staycryptic
Under there.
Thanks!^ Another thing to check out.
-
Enjoy XS400.com? Consider making a donation to help support the site.
XS400.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
What am I getting into?
- Thread starter staycryptic
- Start date
staycryptic
Under there.
So, actually made an effort to get it running today. Pulled the carbs off, a quick shot of cleaner went into the passageways. Honestly, they looked much butter than I expected inside.
Then, threw in a new set of NGKs. Put it on PRI, turned the key on, and
IT RUNS!
and stays running! Slowly backed it off the choke as it heated up. It holds a ready idle with no choke now. It warms up. It charges the battery. It does what it should!
Now that's out of the way, its time to make it road ready. So, new brakes, fluids, chain clean/lube and a look over everything else then its off to get it inspected!
Pretty excited.
Then, threw in a new set of NGKs. Put it on PRI, turned the key on, and
IT RUNS!
and stays running! Slowly backed it off the choke as it heated up. It holds a ready idle with no choke now. It warms up. It charges the battery. It does what it should!
Now that's out of the way, its time to make it road ready. So, new brakes, fluids, chain clean/lube and a look over everything else then its off to get it inspected!
Pretty excited.
hmusket
XS400 Addict
Congratulations. Its a great feeling when the bike starts and works. For me its even more satisfying when I use the kickstart. BTW, did you switch it back from PRI to ON?
staycryptic
Under there.
Yep. I did that when I was backing off the Choke. Is that what I leave it on when Im leaving it sit? I think that doesnt flow fuel unless it's pressurized by the vaccuum, right?
Oh, and a quick cell phone video:
Oh, and a quick cell phone video:
Normally (assuming the petcock is working) you should be able to leave it on "On" all the time unless it sits for a long time or you drain the carbs. Then you turn it to prime, then once it's running, turn it to "On". When it is "On", it will open the fuel flow as soon as there is vacuum and keep it going as long as the engine is running.
Congrats on getting it running. Sounds good......that seat, though....a product of its time, I guess.
Congrats on getting it running. Sounds good......that seat, though....a product of its time, I guess.
staycryptic
Under there.
Oh yes, the 'Porn Couch' strapped to the back of my bike is going. Trust me.
I've been poking around on here to see who has one. I'm just looking for a normal, stock seat.
I've been poking around on here to see who has one. I'm just looking for a normal, stock seat.
Civicalized
XS400 Member
Haha thats awesome. definitely doesnt look right on these bikes.
staycryptic
Under there.
I think its the opposite of what everyone is trying to do.
Including me!
Including me!
new kid on the brat
new kid on the brat
dude i could build a whole retro bike around that seat!!! extend the forks about 18 inches 21" front spoke wheel. ape hangers,stars and stripes on the tank!!! oh what fun that would be!!!
staycryptic
Under there.
Sure thing Easy Rider, I'll sell it to you cheap!
frwinks
XS400 Addict
I'm sure you could build a LOT of things around that seat... some you might even be able to charge good $$$ for...
I have some pics of my stock one for ya sc, send me your email addy
staycryptic
Under there.
So, right now the bike has no airbox on it.
Rather than putting the stock box on, I was going to just install cone K&N Filters on each carb and a tiny breather for the case.
How would I tune for the increase in air? Would I adjust a mixture somewhere? Or completely rejet the carb for this modification? (if that's the case, how?)
Rather than putting the stock box on, I was going to just install cone K&N Filters on each carb and a tiny breather for the case.
How would I tune for the increase in air? Would I adjust a mixture somewhere? Or completely rejet the carb for this modification? (if that's the case, how?)
You need to re-jet; probably 1 stage larger on the pilot jet and 2 stages larger on the main jet, but often it is necessary to buy several sizes and monkey around with it. I say "stage" because each size increase actually goes up by 2.5, so two stages is a 5.0 increase in whatever units the jet orifice is measured in.
There are air/fuel screws on your carbs for minor adjustment in fuel mixture, but it won't be enough for pod filters.
Emgo pod filters are only 14 bucks for a set, but some people say they do bad things. I am not sure I agree because I have a lot of experience with cars and changing air intakes, but that is the word on the street. The K&Ns cost buku dollars, but are arguably the best.
New jets just screw in where the old ones went. mikesxs.com has what you need. I like to pull out the jets and double check the stock sizes before ordering because info can be conflicting. The sizes are printed on the face or the barrel of the respective jet. Mikesxs sells jets for several types of carbs; you want the ones for the bs34.
You probably already know that you can get a crank case breather for 10 bucks at any auto parts store; they fit, but they are a bitch to get on if you don't lube them first.
There are air/fuel screws on your carbs for minor adjustment in fuel mixture, but it won't be enough for pod filters.
