How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Curtis B. Your Own Question
Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 12592
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
30244710
Type Your Small Engine Question Here...
Curtis B. is online now
A new question is answered every 9 seconds

I have a Gravely ZT HD60. When I try to mow, it bogs down

Customer Question

I have a Gravely ZT HD60. When I try to mow, it bogs down like it's under a load and won't cut any faster than a slow walking speed.
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: It started the last time I mowed a couple of weeks ago, in the middle of the mowing session.
JA: Do you have fuel in the tank? If so, is the shut-off valve open and the fuel clean?
Customer: fuel is wide open and a month so old.
JA: Do you plan on doing the work yourself?
Customer: depends on how complex the job is.
JA: Anything else we should know to help you best?
Customer: Nothing more at this time.
Submitted: 4 months ago.
Category: Small Engine
Expert:  JohnF2015 replied 4 months ago.

Hi, my name is***** will be assisting you.

Does this machine have a twin cylinder engine? My first thought is that you are only running on one cylinder which would explain the power loss.

Customer: replied 4 months ago.
it is a two cylinder.
Expert:  JohnF2015 replied 4 months ago.

Being a two or twin cylinder my suspicion would be that you are only running on one cylinder.

The first step that I would take is to remove one of the spark plug wires from the plug and try to start the engine. If it starts then we know that the opposite cylinder is running. Then replace that plug wire and remove the other one. If it still starts then we know that both cylinders are functioning and should not be a problem. However if it fails to start with either of the plug wires removed then we would move on to focusing on the cylinder that did not start. Or the cylinder that would not start with plug wire attached.

Expert:  JohnF2015 replied 4 months ago.

Is this a Briggs, Kohler, Kawasaki branded engine?

Customer: replied 4 months ago.
Kawasaki. I'll run out and pull plug wires now.
Expert:  JohnF2015 replied 4 months ago.

Let me know what you find.

Customer: replied 4 months ago.
sitting in the seat, the left bank is not working.
Expert:  JohnF2015 replied 4 months ago.

So the next thing that I would look at is spark to the left cylinder. Are you getting spark to the plug?

Expert:  JohnF2015 replied 4 months ago.

Everything that you want to do from here would involve the left cylinder since you now know that it is not working.

Customer: replied 4 months ago.
give me 15 min. to pull the plug and check for spark.
Expert:  JohnF2015 replied 4 months ago.

Maybe as simple as a fouled spark plug. If you have a spare plug you might try changing it. If not maybe swap the two plugs.

Customer: replied 4 months ago.
pulled plug, found carbon across the gap. cleaned that up. gap looked good. checked for spark, not quite as blue as I would like. Pulled plug and traded with "good" plug. no start. checked spark on good plug on bad side, better blue spark. put bad plug on good side, engine started, pulled plugs alternating between good/bad side. Bad side still not starting/running. Bad side has some oil, not overly oily. engine oil is good.
Expert:  JohnF2015 replied 4 months ago.

I would move to a compression check on the left cylinder to make certain that it at least has compression.

Customer: replied 4 months ago.
I checked and it is "blowing" out. I don't have a compression gauge handy.
Expert:  JohnF2015 replied 4 months ago.

It "blowing out" is at least a good thing. It would be nice to know exactly what kind of compression the cylinder has. If you want you can move on to removing the valve cover from the left cylinder and check push rods and rocker arms.

Customer: replied 4 months ago.
ok... it's going to an hour + to get a compression gauge. I can pull the valve cover. I'm familiar with rocker arms and push rods. Are we checking for bent, non-functional parts?
Customer: replied 4 months ago.
guidance on pulling valve cover?
Expert:  JohnF2015 replied 4 months ago.

Two bolts in valve cover can be removed then you should be able to pop the valve cover off and check the push rods and rocker arms. I would be looking for bent push rods or broken/loose rocker arms.

Customer: replied 4 months ago.
You've been a lot of help tonight. Unfortunately it getting too late for me to continue tonight. Can we pick this up again tomorrow?
Expert:  JohnF2015 replied 4 months ago.

Yes, you can come back here and continue our conversation at any time. I will not be available until around 7:30 tomorrow evening however.

You can post comments at any time and as soon as I see them I will respond.

Customer: replied 4 months ago.
sounds good. what time zone?
Expert:  JohnF2015 replied 4 months ago.

Eastern time zone

Customer: replied 4 months ago.
ok I'm central talk to you tomorrow
Expert:  JohnF2015 replied 4 months ago.

That will be fine. Have a good night.