When my f4 is still kind of cold, it's peppy and responsive on the low end and even more so in the higher revs. When it gets hotter, it is very sluggish at times on the very low end, especially from a standstill when I try to take off fast. Even in the higher rpms, where I feel less of a difference, it still isn't pulling as hard as I know it ought to, and the throttle response is slow and boggy.

Should I adjust/rejet the carbs first or adjust the valves (by I, I mean my skillful friend and I)?

 

I would look else-ware before I start messing with the carbs, they are often a problem, but not always the problem. just my 2 cents. Have you looked at anyhting other than the carbs as the culprit?

 

How many miles? Might be time to do both. I'm pretty sure the F4 is like all the other 600 Hondas and the valve shims are under the lifter so the whole camshaft has to be taken out. I've heard from a few people though that this design causes them to rarely be out of spec.

 

bout 44k miles, it's a 2000 and doesn't have any service records so.. probably gonna be the first tune-up.

I've installed a new fuel filter, the air filter will get cleaned soon and we'll see what that does but I doubt it's something that simple because it's a pretty noticeable difference.

The only reason I began to suspect the carbs weren't tuned right was that I read a carb cleaning guide and it listed the symptoms of various out-of-tune jet positions and stuff, and it sounded exactly like what's going on with my bike. It also has a slip-on exhaust. One thing about that is that I could envision someone thinking, "Oh awesome, a cool-looking pipe that is supposed to add like 4-6 hp", buying it and installing it without understanding how that affects the tuning of the engine.

One last thing: after my fuel pump got clogged a week ago and, in the process of clearing it, I noticed how grody the fuel filter was, I replaced the filter. I could conceive this changing the flow rate to my carbs IF the old filter was super dirty and full of gunk. I did notice that after installing the new one, the bogging effect I'm experiencing is somewhat more pronounced. Perhaps I'm running just slightly richer now, and when it gets hot, it affects my tuning. Does that sound feasible??

K, thanks for all the input btw.

 

Definitely could be the carbs. It could be a lot of things potentially. If you can't get it through a carb tuning or valve adjustment then I'd check compression. It's a worst case secnario but you could have bad rings. As the engine heats up the metal expands and if your rings are worn then you'll get low compression on the bad cylinder which causes loss or power.
I don't want to panic you but just giving you another thing to check if you can't get it tuned properly.
Good luck.

 

okay. thanks

 

I'm guessing you're a second or third owner of the bike and maybe a PO put in too large of a jet kit. What you're describing could be symptoms of jet sizes that are too big and the air/fuel mixture is fat. Pull your plugs and inspect them. If they are covered with a black soot, then you need to lean your mixture.

 

will do, ty. does anyone know of a thread that entails the process of removing plugs from an f4?

 

Spark plugs?

 

Yeah. I found one that's good but no pics.