No power above 5-6k RPM?

[Tronspeed3]

I took the bike out last night because of the nice 70* weather and while trying to get it up to speed I noticed power fell off dramatically as soon as I hit higher RPM. I can't even get the thing to rev higher once it hits this point!

Does anyone have input on what could be causing this?


Bike is completely stock as far as I know. Might I need a larger main jet ?

Thanks,
Tron

[Big Rich]

Fuel starvation from the tank or carb breather vent, clogged air filter, sticky float not allowing fuel in,........that's all I have. I'm going to bed.....

If the bike is stock and in good running order, it will go above 7 grand.

[craigs449]

If it sat for a while, the main jets could be varnished.  Check to see that all the fuel lines are not kinked and both petcock's are on....if that does not solve it, I would suggest cracking the carbs for a good cleaning.

[mister]

Try getting it past 5k in all gears - 1st, 2nd, 3rd, etc., to see if it is gear related.

If you can get past 5k in the lower gears but it will not play ball in 6th, that is a different issue to not getting past 5k in all gears.

My stock bike will get to redline in the lower gears. 4th gear at 9,000rpm is 140kph (88mph)

Report back which.

Michael

[Kijona]

The most probable cause of your issue lies within your carburetors. If you could, post what year and mileage the bike has.

If you had the bike sitting around for a while it's likely that the carbs are gummed up.

List of possible culprits:

-Cracked/broken diaphragms.
-Stuck or sticking floats.
-Pinched or otherwise malformed fuel lines.
-Sticking frame petcock. To check this easily, set to "PRI" position and try riding it again - just do NOT leave it sitting in this position. As soon as you shut the bike off, turn it back to ON or RES. The floats/needles on these carbs are notoriously weak and leaving it in the PRI position will cause you a huge headache.
-Varnished/clogged main jets. However, it's pretty unlikely considering it runs - usually if they're gummed up bad enough to clog the main jets, the pilots will be completely clogged completely. If this was the case, the bike wouldn't idle or accept any throttle input.
-Clogged or kinked carburetor vent line.

[Tronspeed3]

It's a 1993 with 20K+ miles on it, I have been starting and letting it idle about once a week all winter with a few low speed rides on "warmer" days. I put about 1/4 can of seafoam in the tank when I first got it in December. I just put about a 1/2 tank of new gas in it last night.   

I have been putting it to prime to ride it b/c when its in the ON position it doesn't like to start. I was riding it in 1st-4th gear and hitting the end of the throttle twist and it would not go past 5-6K.

Looks like I'm gonna have to start tearing the carbs apart this weekend...

[Kijona]

It's a 1993 with 20K+ miles on it, I have been starting and letting it idle about once a week all winter with a few low speed rides on "warmer" days. I put about 1/4 can of seafoam in the tank when I first got it in December. I just put about a 1/2 tank of new gas in it last night.   

I have been putting it to prime to ride it b/c when its in the ON position it doesn't like to start. I was riding it in 1st-4th gear and hitting the end of the throttle twist and it would not go past 5-6K.

Looks like I'm gonna have to start tearing the carbs apart this weekend...

This sounds like a good indication of something to me. I'd be willing to bet that you've got a fuel delivery issue...meaning one of your lines. It MIGHT not be your carbs, but then again, the thing you mentioned might also be a completely separate issue.

You should get yourself a set of #40 pilot jets and new float bowl gaskets before you tear into it.

[Tronspeed3]

[quote\

It's a 1993 with 20K+ miles on it, I have been starting and letting it idle about once a week all winter with a few low speed rides on "warmer" days. I put about 1/4 can of seafoam in the tank when I first got it in December. I just put about a 1/2 tank of new gas in it last night.   

I have been putting it to prime to ride it b/c when its in the ON position it doesn't like to start. I was riding it in 1st-4th gear and hitting the end of the throttle twist and it would not go past 5-6K.

Looks like I'm gonna have to start tearing the carbs apart this weekend...

This sounds like a good indication of something to me. I'd be willing to bet that you've got a fuel delivery issue...meaning one of your lines. It MIGHT not be your carbs, but then again, the thing you mentioned might also be a completely separate issue.

You should get yourself a set of #40 pilot jets and new float bowl gaskets before you tear into it.

Good places to get those 2 things ?

[Kijona]

[quote\

It's a 1993 with 20K+ miles on it, I have been starting and letting it idle about once a week all winter with a few low speed rides on "warmer" days. I put about 1/4 can of seafoam in the tank when I first got it in December. I just put about a 1/2 tank of new gas in it last night.   

I have been putting it to prime to ride it b/c when its in the ON position it doesn't like to start. I was riding it in 1st-4th gear and hitting the end of the throttle twist and it would not go past 5-6K.

Looks like I'm gonna have to start tearing the carbs apart this weekend...

