telanerv Posted July 9, 2010 Share Posted July 9, 2010 Hey everyone, my first post to go along with my first bike i bought yesterday: a 1975 yamaha xs 500b it does not run i think the wiring is not hooked up right from what the previous owner said. i bought it to have something I will post many pics later on... It needs a lot of work i believe, but I have never worked on a bike or actually any engine although i am familiar with the idea of how they work. I know i will be replacing many parts but im not exactly sure how to determine which ones need replacing... It came with the repair manual, have not referenced it (and title of course)..So after getting the bike the biggest problem i have is where do i start? I have read some other posts for project bikes even for my exact bike as well and will reference them a lot im sure. How do i know if i need to rebuild the engine? the ODO is broken, so idea on the miles, covered storage for 20+ years... the guy that sold to me got from his ex-wife's family and did not know much about its history, but he did say the engine would turn over, which i gather means it is not seized up? which may indicate that the engine does not need the rebuild? The chrome parts have rust spots but i have not investigated to the extent of the rusting, but in general can i use sandpaper superfine grit and what phosphoric acid gel stuff? Should i just start taking apart each system now? I read a post saying to take apart each system, clean the parts and wrap/box/label it and just work on fixing each system one at a time... The bike is pretty dirty in general, i kinda feel like the easiest thing for me to do to get familiar with it is to just take it completely apart and clean all the crap and rust off then see where it is thanks in advance Link to comment Share on other sites More sharing options...
ramblerdrver Posted July 10, 2010 Share Posted July 10, 2010 Well...to begin with you will need a repair manual...if the one you have is a Yamaha factory manual, good! If not, get one...they can be found on eBay in CD or "paper" form. You also should get a book on repairing/restoring "old" motorcyles, which should give lots of helpful advice. I can't give a specfic title or source for such a book, but am sure they are out there. Also, look over the Yamaha website...they have a parts section where you can find the parts breakdown for your bike, which will be good for determining what goes where and what the part numbers are. parts are a bit hard to find for these, but sources include Yamaha (probably mostly parts that are common to more popular models), eBay and places that specialize in new and used parts for old Yamahas, like Speed & Sport Yamaha. As far as whether to start by tearing it all down and fixing what you find wrong, or try to get it running first...guess that depends on how complete it is to begin with and how much of it is still hooked up. Sounds like you are looking forward to this as a learning project, so starting with a complete disassembly is a viable way to go. However, disasembling (and reassembling!) a complicated motorcycle engine can be intimidating at best and something you might want to avoid if the engine is basically sound to begin with. So you might want to try doing some initial work to try and get it running, to listen for any unwanted noises and see how well it runs and shifts. If you decide to try to get it to run, a few things you need to do or check. First, change the old oil (and filter if possible...they are hard to find...but Speed and Sport Yamaha has them)...and let the old stuff drain out overnite to be sure all the old "crud" has a chance to drain out. Remove the spark plugs and squirt a couple good squirts of oil into each cylinder to oil up the rings and cylinder walls. Now, with clean oil and some oil in cylinders and plugs still out, kick the motor over a few times. This will help prime the oil pump to start oil flowing to the filter and bearings. Put the plugs back in and give it a kick or two to check that it has noticeable compression in both cylinders. If not, it may be a sign to go ahead and start disassembly! If there is compression in both cylinders, take a look into the gas tank...is it clean or filled with foul old gas and/or rust? If so, that will need cleaned out so the new gas doesn't wash any of the crud into the carbs (assuming the fuel shutoffs aren't plugged with rust and old dried fuel!). To just get the motor going you might be able to rig up a separate tank temporarily to supply fuel to the carbs. If bike was put away when last used with fuel still in the carbs, they will most likely need cleaning before the motor will start. Also, the points will likely have corroded over the years and they will need cleaned and adjusted. When everything is "right" the motor should start and run fairly easily (it may take some work, however, to get to the point where "everything is right"!). It should also run fairly quietly (for an aircooled motor) and smoothly, with no knocking, banging, rattling, etc. My TX500 (1974) set for at least 2 years without running before I got it. It now starts easily and runs fine, but to get it there required cleaning the carbs, new spark plugs, and cleaning the points and setting them correctly. If needed, take lots of photos along the way to help you remember how it things go together! Good luck and always try to remember "this is fun!"! :-) Link to comment Share on other sites More sharing options...
telanerv Posted July 10, 2010 Author Share Posted July 10, 2010 hey thanks for the advice! carburetor's are near the top of the list, i only have one carb body and only 1 jet! so i did some looking and found some, but my budget for parts does not get refreshed until the end of july! upon inspection the gas tank has old nasty gas in it and there is SOME rust, but not as extensive as i expected after 30+ years in storage mode last time this bike was registered was '81 hehe. So yeah, i plan on doing a complete teardown, but as u and my friend indicated its probably best to wait and try to get it running first to see what i need to replace, but the frame has too many rust spots and in the end i hope to have this bike both running AND looking well so in the meantime i will just clean all the accessible parts of the oil and dirt (its all over im sure there was a leak somewhere) until i get the funds also, the front shocks are hydraulic and certain they have a massive leak cuz they are coated in this yellowish oily fluid and the rubber seal around the top is cracked and i could pull back a flap super easy and yellow fluid drips. hehe here i will try to post photos of its "before" state heh so as you can see, where my carburetor should be i have a cloth! the guy had one partially assembled carb in a box but no jets and the float? i think its called seems a little sticky. it may take a long time but will b a fun project Link to comment Share on other sites More sharing options...
telanerv Posted July 11, 2010 Author Share Posted July 11, 2010 so in my quest for new carburetors, is it possible that the same carburetor is used on other bikes or other engines made by yamaha? Link to comment Share on other sites More sharing options...
