no top end rpm...

Chief Ten Bears · 05-14-2012, 06:13 AM

I have a 1979 KE100, runs like a champ... but lately I've noticed something strange happening. when the engine gets hot/warm after riding for some time, when you give it throttle to lets say accelerate through the gears, it sputters, burbles, when you get up in the RPM... not like it wants to die, but just like you hit a rev limiter or something. It still idles fine, when its hot power seems a little down though... Any thoughts? Running to rich perhaps? This only happens once the engine gets hot after riding for a while, and only when its hotter outside at well...

Harpua · 05-14-2012, 09:54 AM

One of my bikes did that a while back. Cleaned the carb and problem solved. Must've been some goop somewhere.

If you haven't tried Pinesol, do it! It's awesome. I've found full strength works best.

UnsureFooting · 05-14-2012, 10:01 AM

Valve float?

Tosh Togo · 05-14-2012, 12:27 PM

Quote:

Originally Posted by UnsureFooting

Valve float?

stainlesscycle · 05-14-2012, 03:46 PM

Quote:

Originally Posted by Chief Ten Bears

I have a 1979 KE100, runs like a champ... but lately I've noticed something strange happening. when the engine gets hot/warm after riding for some time, when you give it throttle to lets say accelerate through the gears, it sputters, burbles, when you get up in the RPM... not like it wants to die, but just like you hit a rev limiter or something. It still idles fine, when its hot power seems a little down though... Any thoughts? Running to rich perhaps? This only happens once the engine gets hot after riding for a while, and only when its hotter outside at well...

is this throttle position independent? if throttle position has no bearing it's either the rotary valve or ignition timing. if you can back off the throttle and it will zip to top rpm, it's generally jetting. depending on where your throttle is at, it's either needle positon, or main jet most likely. could be float height/float issue also. if float is letting fuel by, it could be rich up top and not rev out.

JonnyCash · 05-14-2012, 05:13 PM

My first thought was too rich on the main jet, as I've had that before, when trying to get my RD jetted in. But if it was running well before on that jetting, I wouldn't jump and start changing things around, it must be something else. Is your air filter clean? A dirty air filter would cause a rich condition. Overly advanced timing could create a "rev wall".

pdxjim · 05-14-2012, 06:40 PM

I had a KE175 that did that.

The stock exhaust has extensive baffles and tubes that get clogged with carbon.

I got a long drill and reamed out the exhaust and it fixed the problem.

This was when I was about 18, so I might suggest cutting it open cleaning it out and welding it back up if I were to do it again.

Might try cleaning the airfilter as well. Whatever the cause, it sounds like it's too rich when it comes on the mainjet.

darmst6829 · 05-14-2012, 07:16 PM

Quote:

Originally Posted by Chief Ten Bears

I have a 1979 KE100, runs like a champ... but lately I've noticed something strange happening. when the engine gets hot/warm after riding for some time, when you give it throttle to lets say accelerate through the gears, it sputters, burbles, when you get up in the RPM... not like it wants to die, but just like you hit a rev limiter or something. It still idles fine, when its hot power seems a little down though... Any thoughts? Running to rich perhaps? This only happens once the engine gets hot after riding for a while, and only when its hotter outside at well...

Check the flow from the fuel petcock.

UnsureFooting · 05-15-2012, 05:11 AM

Quote:

Originally Posted by Tosh Togo

So... that's a no...

Chief Ten Bears · 05-15-2012, 06:47 AM

Thanks for all the info and insight!

wfopete · 05-17-2012, 08:07 AM

Quote:

Originally Posted by Chief Ten Bears

Thanks for all the info and insight!

Hey Chief,

Before you go chasing all over trying to find the problem, check the basics first (fuel, air, plug). I doubt you need to replace a main jet but a dirty/clogged carb or exhaust might be your most likely issue. Timing? I doubt it, unless YOU changed it. Hell, it's only 30 years old...what could go wrong?

Chief Ten Bears · 05-18-2012, 08:27 AM

Quote:

Originally Posted by wfopete

Hey Chief,

Before you go chasing all over trying to find the problem, check the basics first (fuel, air, plug). I doubt you need to replace a main jet but a dirty/clogged carb or exhaust might be your most likely issue. Timing? I doubt it, unless YOU changed it. Hell, it's only 30 years old...what could go wrong?

