Bike bogs down at high rpm's

[Splittie]

On my way to work yesterday, I noticed that when I went to pass a car my bike was very sluggish.
I own an 89 750L and it has been running pretty good for the last three months or so.
As I rode the rest of the way to work, I tryed in all gears to rev it up and when I would get about 5-5.5k rpm it would flatten out/bog down.
Does this sound like a carb problem? (This is my guess)
Should there be adjustments made or is a carb cleaning in order?
Thanks for any info

[doctorgonzo]

Lots of possible causes. Top of the list is fuel starvation. Is there a kink in your gas line.... dirty petcock filter or inline fuel filter...

[Zook]

Gas cap vent partially clogged?

[Splittie]

Gas cap vent partially clogged?

Where is the vent located at in the cap??
This one should be an easy fix if this is the problem.

[Splittie]

Gas cap vent partially clogged?

By the way, I have noticed a 'sucking' sound coming from the gas tank when it gets hot.
Is this normal??
Could this be my problem?
I would imagine if I run it with the gas cap off and it doesnt act up, this is the problem?

[Splittie]

Lots of possible causes. Top of the list is fuel starvation. Is there a kink in your gas line.... dirty petcock filter or inline fuel filter...

Fuel line not kinked-haven't checked petcock yet-no inline filter

[Zook]

By the way, I have noticed a 'sucking' sound coming from the gas tank when it gets hot.
Is this normal??
Could this be my problem?
I would imagine if I run it with the gas cap off and it doesnt act up, this is the problem?

Sounds like you're on the right track.
Run it with the cap open. Yes, you are correct if it doesn't act up that is the problem.

[Splittie]

Sounds like you're on the right track.
Run it with the cap open.

Looks like I know what I will be doing for lunch
Will post results
Thanks

[Splittie]

Gas cap vent partially clogged?

Is there any way to test the gas cap to see if it is plugged/clogged?
If there is how? And how can it be cleared?

[don_gibb6512]

Flip the cap over and take a look at the outer edges. There should small slit openings all the way around the perimeter. Attach the small red hose that comes with a can of carb cleaner and spray in to each one of those slots until no rusty color comes out. Be sure to wear gloves and safety goggles. you should also notice that the center of the cap has a housing with two very small Phillips screws. Take that hosing off and clean everything inside there. Turn the cap right side up and stick the end of the red carb cleaner hose in to the key slot and spray that direction also. Do all that and it should be clean as a whistle.

Good luck.

Don

[chef1366]

If it's not fuel related that's the first sign of a failing igniter.

[TheCafeKid]

If it's not fuel related that's the first sign of a failing igniter.

Ick Well, there is always a Dyna system if thats the case.

[Splittie]

Do all that and it should be clean as a whistle.
Good luck.
Don

Well it isn't the fuel cap. I took the whole thing apart last night and cleaned it all up.
On the way to work today, I kept on the throttle and got it up past the 6k range and once I did the power kicks in!?!?!?
So I have a flat spot in the 5k-6k rpm range.
WHAT NOW!?!?

[Splittie]

If it's not fuel related that's the first sign of a failing igniter.

Hey Chef,
You feel like coming up here to Lemoore and working on this bike for me???
Seriously though, is there any other troubleshooting I can do before replacing the igniter?
I am looking at giving the carbs a good cleaning this weekend to see if that will help.
I am still able to keep up with traffic on the freeway, so I am going to ride to and from work for the rest of the week.

[Uruka]

I had a similar problem, for me it was restricted fuel flow. I took the petcock apart and cleaned it up, I also re routed the vacuum line for the petcock. If the vacuum to the petcock is bad, you won't get any fuel. Rebuilding the carbs is also a good idea, but be careful. The intake boots that the carbs fit into have a tendency to crack one they get old. New ones cost $35 a piece from the Suzuki dealer.