Got a new (to me) 1980 xs400 Special

[compCoder]

One more thing, it appears that the idle mixture screws are blocked on my carbs (didn't know what exactly it was until today). However, mine seem to be blocked with a brass plug, not plastic like I have heard many of them are...there is a hole in it a bit larger than a needle hole, and I can see where it goes down into the throat in front of the butterfly. I have seen people talk of removing the plastic ones, but how do I get this brass plug out? I am not even positive that mine needs adjustment, as the bike ran well before I cleaned them, idled right at 1200 RPM, and pulled from idle through 9000 without hesitation (other than my crappy shifting...lol).

Anyways, tips here would also be great, and thanks for the links drewpy, I will read them and have my own manometer in no time (i love the name, sounds like a 'man' meter...lol)

[drewpy]

One more thing, it appears that the idle mixture screws are blocked on my carbs (didn't know what exactly it was until today). However, mine seem to be blocked with a brass plug, not plastic like I have heard many of them are...there is a hole in it a bit larger than a needle hole, and I can see where it goes down into the throat in front of the butterfly. I have seen people talk of removing the plastic ones, but how do I get this brass plug out? I am not even positive that mine needs adjustment, as the bike ran well before I cleaned them, idled right at 1200 RPM, and pulled from idle through 9000 without hesitation (other than my crappy shifting...lol).

Anyways, tips here would also be great, and thanks for the links drewpy, I will read them and have my own manometer in no time (i love the name, sounds like a 'man' meter...lol)

you have a choice; leave alone and hope that any rubber o ring is ok (if that's the model carb you have) Or remove the plug and have a look while the carb is out.

personally I'd remove it and check the contents.

I think if you drill a small hole and get a self tapper in there, you should be able to pull the thing out!

drewps

[compCoder]

Well, its raining like crazy here due to Tropical Strom Hermine, so I figured I would work on some stuff since its not so hot out. Anyways, I went to a few places looking for 'filter foam' to rebuild my air filters, but couldn't find anything at any auto places. I went to the hobby store and found some foam made by poly-fil, but it was WAY too dense, there is no way any air was able to get through, so I thought about using the regular polyfil stranded stuff, the same stuff I use in my fine fish tank filter (much much cheaper than buying the precut stuff, and its just as good...lol). Anyways, I found this and decided to give it a try, if it doesn't work out for me then I will probably just order some UNI brand filter foam online and replace it, but I think this will work fine, let me know if you think of any problems.

What I found was some 'dual layer' filter material, that had some fiberous stuff for catching the larger dust particles, and a smaller area for catching finer stuff under that, though it also has carbon in that 'fine zone' to freshen the air, its actually some furnace filter, but this stuff seems like it will do the job great as air actually flows through it, but not freely, seems to flow just like it should, and over the surface area, i think it will work great...here is what I got:

What i did was cut it out into 2 1/8th inch strips, so an 1/8 inch too wide for the holder. Then i cut it long enough to just wrap around. I then took the filter and scrubbed it really good with a harsh wire brush, to clean both layers of mesh, and all the filter material off the sides that I could get. I then glued one end down onto the metal flange by the hole, stuffed it in all the way around, and glued it on the other side of the hole on the flange as well. I then ran hot glue down both sides all the way around. Hopefully this won't be too restrictive and will also filter enough stuff out. Only downside I see for it is that I may have to replace it often, but when i can buy that whole sheet of it for $8, its no big deal, considering I only used a little over 4 inches of it cut off the short side...I will probably run it for about 50 miles, check it, inside the carbs, and anywhere i think there could be any dust, though I know the ones I buy for our home filter, catches very fine stuff, though this is a bit cheaper...anyways, enough blabbering, here is what I came up with:

Let me know if you think its good/bad and if it will work alright, or if I need to do something else, either way, it has to be better than how they were originally :s. After taking apart the carbs however, I think I will eventually be upgrading to pod style filters and a breather, as re-jetting isn't going to be as bad as I was thinking

EDIT: Also, I have one more question before I try to drill into this thing. I just want to make sure what I have circled below is where the idle mixture screw is, and that what is there actually is a plug. Its made of brass as well, so will have to try to drill it out to get it out, maybe just use a self tapping metal screw and put it partway in, then pull it out. One other question, is this 'plug' screwed into the threads in the hole, or is it just pushed in so I can just pull it out?

