running rough

So I recently purchased an xj750 seca bobbed, I've been redoing the wiring and trying to get the bike to run right "didn't feel like I had the power that a 750 should have". this is also the first bike I've owned that wasn't a sport bike and I know there will be a difference in throttle response and acceleration. I seem to have little power when I throttle up or go wide open, the bike just doesn't want to haul a$$. I came across some info last night about cv carbs and pod filters, which my bike has installed. will this make my bike lose that much power

 

Oh yes I'm afraid they will. Especially with those pipes if the jetting hasn't been sorted... What colour are your spark plug tips? (My 50p is on "glazed white") :?

Welcome by the way, please read the links about brakes in my signature below before you ride again, I'd like to think it'll save a life one day

Since the bike's hardtailed & there'll be no room for an airbox, what some people have had success with on these carbs is using the stock airbox to carb rubbers to space the pods back a bit (the rubbers are a velocity stack and smooth the airflow).

You will still likely need to rejet the carbs with the rubbers fitted, as running lean on an air cooled motor will kill it fast, but at least you should have a fighting chance of working out a good compromise...

 

The frame wasn't modified under the seat, I believe I can fit the airbox back in there, I have a parts bike that I'm pulling the airbox out of. I'm new to owning a bike with carbs so I'm slowly figuring out things i shouldn't do, like the pod filters. I had no idea they can kill performance so much.

 

I live just down the road from you (think fountain area), and have picked up a couple of toys to help tune my bike. I know where you live from the pics, been there quite a few times. When you get to the point you need vacuum gauges to check the carb sync, color tune, and compression test I can help you out.

 

that would be awesome!! from what I've read, I also need a YICS eliminator tool to do a vacuum carb sync so I'll order one of those. like I said, I'm new to the whole carbs setup so your help will be much appreciated!!

 

Since my bike is an '80, I don't have to worry about the YICS that's why i don't have one of those. There are a couple of threads on here about building on your self if your interested. The carbs aren't too bad, you just have to make sure you don't miss any of the little things.

 

You do, but a lot of the ones hawked on the innanet and eBay are incorrect and don't work correctly for proper tuning. Your best bet is a replica of the factory tool; XJ4Ever carries them as do a few other vendors.

"wasn't a sport bike and I know there will be a difference in throttle response and acceleration. "

Not really. In stock trim, the XJ was a "racebike for the street" and would seriously surprise you.

You'll need to get the valves in spec before you can sync the carbs; I'd check that oft-overlooked item asap.

And put a front brake on it before you ride it. It's a 130-mph motorcycle, fer chrissakes; you're gonna get seriously hurt if you ride it with no front brake.

 

Fitz is right about the valves, guess I missed that. On that topic, Rocky Mountain Cycle plaza will trade shims with you if you need replacements. I don't know about any of the other places in town. I went to Action Cycles and picked up some used shims for a couple of bucks so I have some to trade with. If you know what you need, you can go there to get some used one's but you better bring a digital caliper because their stock is a mess and not all of them have readable numbers.

 

finally got my stock airbox on, definitely doesn't look as bad as I thought it was going to. I cannot believe how much power I lost by having pod filters on the bike, it now runs just like one of my old sport bikes. still need to tweak and check some stuff but at least its running how it should now. just gotta pull the brakes off my parts bike and fine tune everything and I'll be good to go!!