Honda ATV Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
I went to start my 86 350 fourtrax at -8 degrees Celsius and it had 90 psi compression after I rolled it over a couple of times usually it would start but nothing happened and it had dropped to under 60 psi compression when I checked it what could have happened in the motor.? I’d appreciate honest answers and not random ideas thank you
 

·
Registered
Joined
·
453 Posts
Most that reply to these types of posts don't just throw out vague answers but instead try to give educated guesses based on the limited information provided.
Add a little more information and you'll get better answers.

BTW, the Wright Flier engine would have only given a reading of 65 PSI if the rings and valves were 100% effective at sealing. Trust me. Your starting problem isn't all compression related.
 
  • Like
Reactions: Goober

·
Premium Member
Joined
·
4,729 Posts
Download the service manual from the link in my signature block below.
There are several diagnostics pages in there and one for low compression.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #4 ·
Download the service manual from the link in my signature block below.
There are several diagnostics pages in there and one for low compression.
I have the factory service manual but I don’t think it has the answers I’m looking for maybe the manual you gave the link for will. Thx I will look into the link you sent
 

·
Premium Member
Joined
·
4,729 Posts
Spec is 178-206psi
Could be the way you’re doing the test, worn parts or out of adjustment
Or like 56S said, other influences like choke valve or battery, fuel pump
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #7 ·
choke valve or battery, fuel pump
I replaced the fuel pump after I bought the bike cause it wouldn’t run at all so I took it in and the fuel pump was done so I went and bought one but the price I was told it was supposed to be wasn’t what I paid I paid more than what I was told it cost with tax but the pump is new
 

·
Registered
Joined
·
35 Posts
i overhauled the top end of mine when my compression was only 90. had the cylinder bored out 0.5mm over sized and a new high compression Wiseco piston, new valves, rockers. IT runs like a dream now. Mine had significant scoring in the bore likely due to poor lubrication as my rocker arm surfaces that ride on the camshaft were also cupped severely and beyond repair.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #10 ·
i overhauled the top end of mine when my compression was only 90. had the cylinder bored out 0.5mm over sized and a new high compression Wiseco piston, new valves, rockers. IT runs like a dream now. Mine had significant scoring in the bore likely due to poor lubrication as my rocker arm surfaces that ride on the camshaft were also cupped severely and beyond repair.
right now i'm unable to order parts for my quad cause the manufacturer of the parts is not shipping to canada because of this stupid pandemic
 
1 - 10 of 10 Posts
Top