Thanks again for everyones help, this is coming along great, and I wouldn't have gotten this far without all of you, nor had the guts to do half of it!!!

[kindest]

Well, its raining like crazy here due to Tropical Strom Hermine, so I figured I would work on some stuff since its not so hot out. Anyways, I went to a few places looking for 'filter foam' to rebuild my air filters, but couldn't find anything at any auto places. I went to the hobby store and found some foam made by poly-fil, but it was WAY too dense, there is no way any air was able to get through, so I thought about using the regular polyfil stranded stuff, the same stuff I use in my fine fish tank filter (much much cheaper than buying the precut stuff, and its just as good...lol). Anyways, I found this and decided to give it a try, if it doesn't work out for me then I will probably just order some UNI brand filter foam online and replace it, but I think this will work fine, let me know if you think of any problems.

What I found was some 'dual layer' filter material, that had some fiberous stuff for catching the larger dust particles, and a smaller area for catching finer stuff under that, though it also has carbon in that 'fine zone' to freshen the air, its actually some furnace filter, but this stuff seems like it will do the job great as air actually flows through it, but not freely, seems to flow just like it should, and over the surface area, i think it will work great...here is what I got:

What i did was cut it out into 2 1/8th inch strips, so an 1/8 inch too wide for the holder. Then i cut it long enough to just wrap around. I then took the filter and scrubbed it really good with a harsh wire brush, to clean both layers of mesh, and all the filter material off the sides that I could get. I then glued one end down onto the metal flange by the hole, stuffed it in all the way around, and glued it on the other side of the hole on the flange as well. I then ran hot glue down both sides all the way around. Hopefully this won't be too restrictive and will also filter enough stuff out. Only downside I see for it is that I may have to replace it often, but when i can buy that whole sheet of it for $8, its no big deal, considering I only used a little over 4 inches of it cut off the short side...I will probably run it for about 50 miles, check it, inside the carbs, and anywhere i think there could be any dust, though I know the ones I buy for our home filter, catches very fine stuff, though this is a bit cheaper...anyways, enough blabbering, here is what I came up with:

Let me know if you think its good/bad and if it will work alright, or if I need to do something else, either way, it has to be better than how they were originally :s. After taking apart the carbs however, I think I will eventually be upgrading to pod style filters and a breather, as re-jetting isn't going to be as bad as I was thinking

EDIT: Also, I have one more question before I try to drill into this thing. I just want to make sure what I have circled below is where the idle mixture screw is, and that what is there actually is a plug. Its made of brass as well, so will have to try to drill it out to get it out, maybe just use a self tapping metal screw and put it partway in, then pull it out. One other question, is this 'plug' screwed into the threads in the hole, or is it just pushed in so I can just pull it out?

Thanks again for everyones help, this is coming along great, and I wouldn't have gotten this far without all of you, nor had the guts to do half of it!!!

another idea for your filter if this one fails is any hardware stores will sell lawnmower air filters and some of them are big enough to make work. im in the same boat i need to redo my airfilter soon yours looks like it will work good.

[johnsnownw]

EDIT: Also, I have one more question before I try to drill into this thing. I just want to make sure what I have circled below is where the idle mixture screw is, and that what is there actually is a plug. Its made of brass as well, so will have to try to drill it out to get it out, maybe just use a self tapping metal screw and put it partway in, then pull it out. One other question, is this 'plug' screwed into the threads in the hole, or is it just pushed in so I can just pull it out?

