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brendonna69
XS400 Member
Have you had the carbs apart yet? They are pretty easy and usually the source of these bikes running bad.
I'd get new plugs and check your wires while you're at it. I bought a carb rebuild kit for mine and replaced all the o rings with new ones but didn't see any reason to not reuse stock hard parts (stock hard parts are usually better than the aftermarket, so long as they aren't worn). Make sure you remove the diaphragm before cleaning as well and visually inspect it for pin holes. I would also replace the butterfly shaft seals as well. Once you get it stripped down and get all of the rubber parts removed, you can simmer the carb in hot vinegar +lemon juice, or you can go to your local autozone and buy a carb dip... let me know how it goes.
I'd get new plugs and check your wires while you're at it. I bought a carb rebuild kit for mine and replaced all the o rings with new ones but didn't see any reason to not reuse stock hard parts (stock hard parts are usually better than the aftermarket, so long as they aren't worn). Make sure you remove the diaphragm before cleaning as well and visually inspect it for pin holes. I would also replace the butterfly shaft seals as well. Once you get it stripped down and get all of the rubber parts removed, you can simmer the carb in hot vinegar +lemon juice, or you can go to your local autozone and buy a carb dip... let me know how it goes.
brendonna69
XS400 Member
13651-51010
throttle shaft seal part #
Make sure when you finish cleaning them, set your valve clearances, and balance your carbs with a vacuum balancer
throttle shaft seal part #
Make sure when you finish cleaning them, set your valve clearances, and balance your carbs with a vacuum balancer
jeffjr92
XS400 Member
Thanks for the tips. I don’t have any replacement parts yet or a vacuum balanced. Would it be better to wait or just strip it down and clean anyway?
The shaft seals are sort of a pain to replace, as you pretty much need the carbs to be completely taken apart. You should probably order new screws for the butterflies as well. They are marred at the screw ends to prevent them from backing out and being pulled into the engine and they almost always get ruined upon removal. Shaft seals are almost always overlooked and can cause big air leaks and lean conditions.
Just make sure to keep all parts assigned to their designated carb body. Do one at a time, or get trays for each carb..
Try to be more descriptive when discussing symptoms. The problem you describe could be something as simple as a clogged filter in the gas tank, or a clogged screen on a float valve. What happens when it dies and what are you doing that makes it die?
Just make sure to keep all parts assigned to their designated carb body. Do one at a time, or get trays for each carb..
Try to be more descriptive when discussing symptoms. The problem you describe could be something as simple as a clogged filter in the gas tank, or a clogged screen on a float valve. What happens when it dies and what are you doing that makes it die?
jeffjr92
XS400 Member
I was planing on removing the tank to clean it and coat it since the inside is kinda rusty but not terrible. Eventually I’ll go through everything just to be sure. I just wanted to know what to look for ahead of time since it’ll be sitting on my patio when I start.
I’m not doing anything to make it die. I can ride normally for a few mins and I can hear normal exhaust sounds coming from both sides. After that it’ll bog down for a moment and pick up again but then it starts backfiring. It’ll run a little longer after riding and having it backfire but it continues to bog down, gradually decreasing my speed to the point where I’m unable to keep up with the speed limit. Sometimes I can hear the exhaust on both sides, sometimes I can’t. Once it dies I just have to let it sit for a while before trying to start again. When it starts again it’ll ride normally for a few mins but immediately backfiring and bogging down when I try to do the speed limit (40-50) on backroads. If I barely twist the throttle it seems to run better for longer but the moment I go 30% or more I can tell it’s going to die soon.
I wouldnt even bother with coating the tank. Lots of people do it though and are fine but then theres a lot of horror stories too. A little rust wont matter. My tank has rust in it and its fine. Replace the petcock with a manual one, and get an inline fuel filter. After that, you dont have to worry about fuel.
Try to avoid EBay rebuild kits, unless they are Keyster brand that SiriusSonic sells. Aftermarket jets are junk and you should only have to clean what you have anyways.
Try to avoid EBay rebuild kits, unless they are Keyster brand that SiriusSonic sells. Aftermarket jets are junk and you should only have to clean what you have anyways.
From the vid it sounds like you have a loose baffle in the right side muffler. I have seen this on a few of these in the past. With the bike off, thump the mufflers with the side of your fist. If you hear something rattle that's it. You should replace it as there will be no way to fix it.
jeffjr92
XS400 Member
Thanks for the info. It already has a manual petcock so is it better to disassemble and clean or replace?
jeffjr92
XS400 Member
I’ll try that when I get home. Thanks
As far as lining the tank goes, I paid to have mine done with red kote with mixed results.
The coating itself seems ok but the red color does leech into the fuel.
I believe I've read that it's the ethanol doing it.
A friend swears by POR15 but it's supposed to be harder, without the flexibility of Red kote.
So it's a mixed bag. Though probably minor the fuel contamination from the red kote would make hesitate to use it again.
The coating itself seems ok but the red color does leech into the fuel.
I believe I've read that it's the ethanol doing it.
A friend swears by POR15 but it's supposed to be harder, without the flexibility of Red kote.
So it's a mixed bag. Though probably minor the fuel contamination from the red kote would make hesitate to use it again.
jeffjr92
XS400 Member
I’ll keep that in mind when I get the tank off. I’ve thought about replacing it since mine had a nice sized dent and the cap doesn’t fit flush.
Vinegar does wonders on a rusty gas tank. I buy 4 gallons at a time from Costco. I have a Virago tank on the side of the house that has been soaking for a week or more. Opened it up yesterday and it almost looks new in there. Need to drain and slosh some nuts and bolts around to make sure its all clean then rinse with baking soda.
jeffjr92
XS400 Member
I bought some cleaning vinegar from Home Depot a while back and it worked great for an old lawn mower tank I had. Thanks for the info, I’ll give it a try.
If the petcock is not leaking and shows good flow into a catch can, Id just leave it alone.
Since you have an electronic ignition, you will have no relation to this.. But Ive had the same problem as you with the one cylinder firing since I got my bike on the road. It happens when I first start it up and tap the gas. It would come and go.. I eventually found out that the points/ignition was grounding out on the points cover.
Since you have an electronic ignition, you will have no relation to this.. But Ive had the same problem as you with the one cylinder firing since I got my bike on the road. It happens when I first start it up and tap the gas. It would come and go.. I eventually found out that the points/ignition was grounding out on the points cover.
jeffjr92
XS400 Member
Could you post a photo or video to show what you mean? The guy before me messed around with the wiring so i bet it’s the same issue as yours.
