A Interview with Hugh on his Rephased xs650
A couple days ago I got in touch with Hugh who has been busy working on a Re-phased xs650 chopper. Hugh was nice enough to talk with me a little bit and give me the scoop on his crazy cool project. Hugh a Industrial Design student at Appalachian State University put a lot of work into this XS project. It is pretty apparent that thought and attention to detail was put into every single component on his machine.
Ted: So what’s going on with your engine man? Hugh: I mentioned before that I wanted to re-phase the xs650 engine. In short, the pistons on the stock engine both go up and down at the same time. Basically its a 360 engine. While there is nothing really wrong with it in a stock application, it does vibrate quite a bit. When you add larger pistons, cam, carbs, etc the engine does take a beating with 78MM Pistons, bumping compression to 9.1:1. overbore to 707CCs!! To make the engine run a bit smoother, I want to change the rotation to 277 degrees. ( Rephased xs650 diagram ). Basically, it will allow for one cylinder to be traveling up as the other is fired down. 277 isn’t a magical number. It is as close to 270 degrees as the stock crank will allow you to turn.
Hugh: To make this happen, I had to remove the crank and pull apart the two halves. There are nightmare stories about this, so I had seriously debated NOT doing this modification. Some people have issues getting a 20 ton press to get these apart.
I have read that the Air flows faster and smoother with the Lectron Flatslide carbs 34MM due to the flat slide configuration and the jet blocks makes a smooth effect and better throttle response. What do you think of yours?
Hugh: The Carbs are Vintage Lectron 34MM Flatslides. These particular carbs were used on a drag bike in the late 60-early 70′s according to Fast By Gast who has helped me set them up for this bike. I’m running #FBG XL1 Metering Rods right now. Unfortunately, today’s crappy fuel has been a problem in these carbs. I can’t run the power jets, as they pull from the bottom of the acrylic/plastic bowls on the carbs. The new fuels are eating the bowls as we speak, and the nozzles for the powerjets won’t stay in. I may try to machine my own new bowls in the future, because I do love these carbs. The cool factor of clear bowls will be lost though, unless I can find a suitable material to make new ones out of!! Last time I ran with the Power Jets hooked up, I know I was pushing alot more power to the rear wheel at wide open throttle. So I really wanna get those back on track, but Its not hurting for power as it sits. The intakes are something I made myself, but in all honesty, are probably very similar to the Shell Racing intakes. I wanted longer runners to be port matched to the carbs and head. The intakes flow 34MM all the way to the valves, The power is smooth, and this thing is a torque monster. I have accidentally slipped the foot clutch a few times while goosing the throttle, and it will definitely lift the front wheel. I’m just not cool enough for foot clutched, hand shifted wheelies, yet…. Haha…
Hugh: The cam got so loud that I shut the bike down on I-40 on my way to Maggie Valley for the last leg of the “Long Road Home” ride. My best friends ma brought my truck and we loaded it up. Even so, the thing still ran fine, just a bit on the loud side (kinda like a really large single piston diesel, hahaha). I still managed to fire up the bike and get it to the show, and entered into the Smokeout X ride in Bike Show. I know that the folks from “The Horse” magazine have a prejudice against Jap bikes, and especially the XS’s. Kinda like how the Jockey Journal kicked off all the Jap based builds a while back. Seems to be a trend. Anyways, I got LOTS of great feedback from those in the show and several vendors, but I don’t believe any Jap bikes placed in the show. Oh well, better luck next time right? I got the bike back home to Boone, tore into the engine and saw that the cam had sheered diagonally, thats why it stayed together (Kinda). A good friend of mine (the same guy who turned me onto your website) told me to come get an engine he had that was stuck. I tore it down, found the cam was still good and went to mutilating that one too!!! I sleeved it the full length of the cam, up to the bearings this time. I gun drilled it for the advance rod, and put it all back together. This thing screams. I’m getting upwards of 12K RPM out of it, and the last time I ran with a car traveling next to me, I was pushing 115-120 MPH with more power to come. I don’t run a speedo, so I have to take the Car Driver’s word for it. Lets just say its gets alot of fun at high speeds being so short and low!!!!
Hugh: I’ve been chasing down all the bugs that come with a first build/new bike project. Vibrations from the road won’t let me have a glass lense in the taillight, so I’m going to cut a plastic one of of an old chrysler taillight i have laying around. I also had to fight some charging system issues along the way. Mostly small issues, but stuff that needed addressed regardless. I think I have about 1600 Miles on it by now, and things are looking good. I plan to take it on the “Big Mountain Run” sponsored by the Limpnickielot in a few weeks, its only 4 days after I get married, so I gotta pull a few strings. Anyhow, I’m out for a bit this afternoon, hit me back with your questions, and I’ll be glad to get up with you. We can even do a phone call or whatever if you want. Just let me know, i don’t bite too bad…
So your cam came loose and messed up the inside of your re-phased xs engine and then you switched out all those parts into a new one that you built?
