Why does my '94 1000f sound like a 2 stroke until I give it gas?????.....carbs were just cleaned and sync'd last month.

Idle is ok....but at 25, 35, 45, etc....cruising.....sounds like a BIG DIRTBIKE!!!!
Throttle it up and it's smooth as SILK!!!

PLEASE HELP??!?!?!?!?!?!?!

 

The first thing I would do is find a new gas pump. Try to find one with out ethonal (corn).
Also, make sure that you have the proper spark plugs. The shop only had NKG's in the #8 last year so I tried them. They made the bike bluber.

(NKG) DPR9EA-9
(Nippondenso) X27EPR-U9

gap 0.8-.09 mm (.030-.040 in)

 

timbuctwo, what year is your bike? mine is a 1995cbr1000f and mine takes 8's. looked it up several times and thats what was in it when i bought it.

 

First thought is another carb cleaning. My '94 sat alot before I got it. It took two tries to clean the slow speed circuit out, (below 2500rpm). If it's a 50 state model, like mine, it has all the extra emision crap with a couple miles of vacuum hose. Normally a vac leak will make the idle rough, but yours is good. However, the emission controls may introduce one when they start to do thier job off idle???. I don't think a one step change in plug heat range would be an issue. More like a bad plug. Bad gas, all kinds of performance issues, but might be masked by wider throttle openings, in street riding. 2 cent contribution!

 

now THAT was an intelligent answer.......I don't think that my bike has all the extra emissions stuff like for Cali.....but I am just talking about this:.....when you buy a new bike, it accelerates smoothly....even when you downshift...you get no popping....or backfiring........some people alter their bikes by changing timing or carb adjustments to get more power......I just want my bike to RUN RIGHT.......I think it's powerfull ENOUGH.....I'm sure it'll do 150......but I've only been to 120..........will it be impossible for the motor to run smooth simply because of its age or mileage(50k)????
should I be looking into rebuilding an engine soon??
I just hate when I'm going down side streets to get to my house at 25-30mph....it sounds like it's missing a LOT.....but punch it and it smooths out like a well lubed machine.

 

Any other maintenance done with your carb work? My rule of thumb is do all the mechanicals first, ie: valve lash, ign timing, (check advancer operation),plugs. If it's not been done CORRECTLY, Start there. Then carb tuning, If it ran ok after your carb clean and sync job, and then something changed after some miles, go back into the carbs. The passages in the slow circuit are VERY small and it doesn't take much to cause a problem. Is the tank clean? Need a filter? The California spec bikes will have two valves (Pulse Secondary Air Injection Control Valve, PAIR) mounted above the valve cover, L&R between sparkplugs.

 

Well i am going through the same problem right now i changed the spark plugs and it went away then come back in a few minutes then i cleaned out the air filter and drained out the carbs and it seams to be working better and would gas with ethonal in make a differance in the way it runs.

 

Balance your carbs.
Mine's done 43000 miles and no engine rebuild in sight.
Ethanol will make it pop slightly.
You may also have a leak at the headers - check that too.
Your pilot jet settings could also be out - 21/2 turns is about right.

 

Sounds like the problem I had when I took mine out of storage. Make sure there is no dirt, rust ,sediment in the float bowls. The inside of my tank was pretty rusty and a very fine rust sediment got by the petcock filter. I ended up cleaning the bowls twice because there was some still in the fuel line after the first cleaning. I also now have two sets of slow jets. I keep a clean set on hand now. The blockage of the slow jet(s) seemed to be the main cause.

 

I went from the NGK-8 back to the 9 and it did make a difference. I believe that NGK gets hotter with the higher number unlike other plugs.
Ethanol will make the bike stumble on take off. Here in the states they add 10% but I think it separates and you could get more if drawing from the bottom.

When were the carbs synced last?