This sounds like a good indication of something to me. I'd be willing to bet that you've got a fuel delivery issue...meaning one of your lines. It MIGHT not be your carbs, but then again, the thing you mentioned might also be a completely separate issue.

You should get yourself a set of #40 pilot jets and new float bowl gaskets before you tear into it.

Good places to get those 2 things ?

Ask Adidasguy on here if he has some extra #40 pilot jets. The other guy to ask would be The Buddha. Otherwise, post in the "For Sale/Wanted" section.

Float bowl gaskets: http://www.bikebandit.com/search?dsNav=Ntk:All|13258%2f-44B00|3|

[mister]

Before you go getting new jets blah blah blah, check all your fuel lines. Could be pinched line, clogged fuel filter if you have put one of those in.

[Big Rich]

It's a 1993 with 20K+ miles on it, I have been starting and letting it idle about once a week all winter with a few low speed rides on "warmer" days. I put about 1/4 can of seafoam in the tank when I first got it in December. I just put about a 1/2 tank of new gas in it last night.   

From this paragraph, I would say your carbs need cleaned out. It doesn't take very long for gas to go bad, especially when it comes to gumming up jets.

[Kijona]

Before you go getting new jets blah blah blah, check all your fuel lines. Could be pinched line, clogged fuel filter if you have put one of those in.

I guess I should've asked where he is/where the bike is from first but if he's in the US, the #40 pilot jets are a very worthwhile upgrade even for a stock bike. Since he'll be messing with the carbs anyway, I think it's worthwhile to put the #40 jets in.

If you're in the US, and the bike was sold in the US, it will have either #37 or 37.5 pilot jets. This is what makes the bike have a flat spot in the power band, even right from the factory. It isn't what is causing your issue, but is worth fixing while you're there.

Before you go tearing the carbs apart, you should have a new set of float bowl gaskets waiting. A bike that old that's probably never been messed with is going to need new ones. I tried to reuse mine and it immediately started leaking - even though they looked great and were 5 years newer than yours are.

[gsJack]

With a problem like this I'd first try isolating it, is it a carb problem or is it a petcock/gas line problem?  I'd try running a hose from the gas tank directly to the carbs and take it for a ride and if it revs up OK then forget the carbs for now and look into a petcock/fuel line problem.  And don't completely rule out a battery/ignition problem at this point, starting and letting a bike idle for a while and then shutting it off in the winter just runs the battery down.  Doesn't charge while idling.  If you start it, ride it.  Low voltage can cause spark loss at higher rpms.

[Tronspeed3]

thanks for all the replies, I got some new #40 jets waiting to go in thanks to Adidas and am waiting on new float bowl gaskets from bikebandit... Didn't know about the charging at low RPM thanks for the input I'll just put the battery tender on it and leave it next winter.

Also forgot to turn the petcock back to on after riding yesterday= pool of black ooze under the bike... besides cleaning the motor off so it doesn't start on fire any other issues this might have caused?

[Kijona]

thanks for all the replies, I got some new #40 jets waiting to go in thanks to Adidas and am waiting on new float bowl gaskets from bikebandit... Didn't know about the charging at low RPM thanks for the input I'll just put the battery tender on it and leave it next winter.

Also forgot to turn the petcock back to on after riding yesterday= pool of black ooze under the bike... besides cleaning the motor off so it doesn't start on fire any other issues this might have caused?

Might have flooded your crank case with fuel. No bueno amigo. Might want to check your oil level. If it's "way high" meaning way over "F" you need to change the oil.

[Tronspeed3]

Took the carbs apart tonight after I took the bike for a ride, and cleaned everything inside. None of the jets looked clogged but I replaced the pilots with the #40 ones. Someone has definitely been in those before, as there were 2 washers under the needle, the diaphragm cover had the nipple broken off and was sealed with silicone, and the idle mix screws had been changed.

I'm not even sure where to start if this doesn't work!   

[Big Rich]

What size were the main jets?

[Kijona]

I'd say your problem is the busted nipple. They probably used something non chemical resistant to seal it and over time it's began to leak. That would explain the symptoms of a vacuum leak.

Permatex makes a sealant that is completely resistant to gasoline and can be had from most major autoparts stores. I'd try that first.

[89500inPA]

I would strongly suggest not messing with carb jets until you get the bike running right or at least as good as it was for the past 19 years. Listen to the more reasonable suggestions first (pinched fuel line, bad gas, clogged breather hose) before attempting performance upgrades! All you need is to start chasing new "issues" when the bike is not running right to begin with. Just my 2c.

[Tronspeed3]

I think I found the issue!!! the boot that connects the carb to the cylinder head on the left side was pretty much in 2 pieces. I think the crack around the boot under vacuum would be letting in air and throwing off the air/fuel mix. I ordered another on off bike bandit and am in waiting for it to be delivered .