Thanks again for everyones help, this is coming along great, and I wouldn't have gotten this far without all of you, nor had the guts to do half of it!!!

Yup that's where it is. That plug is not very thick, so don't drill too far down.

Good Luck.

[compCoder]

another idea for your filter if this one fails is any hardware stores will sell lawnmower air filters and some of them are big enough to make work. im in the same boat i need to redo my airfilter soon yours looks like it will work good.

Yeah, I looked at the lawnmower filters, none would go into the air filter boxes for sure, and other than that they woudl just be pods. Some did have the foam, but had to buy a whole filter I didn't need just for a bit of foam, and would need like 4 for enough to cover it

Yup that's where it is. That plug is not very thick, so don't drill too far down.

Good Luck.

Cool, i think i will just get a self tapping screw and drill it in a bit, then pull it right out, thanks again!!

[OllieB]

Yeah, I looked at the lawnmower filters, none would go into the air filter boxes for sure, and other than that they woudl just be pods. Some did have the foam, but had to buy a whole filter I didn't need just for a bit of foam, and would need like 4 for enough to cover it

Cool, i think i will just get a self tapping screw and drill it in a bit, then pull it right out, thanks again!!

Threads do not come all the way up the sides of the hole. The plug is pressed in for a friction fit and is no more than about 1/4" long, if that much.

[compCoder]

Alright, was able to get some more work done today. I went ahead and installed the new plugs, wires, and caps, and they look much better not being all brittle:

Also, I went ahead and removed the cover for the pilot/mixture screw. I removed the screw (after screwing in and seeing it was ~1.5 turns out) and noticed that it does NOT have an o-ring on them, neither of them did, is this normal? The passages were completely clear so i just cleaned the screw real quick, reinstalled it, and backed it out a total of 2 turns, is this a good amount for now, or should I leave it set at 1.5 turns, more turns??

I also filled up the brake fluid reservoir as it was a bit short, and the book talked of a back one, but I don't have one as I have a drum brake in back, which i found a bit odd since it mostly discusses the 1977 model. I also lubed up the chain real good with some spray grease, its multipurpose, but one of them being chains, so I am sure it will work well. I did notice the chain is too lose as it drags on the top of the frame under the chain guard by just a tiny bit, so i will look in the manual how to tighten it properly. I also finished rebuilding the air filters into their boxes.

Now just waiting for that carb part kit to come in and I can finish those up right quick. Though one question on that too, in my manual it says to set the floats at 27.3mm +/- 0.5, is this the correct amount? As I have seen some other numbers thrown around in other posts and its confusing what the 'true' value is. i doubt I will be able to hit tenths of millimeters, but I figure if i get it between 27 and 28 it should be good. I also need to just go pick up some clear tubing to make my manometer, but already have everything else. i also am using a mixture of Hex bolts and allen bolts, as its all I could find, you can see the carb top bolts in my last pic, and I think they work and look great. Though I was able to find most sizes in the allen heads. Anyways, once I finish up these carbs, i will post a before/after pic of the carburetors so you can see the awesome cleanliness in all its glory!! Any help on the above questions is appreciated as always.

[johnsnownw]

Yes you need the o-ring on the mixture screws. You should turn the screws 3.5 turns out to start, and adjust from there. Most likely you will turn them more than 3.5 out when you are fine tuning.

Yup, your float height should be 27.3mm

[compCoder]

Yes you need the o-ring on the mixture screws. You should turn the screws 3.5 turns out to start, and adjust from there. Most likely you will turn them more than 3.5 out when you are fine tuning.

