I recently bought a fl400 - it's idles perfect, in the mid range it starts to spudder and completely shuts down at full throttle.

The guy I bought it from said it ran but he took it apart nd had it painted. How many grounds are there? I ground down the one under the fuses and another under the fan. It ran a bit better after this. It has been sitting outside for awhile.

I have cleaned all the grounds - 2 that I found. cleaned all the electrical connections, changed the plug, changed the coil, cut the coil wire back, changed the CDI (Capacitor Discharge Ignition), cleaned the gas tank, cleaned the full pump, changed the fuel filter, cleaned the carb like 5 times, changed the float level, checked the wires, cleaned out the mag, cut the reverse rev limiter off the CDI (Capacitor Discharge Ignition). New battery, clean air filter, ran a manual feed gas take to make sure it was not the fuel pump, ran without the gas cap to make sure vent was working, checked the 2 fuses - are there more fuses? I feel I have done everything.

The check box is missing the 2 proud wires but I cannot find them.

It runs like the carb is clogged but it's not or like the rev limiter is kicking in.

The rear light does not work and it doesn't have break lights - could this cause the problem?

Any suggestions?

I don't own a pilot but if it idles I call bullshxx on the ground thing. I don't think it is that.
It can't be fuses or you would have no electrical powerl or spark.
I also don't feel it is electrical or it would not idle perfectly as you say.
No rear light or brake light could just be a damaged or not plugged in wire or light bulb.
Please clarify "at full throttle it shuts down completely". What do you mean ??
Does it just sputter or does the Engine shut off (electrically) ??
My money says its fuel.

What is your compression ??

Sure its not a rev limiter? If not done correctly the reverse rev limiter mod could cause the rev limiter all the time.

Time to clean the carb. Its running out of gas at high speeds

Humour me.
Please answer all of the questions above as well as do a flow test on your fuel pump and then
post the flow number here.
Just in case you don't know how to do this: 1) remove the fuel line from carb 2) put the end of the fuel line into a cup or something that measures ounces 3) crank the Engine over for 10 seconds no more -- use a stopwatch. What did you get ??

I must edit this: Please don't be offended but I don't know you and I am assuming your smart enough to make sure the ignition is off. We don't want a fire or a run away Engine when it starts to leans out.

Sounds to me like classic fuel filter blockage.
Allows enough fuel at low demands,but then inadequate supply at fuller throttle/revs.
Check your fuel filter,bang it out in a white bowl,blow thru it in reverse.
Flush it out clean,then try it again.
What's your plug look like at problem area?

Right on filter needs checked either way, should be done once a year,,, from another post in the past on flushing the filter.

You try flushing the stock filter?

I know it sounds stupid but the stock fuel filter is a real quality filter, I have never found dirt past the stock filter in the float bowl of the carb, what I do with the Pilot fuel filters is remove it, when you do it will have some gas inside, put your thumbs over both openings then shake the hell out of it then dump the gas out the INLET side onto a white paper towel then look to see what was inside, I usually find real small rusty particles inside, I then spray carb cleaner in the inlet side and fill the filter about 3/4 the way full then shake it up again and dump, I keep doing this until nothing comes out the INLET, after doing this their is always more than good enough flow you don't need to worry about fuel starvation problems this is not to say you will find the same, its worked for me for 14 years.. everybody knows the BEST solution would be to buy and install a NEW Honda filter...

Once a year I drained my stock tank to ensure their was no moisture in the bottom and to flush out any dirt, I also flushed my fuel filter, no matter how hard you try to keep your gas cans clean and try to keep dirt out when filling the tank you always seem to get dirt in the tank.
viewtopic.php?f=2&t=13183

Thanks a for the help guys.

Here is an update - still sputtering though. Cleaned out the gas tank again. Cleaned the carb again. Tested the fuel volume and the fuel pump works good.

It idles good and starts sputtering at mid throttle. Lots of white / grey smoke out the exhaust when it's starts to miss.

You think the white smoke is fuel or electrical?

