no power below 6k - Awesome up to redline
 

Last night my bike broke but in the opposite way I'm used to things breaking, I could use some suggestions on where to look first.

How it's acting:
kinda idles ok as long as you don't do anything
no power up to 6k - 7k. not just low power, barely more than idle pull.
Get it up to 6k -7k and hold on tight - as if nothing was wrong at all.

What happened?:
Has been running well, was actually 20 miles or so into the ride, coming off a high speed straight when I dropped the RPM down below 5k and it just felt and sounded wrong. no smoke that I noticed but it was dark. no clanging metal sound, do get a few more pops on decel but keep the RPM up and it's great. Got it home ok, just had to keep 7K and up on the RPM.
Right now I am in a condo with no garage so I'm trying to figure where to start troubleshooting with limited time to complete at a friends house.

So the basics:
2003 with Factory Pro jet kit, TPS adjusted and Jardine high mount exhaust. Bike has been running great with nothing more than a battery, tires, oil and filter changes (Shorai LFX, stock and a good synth oil) in the last 3 years - so pretty basic setup. Petcock tubes are correct, haven't touched them in 3 years.

Anyone else remember having this issue? I'm thinking maybe the petcock diaphragm - really not sure where to start on this one.

my ex's bike had a similar issue, not the same bike but same symptoms, it ended up being the carb diaphragms, one was ripped and the other had a pin hole in it. replaced them and did a thorough check to make sure everything else was fine and buttoned it up and it was perfect.... someone else may have more insight, good luck

Carb diaphragm, or petcock diaphragm... Like has been said, either torn or cracked, with a small leak... My money is on the petcock, since you have low rev stumbles...

Thanks for the input. I guess I'm going to hope for the petcock, assuming that is easier (cheaper) to get parts for.
I will use the good ol' search function to start but offhand, does anyone know if petcock rebuild kits are available (USA), or at least a reasonable price on replacement? Same goes for the carb diaphragms, are they available?

Actually, I'm a bit surprised that a 10 year old bike has any original rubber parts here in AZ. Between the UV and ground level ozone, everything cracks and crumbles.

Time to see if any of my friends have an air-conditioned garage I can squat in for a bit.
Thanks again.

Whoa, I didn't remember seeing anyone else in the Phoenix area!

The best way is to buy the OEM part with the diaphragm in it; some of the aftermarket kits don't rebuild so well.

Part # 16953-ML0-034

I have a garage available, but no AC, so it gets hot fast working on the bike! (that's an open invite) ;)

Right on, Thanks. And good call as well, that part from Western Honda is cheaper than some of the rebuild kits I found. I just hope that is the cause of the issue.

I'm in Scottsdale / Tempe area, been around the sportbikes here for a long time, just don't get on the forums much.
I'll PM you later, may take you up on that invite :)

Thanks

So I finally got time to tear into the bike and fount the problem:
The clip that holds the needle in the slide (Factory Pro kit) broke. The needle was full closed until enough RPM / vac to pop it full open. new clip, tune and it runs great...

but....

I noticed the left fork seal starting to leak so I took that apart and found that BOTH FORK TUBES ARE BENT!! Ever so slightly right at the bottom of the clamp. I never noticed it, couldn't see it with the forks on, it rode great and I never hit anything - must have been that way when I got it 25K miles ago!

So now I need to find some straight fork tubes before I can ride - now that the weather is perfect for riding - damn.

Anyone in AZ have a straight stock fork set you'd sell?

I don't remember if I sold mine or not when I swapped front ends. I'll have to go through my storage box and see... if I do I'll shoot you a pm.

Thanks. I am ready to just order a new set of tubes from Western but it's not going to matter if I order them tonight or tomorrow. I'd rather save some $$ since this all comes from my "FJ needs a lift" fund.

You must have one quick steering SH!

It could also be some trash from the tank ended up in the carbs, or a cracked vacuum hose as well, if the bike is only pulling enough vacuum through the line that goes to the petcock to open it up at higher revs because its leaking this could easily be the problem.... dont ask me how I know :banghead:

Now that I was able to take mine out again today, this sounds like my problem as well. I popped the tank after I got back and found fresh fuel around the petcock on the underside of the tank and on the rubber piece under the tank itself. Guess I'll just put it away like that and deal with it in the spring.