only getting about 5# compression. 1990 G2

Mitty888 · 03-31-2009, 08:36 AM

Two days ago the cart was running but now it won't turn over. I checked the compression last night and found it only had about 5psf. It wasn't ever shooting blue smoke out of the exaust so i don't think its the rings. Does a 1990 G2 has a compression release valve that could be stuck open or could it possibly be the head gasket? Any help is appreciated.....I'm stumped.

TheNewGuy · 03-31-2009, 10:37 AM

Could be a hung up valve. Pull the valve cover off. turn the engine and check to see everything is working properly.

Mitty888 · 03-31-2009, 12:05 PM

I pulled the valve cover last night and the rockers both seeemed to be functioning properly and looked as if they both had the same amount of travel, leading me to believe the cam is ok.

crash12888 · 03-31-2009, 03:34 PM

Did you check the clearance of the rocker while you had it open?
I ask because the valves might be moving but a piece of carbon between the valve and seat could cause the valve not to close completely. A big difference in air gap would indicate this.
Checking valve clearance might show no gap which would mean the valve is being held open and isn't seating properly as well.

Mitty888 · 03-31-2009, 03:45 PM

No i didn't check and i'm not really sure how to. I will ask one of my buddies to see if he knows how. Do you have any helpful suggestions?

crash12888 · 03-31-2009, 04:13 PM

Sure, with the valve cover off and where you were looking to see the valves and springs moving, rotate the crank and watch for the intake valve to open and close.
When it closes rotate the piston up to what is called TDC or top dead center. At that time the spark plug fires and the valves are fully closed with a .004 gap.
Use a feeler gauge set at .004 (4 thousanths)(sp?) to check between the top of the valve stem and the rocker arm.
It should slide in with just a hint of resistance. If it has a very big gap you might have carbon holding it open.
Tapping the top or the valve stem with a brass or rubber hammer might break it away and close it or head might need to come off to clean.
If it will not slide in you might have a rocker holding it open causing the compression loss and just need to adjust the gap to correct the compression problem.

craig tn · 03-31-2009, 04:42 PM

Check to make sure accelerator cable is working the carb, on a g-16 if broke it will not have enough compression to run.

Mitty888 · 04-08-2009, 07:44 AM

I finally had a chance to pull the the engine apart last night and it appears the rings and cylider wall are fine (good news!). One of the lifting rods had slipped off its seating and was just sitting there. Nevertheless, it felt as if the valve guides are fine and the valves are getting a good seating. There was very little oil around the rockers so i think the vacuum hose from the crank case was cracked (I think this is how it recieves oil?). Can one of you guys verify that oil gets to the rockers by the rear hose attached to the valve cover that runs to the crank case? Also, where can I order a new head and valve cover gasket along with the three hoses that come into the valve cover? They are all cracked and brittle.

03-31-2009, 08:36 AM	#1
Mitty888 Not Yet Wild Join Date: Mar 2009 Location: Fort Wayne, IN Posts: 8	only getting about 5# compression. 1990 G2 Two days ago the cart was running but now it won't turn over. I checked the compression last night and found it only had about 5psf. It wasn't ever shooting blue smoke out of the exaust so i don't think its the rings. Does a 1990 G2 has a compression release valve that could be stuck open or could it possibly be the head gasket? Any help is appreciated.....I'm stumped.

03-31-2009, 10:37 AM	#2
TheNewGuy Admin/Moderator Join Date: Dec 2006 Location: Ohio Posts: 18,052	Re: only getting about 5# compression. 1990 G2 Could be a hung up valve. Pull the valve cover off. turn the engine and check to see everything is working properly.
	Ron PLEASE VISIT Our Sponsors * BGW GEAR The Store The G2 Project * Swing Arm Drop & Repair * Geep1 Project

03-31-2009, 12:05 PM	#3
Mitty888 Not Yet Wild Join Date: Mar 2009 Location: Fort Wayne, IN Posts: 8	Re: only getting about 5# compression. 1990 G2 I pulled the valve cover last night and the rockers both seeemed to be functioning properly and looked as if they both had the same amount of travel, leading me to believe the cam is ok.

03-31-2009, 03:34 PM	#4
crash12888 Gone Crazy Join Date: Jan 2007 Location: Chesterfield, Va Posts: 6,021	Re: only getting about 5# compression. 1990 G2 Did you check the clearance of the rocker while you had it open? I ask because the valves might be moving but a piece of carbon between the valve and seat could cause the valve not to close completely. A big difference in air gap would indicate this. Checking valve clearance might show no gap which would mean the valve is being held open and isn't seating properly as well.

03-31-2009, 03:45 PM	#5
Mitty888 Not Yet Wild Join Date: Mar 2009 Location: Fort Wayne, IN Posts: 8	Re: only getting about 5# compression. 1990 G2 No i didn't check and i'm not really sure how to. I will ask one of my buddies to see if he knows how. Do you have any helpful suggestions?

Today
BGW	Sponsored Links __________________ This advertising will not be shown in this way to registered members. Register your free account today and become a member on Buggies Gone Wild Golf Cart Forum

03-31-2009, 04:13 PM	#6
crash12888 Gone Crazy Join Date: Jan 2007 Location: Chesterfield, Va Posts: 6,021	Re: only getting about 5# compression. 1990 G2 Sure, with the valve cover off and where you were looking to see the valves and springs moving, rotate the crank and watch for the intake valve to open and close. When it closes rotate the piston up to what is called TDC or top dead center. At that time the spark plug fires and the valves are fully closed with a .004 gap. Use a feeler gauge set at .004 (4 thousanths)(sp?) to check between the top of the valve stem and the rocker arm. It should slide in with just a hint of resistance. If it has a very big gap you might have carbon holding it open. Tapping the top or the valve stem with a brass or rubber hammer might break it away and close it or head might need to come off to clean. If it will not slide in you might have a rocker holding it open causing the compression loss and just need to adjust the gap to correct the compression problem.

03-31-2009, 04:42 PM	#7
craig tn Gone Wild Join Date: Jan 2008 Location: Covington, TN Posts: 1,942	Re: only getting about 5# compression. 1990 G2 Check to make sure accelerator cable is working the carb, on a g-16 if broke it will not have enough compression to run.

04-08-2009, 07:44 AM	#8
Mitty888 Not Yet Wild Join Date: Mar 2009 Location: Fort Wayne, IN Posts: 8	Re: only getting about 5# compression. 1990 G2 I finally had a chance to pull the the engine apart last night and it appears the rings and cylider wall are fine (good news!). One of the lifting rods had slipped off its seating and was just sitting there. Nevertheless, it felt as if the valve guides are fine and the valves are getting a good seating. There was very little oil around the rockers so i think the vacuum hose from the crank case was cracked (I think this is how it recieves oil?). Can one of you guys verify that oil gets to the rockers by the rear hose attached to the valve cover that runs to the crank case? Also, where can I order a new head and valve cover gasket along with the three hoses that come into the valve cover? They are all cracked and brittle.

Similar Threads
Thread	Forum
G-2 compression	Gas Yamaha
low compression fix	Gas EZGO
g1 compression	Gas Yamaha
No Compression	Gas EZGO
compression	Gas EZGO