its just a matter of getting the flywheel key and putting it back together and I am expecting much better results.

 

[Scrubcadet10]

what were you torquing the flywheel bolt to?

 

[Rivets]

Briggs part number is 222698.

 

[MasonH]

@scrubcadet - you know that may be the cause of why it sheared because I tightened it down but not to the 100ft-lbs spec. I was going to torque it later when I got the lower pulley back on. Also, the key did not slide in freely I had to tap it in and I thought at the time that was not good on my part. So this time I am going to deburr it with a small file or whatnot.

@Rivets - thanks for the part#!