Hugh: Nah, the cam sheared right at the end of the sleeve that i had done. Note to self, sleeve a cam PAST the cam lobes, haha… That was a learning process for sure!! The engine ran perfect, even with the broken cam, the points rod was keeping it all aligned, and the bearings were keeping it from pushing the two halves away from each other. I’ll tell ya, XS engines run no matter what!! I’ve had this thing so rich gas was dripping out of the exhaust and it still sat and idled!!! These older carbs were only available with clear bowls, so I won’t be able to find “stock” bowls to fit. They are quite unique in their design really. I’ll just machine some out in the next few weeks, no big deal really. Tuning was a pain, but I’m a glutton for punishment and very meticulous when it comes to tuning, so I guess it wasn’t too bad. Unfortunately, the metering rods are fairly expensive, but they are equal to having about 10 Jets. There are no main jets, primary jets, etc… Just the metering rods. They do have a powerjet in the top of the carb, but as I mentioned, the barbs won’t stay in the bowls any more, so they are temporarily disconnected. I’ve looked on ebay for these carbs before, and they are tough to find.
COOL!!! Have you looked into running a banshee permit magneto? I’m running one on my bike and you can run without a battery.. May help your charging issue. Dude, you’re bike is unique enough to make it in the magazine’s it just sucks that some dudes have to have a prejudiced against the Jap bikes. Nothing like a snobby biker. haha.. I don’t know very many guys that could afford droping 10 grand on a Harley just to chop it up and then spend another $400 for forward controls and shit. The 650 just makes sense in so many different ways. “I was pushing 115-120 MPH with more power to come.” That’s crazy. So, with a re-phased engine does it run a lot smoother or still vibrate like crazy At speed?
Hugh: The re-phased engine runs really smooth at High RPM’s. I can’t say %100 compared to a stock engine, as I have never ridden one. I can say that my roommate runs an XS650 (its blue and black, and has been seen on your site I believe, somebody’s top ten XS650 pics???) And he knows it runs smoother. I run solid aluminum handlebar grips, and my hands do not go numb like on other vertical twins I have ridden. That must say something. I guess the coolest part is the sound of the bike, along with the ability to reach higher rpms… Its a peaky little motor now, and I think it would run as fast as it wanted so long as I could keep feeding it a proper fuel mixture. I met a fella at the Smokeout X that was running the magneto from a banshee, it was cool as hell. I’ve already got a battery box bracket welded to my frame, so this bike is gonna keep a battery. I have solved all my charging issues at this point, so Im not terribly concerned. I am planning to help a friend build 2 bikes, and we are planning another re-phased engine and the battery-less setup. Hes the same guy that gave me the donor engine for the cam I needed after splitting mine into pieces.
Hugh: Like I said, this was my first bike build. I really wanted to push my skills further while building this thing. I wanted to learn the lathe, mill, etc… I even taught myself to TIG, but that was after the bike was finished really. I’ve noticed a trend in the “biker” world that kinda bothers me I guess. I have noticed that your bike is only cool if you use all the “new” cool parts. Bars from Front St Cycles, pegs and grips from Hippy Killer, Seat from Biltwell, the list goes on and on. I know WHY your average Joe does this, its easier than fabbing up your own mess, and its proven. What really gets me is seeing a respected builder cutting corners instead of pushing the envelope. Why build your own frame, lace your own wheels, and then throw a pre-made set of pegs on it?? Kills me, but thats what the industry wants to see, support of those who are advertising in their mags and on their websites. Don’t get me wrong, these company’s make great parts and components, but I would like to see more “Truly Custom” stuff coming from these shops. Thats not entirely the reason I wanted to build every part and piece that I could, but looking back, thats part of the reason I didn’t buy other peoples products, I wanted a bike that was all mine, mistakes and all!!! I still can’t keep a taillight lense in the stupid thing, but I have no one to blame but me, HAHA.
Hugh: Anyhow, I’m off to the basement, I have a few more parts to make and try tidy up some loose ends so I can hit the road for a few miles tomorrow. Might try to take it about 200 miles in one trip, see the folks, and come home. I built it to be nice, but a few road scratches just makes the whole thing worth it to me!
You can read the entire xs650 chopper build threat on pirate4x4.com.