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Hello all, hoping you can point me in the right direction. I have a 27hp v twin on my hasqvarna garden tractor that has begun to run rough while the PTO is engaged.

From the testing I have done so far the cylinder on the passenger side of the motor when sitting in the seat has spark but is not firing when doing the test of removing one wire at a time to see if the engine continues to run. When i remove this side the engine does not change but when I pull the drivers side off the engine dies leading me to believe this is my issue.

Ive tried swapping plugs with no change and both plugs are showing a good blue spark when tested.

Ive removed the valve cover on the dead side and the valves appearing to be moving freely with no excessive slop, but I havent checked the lash yet.

Any suggestions to check?

Hello,

If you have good spark (at the right time), you need fuel mixture and compression... If you have a compression tester it's easy to compare both cylinder. I don't know how your carb is but looks strange to have only one side working ?

When mine exhibited the same symptoms the cause was that one of the pushrods had popped loose and was just rattling around inside the valve cover. Did you verify that both push rods were in place and seated correctly when you had the valve cover off?

Elkins45 said:

When mine exhibited the same symptoms the cause was that one of the pushrods had popped loose and was just rattling around inside the valve cover. Did you verify that both push rods were in place and seated correctly when you had the valve cover off?

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I agree take valve cover off and look see

Also, make sure that you have determined the dead side, when doing the plug wire pull test, I have mixed it up in my mind before. Best to just pull both valve covers and check both sides while you are at it.

Thanks to those that replied, I tested compression and it looked fine, I think the problem is solved, the valve lashing was off on the dead side, primarily the valve with the aluminum push rod but the steel rod was off as well, owners manual called for .004-.006 on both so I set them to .005 and the dead side fired right up on its own

I checked the lash on what was the good side and it was sloppy as well so i dusted them them to .005 as well, both sides where set at 1/4" down from TDC

I temporarily put the valve covers back on and fired it up, sounded great like it did new, PTO has its power back no longer wants to die when turning it on, sounds like a helicopter taking off again, ran it for about 20 mins and then verified the lash was still good before sealing up the covers one last time.

Going forward how often so lash be checked? Hopefully this is the last time for awhile I have issues with then Briggs engine, first the sump gasket and crank seal went causing an oil leak, then a couple months later the governor came apart in the pan, prolly what messed up the lash since it never ran the same after.

In the process of troubleshooting the issue new coil packs where installed and the carb was torn down and cleaned.

Wanted to give a quick update, used the tractor a couple times over the weekend and both cylinders are running string, adjusting the lash did the trick.

Wanted to ask though I noticed for the first 5-10 minutes that the engine is fired up from a cold start the engine has a bit of a surge in rpms until the engine heats up then the surge goes away. I dont remember it doing this before

I recall when I replaced the governor it came with an insert that said if engine was produced before said date code 06081500 replace the governor spring to get correct rpm setting, i never did this and have just been using the one that was on it

With that said does anyone know the correct rpm for a 44Q777 2406G5 and also what could be causing the surging at cold start full throttle?

Briggs doesn't list a top rpm for your engine, but 3600 should be safe, idle is 1300. The surge just means that the engine is running too lean when cold, I wouldn't worry too much about it since it smooths out as it warms up. You should see how some of the new engines start.

ILENGINE said:

Briggs doesn't list a top rpm for your engine, but 3600 should be safe, idle is 1300. The surge just means that the engine is running too lean when cold, I wouldn't worry too much about it since it smooths out as it warms up. You should see how some of the new engines start.

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thanks, did they happen to have a lot of issues with this 27hp v twin? i see on the newer models they got rid of the 27hp and went down to a 24hp, i only have 250 hours on this thing, bought it used in fall of 2017 from an older gentlemen, already had to replace the oil sump/pan gasket (had the old style on it and looked like someone had been in it before due to the silicone gasket maker applied to the gasket, the governor came apart on me out of nowhere, and then the push rod adjuster/lock nut backed off on me causing the dead cylinder

Manufacturers change HP rating on a daily basis. Some of them are due to changes in manufacturing called product improvement. Other changes come about due to emission changes and the changes made to the engine reduce the HP rating. Some HP changes are due to the mower manufacturer says that they want a 24 HP engine because they are not willing to pay for the same engine with the 27 HP stickers. Maybe that 24 HP engine is the same as the 27 HP engine but turns at 3400 rpm instead of 3600.

Bringing this topic back from the dead, the motor is again not running smooth with the PTO engaged, and is leaking oil again from the oil filter side of the engine. I am at my wits end with this tractor. the updated sump gasket and crank seal where just installed on this earlier this year when the governor decided to let go, after all of that was taken care of we had a dead cylinder which turned out to be a push rod valve that had backed out and after fixing that it ran good for a bit and is acting up again now. Also the card was replaced due to the fact it was cheap to replace the entire carb vs doing a rebuild kit.

since this engine has a larger than normal crank shaft which affecting the drive pulley and pto pulley is there a retro fit engine that can be put on this so a good frame and trans does not get left behind?

44 series engines run all the way from 22 hp to ? Basically the same, different label. I am suspicious about both push rods being off.

Walt Conner

Did you remove the blower housing and clean the grass clippings/mouse nests from the cooling fins? It may be overheating causing the rocker stud to loosen and back out.

Romore said:

Did you remove the blower housing and clean the grass clippings/mouse nests from the cooling fins? It may be overheating causing the rocker stud to loosen and back out.

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As above, I said both push rods being off is suspicious and something caused it, perhaps above, perhaps a valve guide has slipped up. Should not be more than 1/8" above head casting. IF valve guide has slipped, I have a fix, address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com