Yamaha XS1100 Cafe Racer Project - Episode 18 - Carb Assembly and New Diaphragms

[@dawnsmith2876]

There’s not enough information about these vintage Yamahas I’ve been combing the web looking for helpful information on my XS750. Thanks so much for these videos. They’ve been super helpful.

[@wreckedemmotorcyclesbikepr8097]

Hi Andy, Still trying to finish my trike off been building it since lockdown 🙂 too busy in the music industry since lock down. Just delivered are a set of 4 x Diaphragms from JBM re your suggestion. They look ok and only took about 3 weeks to arrive in the UK. I'll be fitting them this weekend 🙂 and hopefully be able to get the carbs back on the trike and carry on the build 🙂 Thanks for the info great channel by the way, I've mentioned you a few times in my Vlogs

[@codygale8254]

Great video! I have found that using a small spring loaded punch works excellent for removing stuck float pins. Just make sure you have a hand ready on the opposite post where the pin exits or the pin could shoot across the room once it breaks free.

[@ANDY5]

+Cody Gale Thanks for the hot tip Cody, I used it in Episode 34

[@codygale8254]

No problem, glad I could help out. In the process of building an XJ myself. It is the 750 Maxim model though, wish it was a 900 or 1100 but they are hard to find around here.

[@GTsGarage]

Great vid, a nice walk through of the carbs, if I had a pound for every time I thought I was filming when I wasn't, I would be rich. Nothing wrong with making hay whilst the sun shines, heaven knows we will have all the time in the world to tinker throughout the winter.

[@ANDY5]

+GTs Garage Thanks old mate. I may do a follow up, I hate not delivering on promises. I'm sure there are guys and girls out there looking to do this work and could benefit from a visual aid.

[@GTsGarage]

definately

[@roythearcher]

The material that most motorcycle carburettors are made from is a Zinc alloy not aluminium which will react to the fuel, fur up over time and be very difficult to disassemble. The Zinc alloy is relatively soft and great care must be taken not to over-tighten jets and float bowl screws as they will be easily stripped out and the jets are soft too. The slightly grippy nature of the alloy means that it is not necessary anyway to over tighten screws and jets as they will hold just fine as long as they're not too loose!

[@ANDY5]

+roythearcher correct on all counts Roy. I work in a zinc smelter and we make casting alloys for just this type of thing, thanks for watching

[@alif.seyran2803]

Like your views. Kinda serious and more useful version of Ichiban Moto :D

[@scottroger5859]

Hello Andy! Greetings from Florida. Just want to say your videos are extremely detailed and helpful. Editing and organization is superb! Looking forward to more. I too have an xs1100. 1980. Runs fairly good but a bit of a hard start most of the time.... I feel like the right side is lean and the left is rich. I pulled the plugs and sure enough, left side is really dirty and right side has a clean white dust on it. I wrapped electrical tape around the 2 right pod filters and that seemed to fix the problem, but, I also notice that when I rev the motor, especially when warmed up, my rev hangs a bit before dropping to idle. Idle is a nice steady idle.... I HAVE to open the choke up to start it every time, but then immediately close it or she dies. While running, if I open the choke she dies too. Symptoms of both lean and rich are what I've explained....any advice on what I should do first? Thanks!

[@ANDY5]

+Scott Roger G'day Scott. Always best to go back to basics mate. Check the float levels, and there is a good chance that your diaphragms are on the way out. The engine requires fuel/air mixed between the upper explosive limit (UEL) and lower explosive limit (LEL) When the engine is cold you need a very rich mixture, which is why you have a choke circuit. The choke circuit is a large diameter fuel feed and it draws air from directly below the diaphragms which is why I think they are worth looking at. The lag you're experiencing is likely to be the slides hanging up momentarily causing a very rich mixture. When you're on the choke circuit a large quantity of air bypasses the venturi so your not getting the correct fuel/air ratio from your pilot jet when the engine is hot. If you exceed the UEL (flooding) the fuel won't ignite. Take the diaphragms out and inspect them properly to see if there are any holes. And you need to sort those jets out. A dyno is the way to go because you can test under load and with an exhaust analyser. Always hard trying to diagnose issue over the internet, sorry.

[@steveright1937]

I have a 1980 XS100 Midnight Special and have owned it since 1987 . I am considering selling it sadly due to a neck problem .

[@56CrazyCruiserCaddy]

On my XS850 I couldn't find the rubber boots for the air box so without any filter I can't seem to run it rich. My vacuum line synchronizer says it's still running lean. Also as soon as I apply throttle it nearly dies.

