Modified Air Box

well I didn't believe what everyone was saying about tuning your carbs with pods. Well they were all correct. Tried numerous times (like about 30+times) to get the carbs tuned. Would be good one day then awful the next. And the bike was actually slower in the quarter mile. So I decided to modify my air box. First I had to plastic weld it back together. Had to cut it out since I didn't want to roll the engine forward. Then I cut the stock filter housing off. So now the air box should go back in with no issues. Fingers crossed. I then mounted one of the k&n air filters to the back of the air box. I am hoping this gets rid of the tuning issues. I will keep you updated when I get the bike down from off the shelf as it is still winter up here in the north.
Any thoughts or ideas would be appreciated.
Thanks Dean

 

That looks promising, I've contemplated doing similar on bikes I've owned. From my reading/research on intake designs for these UJM's I've found that the filter itself is often not the limiting factor which determines how may CFM of air the intake flows, its the design of the airbox itself. In theory pods should work, and they can be made to work exceptionally well on vm/flatslide carbs that aren't dependent on carb vacuum to lift the slides. With this style of carb power does increase approximately 5-8%. However on CV style carbs, pods are never a good idea. In order to maintain a non turbulent flow of air from entering the CV carbs (turbulent airflow is the main reason CV carbs don't work with pods) the main airbox plenum should remain (which you have done) but the inlet from the airbox can be enlarged to allow more CFM while maintain non turbulent flow and inlet airspeed velocity.

The reason the air boxes on these bikes are restrictive is because of noise regulations back in the day, if the inlet to the airbox is large or the filter is directly exposed to the elements the induction noise of the engine is far more prominent (I think it sounds amazing). With the air box inlet being a relatively small slit (atleast on my 550 seca) induction noise is practically no existent.
Give it a shot and let us know how it turns out!

What model XJ is your bike by the way? I'm in ontario as well, what did it run in the 1/4? I'm building a fj600 engine to stick in my 550 seca, hoping to race it at cayuga a few times this summer.

 

1982 XJ550. My fastest 1/4 miles was 14.0 with a stock bike. Last year was 14.5. The bike should be faster with the wheelie bar and a jet kit. So that is why I am going back to the air box with the jet kit.

 

Nice! That sounds spot on. I ran 14.1 on my seca 550, I'm about 215lbs with gear on. Heres a video if you'd like to see it. I'm hoping to get into the high 12's with the built 600 engine.

 

That sounds like my bike. But at the drags I take the baffle out. Sounds like a 900cc. Mac 4into1. Let me know how that 600 goes. A few of my buddy's want to put the ZX-10 engine into my bike. The bike was given to me and I know how fast it is. Will measure in the spring. I think it will be to big. Thanks for the video.

 

I'll be taking my FZ600 to St.Thomas this year. They have test & tune Sundays, $20 I think it was.
I'll try to remember and let you know when I'm going, I'm about 220 lbs, should be a good race!

 

I bet it does sound pretty mean! I'll have to try that next time. If you can make a ZX-10 engine work in the seca frame I will be absolutely amazed! Anything is possible!

 

Yeah that'd be great! Always a fun time at the track

 

The measuring tape won't lie.

 

You may as well consider a small block Chevy, won't be any less possible.

 

E.J. Potter mdea career around that setup. Not a Yamaha frame, but who cares.

 

Lol

 

Here is the finished product. I hope it solves the tuning issues? Fingers crossed.

 

Looks promising! Just need the weather to cooperate now. My guess would be you'll have to up the main jet two sizes from stock and the pilot one if you havent already, especially with the 4-1 exhaust.

 

Ya. I purchased a Sigma 6 kit for the bike last summer. Hoping for better results without the pods.

 

What was sigma 6 recommandation for this type of mod? I have the kit and they suggest +2 for main jet and stock pilot jet for my opened airbox and I havent tried it yet

 

Yes correct. Plus drill out the slides. And cut the springs. Raise the needle. I tried everything. Had a bog at about 7000rpm. Tried all kinds of combinations and synced carbs every time. Sometimes it would work good for a few days then the bog would come back. All with the k&n pods on the carbs. I am so tired of trying to tune the bike I am putting the air box back on but with the k&n filter in place of the stock filter. I sure hope this solves the problem. With all the posts of tuning problems with cv carbs with pods I am a believer now that it is a tuning nightmare.

 

Hopefully the slides you drilled weren't the original, otherwise you still won't be done with tuning! Good luck, riding season is almost here.

 

+1

You will need to go back to using uncut springs and undrilled sides.