'77 XS650 Chopper Build: My First Chop!

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  • TriNortchopz
    Senior Member
    • Dec 2017
    • 3246

    Right on, good to hear you been ridin'!
    Can you share two photos; one of the stock xs before you started and a recent one with what you built...
    If buildin' old school choppers was easy, anyone could do it... ain't nobody said it's gonna be easy...

    Comment

    • choppersbydavid
      Member
      • Oct 2017
      • 65

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      Here's the before and after. It's one hell of a difference, and still tons I want to change/add on.
      My instagram is @davidz30 if you guys wanna follow me and my bike around on there

      Comment

      • choppersbydavid
        Member
        • Oct 2017
        • 65

        Hey all,(if you're still following this thread) I thought I'd give an update on some minor changes and some future plans of the bike. So heres what I changed up:
        pull back bars(still 7/8)
        ditched turn signals, horn,electric start(never worked anyways)
        1" shorter seat springs
        Round headlight

        Also, I tool this bad larry to Gypsy Run and it was a blast. blew my fork seals and crashed in the dirt, but it was still kickass.Some issues though. So my fender kept cracking by the mounts at the sissy bar, so I welded the fuck out of it before gypsy run (kept it raw w no grinding them down) and only minor hairline cracks now. So I'm going to be caving in and just buying a new fender. And, a much bigger issue, in my oil theres metal shavings and a tooth of a gear was magnetized to my drain plug. It was my first time changing the oil since owning the bike, so I don't know how long its been like that. So it looks like I'm going to have to either tear into the motor, or buy another one.

        Some plans for the future, which are very subject to change:
        I had the idea to run a disc in the rear, ditching the front brakes. My idea was to run a harley dual flange hub laced to an 18 rear wheel, because i love the 18 for this bike. My stock rear wheel is 36 spoke, and the harley hub is 40 spoke. so i'm hunting around for a cheap 18 inch 40 spoke hub. This whole set up is seeming like its gonna be pretty expensive, so I'm highly debating this, but if i can do it for cheap then I'd love the project.
        That also means a 21 spool up front and extended forks.(4-6 over)
        Next is a new lowbrow manta ray style fender, and what makes it easier is that I wanted a new sissy bar anyways, so hopefully I can come up with something. My idea for now was to make a narrow version of a trident out of round stock.
        Paired with that is a new seat. not digging the solo anymore. Maybe a cobra, maybe a 2 up, maybe a rigid solo. we'll see.
        Probably different bars/risers. 1" bar swap if I can do it cheap.

        All this is subject to change. The biggest issue is money and time over the winter. I just started school, I have work, and I bought a shoveled that needs loving on top of that. But a lot of these plans have been brewing for a while. some might just take longer than others.

        I'll keep you posted as I make progress. But biggest concern is the motor, so any advice would help a lot, thanks!

        side note:
        Give me your thoughts on a big bore kit/rephasing. And I know my carbs desperately need to be tuned, so any of you gurus have some advise?

        Comment

        • choppersbydavid
          Member
          • Oct 2017
          • 65

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          Comment

          • TriNortchopz
            Senior Member
            • Dec 2017
            • 3246

            Sounds like a good time has been had on that chop ya built! I remember that little spring that disappeared in the engine - from the shifting mechanism wasn't it? That coulda got ground up in there to form some of that metal on the magnet. That gear tooth - are you sure it's not a piece of a gear dog? Is there any kind of a skip in the trans in any gear, which would indicate a missing tooth. Try spinning the trans through the gears with the rear wheel, with clutch disengaged and rear wheel off the ground...any skip?

            Read the gear dogs break off, typically on the mainshaft third gear, caused by high loading during rapid engine deceleration - using the engine as the brake:
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            "This is almost always caused by decelerative forces, not the driving power or torque, in effect reverse torque production, the end result when the gearbox is subjected to the immense forces produced when substantial engine braking is used."
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            "This is the 3rd gear main-shaft on a late XS650 gearbox; as can be seen the driving dogs are not overly wide, when the bike is ridden hard and subjected to hard downshifts, the inertia of the bike is transmitted through the gearbox, and ultimately in this case through three drive dogs. The forces are high enough to shear the driving dog from the main body of the gear...Yamaha changed the gear tooth shape in 1978 to a more rolling design. By increasing the area of the gear tooth in engagement at any one time, it decreased individual tooth loadings. To differentiate the old and new tooth shapes, Yamaha machined a shallow groove around the periphery of the gear."

            Can just get new gears, there are overdrive 5th gear sets available: http://www.xs650direct.com/products-22.html
            or swap out the whole assembly from a triple XS750 for an even stronger set than the '78-on 650's.

