Flat spot / stuttering 6 - 7.5K
Joined the forum as there seems to be a lot of useful information on here.
I have an issue with my ZX6R F3 (97)...
First issue was that between 6K and 7.5K i had a noticeable drop in power and the revs slowed down, it bogged slightly but once past that range it tore off. I had changed the manifold to a full stainless and fitted a stubby exhaust.
I would have thought it would be running a little lean after that but it is running really rich, the smell of the exhaust is very petroly (sic) and there is black soot like stuff on the exit of the exhaust.
I researched the problem and it pointed to the carbs being adjusted wrongly, i toop the caps off and looked at the needles but theyre not adjustable. I i was to shim them it would make them very very rich (i tested this).
I also cleaned the air filter a little as it was majorly bunged up but didnt clean it too much as i wasnt sure how clean it had to be. ?(It's a pipercross aftermarket one).
Since that i moved the exhaust further back up the pipe so that less of the link pipe was inside the can, figuring that if the stubby was making it run rich, making the exhaust system longer would lean it out. Which it appears to have done! I no longer have such a noticeable flat spot at that rev range, although I am now faced with another issue!
If i am on half throttle, cruising on a motorway or something, the bike slowly starts to bog, like someone has put way too much fuel into the carbs, it seems almost like the air pressure is dropping or maybe leaking and it's being starved of oxygen?
What should i look at next? I am thinking about taking the airbox off, really cleaning the filter out, putting it all back together again and being extra careful to make an airtight seal. I'll also look at the breather pipes / vacuum and make sure theyre all connected OK.
I've been very thorough explaining looking at the length of this post!
TL;DR - My bikes running way too rich, no adjustable needles - what do?