Thanks, I tend to agree... It ran fine all last year, not a problem... It ran fine for the first month I was driving it this year as well. I haven't changed any timing or jetting or anything.

Its 30 years old, but only has 4000km on it, not that, that means anything...

Hunsta · 05-28-2012, 01:17 AM

Dismiss this if Im completely off base, as Im not familiar with the KE100 that well. Do they run reed valves?
I had a 1977 YZ125 that had similar problems. Turned out to be the reed valves. Seems they were alittle worn out and the bike would sputter and run rough if you tried to give it too much gas up high. You would have gas it very slowly to get around it.

SprintSix · 05-28-2012, 02:28 AM

Failing oil pump. Mine did, it would break up in the mid range. Sounded lean but was really no oil and seizing. Add some premix to tank, mine revved out after I did. Still had to re-do the top end...again.
Points timing. They do wear so after 30 yrs might be time to adjust.
Failing coil or magneto.
Worn carb needle could cause a rich condition in the mid.

All from KE100 experience.

05-14-2012, 06:13 AM	#1
Chief Ten Bears ^OP Adventurer Joined: Oct 2011 Location: Winnipeg Oddometer: 10	no top end rpm... I have a 1979 KE100, runs like a champ... but lately I've noticed something strange happening. when the engine gets hot/warm after riding for some time, when you give it throttle to lets say accelerate through the gears, it sputters, burbles, when you get up in the RPM... not like it wants to die, but just like you hit a rev limiter or something. It still idles fine, when its hot power seems a little down though... Any thoughts? Running to rich perhaps? This only happens once the engine gets hot after riding for a while, and only when its hotter outside at well...

05-14-2012, 05:13 PM	#6
JonnyCash turd polisher Joined: Jan 2011 Location: Midcoast, Maine Oddometer: 774	My first thought was too rich on the main jet, as I've had that before, when trying to get my RD jetted in. But if it was running well before on that jetting, I wouldn't jump and start changing things around, it must be something else. Is your air filter clean? A dirty air filter would cause a rich condition. Overly advanced timing could create a "rev wall". __________________ I wouldn't bring her home to Mama, but Mama ain't home tonight.

05-28-2012, 01:17 AM	#13
Hunsta Have guns will hunt Joined: Jan 2006 Location: Gympie Queensland Australia Oddometer: 5,405	Dismiss this if Im completely off base, as Im not familiar with the KE100 that well. Do they run reed valves? I had a 1977 YZ125 that had similar problems. Turned out to be the reed valves. Seems they were alittle worn out and the bike would sputter and run rough if you tried to give it too much gas up high. You would have gas it very slowly to get around it. __________________ I REALLY AM A NICE GUY. JUST ASK ANYONE WHO HASN`T MET ME.

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05-14-2012, 09:54 AM	#2
Harpua formerly josdavlar Joined: Apr 2011 Location: Edgewood, New Mexico Oddometer: 175	One of my bikes did that a while back. Cleaned the carb and problem solved. Must've been some goop somewhere. If you haven't tried Pinesol, do it! It's awesome. I've found full strength works best.

05-14-2012, 10:01 AM	#3
UnsureFooting Beastly Adventurer Joined: May 2011 Location: DFW, Texas Oddometer: 1,422	Valve float?

05-14-2012, 06:40 PM	#7
pdxjim Two Stroke Terror Joined: Sep 2009 Location: Portland, OR Oddometer: 65	I had a KE175 that did that. The stock exhaust has extensive baffles and tubes that get clogged with carbon. I got a long drill and reamed out the exhaust and it fixed the problem. This was when I was about 18, so I might suggest cutting it open cleaning it out and welding it back up if I were to do it again. Might try cleaning the airfilter as well. Whatever the cause, it sounds like it's too rich when it comes on the mainjet.

05-15-2012, 06:47 AM	#10
Chief Ten Bears ^OP Adventurer Joined: Oct 2011 Location: Winnipeg Oddometer: 10	Thanks for all the info and insight!

05-28-2012, 02:28 AM	#14
SprintSix Gnarly Adventurer Joined: Dec 2009 Location: Ohio Oddometer: 132	Failing oil pump. Mine did, it would break up in the mid range. Sounded lean but was really no oil and seizing. Add some premix to tank, mine revved out after I did. Still had to re-do the top end...again. Points timing. They do wear so after 30 yrs might be time to adjust. Failing coil or magneto. Worn carb needle could cause a rich condition in the mid. All from KE100 experience.