XJ550 Seca is sluggish at 55mph+

I have been riding my XJ550 around and find that it has slow acceleration at 55+ MPH. I've done the valves and carbs were supposedly jetted for pods (which it has) before I got it. Plugs look nice and tan and the bike seems great below 55 but once I reach about 55ish it seems flat. It will trickle up to 70 and maybe more but pretty mellow. Not enough to make a convincing pass. Should I expect more from it? Anything I should check?

 

What gear are you in? If you are in 6th you probably need to change down a gear or two and rev it higher

 

I will be cruising at 65mph at 6K RPM. So how high of RPM should I expect to hit in the situation I describe above? Mainly my concern is driving along and needing to get away from a car or something on the freeway. Does the 550 just not have that kind of power? I can try a down shift but at that speed it seems sketchy.

 

If you're running 6K rpm it should have plenty of "go" but there's nothing wrong with grabbing a lower gear or two.

Is this a stock bike or does it have mods to the intake and/or exhaust?

 

The bike has both. Intake is modified to a K&N pod system and the exhaust is 4into1. No idea what brand the exhaust system is. Just seems gutless on the freeway.

 

Most likely a jetting issue. I've gotten my Max beyond 100. You say it was supposedly jetted, but pods and a 4to1 exhaust changes the running mixture for sure.

Other possibilities: Brakes sticking? Tight chain? Axles too tight?

 

The carbs aren't set up properly.

Once you remove the airbox AND the exhaust collector box, you've effectively given yourself "clean sheet of paper" jetting-wise. Whoever allegedly rejetted it for the mods didn't get it right is all. There's no set formula for restoring the magic.

Pull the carbs, and let's see what jets are actually in it. You should be able to get it a lot closer than where it is now.

 

Will do bigfitz. Maybe I can get them off tonight.

 

A 550 has plenty of power. If I really open it up I can hit 75 in 3rd gear without red lining it. I would also say to start with the jets to see what you have.

 

I have this same problem with my 550 but with some popping out the exhaust. It has pods with stock exhaust. I do know that it has 112.5 for main jets. The valves and in spec, carbs cleaned and fuel level set. Am I right in thinking I should jet it and see if it fixes the issue?


(Bike is not in signature because it is my brothers)

 

here ya go, i'll tell you right now, a air box is easier
http://www.factorypro.com/tech/tech_tun ... gines.html

 

i think I saw a chart on this site somewhere that had a basic starting point for the XJ550 in which it stated what to do when you add pods, pipe etc. Then it had the corresponding jetting change for each mod. Of coarse they said it was only a starting point and would likely need further tuning depending on your bikes specific mods. If anyone knows where that might be I would really appreciate the link. ASAP I will post up what my carbs have now, work just isn't giving me time to do it yet.

 

XJ4Ever section... information Overload page I think

 

It's in "The Church of Clean" almost to the bottom of the page: http://xjbikes.com/Forums/viewtopic/t=14692.html

Right below the section listing all the stock jets for the different XJs.

Patrickw, you need to keep an eye on the plugs in the 550. Popping indicates a lean condition and if he's riding it that way on the stock jetting you don't want him to blow it up before you can re-jet it.

 

It sounds to me like it is way too lean. Popping from the exhaust means that you are getting miss-fires and the mixture from the unlit cylinder is igniting in the exhaust. You can get popping from either a lean, or super rich condition. But if the bike is gutless on the freeway then it's my experience that you need larger main jets. I'd bet that the bike seems to accelerate better at 3/4 throttle than at WOT.

 

Will do bigfitz. Maybe I can get them off tonight.

 

OK I took a look at the main and it's a 120 from some carb picks I took before when it was appart. Too bad no pic of the pilot jet. Based on the pod/4-1 exhaust, 2600ft altitude and the comments on Chocal's page "the church of clean I should start with 116.5 main. So if anything it's richer than base line but that could be OK as it's all a bit test and go. I still need to look at the Pilot. It could be that they only updated the main.
Now for an interesting fact....
I just tested the bike and this time revved it out to about 9K+. Wow it kicks in at 7k and feels amazing. Seems in the 4-6k range it dogs a bit. Especially true a higher gears. I need to get into the carb and look at that Pilot jet. Sounds like a great Friday job.

 

Try raising the needles, do this by lowering the clip if you have that type or put 1 or 2 #4 flat washers on the needle before inserting it in the slides. If you can adjust the pilots to blacken the plugs and not be out more than about 3 1/2 turns then your pilots are big enough.

 

Seriously you need to fatten up the midrange and that isn't done with the pilot jets.

 

Polock's link is the key! Read it and follow those steps and you will be very close - skip one - and you will never get anywhere.