            I think you are better working with what you got, unless there is more wrong than the trans, and you can find a very low mileage engine, or you just end up buying someone else's headache. How is the compression? Maybe do a leakdown test too.
            One area to wake it up is with the cams; "The XS650 camshaft was never a performance item; its design brief would have called for good fuel economy, ease and cheapness of production and reasonable power for an engine of its type...".

            Rephasing will increase power, but power costs money - you also need a new cam and ignition timing system.
            Sounds like that 'new' shovel you got is a competing interest and the school and $$ things will further reduce your ability to get your re-phased big bore engine done. If it don't need it, fix what's broke and continue to have a blast on it.
            Sounds like the rear fender was under stress and tension, leading to the cracking - careful setup will prevent that next time.
            Can't just swap out a spoked disc rear wheel from another jap bike? Most likely the cheapest option to achieve what ya want, maybe only additional cost once caliper, master cylinder, brake hoses, brake light switch and lever are setup, is a set of wheel bearings and axle spacers...and maybe a rear sprocket depending on fitment.
            Any problems with the drum you got now?


            Lots of great info here, which some you just read, including engine rebuild, re-phasing, 750 kit, building a re-phased 880, gearbox, carbs, clutches and more:



            Chop on!
            If buildin' old school choppers was easy, anyone could do it... ain't nobody said it's gonna be easy...

            Comment

            • choppersbydavid
              Member
              • Oct 2017
              • 65

              Wow, thanks for all the great info!

              Trans doesn't slip at all and it is 100% a tooth. looks exactly like one of the teeth on that 3rd gear. So it seems like going over the motor myself id my best/cheapest option. I just have to figure out what I'm doing so I can get it done. a new cam sounds like a good idea, after I get around to tuning the carbs. I definitely wanna get more power out if though, It was tough keeping up on the highway.

              Definitely the shovel has been grabbing my attention, but it doesn't need too much as it seems. And for now I wanna enjoy it stock while I save up money and parts. School definitely is gonna get in the way, but I'm no stranger to staying up all night to get er done.

              Getting a rear wheel off another jap bike isn't such a bad idea, just gotta look around for what might work. The drum now work decent, and definitely needs adjusting, but to have a disc i would just feel better since I wanna ditch the front brakes.

              as always, will keep you updated. Haven't ridden much after gypsy, but I need to get it out of my system before winter. A lot of changes to the bike are coming, and I'm excited to make it fit me that much better.

              Comment

              • TriNortchopz
                Senior Member
                • Dec 2017
                • 3246

                This could be helpful for your engine rebuild:

                Step-By-Step Yamaha XS650 Engine Overhaul Instructions
                Mikes XS is the leading supplier of vintage parts for Yamaha XS motorcycles. Filters, Chassis, Brakes, Wheels, Suspension and Engine products are just some of the items we carry.


                This place, specialized in the XS650, may be helpful as a reference for specs of performance parts you want:
                Camshafts, camchains, Valves, Guides. Yamaha XS650 Camshafts, camchains, Valves, Guides at Heiden Tuning in the Netherlands Read more


                one example of a full gearset from an 1981 xs650 for under $100:


                EDIT:
                Lots of reading here; Yamaha XS650 Technical References;
                "Listed below are quick-reference links to threads in the forum on specific XS650 technical topics."

                Saw a thread for wheel swaps, front end swaps and much more of everything XS: http://www.xs650.com/pages/tech/
                Last edited by TriNortchopz; 09-22-2019, 1:21 AM. Reason: Tech refs
                If buildin' old school choppers was easy, anyone could do it... ain't nobody said it's gonna be easy...

                Comment

                • farmall
                  Senior Member
                  • Apr 2013
                  • 9976

                  If ya wanna ride keep something PURELY built for reliability instead of getting spread out too thin on mods. Since the Yam is proven I'd sort that out and since engines are cheap I'd work towards having a ready to bolt in spare. On my 650 I removed the starter and replaced it with an expanding rubber engine core plug. They're so easy to kick it wasn't worth fucking with and the plugs are almost instantly removable should you need the e-start. Your local auto electric shop should be able to test and rebuild your starter motor or you can do that yourself.

                  You can fab a piece of flat bar to match the inside of the fender and run your mount bolts through both in the frame and bitch bar mount areas. Fenders are to keep shit off the motorcycle. If you want them to be structural parts modify accordingly. Steel is cheap.

                  Shovels are fun and cool and eat money. Look after yours carefully because preventive maintenance is king.

