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Flat spot through higher rev range.

778 views 14 replies 5 participants last post by  shark 
#1 ·
Hi All
I have recently done the TPS and carb sync.Bike ran perfectly .
I fitted a K&N air filter.After fitting the K&N my Sv has now picked up bad flat spots in the higher rev range and not pulling as well with the k&N air filter.
Should I go back to the stock air filter again or have the bike dynotuned?
Your input will be appreciated.
Regards
Shark
 
#4 ·
Bike we running fine, fit an airfilter bike runs bad.
Either the new fileter doesn't work so good, at least without further modification, or something got disturbed when you did the work or something went awry coincidentally at the same time.
I think the first thing I'd do is un-swap the filter to see if this returns you back to original state, if it does you need to decide whether to ditch the new filter or do additional work.

Must admit I find it hard to believe that the new filter should cause such a problem if it is 'better', could understand if it were more restrictive. Must admit I've heard variable reports about K&N some say better, some say no change some say worse.
 
#6 ·
The SV's are mapped really rich....and most will take the K&N and be happy about it because it slightly leans the mixture which is a good thing. But when the fuel system is getting into trouble due to clogged inlet screen or filter, doing anything to lean it out will make it run worse. It's not the K&N that's causing you problems....look into the fuel delivery as it's going to keep getting worse until you fix it.
 
#10 ·
Thanks for the replies, i have ordered a pair removal blanking kit, i will have another go at it when it arrives, i must have done something to make it run like crap.
Will keep you posted.
Are you fitting the PAIR removal kit in an attempt to sort out your problem?

If so then I've got so say that is completely illogical although unfortunatly quite typical. Maybe I'm wrong but as I understand from your original post the sequence of events was.

You had a bike running at least OK.
You adjusted the TPS and sync'ed the TBs - Presumably it still ran OK, hopefully even better.
You swapped out the air filter for the K&N - The bike developed a problem.

It seems to be the best course of action is to backtrack, check the filter install and put the original filter back.
The idea of adding more parts or changing more things when you know where the problem occurred.
Sorry to go on but I spend a good deal of my life problem solving and this kind of "scatter gun" approach (which I meet frequently) just drives me mental (apologies to any mental people reading this), keep it simple and solve one problem before potentially creating another is my advice.
I'm not saying don't remove the PAIR, but get back to a steady state first, but it's up to you.
 
#14 ·
GDCobra posed a question in his May 5 reply......you did the TPS and sync....was the bike running well then ?
Then placing the airbox and filter back in caused the issue ?

Does your bike have the air pressure sensor under the airbox ? Has it, or any other vac hose been dislodged ?
The vac lines to the base of the throttle bodies even ?
 
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