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Discussion Starter #1
My mechanic replaced the air filter yesterday as a part of the full service that didn't get done last fall because he didn't get the filter he thought would be the best in time. This is a carb Bird with Dyno stage 1 and Laser slip-ons. I believe the previous filter used (in another shop) was a standard filter, while this one was a Hiflofiltro, supposedly best for my tuning. But something's very weird. Now the Bird is "choppy" up to around 2800 RPM's in any kind of extra load, like a small uphill. And below 2000 it's basically impossible to use. I have never had that problem before the filter replacement, so if he didn't do anything wrong while replacing it (a pain in the ass on that bike according to him...) I can only conclude that it's the filter. There seems to be at least as much power in the rest of the range, I even feel there may be a bit more on top. But that can of course also be me wanting there to be... ;) Is this simply a case of "get another filter", or is this me getting the full use of Stage 1 from 2800 and up? :D
 

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If the filter flows different to original one fitted, carbs will need retuning. Either fit standard back in or have this done. This assumes he fitted it correctly. He should also have known you could have issues by changing the air flow.
 

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Discussion Starter #3
THanks! And yeah, he thought that a more open filter would fit the Dyno better and give more power on the top. So the reason is probably that after the Dyno Stage 1 the carbs were tuned to a regular air filter?
 

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Discussion Starter #5
OK, thanks! So the coice is tuning the carbs and maybe get a little bit extra power or just replace the filter again and never know if I could actually be a bit faster... I guess that wins, tuning the carbs is probably quite expensive!

Edit: I see that a Dyno company has their workshop close to where my daughter lives. It costs 1100 Norwegian kroner per hour to adjust carbs after jetting. That's around 90 pounds, or 120 dollars per hour. How much time should I expect them to use on that? I guess I will see exactly how many HP I have in the bike too, which would be interesting.
 

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OK, thanks! So the coice is tuning the carbs and maybe get a little bit extra power or just replace the filter again and never know if I could actually be a bit faster... I guess that wins, tuning the carbs is probably quite expensive!

Edit: I see that a Dyno company has their workshop close to where my daughter lives. It costs 1100 Norwegian kroner per hour to adjust carbs after jetting. That's around 90 pounds, or 120 dollars per hour. How much time should I expect them to use on that? I guess I will see exactly how many HP I have in the bike too, which would be interesting.
Really depends on how good the mechanic is and what changes are required? Will a simple clip change on the needle sort it or will it require new jets etc?
Even if it's just something simple like a change in clip height I'd say you'd be looking at a couple of hours :idunno:

Unless you're dragging the bike or really wanting every last HP out of the bike I'd just go back to a std filter ;) There are many posts on various forums that seem to indicate that an OEM filter is superior in most ways to aftermarket :)

Just one thing, the hose on the front of the airbox hasn't been dislodged allowing excess air into the airbox?
 

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Discussion Starter #7
OK, thanks! Back to standard filter, then. ;) No doubt in this case.And no, he's quite sure he didn't tear anything loose.
 

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Discussion Starter #8
Btw is it possible to check that hose without removing the tank and all that stuff? I still haven't mounted the sides of the fairing.
 

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Btw is it possible to check that hose without removing the tank and all that stuff? I still haven't mounted the sides of the fairing.
You should be able to see it from underneath I would think with a torch :hmm: That or if you can lift the rear of the tank you might be able to get a hand in there and feel if it's loose :idunno:
 

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so if he didn't do anything wrong while replacing it (a pain in the ass on that bike according to him...)
can't see why it would be any more difficult than on the inj's that I am familiar with. Remove bolts at rear of tank, pullout side poppers (if you have the panels fitted), pull tank backwards. Lift at front and prop with a piece of timber. Remove airbox lid, remove/replace filter and revers process.
I did mine a couple of weeks ago, took me less than 15 minutes!

Just don't have a full tank before you start.
 

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The hi flo air filter says it gives 15 percent more air flow on the box.Would fifteen percent difference affect the bike so much down low?
I have one fitted last four thousand miles no ill effect on stock 98 BB.
I would try a bottle of redex in your next full tank,in case bits were disturbed in the tank and made their way into carbs.Got a feeling he didn't put the air box back together properly.Its an easy job to check ,you just need a short stubby screwdriver to help access to the seat end screws of the airbox with the tank lifted like The Duck described.
 

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Depends on where the carbs were with the stock filter. If it's on the lean end already and you open it up to more air you'll get exactly what he is seeing.
 

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You dont even have to turn off the tap. Nothing runs out unless there is vacuum. ( I didn't know there WAS a tap until recently). I've changed the air filter twice. It's a 20 minute job at most.
 

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Sounds as if this could possibly be an air leak issue around the filter cover/housing..check obvious before changing anything..(past experience)..good luck⚓
 

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Discussion Starter #18
Well, he's taking it back this weekend or next (I won't have time to ride next week anyway because of a heavy/black/death metal festival) to replace with a stock filter. I hope it will be OK with that.
 
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