[@56CrazyCruiserCaddy]

What is the size of your carbs 32MM or 34MM. And what was the measurement for the air pod filter outlet.

[@phillipj.m.224]

Do you replace the circle clip thing? If not what holds the diaphragm on?

[@henrryvilleta9136]

Hello Andy, i have a XS850 1980, and i wonder if i can run the bike with a XS750? because my carbs are in bad shape and are very rare and complicated, i found a lot of 750 options that are very similar of those you are cleaning but has 3 carbs because it is a 3 cylinder bike.

[@meatcreap]

How are those diaphragms holding up? I'm thinking about getting some myself!

[@56CrazyCruiserCaddy]

I fully jetted the carbs to original OEM jetting.but it still runs lean. HELP.

[@colinhurford8187]

Hi Your doing a great job, Where did you purchase the new carb diaphragms from mate ?? Many thanks Colin

[@ANDY5]

JBM Industries

[@a.w.5591]

Great vid! I have an xs1100 that I’m trying to get running correctly. Runs beautifully once it hits 3000rpm, but is very cold blooded (needs to run on full choke for about 5 min, then half choke for another 5 min, then it still feels lean). Had the carbs cleaned and the intake boots replaced. Runs better, but still having these issues. Any ideas? After running on the freeway for 5-10 min and it’s really warmed up, it runs borderline perfect.

[@ANDY5]

Have you tried adjusting the mixture screws?

[@scottroger5859]

Great thanks Andy. I removed the pod filters, what's the easiest method to remove the carbs at this point? Thanks

[@ANDY5]

+Scott Roger Well you don't have that pesky airbox to deal with so it should be fairly straight forward. Close the petcocks and remove the fuel tank. Pop the vacuum advance hose off the engine side of carb #2. You may have a wire support for the throttle cable on the rocker cover, remove that if you do. Drain the carbs. Loosen the clamps on the rubber manifold boots at the carbs, make sure they are completely loose and break them free so they are floating on the rubber boots. Then you will require some brute force to release the carbs. Rocking them up and down is usually the best method here but I have had to resort to a piece of timber to help pry them out. Just be sure not to damage any engine cooling fins or the carbs themselves. Once free you can more easily deal with the throttle cable removal. Good luck mate, let me know how you get on.

[@scottroger5859]

+Andy's Motorcycle Obsessions Andy so I removed the carbs no problem. Diaphragms have no tears. My main jet is 127.5 I believe? Very faint print on it but with a flash light pretty sure it's 127.5. Oddly because stock 1980xs1100 standards are 115. All spark plugs appear lean except carb #1. #1 is rich. Also the idle screw in carb 1 is stuck in its lowest, seated position and is almost 100% stripped... This is the carb that has a rich plug and also the side of the engine I get the most popping out of my exhaust especially when decease get speed... I'm thinking since I have pods and straight pipes, I should replace with a 140 main? What's your take?

[@scottroger5859]

+Andy's Motorcycle Obsessions Andy I just noticed on all 4 carbs there is no pilot jet screw top and the pilot jet head in carb 1 and 2 are completely stripped... 3 & 4 are good. They measure 42.5.

[@ANDY5]

+Scott Roger Sounds like you have some issues mate. You need to cap those pilot jets. A small brass 6mm screw will do the job. If they are stripped out some Mikuni models had rubber plugs, you may be able to track some down. Or you may be able to repair them, and the thread in the idle screw, by fitting a heli-coil type thread repair. I have pods and 4 into 1 with a shorty muffler. It has not run yet, and I have never seen this thing run, but I am starting with 147.5 on the mains. Just remember to increase your pilot jet by one size for every three sizes up on your main jet. Don't be frightened to play with the jets, just make sure you write down what you have as a starting point. Manufacturers often run different jets for the same market across the duration of the model and it is usually to comply with emission standards at the time of manufacture.

[@xBIOHZRDx]

Hey Andy! I have been watching your vid series on the XS and it has been super helpful! I have the carbs off the bike and I'm am going to re jet them. Had the bike running for a little but after sitting for a couple weeks she wont start again. One thing I really don't understand is the vacuum of the carbs and how that should be set up, and with my extremely little mechanical knowledge (My xs1100 is my first project) the diagrams I have found leave a lot of questions. Is there a resource that you could recommend, or am I over complicating it in my head... like I said this is a project to learn these things so if thats a dumb question I do apologize! haha but loving the videos, keep it up!