Yup, your float height should be 27.3mm

If they need to be there, why weren't there any to begin with? It had never been opened, as those caps were never tampered with, and even in the back of the Haynes manual it says for my model (xs400sg) that there is no recommended setting at all, as its 'factory set' and should not be tampered with...lol. Anyways, just seems odd its necessary but wasn't equipped with one from the factory, and it wasn't fallen off in the hole or anything, i looked in there, sprayed in cleaner and compressed air...its nice and clean!! Does it go on bottom or top of screw? there is the screw, then a spring, then a metal washer on the bottom of spring, at what point does this o-ring go? I will try to hunt one down locally tomorrow once I know where it goes, just a tiny one, as long as its gas stable then I guess I should be good to go...

Thanks again for all the help, I guess I will have to order one, but may be a while, I am ready to ride and only thing holding me back so far was the float bowl gasket and new float needle/seat coming in, which is tomorrow, and I was going to build my manometer and get everything sync'd as well...

[OllieB]

If they need to be there, why weren't there any to begin with? It had never been opened, as those caps were never tampered with, and even in the back of the Haynes manual it says for my model (xs400sg) that there is no recommended setting at all, as its 'factory set' and should not be tampered with...lol. Anyways, just seems odd its necessary but wasn't equipped with one from the factory, and it wasn't fallen off in the hole or anything, i looked in there, sprayed in cleaner and compressed air...its nice and clean!! Does it go on bottom or top of screw? there is the screw, then a spring, then a metal washer on the bottom of spring, at what point does this o-ring go? I will try to hunt one down locally tomorrow once I know where it goes, just a tiny one, as long as its gas stable then I guess I should be good to go...

Thanks again for all the help, I guess I will have to order one, but may be a while, I am ready to ride and only thing holding me back so far was the float bowl gasket and new float needle/seat coming in, which is tomorrow, and I was going to build my manometer and get everything sync'd as well...

Factory setting to reduce emissions and comply with EPA regs was 1.5 turns. I just installed new idle mix kits on my '80 yesterday. While the plugs had already been drilled out, there were o-rings down at the bottom of the opening. The o-rings are very small and get flattened. Could you have missed them? Order of parts install: coil spring, small washer, o-ring. The o-rings are VERY SMALL. Without the o-rings you will have vacuum leaks and not be able to get proper adjustment. It made quite a difference on my bike.

Get 2 new choke rod seals also. Mine were very hard and broke apart as I took them off. Be careful to not loose the small ball bearings located inside each rod guide as you slide the choke rod out. Best to unscrew the enricher plunger mechanism and pull the plunger out of the nut to make it easy to install the new seal.

[johnsnownw]

If those screws were not tampered with, the likely issue is that the o-rings have disintegrated over time. That's what happened to mine, as they were not there when I took mine out for the first time. I believe MikesXS has the same explanation on the kit you can buy that contains the o-ring. You can't put just any old o-ring down there, the o-ring needs to be able to handle corrosion from gasoline and be heat resistant. I would order the kit from MikesXS.

[compCoder]

If those screws were not tampered with, the likely issue is that the o-rings have disintegrated over time. That's what happened to mine, as they were not there when I took mine out for the first time. I believe MikesXS has the same explanation on the kit you can buy that contains the o-ring. You can't put just any old o-ring down there, the o-ring needs to be able to handle corrosion from gasoline and be heat resistant. I would order the kit from MikesXS.

I found some at Pep Boys that were made out of 'Viton' plastic by DuPont Elastomers, it says it withstands extended exposure to heat and fuel, so I think they will work fine, they are a reddish brown color, and a bit harder than your standard o-ring. Also, Ollie, on your ordering, I think mine may have been different unless I am misreading what you wrote, it was like this

____

|____| <-- screw head

..|| ^

..|| Between these is the spring

..||

..|| v

..|| <-- small washer and needle like point of screw

So does the o-ring go under the head, or between the washer and spring at bottom of needle? I would guess right up under the head of screw. I also picked up 24ft of 1/4 inch clear vinyl tubing from lowes for my manometer, only like $3 too, so was a good price...