                  I definitely wanna get more power out if though, It was tough keeping up on the highway.
                  I'd pimp it then sell it for a larger displacement more modern motorcycle if you can't afford to keep it for around town fun. Dumping money into little engines just produces an expensive little engine needing specialty parts when those wear out. Your Yam looks good and could sell for enough cash to buy a five speed Evo Sporty. Nothing one can do to an XS will make it as capable a machine because there's no replacement for displacement. Never marry what you can pimp.

                  You can always build another one that's even cooler. They've always been good bikes to flip. I was flipping them before they were fashionable to chop. They're stout engines and what the Brits should have done instead of clinging to 1930s twins. Too bad they lacked Brit styling but chopping totally fixes that by removing the fugly stock shit. If you have space to hoard XS650 parts and get them cheap that's not a bad idea. Restorers want the stock leftovers, especially bodywork and exhausts.

                  Comment

                  • choppersbydavid
                    Member
                    • Oct 2017
                    • 65

                    I definitely need to mange my expectations and realize that a lot of these mods aren't worth it. I see it as a fun little ripper for around town, so i'd wanna do mods related to that. I know I will most likely eventually sell it, but its fun and cheap to gain experience on. I could easily see this bike going though many versions.
                    You may be right, I shouldn't worry too much about crazy mods, but focus on fixing it with some smart upgrades along the way. I'm just dying to know what's happening inside the motor and where all that metal came from. there was a lot of it. Reliability is definitely the most important, the shovelhead will be my broken beauty.

                    Comment

                    • choppersbydavid
                      Member
                      • Oct 2017
                      • 65

                      Summers over and wrenching season is upon us. Got the bike up on the lift with some changes on the way, so get ready. One thing that i want to sort out quick is tuning the carbs. I don't know much about jetting, but I know I need different ones because its been running like shit all year. It backfires ALL the time. Going on the highway it was tough to keep up going 60-65, let alone anything beyond that. From what I've heard from old dudes who used to have one, they said they had no problem keeping up with old sportys and big twins back in the day. Would I need smaller jets?(too much gas burning off in the exhaust?) I don't even know which jets are on there now, and I don't want to assume they're stock. How would I measure them?

                      Any info pointing me in the right direction would be helpful, happy holidays motherfuckers

                      Comment

                      • farmall
                        Senior Member
                        • Apr 2013
                        • 9976

                        If ya haven't already rebuilt and cleaned the carbs, start there (as in soaking, not blowing with carb cleaner) and ensure you have no air leaks, the rubber boots holding the carbs to the head are undamaged.

                        Does it backfire out the carb or exhaust? Verify ignition timing is correct. Post a clear pic of your plugs.

                        Perform a compression test for reference. That's pretty much a tuneup rule and what we do on everything that comes into the shop.

                        http://www.xs650.com/threads/carb-jetting.283/ covers things nicely including http://www.xs650.com/pages/tech/ (scroll down for carbs then electrical including ignition).

                        Ensure you have good power and check for shit like a loose ignition switch. I get about ten years out of generic Drag Specialtie/Emgo/whatever switches.

                        Post your results here to help the next guy/gal/nullo.

                        Comment

                        • RedHerring
                          Senior Member
                          • Feb 2018
                          • 106

                          Sportster tuning problems

                          Hey guys. My 74 xlch is pretty much together and running. I am still waiting on my chain to show up so I've started it a few times to get some warmth into the fresh top end, and seem to find the sweet spot between lean and rich. I vary the rpms, as I know that the new rings need loading and unloading and I'm not going to go into the whole heat cycle debate. Like I said, it seems like the mix or the timing is changing from one cylinder to the other. I think timing.

                          MY QUESTION.

                          Can the the advancer cause this? The gap is 004 difference between the 2 cylinders. I have tried tapping to get them even but it seems like a lot of force and no result. Is this difference enough to do this? Am I being a poon? Wtf?

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                          Comment

                          • Tattooo
                            Senior Member
                            • Sep 2012
                            • 12407

                            Originally posted by RedHerring
                            Hey guys. My 74 xlch is pretty much together and running. I am still waiting on my chain to show up so I've started it a few times to get some warmth into the fresh top end, and seem to find the sweet spot between lean and rich. I vary the rpms, as I know that the new rings need loading and unloading and I'm not going to go into the whole heat cycle debate. Like I said, it seems like the mix or the timing is changing from one cylinder to the other. I think timing.

                            MY QUESTION.

                            Can the the advancer cause this? The gap is 004 difference between the 2 cylinders. I have tried tapping to get them even but it seems like a lot of force and no result. Is this difference enough to do this? Am I being a poon? Wtf?
                            I think you have an intake leak..... Also you should always have a bike set up rich on a new build........

                            I don't think I would run it much until you figure out your problem............. That doesn't look good...........

                            I hope you have a fan blowing on the motor since you can't ride it..............

                            Comment

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