johnsnownw Posted July 11, 2010 Share Posted July 11, 2010 so in my quest for new carburetors, is it possible that the same carburetor is used on other bikes or other engines made by yamaha? Yes, carbs are not cheap though. Get the owners manual or a Haynes manual and you'll have most of the info you need on parts and interchangeability. Also, what carb do you have? Link to comment Share on other sites More sharing options...
telanerv Posted July 11, 2010 Author Share Posted July 11, 2010 original service manual came with it carb is keihin cv32 (two) .. i have ONE of them but its missing parts so blah from what i've gathered they used this carb for the '73 tx500 through the 75 xs500b and in '76-'78 they used a different carb. been hard to find online i probably need to find a junked bike Link to comment Share on other sites More sharing options...
johnsnownw Posted July 11, 2010 Share Posted July 11, 2010 original service manual came with it carb is keihin cv32 (two) .. i have ONE of them but its missing parts so blah from what i've gathered they used this carb for the '73 tx500 through the 75 xs500b and in '76-'78 they used a different carb. been hard to find online i probably need to find a junked bike I'm not positive, but you may be able to use the Mikuni BS34 carbs on your bike, and they are easier to come by. I would check for junked ones first, as they will be cheaper. Also, where do you live? Link to comment Share on other sites More sharing options...
telanerv Posted July 11, 2010 Author Share Posted July 11, 2010 I'm not positive, but you may be able to use the Mikuni BS34 carbs on your bike, and they are easier to come by. I would check for junked ones first, as they will be cheaper. Also, where do you live? damn how do you come to know these things?? i found a 74 yamaha tx-500 in a salvage yard out of state with both carbs and they are parting/shipping regularly, im tryin to find out if this carb is the same carb as mine and from the pictures i've found it LOOKS very similar, but the '76 500xs carburetor looks like 99% the same to me except it is missing a port with a jet and i know thats a major difference, so if this '74 carb is the same i can get it Link to comment Share on other sites More sharing options...
ramblerdrver Posted July 12, 2010 Share Posted July 12, 2010 Here's a link to the Yamaha Parts catalog on the web: http://www.yamaha-motor.com/sport/parts/home.aspx You can compare parts there between years and models. The carbs on a 74 TX500 look to be same as the 1975 XS500. But the 1976 carbs appear different...the 74 & 75 venturie slides are activated by pistons, while the 76 has rubber diaphrams. They might still be exchangable (as a pair). These carbs (from all years of the XS & TX500) are attached to a common plate with screws and then the plate is clamped to the head thru a short rubber coupling. Not sure what other motorcycles used this method, so finding other carbs to use from other makes and/or models may be hard to do. CORRECTION!...the carbs on the 1976 XS500 (and 77 & 78 probably) DO NOT first mount to a plate... they clamp to the head directly thru a rubber manifold, like many other motorcycles. Link to comment Share on other sites More sharing options...
johnsnownw Posted July 12, 2010 Share Posted July 12, 2010 damn how do you come to know these things?? i found a 74 yamaha tx-500 in a salvage yard out of state with both carbs and they are parting/shipping regularly, im tryin to find out if this carb is the same carb as mine and from the pictures i've found it LOOKS very similar, but the '76 500xs carburetor looks like 99% the same to me except it is missing a port with a jet and i know thats a major difference, so if this '74 carb is the same i can get it Well both the XS400's and XS650's use Mikuni BS34 CV carbs, so the likelihood of them working on the XS500 is rather high. If you're looking at salvage yards out of state you may want to check this one out, as they are the biggest in the U.S.: At least you can compare costs anyhow. Link to comment Share on other sites More sharing options...
telanerv Posted July 12, 2010 Author Share Posted July 12, 2010 alright! you guys helped me out a lot already!! yeah looks like that 1974 carb is the same as the 1975, i think its the same for 73-75 after looking through that yamaha parts guide. that makes figuring out where to find parts a lot less mysterious hehe. if this carb is still at this one shop im in business Link to comment Share on other sites More sharing options...
Corpsegrind Posted September 3, 2010 Share Posted September 3, 2010 Hey man cool post, I just bought my first bike a few months ago - a 1978 Yamaha XS500E, pretty similar to your bike, it's been in storage not running for 15 years, it's my first bike and I know pretty much nothing about bike engines either haha. I was gonna post you some schematic links because I found them pretty useful but looks like someone beat me to it . If you can get a Haynes manual on your bike grab it they're awesome. I tore the whole thing down in my garage and found the missing and broken parts, ordered what I needed from wreckers off ebay (because quite a few parts I wanted are now OBSOLETE and unavailable anywhere) I'm doing a rebore + new oversized pistons next week, might even chuck some pics and info up on a thread on here when it's done Just wanted to say cool bike, keep us posted on progress and good luck! Link to comment Share on other sites More sharing options...
monsterxs Posted August 26, 2013 Share Posted August 26, 2013 I'm in the middle of restoring/ressurecting a 1974xs500b myself, its the exact bike you have. The carbs are pretty simple on this bike. If you have one complete one, take it apart and see if you can figure out what's missing on the other. it may be too late now but if you don't take the two apart from each other, you wont have to sync them. Simply, if the motor spins, it'll run, these are pretty basic animals. clean ther jets (the jet orifices are pretty small, a strand from a bicycle cable will work) the bowls and make sure the floats move freely. Check for spark (pull a plug wire and see if it arcs to a closely placed piece a bare metal. Remember, this bike has a kick start, you may have enough wiring connetcted for it to run. Lastly, remember, this isn't the most popular bike out there,some parts are scarce. MikesXS.com hasgood info and parts. If you find a helpful site, please post it. Happy wrenching! Link to comment Share on other sites More sharing options...
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