Later engine in older chassis

5Twins, thanks for that, makes this a little easier. I'm looking forward to hopefully getting this bike running. My only ready to go street bike is a Kawasaki Vulcan Nomad. Great bike, but seems to get heavier every year.
 
Thanks to 5twins for that info. That makes the swap pretty easy, or would have been easy. Got the stator on OK, but noticed on the advance weight side that the camshaft oil seal was leaking a little. Appears to be a faulty installation from the factory all those years ago, go figure. So, now waiting for a new seal. Two steps forward, one step back. But I am having fun.
 
Just a thought; if points is not a deal breaker for you, it would actually be easier and cheaper to switch the '79 electrics on to the '83 motor. The only touchy part is ensuring the advance rod bushings are fit into the '83 camshaft properly. That way the harness, stator and all components work from the '79 chassis
I guess I didn't catch the part about the advance rod bushings. Unless there's an easy way to remove them from the old camshaft, I'll have to get new ones. I read on the forum that there have been some issues with these parts from Mike's. I found them on XS650 Direct, actually a little cheaper. Also saw that the inside of the camshaft may not have been reamed and there is a method to clean up the cam bore and sand the seal and bushing OD if needed. The info on this forum is very helpful.
 
Well, bike is mostly together. Going to order the rest of the stuff I think I need to get it running. Meanwhile, taking a few days off with the camper and my understanding wife. Parts should be here on return. If it actually runs, I'll post a photo. It won't be pretty, there's parts from at least 3 different bikes, but right now all I want is a runner. Winter is long here, time enough for cosmetic stuff then.
 
Making progress, installed camshaft bushings, points, advancer unit, set point gap and rough set timing. Installed battery and had spark at the plugs, yay!
That's the good news. Set up my accessory gas can and ran fuel to the carbs. No leaks, but fuel doesn't seem to be getting into the cylinders. Bike will start on starting fluid so I think I'm close. Looks like the carbs will need to come off again. Oh joy.
A comment about the camshaft bushings. This is my first time working on an xs650 and I have found this forum to be a really valuable resource. I also have the Haynes manual, which is OK, but missing some of the details I've found on this forum. The cam bushings gave me a chance to dig out my old micrometers and snap gages. Also found the tip about putting the bushings on a mandrel in a drill to sand the OD for a perfect fit to be really useful.
I've had 5 old Triumphs over the years, still have 2, and probably will never sell them, but I don't ride them anymore either. I'm hoping this '79 xs650 will turn out to be a dependable old beastie I can ride and enjoy. Still have a ways to go, but I'm happy so far.
Thanks for the comments and help.
 
Yes, this bike is perfect for local riding and running around. That's when it is "in it's element". It was never meant to be a high speed, interstate cruiser, it wasn't designed for that. And yes, you can make it very dependable. I've been running my '78 for nearly 20 years now and it's never let me down. It's near time to go through the top end again (head gasket is leaking) but it still runs great. The last time I just honed it and installed new rings, this time it will get bored.
 
I put an '81 engine and TCI into a '77. Using the pic from inxs, I swapped in the TCI parts and pieces by adapting the '77 harness. Let me add that pic ......never know what the future holds.
IMG_0053.PNG
 
Tha saga continues.
Well, it runs! Not great, but it does run. I've had the carbs apart 3 times so far, removing and cleaning jets an blowing out passages. I'm getting backfiring both exhaust and occasionally through the carbs. So far it has difficulty running with the choke off also. I have no idea what #'s the jets are as PO made a mess. I can't see any markings on the jets at all. Looks like a cold chisel was ised instead of a screwdriver.
Bearing in mind these are the '79 carbs on an '83 motor, I think I will opt to replace all the jets with new. Bike has a 2 into one exhaust of unknown make that seems to be in decent shape which I will keep. When I start it again, I will run Sea Foam in with the gas.
My big question is, since the carbs I have are BS38 and the motor is 1983 and came with BS34 carbs, what jet sizes would be recommended to at least get me in the ballpark?
 
Tha saga continues.
Well, it runs! Not great, but it does run. I've had the carbs apart 3 times so far, removing and cleaning jets an blowing out passages. I'm getting backfiring both exhaust and occasionally through the carbs. So far it has difficulty running with the choke off also. I have no idea what #'s the jets are as PO made a mess. I can't see any markings on the jets at all. Looks like a cold chisel was ised instead of a screwdriver.
Bearing in mind these are the '79 carbs on an '83 motor, I think I will opt to replace all the jets with new. Bike has a 2 into one exhaust of unknown make that seems to be in decent shape which I will keep. When I start it again, I will run Sea Foam in with the gas.
My big question is, since the carbs I have are BS38 and the motor is 1983 and came with BS34 carbs, what jet sizes would be recommended to at least get me in the ballpark?
That sounds like a reasonable plan........It should take the jetting for the '79 BS38 carbs
http://www.nichecycle.com/ncs/categories/carburetor/mikuni-parts-by-category/jettting-tuning.html


1687611919665.jpeg
 
However, the old saying "Never let an ignition problem fool you into blaming the carbs". I'd want to be confident that the points are spot-on before venturing into the carbs a 4th time (point gap and timing with a strobe).
 