Try taking the airbox lid off and ridding it. This will let more air in and if it cleans out you know your jetting is to fat. If it doesn't clean out don't rag on it because if it is a fuel starvation issue you will be leaning it out even more. But if your saying its smoking a lot im guessing it's running fat so running without the airbox lid on should clean it out.

Ok - broke down and bought a compression tester. Only 90!!! Tore it apart and the piston and rings look new. Miked the cylinder at 82 and the piston just under 81.5.

Think that's the issue?

After more research, the part number says it's for a 82mm bore. The cylinder is in ok shape and the piston and rings look good - any thoughts why there would only be compression of 90?

Maybe the wrong gasket? I have a Paul Turner head.

compression is an issue for sure, white smoke is normally associated with steam, you may have a bad head gasket.
Blueish smoke is oil, if it is steam it will dissipate quickly, oil will hang in the air for a while, if oil and your mixture is right then you have a bad crank seal, wait, no gearbox, will oil get in from the counter balance?

piston to cylinder clearance is measured across the bottom of the skirt, that is the largest diameter of the piston when cool.

Can you still see the hone marks in the bore?

I'm not familiar with that head is it like a cool head with replicable domes? if so check, replace the O-ring

After looking closer at the piston it looks like a rock or small metal is melted into the piston and making the bottom ring stick - ordered all new top end - should have it back together tomorrow and we will see if that was the issue.

Can I ask you what the flow number was on the fuel pump when you checked it.
You said the fuel pump was good when you checked it but I am curious what number you got.
I think you have already figured out what is wrong with your machine. It needed a re&re.

What I did was add another large fuel filter right b4 the carb to be able to watch the fuel column and I also changed to a manual tank.

Post some really clear detailed pictures of the small metal that stuck the ring, you might have to take 20 pictures to get one nice detailed picture, I want to identify what stuck the ring, sounds like metal from the bottom end, part of a crank bearing or the metal cage that holds the rollers in the lower rod bearing, either way if you put it back together and a bearing is failing your going to trash that top end again, your Engine is talking to you, time to listen to it.

Also take detailed pictures of the cylinder, crankcase, rod, head etc. Its hard to CSI parts in pictures but some times we get lucky and spot something we have seen before.

It would be worth your time to go here viewforum.php?f=25 and start reading the Pilot Engine CSI's before you go any further, most if not all the problems you can have with a Pilot Engine has been discovered and covered in those pages, tons of info you wont find any place else and definitely not in the service manual.

Hoser - thanks for the suggestion. I did a good check of the bottom end and there was no metal in there and the bearning felt good.

Here are a few pics of the piston.

The cyclinder was a bit wavey after a harder look. I am at 82 and my local store said there is noting larger. I put in a new piston and the compression got a bit better from 90 to 125, but that is still too low. I guess its time for a new sleeve or plating - any suggestions?

oh - and yes it still runs like crap

took it all back apart and here are some more pictures.

I really want this to be running for new years at Glamis!!!

Any thoughts

Free bump. Hopefully someone can help.

Did you check the O-rings in that power head ??
It looks to me like that head will allow you to use different size domes. That means it comes apart and in order to get a seal you need O-rings. Did you check them ??
The reason I ask is because of the way you describe the "smoke" behind the machine. It does seem like water is getting in there.
I have 125psi on my fl350 and it runs like a raped ape. To me 125psi is good enough for now so it should run well but just not have peak HP.
My money says that you have a coolant leak. If the previous owner got the Engine hot he may have cooked those O-rings.

How about some close up pictures of the lower rod bearing that metal had to come from some place.

here are a few pics

After continuing to look at the head and the bottom end i thing that the prior owner blew up the top end and did not do a good job of cleaning out the bottom end and there were left over particales that toasted the top end again?

Also back to the carb, its stock and it has a 158 main and 58 pilot - the motor (( Internal Combustion Engine ? )) seems stock other than the power head. I am in San Diego at sea level - doesnt that see like way to high of jetting?

Thanks