New member here, just bought an xs1100 special

[Bax]

Three MNS under one roof........ cajun31 you are the man.

---Bax

[cajun31]

Three MNS under one roof........ cajun31 you are the man.

---Bax

What can I say... it's an addiction.

[wingnut]

Instead of the 4mm tap just screw a pointy sheet metal screw in the small hole you drilled and grab it with your small vicegrips and pull it out of your way. This way you avoid damaging the heads of the idle mixture screw. Speaking of those, they may be difficult to get out. Soak them in PB blaster and custom grind a screw driver to fit the screw slots. They are soft and you can create a drill it out situation if not careful.

[TheNannerpus]

wingnut
Your post is borderline prophetic. I worked in this today, read on.

cajun31
Your recommendation using the 1/8" drill and 4mm tap worked flawlessly. Thank you!

[TheNannerpus]

As cajun31 pointed out, I missed checking the pilot screws in my carb rebuild. So today I took it off again, removed all the rubber parts and got to removing them.

All the parts looked good to my untrained eye, but I replaced everything anyway. This picture shows the old parts.

Two things happened that made the day interesting:

1. I checked the screws' positions before removing, and the #3 screw was all the way in. When I took it out, there was no spring inside!?! I'm convinced I just dropped it somewhere.
2. The #4 screw stripped. I ended up drilling it out, but I drilled off-center and couldn't use my screw extractor! 😬. As I began to panic, I decided to make decisions on how to fix it. If 1 hole got me in this mess, then a 2nd hole might get me out of it. So I drilled a 2nd hole next to the 1st one. Luckily, the two holes merged and created a new slot for me to use a screwdriver again. Luckily, it worked! I did score the edge of the hole a bit, but not enough to matter.

So with that tail-clenching fun behind me, I put the carb back together and reinstalled. I used a hanging gas tank with a splitter to see if removing the octy, plus the carb rework did anything.

After a few cranks, the bike fired up. Eventually, I could take it off choke, and even rev it! It was great to hear the sweet music. Keep in mind, I have yet to even ride this bike, and this was the first time I heard it in real life. I've had to resort to YouTube videos to watch others ride their XS.

I realized I didn't cap the old vacuum nipple, so that is next on the list, along with synching.

Also, it leaked gas as I tried restarting, but once it fired up, it stopped leaking. From what I can tell, it looks like it's leaking from the airbox? Wouldn't that mean the float valves are not working and the bowls are flooding? I replaced all those parts, and checked them, so I'd be surprised if they are the culprit.

Any thoughts?

[cajun31]

As cajun31 pointed out, I missed checking the pilot screws in my carb rebuild. So today I took it off again, removed all the rubber parts and got to removing them.

All the parts looked good to my untrained eye, but I replaced everything anyway. This picture shows the old parts.

Two things happened that made the day interesting:

1. I checked the screws' positions before removing, and the #3 screw was all the way in. When I took it out, there was no spring inside!?! I'm convinced I just dropped it somewhere.
2. The #4 screw stripped. I ended up drilling it out, but I drilled off-center and couldn't use my screw extractor! 😬. As I began to panic, I decided to make decisions on how to fix it. If 1 hole got me in this mess, then a 2nd hole might get me out of it. So I drilled a 2nd hole next to the 1st one. Luckily, the two holes merged and created a new slot for me to use a screwdriver again. Luckily, it worked! I did score the edge of the hole a bit, but not enough to matter.

So with that tail-clenching fun behind me, I put the carb back together and reinstalled. I used a hanging gas tank with a splitter to see if removing the octy, plus the carb rework did anything.

After a few cranks, the bike fired up. Eventually, I could take it off choke, and even rev it! It was great to hear the sweet music. Keep in mind, I have yet to even ride this bike, and this was the first time I heard it in real life. I've had to resort to YouTube videos to watch others ride their XS.

I realized I didn't cap the old vacuum nipple, so that is next on the list, along with synching.

Also, it leaked gas as I tried restarting, but once it fired up, it stopped leaking. From what I can tell, it looks like it's leaking from the airbox? Wouldn't that mean the float valves are not working and the bowls are flooding? I replaced all those parts, and checked them, so I'd be surprised if they are the culprit.

Any thoughts?

Can honestly say have been there and done that with having to drill out a pilot screw. It really helps to soak it with penetrating oil but it doesn't always do the trick. Glad to see you got them out. With all the brass plugs still in place to begin with I would have to agree with you that you dropped that spring. The most important part was to have the spare parts with new o rings to reinstall. On the carb that you couldn't count how many turns it was... I would just start at two and a half turns out from lightly seated and go from there. I use the Gunson's Colortune tool to set all my pilot screws. Many on here like it and some hate it. I am sold on it. You obviously will need to plug the intake manifold nipple that the Octy was hooked up to in order for the bike to even start to run right. Gas coming out of your airbox is why I don't get rid of the Octy. Did you verify your float heights when back in the carbs? It is critical that they be set at 23mm from the base of the carb body with the gasket removed to the highest point of the float. That will help to stop the flooding into the airbox. When you notice the gas coming out of the airbox it is very dangerous to start the bike... especially while the carbs are not properly tuned. DAMHIK... but one little backfire can set your bike on fire. While I am tuning a new to me set of carbs I have both a fire extinguisher and a wet towel next to me if the event that occurs. You are getting close. You will need to get the pilot jets set properly and the carbs need to be synched. I am glad to hear that the drill bit tap die worked well for you.