[@ANDY5]

+xBIOHZRDx G'day mate. I'm not sure what you mean by Vacuum set - up. Essentially you only need a few things for an engine to run. Compression, spark, timing and fuel/air mix between the upper and lower explosive limits. When it comes to the carbs you must ensure that you have no leaks on the suction side to ensure the best performance, butterfly shafts, vacuum ports on your intake manifolds or the manifolds themselves. Float levels must be set correctly and all of the fuel paths, including jets, must be clean. Diaphragms must not leak. Flow is induced through the carb during the intake stroke, the "Vacuum" above the diaphragms is actually a pressure differential created by the venturi and you can't alter its effect. If you are referring to synchronisation using vacuum gauges I will be doing that when I get mine running but there are plenty of videos available on KZbin for that now, try this one kzbin.info/www/bejne/qmHUl2Rnd7SrbNE. Check your diaphragms for holes, pull them out of the carbs and inspect them properly. If they are U/S you can order new ones here jbmindustries.com/Yamaha650.html just be sure to click on the link for "How to Order" and follow the instructions. I'm happy to chat more if you need more help. Message me your email address if you want.Hope this helps, Andy

[@KotBayun777]

What air filter?

[@jimaylward2396]

Might be a bit late but did you put washer on worng get sorry to be a pain

[@ANDY5]

+Jim Aylward Not sure what you mean mate? The main jet has a washer, it stops the emulsion tube from lifting into the Venturi, and the cap over the primary has a washer, unless it's a model of carb that has a rubber bung. You're not being a pain Jim, I am learning as I go and the only stupid question is the one you don't ask

[@jasondonovan867]

Hey Andy great vid maybe I missed it but what size did u change the Jets to I have a 79 xs11 midnight special and im doing the same type of build or if u have a link or something that would be awesome thank you

[@ANDY5]

From memory I used 147.5 mains

[@matster4160]

Hey Andy I just wanted to ask, I got my dad's Yamaha xs1.1 and I had the carbs cleaned and serviced etc but the guys workshop got broken into and cleared him out and now I can't get hold of him, do you perhaps know which other carbs from a different bike will fit as I can't find a original replacement

[@ANDY5]

The XJ1200 is a popular upgrade

[@markprice6493]

Hi Andy , hope all well . I've been trying to put new petrol pipe on my xs 1100, the octupuss valve is a pain , how did you set up , the fuel lines with out the octupuss valve on basket case ? Only if you time to answer mate, I know you a busy man , cheers , Mark.:0)

[@ANDY5]

G’day Mark, I fitted aftermarket manual fuel valves. You can use the factory valves and omit the octy valve. Essentially you remove the octy and plug the manifold vacuum port. Connect fuel hose from the “prime” hose tails of the fuel valves to the tees (the lower fuel delivery tees NOT the higher vent tees) between the carburetors. In terms of plumbing it is easier to plumb the right side valve to the left side tee, and visa versa. Then you plug the “run” hose tails off on the fuel valves. You place them in “prime” when you’re running and, most importantly, you place them in “run” whenever you shut the engine off (and I mean every time). Be warned. If you do this modification you will no longer have a reserve function as the “prime” position is fed from the reserve port in the valve. Even though it is a slightly different valve it might be worth you watching the video linked below, it will help you understand the methodology. kzbin.info/www/bejne/eqHRmqh6ncSHfKs

[@markprice6493]

@@ANDY5 Hi Andy , thank you very much for your advise mate, and your time, it's most appreciated. I will give it a go , watched the gs petrol tap video , made sense , thank you. P.s. Mite have a go on an English wheel ,could use some no more nails , and buy some clay , to make my rear end and put loads of copper grease on me brakes , and put some water less stuff in me rad , what do you think mate , :0))) Cheers once again. Mark

[@MrCoreymart]

+Andy's Motorcycle Obsessions what size main jets and pilot jets did you get and where can I find those?

[@ANDY5]

+Corey Martinez Hi Cory. I ended up having to ditch them because the pilot circuit was damaged, fitted Mikuni flat slides. When it was running I had standard pilot jets and 47.5 main jets. I never got to have them dialed in so I'm not sure what I would have ended up with. You can get all your jets on line from jetsrus.com

[@MrCoreymart]

+Andy's Motorcycle Obsessions the main jet for an 81 xs1100 is 110, if I put 120 jets in would that be enough for having pod filters?

