Loss of power on the top end?

[austexjg]

My brother has a '01 EX250 that he feels is lossing power on the top end - I know he has had his carbs synced and maybe a valve ajustment when they were doing the carbs - will have to double check.

He feels like the bike runs sluggish in the upper RPMs at higher speeds and it will not hold the speed going up hill at highway speeds. He seems to stay in the lower gears longer than I do on my '09, but he seems to fade away over speeds of 80 mph. He also says his bike will not reach the upper RPMs (11K+) in sixth gear.

Any possible suggestions are appreciated - I'm tired of hearing him whine.

[kkim]

is this something that is developing or has his bike always been this way?

if developing, check the air filter, check valve clearance...

[austexjg]

I am still trying to find out about the valves - will do on the air filter.

EDIT:

He has had the carbs adjusted, the valves adjusted, and new battery and spark plugs.
He feels like it has always ran sluggish on top end - he bought it used with about 4k miles.
This weekend we were riding on some highways with hills - I was in front and he could not keep up (he claims) and the bike started to slow down going uphill, while I just sped away (he claims) up the hill.

[leesic66]

mebbe runnin lean??

[austexjg]

Didn't ask the mechanic about the condition of the spark plugs when they were changed - could be possible.

[kkim]

is the gearing stock? maybe the PO changed it.

how does the bike feel getting to redline in the lower gears?

[austexjg]

I think the gearing is stock - will check to make sure.

He had always said that he felt the bike loss power (pulling) in the upper RPM range in all gears. This feeling is what led hime to take it to the shop for a carb sync. and I believe that they did do a valve adjustment after he took it back the next day saying the problem was still present.

I will contact him to ask more details about the exact RPM numbers where the power hits a wall.

[Guinss]

I would start with ruling stuff out a bit.
Check if he can revv the engine up to the rev limiter in neutral. And in the lower gears.
If he manage to do that without problem, i think there is a problem with the fuel, running to lean. Atleast, with that symptom it sounds very much like its not getting enough fuel when its pulling the heaviest gears/rpm.

[Postiez]

My bike does this too!

Gets a bit boggy around 11kish in the higher gears. I don't think it does it at all in neutral or even 2nd gear for that matter. Not to steal your thread but I am extremely interested in an answer.

[kkim]

Originally Posted by Postiez

My bike does this too!

Gets a bit boggy around 11kish in the higher gears. I don't think it does it at all in neutral or even 2nd gear for that matter. Not to steal your thread but I am extremely interested in an answer.

define "boggy". has your bike been rejetted?

[Postiez]

Originally Posted by kkim

define "boggy". has your bike been rejetted?

nope, not that I'm aware of. I bought the bike pretty virginal w/ like 3k miles and it definitely wasnt doing it then.

and its almost like the revs are pretty linear up to the point of the bog

like waaaAAAAAHHHH bwoah

I can still get over the little boggy hump but its slow and hard so i just shift

I'm not sure it does it all the time either

I remember the rpms just flying up to the red line and now it hits a point where it slows dramatically and I can feel the bike sorta... losing acceleration dramatically

EDIT: I should also say I have been terrible with maintenance, transferring to a new school is leaving very very broke. So I haven't done anything to troubleshoot this issue and its why I hadn't made my own thread.

[kkim]

is your air filter clean?

[Postiez]

Originally Posted by kkim

is your air filter clean?

I am pretty close to my 7.5k mile maintenance so I haven't checked it but after reading up on it seems like it could very likely be the problem and isn't hard to inspect so I'll do that today. Perhaps now or perhaps when the temp outside goes down about 20 degrees.

[Postiez]

OMG GRODY!

Thanks kkim, you are a guru ^_^

EDIT: How do I clean this, mom says high flash point solvent and oil WTF!

can water be my high flash point solvent?

[kkim]

Disclamer!!! use info at your own risk.

I use gasoline to clean my air filter elements as you have oil impregnated dirt embedded in the filter now. Gas, for me, has always done the best job to dissolve the gunk that's on there now. you can also use something like kerosene. Wear gloves when cleaning the filter and clean it by squeezing the solvent through the filter. I use my oil drain pan to work in as a I do this.

After you get the filter clean with gas, take the filter and wash it it warm, soapy water to clean out the filter so it's spotless. I use Dawn dish washinig detergent as it's noted for it's grease cutting abilities.

Rinse the filter clean with water, squeeze it as dry as you can and then set it aside and allow to air dry overnight.

When dry, saturate the dry filter with oil. The service manual says to use 30w motor oil. There are better alternatives, but motor oil is cheap and works well for street bikes.

Squeeze out as much oil as you can from the filter, then reinstall into the bike.

[WELLS]

For what its worth I had a similar problem with mine. I cleaned air filter regularly and still checked when I noticed this issue. I also installed an online fuel filter. Still no help. I tore the carbs down and found trash (suggesting fuel fuel filter was a good idea). At that point I noticed an improvement. I have since changed my gear and that is way to go, not taking anything away from the 250 but they are not an extreme powerhouse and this just helped get it up to redline in sixth.
Posted via Mobile Device

[austexjg]

Well, I finally got a chance to look at the air filter - it was so brittle that it fell apart as we took it out. Will get a new one and see if the problem is fixed - might take him a few days to actually get the filter - will update on progress.

Question:
Does having an air filter that left tons of debris behind - on the screen and in the air box - cause problems to other parts of the bike? What should we look into?

[kkim]

clean the airbox as well as you can. The bits left behind can be sucked into the engine and possibly cause problems by fouling the plugs. a rag with some gas on it will most likely remove what's left.

picture of the debris?

[austexjg]

I don't think he'll take photos - it was just foam dust particles from the filter degrading inside the airbox. Just touching the foam caused it to turn into dust between your fingers. I think he was going to use a shop vac to vaccuum out the airbox, I'll tell him to use just a rag/gas.

[kkim]

vacuuming is an excellent idea, too.

[austexjg]

Finally got around to going on a ride with my brother - we installed a clean air filter and put some seafoam in the gas tank.

He said he could not notice a difference - it still drops off before redline.
Could a compression test be in order?

[kkim]

couldn't hurt. how many miles on the bike?

[austexjg]

Only like 6,500 (roughly)