[cajun31]

Instead of the 4mm tap just screw a pointy sheet metal screw in the small hole you drilled and grab it with your small vicegrips and pull it out of your way. This way you avoid damaging the heads of the idle mixture screw. Speaking of those, they may be difficult to get out. Soak them in PB blaster and custom grind a screw driver to fit the screw slots. They are soft and you can create a drill it out situation if not careful.

I have seen many broken pilot screw towers due to the sheet metal screw approach. Not that it is the culprit .. just some folks act like a gorilla doing that method.

[TheNannerpus]

After pulling the carbs yet again, I got the floats where I think they're pretty good, mainly because gas isn't leaking anymore. See this thread for more.

Carbs were synched with carbtune. I tried the colortune by ear, but I couldn't hear the revs change, so the pilot screws are set at 2 turns out until I get me one of those tools.



My octy is on vacation until further notice (per this thread), replaced with these. Coincidentally, also an octy (once I put the final section of tubing after the filters). Go figure. I still have to test fit to get the best tube lengths.

I plan on putting stuff back together between now and the weekend and see if this thing is road worthy. I'd like to get even a short ride on it before winter.

[cajun31]

After pulling the carbs yet again, I got the floats where I think they're pretty good, mainly because gas isn't leaking anymore. See this thread for more.

Carbs were synched with carbtune. I tried the colortune by ear, but I couldn't hear the revs change, so the pilot screws are set at 2 turns out until I get me one of those tools.



My octy is on vacation until further notice (per this thread), replaced with these. Coincidentally, also an octy (once I put the final section of tubing after the filters). Go figure. I still have to test fit to get the best tube lengths.

I plan on putting stuff back together between now and the weekend and see if this thing is road worthy. I'd like to get even a short ride on it before winter.

you probably won't have to deal with it again but another trick to drill that stuck pilot screw out would have been to simply reinstall the drilled brass plug into the top of the tower to use as a guide to drill the screw. It would ha ve prevented you from getting off center and at a angle to begin with. The screws are brass as well and drill like butter with a good sharp drill bit. As I have stated... I have had to do this several times and once properly drilled then it is generally no problem to employ penetrating oil and a quality extractor to get the screw out without damaging the tower or the the threads that hold the screw in.
If I read correctly ... you ordered a color tune tool? If so then when you get it in .. tune each cylinder to just the hint of a yellowish orange. Makes things a tad rich and is where these bike run best. Actually will let them idle a bit cooler. To tune them by ear takes a bit of practice. Best I can explain it is you will be turning the screw counter clockwise until you start to hear the bike stall or stumble. I always hear that and the bike may even begin to pop or backfire a tad. Once you hear that then slowly begin to turn the screw back in until that clears up. At that point you are where you want to be.
Also.... and I find this helps everything else is to make sure the carbs are synched before doing the final pilot screw adjustments. You will want to re synch a final time once you are finished too and periodically as you keep and ride the bike.

[TheNannerpus]

cajun31
I can't seem to find a colortune available that fits, unfortunately. Seems to be backordered.

Even if I won't use this info now, I may need it down the road. Or, perhaps more importantly, our posterity will find this useful. I know I've come across many old posts that have been valuable because there was some nugget of info I needed. I recently read a post on here from a member that has passed on, which made me sad, but grateful.

[DiverRay]

If you can hear the difference in idle speed, you can adjust by ear. You can also use the tach, but it is NOT that accurate at low RPM's.
1. From your start point, turn #4 clockwise SLOWLY until the idle seems to slow.
2. Turn 1/8 turn counterclockwise.
3. Rev engine slightly and let settle.
4. move to #3 and repeat steps 1-3. continue until done with all 4 carbs.
5. RESYNC the carbs, or at least check to make sure they have not gone out of sync. I use a set of 4 gauges, and check all 4 before each use. They WILL move now and then!
You may need to turn the idle up or down, depending on how close the carbs are.

[cajun31]

cajun31
I can't seem to find a colortune available that fits, unfortunately. Seems to be backordered.

Even if I won't use this info now, I may need it down the road. Or, perhaps more importantly, our posterity will find this useful. I know I've come across many old posts that have been valuable because there was some nugget of info I needed. I recently read a post on here from a member that has passed on, which made me sad, but grateful.

This supply chain problem and people staying at home is really limiting what you can buy. I have noticed that they are hit and miss on Ebay.

[DiverRay]

The MNS NEEDS to be stock!! I miss the one I had, but it went to someone who knew what it was, and wanted another after a long break. My '79 was worked on by Bob Jones, and it does have a bit more than a stock bike. 175psi readings on my gauge. I still need to get the '78 engine back together and see what it will do.

[cajun31]

The MNS NEEDS to be stock!! I miss the one I had, but it went to someone who knew what it was, and wanted another after a long break. My '79 was worked on by Bob Jones, and it does have a bit more than a stock bike. 175psi readings on my gauge. I still need to get the '78 engine back together and see what it will do.

My thoughts exactly Ray. That was quite a gesture on your part to sell the MNS. I know I could never sell the one I bought brand new, however I do have 2 others that don't hold the sentimental value the original does. I am in the process of completing my barn find I picked up last October. Finally got everything sprayed and am now wet sanding and buffing the main body parts. I was slowed a bit by an accident I suffered in late September. Trimming tree limbs and took a fall on my right shoulder. Makes doing things like sanding and wrenching a bit more painful. Amazing how slowly you heal when you get to your mid 60s.

[Aches n Pains]

This worked great for me. Removed octy. Set up with a T to feed from both sides of the tank to all four carbs. Added a shutoff on each side so I don't need to sweat the petcock leaking into the carbs. Always shut off the fuel line and ran the carbs dry if I wasn't going to be riding for a couple of weeks.