[@ANDY5]

Sorry, typo. I had 147.5 mains. Look at the jet sizes at Jets are us and go up at least two sizes from standard and one pilot jet size for every three main jet size increase. Fuel quality, humidity and air density are going to impact jet sizing so what works for me here won't necessarily work for you. The only way to know for sure is by color tuning or exhaust analyser on a dyno

[@magnusandersen4682]

Hi Andy. Im having some troubles with my carbs, and i hope you can help me here :) Two out of my four carbs, are like spitting gas out instead of sucking it into the engine. Its the two to the left watching the bike from behind. If Im running above 3000 rpm, everything is fine. Do you have any idea why it does this? Cheers Magnus, Denmark.

[@ANDY5]

+Magnus Andersen hi Magnus, thanks for watching. Have you done a compression test on the engine? It maybe that the inlet valves are not closing. That being said, as it is two carbs that share the same fuel supply I would suggest that one of them is flooding badly enough to fill the one beside it via the vent tee.You most likely have a stuck float or needle and seat. If the bike ran fine before, and has been parked awhile, try lightly tapping the fuel bowl with a plastic screwdriver handle. Failing that remove the bowls and check everything out, recheck your float heights and see if that helps. Andy

[@jurgenvandehoef2192]

Where did you buy those cover diagrams? I can't find them.

[@ANDY5]

Hi Jurgen. Are you speaking about the rubber diaphragms or the aluminium covers?

[@jakemota7447]

Hi Andy I have an 1979 Yamaha XS 1100 and I’m trying to put the fuel lines in and I am seeing 4 ports where the tubing can go in however I only have 2 off the gas tank not 4. how do I fix this?

[@ANDY5]

G’day Jake. There are two tees mounted between carburetors 1&2 as well as 3&4. The lower tees are the fuel feeds and the upper tees are the vents for the fuel bowls. They connect to your air cleaner plenum chamber (air box)

[@jakemota7447]

Andy's Motorcycle Obsessions If I have pod filters then the top two tees don’t connect to anything? Thanks for the help!

[@ANDY5]

If you’re using pod filters turn the top two tees to face down and don’t fit any hoses to them.

[@jakemota7447]

Andy's Motorcycle Obsessions thank you! Love your videos they have really helped me throughout my project! Almost done.

[@pendleton123]

Where do you buy your parts from? I just bought a xs1100 and plan on cleaning out the Carb soon

[@ANDY5]

G'day mate. I purchased the diaphragms from JBM Industries jbmindustries.com/Yamaha650.html and the jets from Jets'R'us www.jetsrus.com/

[@montwolfman]

Hi Andy. Just started watching your vids. Very well done. Thanks for posting. Question. I'm about to purchase a stock (20k miles) 1981 xs. I live at +_ 6000ft altitude. What hp gain do you expect from the 147's and what would you do to get best performance. BTW, she won't idle very well at all, so a carb cleanup is due anyway. Thumbs up and sub from me. Wolfgang W.

[@ANDY5]

G'day mate, thanks for tuning in. The truth is that the HP gains would be moderate, to be honest. I have stated from day one that you can get CV carbs to run with pod filters, that's true. Can you get them to perform???? Probably not, watch episode 51 kzbin.info/www/bejne/jKWZeaepnMyWp7c I got pretty deep into successfully getting them to run but made the decision to replace them with performance carbs, episode 37 kzbin.info/www/bejne/a5a4n5WMdtVrnqs This was a result of damage to the carbs from a previous owner and me making the decision that I was not going to spend more money on them. I donated them to a guy here in Aus who rebuilds them for other XS11 owners. He managed to resurrect them and they now reside in someones bike, in standard trim. I spoke to a Mikuni dealer here in Aus and he told me that the BS34's were designed to choke a perfectly good engine to death so they could sell them in California, and after fitting the RS36 Flat Slides I have to agree with him. Cheers, Andy.

[@montwolfman]

Thanks for the comeback. The decision is done. The bike already has pods and I can get the rs36's for us$650 on Amazon with free shipping. Minus the $130 for the overhaul/jet kit I almost bought.... appreciate you. By chance, do you still have the part numbers for the push pull assy?

[@ANDY5]

+montwolfman good choice, trust me you will not be sorry. I paid $1200AUD for the whole kit and caboodle lobbed at the door, so that sounds about right. No I don't have the part numbers, and as it turns out they aren't Mikuni items anyway. Any 7/8" push pull twist grip will work. I was going to go to the wreckers and hunt around for one that suited the bike but never got around to it. Awesome mate, let me know how you get on please, Andy

[@montwolfman]

Count on it. Thanks for your help.

[@wlingrell]

You don't have to split the carbs to change the needle and seat. Other than that good video