[Tractorboy]

hello again everybody
I am having trouble with my 1996 honda foreman 400 4X4 starts and runs great but has no power
I am thinking it is compression but I don't know

 

[retro]

Can you tell us a little more about its symptoms? How exactly does it act up..?

What does the spark plug look like? Plugs have a story to tell...
Does it start easily when cold with the choke on?
If you give it some choke while its accelerating hard, does it run worse or better?
Is the muffler and spark arrester relatively clear of any heavy carbon deposits?
Is the fuel filter plugging up...? has the machine sat for periods of time with ethanol fuel in it?

Thanks,

 

[Tractorboy]

it starts good in the cold with choke
it burns a little oil
the rubber boot on the primmer leaks
bogs down when it has to work
top speed in high gear on level ground is about 35 kmh rpm very low
in first gear rpm go up
spark plug almost new
muffler still stock hasn't bean cleaned as far as i now fell apart once so welded it back together so it has some holes in it

 

[mrbb]

start with a compression test?
as if its been used a lot and still on OEM motor work, it very easy could be time for a top end

 

[misterclean59]

My opinion is it doesn't run good after hearing you explain it better. Check your carb. Probably needs cleaning or an overhaul. On an old wheeler like this I'd go ahead and clean the tank and petcock. I'd also check the valve lash and cam chain adjustment. You will probably be ok after that.

 

[retro]

Ya, sounds like the maintenance schedule has slipped way off the page... I'd do a compression check though, right along with the maintenance and other repairs that you'll be doing to catch back up... no such thing as too much knowledge...

Have fun and enjoy your work! Keep us posted if you can...?

 

[Tractorboy]

i tried working it with the choke on it ran pretty much the same till i let out the throttle than it stalled
and the motor is totally stock except the seals and gaskets which were done once

 

[retro]

You can start wherever you want to I imagine. I'd flush out the fuel tank, change the oil (use JASO MA - MA/2 spec'd oil only) and oil filter, new fuel filter, clean and restore the carb to stock specs per the FSM, check the timing chain, adjust the valves, adjust the clutch, clean the battery terminals and cables, clean the ground cable connections on the frame and motor, fix or replace the muffler, replace the brake fluid, check the tie rods and ball joints and relube them, adjust the brakes front and rear, check and relube the wheel bearings, replace the oil in both the frontend and rearend, lubricate and adjust all control cables, perform a compression test per the FSM (a dry+wet check) on a warmed motor.... by then you'll probably have any problems solved you thought you might have... and had so much fun working on your machine that you'll wish you had another one to fix up...

 

[Tractorboy]

thank you all i'll try a few things and see what happens

 

[Tractorboy]

well I flushed the fuel tank and line (no difference) so did a compression test which showed a max of 90 PSI (but usually showed 60 PSI) so i took off the head and I could move the piston back and forth in the cylinder. Is this a problem?

 

[misterclean59]

Yep, that's a problem. You probably need to bore to the next oversized piston. This is a good time to check every thing else out on the top end. Chain, rockers, cam, valve seals, chain tensioner.

 

[fishfiles]

well I flushed the fuel tank and line (no difference) so did a compression test which showed a max of 90 PSI (but usually showed 60 PSI) so i took off the head and I could move the piston back and forth in the cylinder. Is this a problem?

How much piston movement is key ------- but going back a step , when you done the compression test , did you go by the manual , I don't have a 400 but have a 450 , I am pretty sure your 400 is the same way , there is a compression release built into the cam for easy start up , if you don't follow the procedure for compression testing you will get an inaccurate reading

 

[Tractorboy]

I do not have a manual so can you tell me how this is done

 

[retro]

The service manual is HERE.

Some amount of piston crown slop in the bore is normal. You'll have to remove the cylinder and measure the piston & bore to find out if it is worn out. Everything you need is in the manual. Have fun!

 

[b52bombardier1]

Was the compression test with the engine vigorously cranking and the throttle held wide open?

Rick

 

[Tractorboy]

vigorously cranking but no throttle

 

[retro]

vigorously cranking but no throttle

Hold throttle wide open when testing compression. Crank it over until the gauge stops showing increase in pressure. Its covered in the FSM if you need any assistance doing it