Thanks all

EDIT: After looking at the picture, it looks like things actually go like this

Screw head

Spring

small Washer

o-ring

Well, after taking the screws back out this time, the o-rings actually DID come out, i guess they stayed at very bottom of hole last time, I even looked in there with light, just must have missed, and though it was the black hole into the carb as now i can see silver flanged area where they sit. Not only that they are in fine shape, flexible, whole, not nicks or holes in them at all, so now I can return this pack I bought and just use those for now, though on my next order of whatever, i will probably order the replacement kits for $4 each, i just don't want to pay 6.95 shipping for 8 dollars of parts...

[OllieB]

I found some at Pep Boys that were made out of 'Viton' plastic by DuPont Elastomers, it says it withstands extended exposure to heat and fuel, so I think they will work fine, they are a reddish brown color, and a bit harder than your standard o-ring. Also, Ollie, on your ordering, I think mine may have been different unless I am misreading what you wrote, it was like this

____

|____| <-- screw head

..|| ^

..|| Between these is the spring

..||

..|| v

..|| <-- small washer and needle like point of screw

So does the o-ring go under the head, or between the washer and spring at bottom of needle? I would guess right up under the head of screw. I also picked up 24ft of 1/4 inch clear vinyl tubing from lowes for my manometer, only like $3 too, so was a good price...

Thanks all

EDIT: After looking at the picture, it looks like things actually go like this

Screw head

Spring

small Washer

o-ring

Well, after taking the screws back out this time, the o-rings actually DID come out, i guess they stayed at very bottom of hole last time, I even looked in there with light, just must have missed, and though it was the black hole into the carb as now i can see silver flanged area where they sit. Not only that they are in fine shape, flexible, whole, not nicks or holes in them at all, so now I can return this pack I bought and just use those for now, though on my next order of whatever, i will probably order the replacement kits for $4 each, i just don't want to pay 6.95 shipping for 8 dollars of parts...

Yep, o-ring at very bottom. With the plugs still in there, I am surprised the o-rings are in such good shape. Maybe someone previously replaced them and installed new plugs like come with MikesXS kits. Who knows!!

[compCoder]

The rings are a little flattened, but will still seal, its easy to tell, and I also blowed into the hole and no air would pass. Unfortunately the chump of a UPS guy didn't show up with my parts today even though they were scheduled..I'm sure they will be here tomorrow.

So an update on some things i did. I tightened up the chain a bit as it was too loose, just followed the directions here and have it nice and tight. And even though I oiled it the other day, I noticed it was quite dirty and caked in grease, so I just spun rear wheel and cleaned it off real good with a rag, and also the sprocket a bit, and went ahead and resprayed it. I then tightened the chain to where there is now about a 3/4 inch play in bottom portion in the middle of chain, just like book said. Had to move the tensioner back to just a tiny bit past the third alignment mark, like half a mm, much less than I thought I would have to, but its now tightened as per the manual. Also had to adjust the rear drum brake lever a bit from the movement, but got it adjusted, and even a little better, took out a tiny bit of the play so I don't have to push the pedal down as far. I then went on to clean up the front disc and caliper with some brake parts cleaner, just gave it a good spray down and a wipe off. I think I have a VERY SLOW leak somewhere in my front brake line, it was wet with brake fluid whenever I got the bike, and I refilled the reservoir yesterday, and now, there is one tiny spot about the size of a BB that is wet again. I will be safe and keep an eye on it, and eventually upgrade to the metal braided cables whenever i rebuild the caliper this winter during no ride time. i also plan to take of tires and repack the bearings with grease, do the forks w/ new fork oil and seals and whatnot, and also grease whatever other bearings it says in the steering.

I was also able to build my manometer, and I feel quite proud of it, one of the few tools I have built and it came out very nice. Going to use some water w/ food coloring to do the balancing instead of ATF, as I don't have any and don't feel like buying just for that, as long as I keep an eye on it and watch closely I should stay safe on that part. Anyways, here is a picture of my manometer, let me know what you think!!!

