Losing power at about 5k rpm, also running extremely hot (smoking)

[lilbilly]

Okay guys... I did a search and had a hard time finding a similar scenario. Hoping you bike gurus can give me some help.

Bike had been running fine lately - still tough to start, but will go after giving some throttle. Anyways, pulled the bike out today after it sitting for 2 weeks (no time to ride).

First issue - Running great up until 5k rpm and then it's got no guts, barely pulling at all even with the throttle wide open. Seems to do it in all gears as far as I can tell. Air/fuel mixture problem? Spark problem? Any ideas?

Second issue - I know these are air-cooled so they run a little hot right, but when I stopped after 20-30 minutes of riding it was smoking noticeably from the motor. Didn't really see it in one particular spot, kinda just the whole thing in general. Not a ton of smoke, but noticeably some. I do have a small oil leak coming from the base gasket, but it wasn't just that spot. Also, I might be a overfilled a bit on the oil too. Could that be causing it to froth up and smoke from different areas? What say ye?

My wife has a small day trip planned next Saturday and I'd really like to go, but this has got me a bit worried.

[Nessism]

Sounds like maybe a fuel supply issue. Maybe check the petcock for proper flow and the tank for proper venting?

[lilbilly]

Sounds like maybe a fuel supply issue. Maybe check the petcock for proper flow and the tank for proper venting?

This could happen only at high rpms? What should I be looking for? What about the smoking issue? Any ideas there?Thanks again!

[BassCliff]

This could happen only at high rpms? What should I be looking for? What about the smoking issue? Any ideas there?Thanks again!

Hi Mr. lilbilly,

A few thoughts....

Yes, it sounds like a fuel starvation issue causing a lean condition which makes your engine stagger at high rpms and run extra hot. This could be a faulty petcock, bad jetting, clogged fuel passages, or a restrictive inline fuel filter. The extra heat may be cooking oil from the leaks in your motor. If you're not leaking from the valve cover gasket, head gasket, or base gasket, it could be the cam chain tensioner gasket or the tach cable seal.

Is your motor oily and dirty? Clean it well and check for leaks. Spray powder (like foot powder) is good for finding leaks on a clean motor. Just check for the wet spot.

Are there leaks in the air intake system? This will cause a lean condition which will lead to a hotter running engine.

Thank you for your indulgence,

BassCliff

[lilbilly]

Hi Mr. lilbilly,

A few thoughts....

Yes, it sounds like a fuel starvation issue causing a lean condition which makes your engine stagger at high rpms and run extra hot. This could be a faulty petcock, bad jetting, clogged fuel passages, or a restrictive inline fuel filter.

Will start looking there thanks.

The extra heat may be cooking oil from the leaks in your motor. If you're not leaking from the valve cover gasket, head gasket, or base gasket, it could be the cam chain tensioner gasket or the tach cable seal.

The leak that I know of is from the base gasket - something that I am putting off getting too.


Are there leaks in the air intake system? This will cause a lean condition which will lead to a hotter running engine.

I have sprayed the carb cleaner around the intake boots before and didn't notice a drop - I will try it again today to double check.

Thank you for your indulgence,

BassCliff

Thanks for your help.

[lilbilly]

So I had an opportunity to meet up with an extremely generous fellow GSer I have made friends with on Sunday (twr1776) and we took a gander at a few things fuel related. What a generous group of posters on this board!

Apparently the aftermarket in-line fuel filter installed by a PO is sized for a 1/8" line and not 1/4". Picked the correct size up today in hopes that this will solve my loss of power issue and lean condition. Although it seems to be intermittent because Sunday it was pulling hard above 5k rpms... but nevertheless, good chance it was causing the problem and need to correct it.

Does it sound like this could be causing an intermittent loss of power in high revs as well as a lean condition? I'm hoping so... What do you guys think? Anything else I should check?

[chef1366]

It would cause all the above.
It is running right now?

[Budge]

If it's intermittent it may be electrical rather than fuel. Maybe stator or battery causing a loss of spark at higher revs resulting in overfuelling which is then burn't at lower revs. You might get some afterfiring in that case though. I'm interested to hear what fixes your bike, and hope it's not expensice. Good luck.

[mighty13d]

If it's intermittent it may be electrical rather than fuel. Maybe stator or battery causing a loss of spark at higher revs resulting in overfuelling which is then burn't at lower revs. You might get some afterfiring in that case though. I'm interested to hear what fixes your bike, and hope it's not expensice. Good luck.

nice first post!

[lilbilly]

It would cause all the above.
It is running right now?

If it's intermittent it may be electrical rather than fuel. Maybe stator or battery causing a loss of spark at higher revs resulting in overfuelling which is then burn't at lower revs. You might get some afterfiring in that case though. I'm interested to hear what fixes your bike, and hope it's not expensice. Good luck.

I put in on today and rode around the block a few times. Seems fine. Although it was fine on Sunday before I replaced it anyways. I guess I will have to see if it comes back.

If I pull my spark plug and it's very dark grey/close to black - what does that mean? Is it lean or rich? Mine was very dark (they were replaced a maybe 200-300 miles ago).

[TheCafeKid]

Grey is ok...BLACK is rich (or oil fouled but that would be black and SHINEY) Grey like ash is doin fine, on the richer side, but thats better than the leaner side unless you're a racer...

[lilbilly]

Grey is ok...BLACK is rich (or oil fouled but that would be black and SHINEY) Grey like ash is doin fine, on the richer side, but thats better than the leaner side unless you're a racer...

Well it's leaning to the black side, but not shiny - so I guess it's running rich. I still have yet to color tune and try the highest rpm method to get the mixture right, not sure if those will help but want to try and get it right if I can.