So I'm having a little trouble diagnosing my bike. It's a 1998 cbr600f3. It started having some carb issues a couple months ago and so I had somebody rebuild them completely with all new Jets needles floats gaskets and o rings. It ran great for a couple of months.. And then started having a bunch of electrical issues with the fuel pump. I got all that sorted out. Fuel pumps working great , it's brand new. but when I get to about 5 to 7 RPMs it starts sputtering and total power loss. Definitely feels like a fuel issue but it can't be the carbs because they were so recently done. When the bike is in neutral I can rev it up past 7 and it sounds super clean. Doesn't stutter at all. But as soon as I'm in gear it feels like a fuel starvation issue. I've changed the stator, the regulator rectifier, the fuel cut relay, brand new fuel filter fuel pump and air filter. Also new spark plugs. I have no idea what it's doing but it's really starting to **** me off. Any help would be much appreciated

 

I was having the same issue with my bike. Cleaned the carbs drained the tank flushed the filter out. Put fresh gas 93 octane and 3/4 bottle of seafoam. Just ran it through the tank today and I got all my power back.

It literally happened well I was riding, my bike would sputter at 8k and on the trip home it was all good.

I suggest putting some seafoam in and running the tank till it really gets through it.

 

Awesome thank you for your response! I think you're 100% right. I pulled off the air filter air box and intake ports yesterday and noticed that the slide in carb number 4 wasn't going up with the rest. It wasn't physically stuck, but it wouldn't left with the rest. I took the carbs off today and thought it might be a tear in the diaphragm so I open that up and there wasn't. I think it just wasn't seated right. Anyways so I got that all sorted out. Now all four slides go up in sync. It improved my power just a tiny bit. but me being in such a hurry to get back on the road and me being a dumbass I didn't even think to open the float bowls and check the other three. Even after I found a little bit of silicone type gasket sealer inside the fourth 4th float Bowl. To be honest I was just a little intimidated because I've never cleaned carbs and I didn't want to take them out of sync. Especially because I don't have carb syncing instruments. But anyways, I'll do some more youtubing on how to clean them properly and I'll be back at it tomorrow. Thank you again for your response

 

I've never synced my own carbs before but if I'm correct syncing the carbs only applies to getting all four butterflys to open at the same time. So you taking the bowls off pulling the Jets out and cleaning won't affect your sync.

 

In a round about way that is true. A more technical way to look at it is when you sync your carbs you are compensating for the small imperfections in the mechanical parts as well as the difference in valve clearances. The end goal is you want all four carbs to act in perfect unison as they create vacuum. That is why one adjustment screw can be x amount of turns in and another y amount. In reality it isn't hard but it does take patience as even the smallest tweak on an adjustment screw has a direct affect on the others. There's a lot of give and take if will.


As GameKiller7 pointed out, you can remove the bowls without getting things out of sync.

 

Definitely a blocked main jet.

 

Thank you everyone for the responses! It was in fact clogged jets. From the gasket sealer the mechanic used. It's back on the road and with more power then it has since I've owned it

 

Great news. Glad you got to the bottom of it. Just an FYI, The bowl gaskets do not require sealer if the are in proper condition.

 

Gasket sealer? WTH?

I use silicone grease on the rubber gaskets, but sealer is a no-no.