Taking carbs back to stock.

[Hurdj2585]

Two years ago I decided to install a K & N air filter onto my bike. It would bog down when I would open the throttle. I took it to the local shop and they told me because I had the new air filter I needed to jet it. I had them install a DynaJet kit in it. In the process they cleaned and rebuilt the carbs.

All this was before I started reading on the forums here. I have a 93 katana 750. I want to put the stock air filter back on as well as cleaning/rebuilding the carbs back to stock. I probably won't get to this for another month or so but while I have the funds I would like to get everything together so the parts are sitting here waiting on me to start when I finish classes. Because I am really unsure what they swapped out inside the carbs, is there a kit I can buy with stock jets, gaskets, etc or will I have to buy it by the piece after I get into the carbs?

Thanks in advance for the help

-Jason

[MEngineer]

Why not keep the jet kit and just use a stock filter? Dig into the carbs to fully clean them and verify everything in there is correct, or replace what needs to be. No reason to go back to stock just because you think it's wrong. Just verify it's right.

[Hurdj2585]

Right now my bike seems to be running too rich. I've fouled a couple plugs already, smell gas from time to time from the exhaust, and I get roughly 30mpg and I don't ride aggressive. If I keep the jet kits installed how would I lean it out...or would the stock air filter help correct the issue.

I plan on stripping the carbs and cleaning them per carbs 101 as well as coating my gas tank with por-15.

[MEngineer]

You should be able to set the jetkit to relatively stock settings. The air/fuel mixture screw will help lean it out, but the mains could be far too large. It depends on what was installed, but you can definitely set it better. It will also help to determine when it is too rich.

[Stumpy]

Your needles are probably set wrong to compensate for the massive airflow from the K&N filter.

Once you have a stock type filter in there, I wouldn't be surprised if you run a bit lean. It's a simple case of run hot, throttle off, and listen to the pop chorus

Of course, that may not happen at all, and you'll be running good without bogups! Check your plugs to be sure how it's working internally.

If it runs badly, then yeah - go ahead and clean the carbs. Be sure to post pictures so we can help as best we can. I'm hoping you really do find a jet kit in there. If they are stock......

[Hurdj2585]

I'm hoping you really do find a jet kit in there. If they are stock......

There better be a jet kit in there. I don't remember exact numbers but I paid them at least $600 to clean/rebuild and install the jet kit in the carbs.

I guess it wouldn't hurt none to put the stock filter back on and see how it runs.


On a side note I will miss the sound difference of the K & N filters when this is all done.

[AnthomX]

There better be a jet kit in there. I don't remember exact numbers but I paid them at least $600 to clean/rebuild and install the jet kit in the carbs.

I guess it wouldn't hurt none to put the stock filter back on and see how it runs.


On a side note I will miss the sound difference of the K & N filters when this is all done.

That is funny actually. I enjoyed the sound more on mine after putting the stock airbox on. A bit throatier.

[pnut1236]

There better be a jet kit in there. I don't remember exact numbers but I paid them at least $600 to clean/rebuild and install the jet kit in the carbs.

I guess it wouldn't hurt none to put the stock filter back on and see how it runs.


On a side note I will miss the sound difference of the K & N filters when this is all done.

Tip: get rid of the k&n for the stock, even with a jet kit it'll run like crap. I would also suggest a factory pro jet kit for your bike as a very high number of members including myself have very good experience with them. Theres a sticky on here called carbs 101/102 that will basically hold you hand through tearing apart and rebuilding the carbs and while there apart put the jet kit in it.

30mpg is pretty bad considering my 750 usually get 45

[TRPUT]

Your needles are probably set wrong to compensate for the massive airflow from the K&N filter.

I guarantee they are! The general approach is to set all the adjustments richer than standard. More air therefore more fuel right!!?? But it's not just more air, but how less restriction alters the operation of the carbs (eg slide). I don't know exactly why, but what my A/F meter confirmed was I needed to lean off the AF screws and needles and floats with the K&N fitted. I have it running super sweet, recording AF ratios of 14.4 - 14.8:1 at idle and cruising at 4000 - 5000 RPM - and since that's 99% of what it does, I'm happy. It is fractionally rich (about 13.7:1) in between at light throttle and fractionally lean (dropping to 15.5:1) beyond 6000 RPM. I could fiddle with jetting more, but for what she does, there would be no tangible gains. (It's hard to improve on smooth delivery, plenty of low torque and over 300 miles on a tank.)

[crazycraven420]

Tip: get rid of the k&n for the stock, even with a jet kit it'll run like crap. I would also suggest a factory pro jet kit for your bike as a very high number of members including myself have very good experience with them. Theres a sticky on here called carbs 101/102 that will basically hold you hand through tearing apart and rebuilding the carbs and while there apart put the jet kit in it.

30mpg is pretty bad considering my 750 usually get 45

yea I agree, if youve got the money get rebuild kits with gaskets etc and a factory pro jet kit. Then tear down, soak, clean, reassemble and not have to worry or second guess what's in there.