Emgo pod filters are only 14 bucks for a set, but some people say they do bad things. I am not sure I agree because I have a lot of experience with cars and changing air intakes, but that is the word on the street. The K&Ns cost buku dollars, but are arguably the best.
New jets just screw in where the old ones went. mikesxs.com has what you need. I like to pull out the jets and double check the stock sizes before ordering because info can be conflicting. The sizes are printed on the face or the barrel of the respective jet. Mikesxs sells jets for several types of carbs; you want the ones for the bs34.
You probably already know that you can get a crank case breather for 10 bucks at any auto parts store; they fit, but they are a bitch to get on if you don't lube them first.
staycryptic
Under there.
Bc, you've got the tech info on this site memorized! Thanks dude.
I'm going to order up a few jets and see where it gets me.
Is it a pain to rejet them?
Also, I'm used to having my laptop measure my air/fuel ratios on the racecar. It also can tell me if its running hot. What are we using for our bikes? Just ballpark it?
I'm going to order up a few jets and see where it gets me.
Is it a pain to rejet them?
Also, I'm used to having my laptop measure my air/fuel ratios on the racecar. It also can tell me if its running hot. What are we using for our bikes? Just ballpark it?
No, once you know your carbs it takes 10 minutes or less from removal to bike running. I have the cheap emgo pod filters and a very unrestricted exhaust and I am running 2 sizes up on the pilot and 3 sizes up on the main. Another guy on here, mcrowell75, has pod filters and a more tame exhaust and is running 1 size up on the pilot, and 2 sizes up on the main with some adjustment to the slide needle. I have not gone farther than my driveway, so I cannot say how well my bike is truly running other than that it sounds fine now, doesn't backfire, and revs smoothly.
People have all sorts of wacky methods for guessing at air fuel ratios. The way the bike acts when stationary and being revved to different rpms can show large discrepancies; rpms hang, bike backfires, etc.
Once the bike seems like it is running fairly well you can synch the carbs using a manometer. A manometer can be made for like 10 bucks using wood, vinyl tubing, and zip ties. I have not done it yet, but I am guessing the air flow is "synched" by adjusting the butterfly flaps via the screw/spring mechanism that links them together between each carb. I am not sure if they are synched using the fuel screw to get a more precise mixture; it's something for me to explore further.
Once you're synched you can test drive the bike and see if you "feel" any flat spots, hesitation, bogging down, etc. Putting the engine under load probably helps reveal more fueling problems.
Then there is plug chopping and reading spark plugs. Apparently, the color/condition of the plug can give clues as to the a/f ratio and they can also be chopped in half to reveal, I guess, a smoke ring that forms on the inside of the electrode.
If you have a wideband you can essentially skip all this bs and just measure things properly
Jetting is analogous to putting bigger injectors in your car.
People have all sorts of wacky methods for guessing at air fuel ratios. The way the bike acts when stationary and being revved to different rpms can show large discrepancies; rpms hang, bike backfires, etc.
Once the bike seems like it is running fairly well you can synch the carbs using a manometer. A manometer can be made for like 10 bucks using wood, vinyl tubing, and zip ties. I have not done it yet, but I am guessing the air flow is "synched" by adjusting the butterfly flaps via the screw/spring mechanism that links them together between each carb. I am not sure if they are synched using the fuel screw to get a more precise mixture; it's something for me to explore further.
Once you're synched you can test drive the bike and see if you "feel" any flat spots, hesitation, bogging down, etc. Putting the engine under load probably helps reveal more fueling problems.
Then there is plug chopping and reading spark plugs. Apparently, the color/condition of the plug can give clues as to the a/f ratio and they can also be chopped in half to reveal, I guess, a smoke ring that forms on the inside of the electrode.
If you have a wideband you can essentially skip all this bs and just measure things properly
Jetting is analogous to putting bigger injectors in your car.
Last edited:
cturek
XS400 Addict
You should make sure you valves are in spec before you attempt to sync and tune mixtures.
frwinks
XS400 Addict
I went with UNI filters, and grabbed 140 and 145 main jets (stock is 132.5). I was told the "slow" jets can be adjusted with the screw only.
Adjusting the valves is routine maintenance. In the manual, it is in the "Tune-Up" section, but a specific interval is not given (that I can find). I check clearances once a riding season unless sound tells me to check sooner. I think it's something that should be done before trying to fine tune the carbs. Assuming everything is running pretty well, I would adjust the valves, then set the idle mixture screws (or otherwise get the mixture right), then synchronize the carbs, then set the idle speed. In that order.
staycryptic
Under there.
Really quickly, before I pull the trigger on these. Are these the correct air filter for this bike?
http://www.powersportsuperstore.com/ProductDetails.asp?ProductCode=PU10111685&CartID=1
http://www.powersportsuperstore.com/ProductDetails.asp?ProductCode=PU10111685&CartID=1