Also, how high would you recommend i do the fluid? I was thinking about 1/3 the way up the board, which is 4ft long. Should be able to get a nice balance with it I think, and I had everything other than the tubing, so it was very cheap, only $3 and some time to get it built, the hose was very cheap at lowes. Anyways, tomorrow should have the new float valve and seat and gasket, so can finish up the carbs w/ float high setting and new parts and get everything back installed, should be able to start it by then, and start with the carb setting. What is a good order for doing the carbs, will fire it up first to make sure it runs, then get the idle good and stable I am guessing, through use of the mixture screws (right now at exactly 3 turns out) and the idle stop screw. Once that is done I do the balancing by turning off bike, removing the one vacuum blocker, hooking up my awesome manometer, and start the bike with it connected (have the petcock set on prime, since the vacuum will be detached from petcock). Hopefully will be riding sometime this weekend!!!

[johnsnownw]

I would do something about that leak in your brake line, brake fluid is horribly corrosive. It will ruin paint and pit metal.

[compCoder]

I would do something about that leak in your brake line, brake fluid is horribly corrosive. It will ruin paint and pit metal.

I will be, but I am not made of money, so can only do one thing at a time, its the very next thing on the list. And its so slow I will just keep an eye on it. There wasn't any on any metal other than the caliper itself, which is missing a tiny bit of paint, but the leak is so slow, it was still just under the 'lower level' after being filled over a year ago when the father-in-law rebuilt it. Going to redo it with some steel braided line instead of the rubber line...and while I am at it, may as well rebuild the caliper itself too...was thinking of drilling out the rotors, but seems like its a TON of work for not much gain, so will probably just use as it is...

[OllieB]

I will be, but I am not made of money, so can only do one thing at a time, its the very next thing on the list. And its so slow I will just keep an eye on it. There wasn't any on any metal other than the caliper itself, which is missing a tiny bit of paint, but the leak is so slow, it was still just under the 'lower level' after being filled over a year ago when the father-in-law rebuilt it. Going to redo it with some steel braided line instead of the rubber line...and while I am at it, may as well rebuild the caliper itself too...was thinking of drilling out the rotors, but seems like its a TON of work for not much gain, so will probably just use as it is...

I am sure you will be on the safe side with the brake leak but be careful as the front brake does the majority of the braking. Can you determine just where the leak is coming from? Could it be something as simple as the brake hose attachment banjo bolt or caliper bleed screw needing a slight bit of tightening?

BTW, manometer looks good!

[compCoder]

Alright, I know this seems basic, but I am having trouble figuring out where to measure from on setting the float hight. This is the image the book shows:

And this is a pic of my carb in the same position as book:

As you can see, the front edge they measure from, what I highlighted in green, is certainly not right, its way higher than the book, and there is no way I can get that to measure 27.3mm from there. So, there is the surfaces I highlighted in yellow and in red to choose from, or even right behind the yellow down inside where the parts actually meet, which of these is actually correct, as there is 1mm difference between yellow and red alone, and even moreso if i go for behind the yellow lip right by float...I am shooting for between 27 and 28mm (close to 27 as possible), as all I have is a ruler or a sewing tape, I don't have calipers or anything super accurate, I used to have a slide rule somewhere, but I cannot find it, and don't even remember if it actually had that type of measurement on it (we used it in geology back in college)...

Thanks for the answer to this noob question, but I am stuck here until I get this part figured.

EDIT: Did some research online, and most people say to measure from where the float bowl gasket seats, so would be 'over the ledge' of the yellow line right up next to the float, so that is what I am going to go with for now, hopefully can get carbs on bike and attempt a start sometime tomorrow, but may be going into work, so we will see...

[HoughMade]

You measure from the surface where the bowl seat, not the rim, but where the surface of the bowl actually sits- so just inside the yellow.