Yes, replace the jets, and yes, you jet based on the year of the carb set, not the year of the bike. For the '78-'79 carb set, you'll want one to two sizes up on the pilots (#30 or #32.5) and two to three up on the mains (#140 or #142.5). The larger mains will also require you to lean the needles a step. But jetting for a 2-1 exhaust can sometimes be difficult. Most aren't designed for best performance but rather just to fit on the bike in question. Header lengths and collector diameter are often not ideal. You would be better off replacing it with a regular 2-2 system and YamahaXS650.com happens to have just what you need on sale now (1.5" headpipes and 1.5" inlet Commando mufflers). The entire system will only set you back about $215. That's cheap for a complete exhaust.
 
Thanks to all for the help and info. And I thought this was going to be a low budget project! Murphys Law, and Murphy was an optimist.
In reference to the timing, I think it's as close as I can get it without using my light. I need to get it running better so I can time it with the light. Right now, it only runs with the choke on, will run on both cylinders above 3k rpm, and right cylinder runs hotter than left probably because it fires right up on that side first and is running rich because of the choke being on. I just don't have enough hands to keep it running and check the timing at the same time.
Like I said, the PO really did a number on things.
Thanks for the info on the jetting. I think I'll order 2 sizes up for both the mains and pilots. That can't hurt. Also I must have missed cleaning some passage or other so will go through all again when the jets arrive. Actually, the last time I pulled the carbs off it went very easily. Since I have pods and no airbox there's not much in the way.
If the 2 into 1 exhaust becomes an issue, I have a '79 Special 'parts bike' with a seized motor but it does have a complete stock exhaust, not pretty but it's all there.
This bike I'm working on does remind me of my Triumphs in a way, when you rev it, it dances across the floor. The really good part, so far no oil leaks.
 
Still waiting for carb parts, probably arriving Wed. or Thurs.
I had new points so I figured I would install them while waiting for cab stuff. Since bike is not running, I used my multimeter to set the timing. The points now open right on the 'F' mark for both cylinders. What is weird is that if I connect the gray ( right side points) wire to the gray (right side) coil wire, the crank is 360° off, meaning the left cylinder is in position to fire. The opposite is true for the orange points wire. Orange points wire to orange coil wire sends the spark to the left cylinder when it's the right cylinder that is in firing position. Switching the orange points wire to gray coil and gray points to orange coil puts everything in the correct position.
I looked at one of my parts bikes and the wires are orange/orange and gray/gray.
If it works, I guess that's OK? I think I did everything correctly and alcohol was not involved.
 
This bike I'm working on does remind me of my Triumphs in a way, when you rev it, it dances across the floor.
Yeah, the centrestand shuffle. Amuses me every time it does it, until it backs into something.
 
Still wondering about the points situation. Is there something I did wrong, or am I OK with the ignition as I have it? Appreciate any comments.
I'm hoping the carb parts show up tomorrow. The biggest thing is to get the bike running, hopefully well. The electrical is still a work in progress. I have to replace the fuses with a new fuse box. Current configuration has only 3 glass fuses in idividual holders. I haven't taken the time yet to figure out which wires were combined, and still have some extra stuff in the headlight. Also have to replace a lot of the turn signal wiring. Last will be the gas tank. I have a decent standard tank which has no dents and only needs a little cleaning inside. Still a ways to go, but enjoying the process.
 
It sounds like you assembled the advance rod incorrectly. There's a locating pin for the little disc on the advance end and another for the points cam on the points end. They must align and point in the same direction .....

Advance Rod.jpg


It's possible to assemble the rod with the locating pins pointing in opposite directions, 180° to one another. If you do that, it throws the timing off 180°. It's possible to make it work that way by switching the points wires and connection like you did, but that's not the factory correct way to set up the system. The top set of points with the gray wire are no longer connected to or firing the right cylinder as they should and the lower set with the orange wire are no longer doing the left cylinder .....

650Points3.jpg


This may be confusing in the future for you and would definitely confuse future owners, lol
 
There are slash alignment marks on the little advance disc and the advance backing plate. They should point to one another if assembly is correct .....

AdvanceAlignment.jpg
 
OK, thanks a lot. The photo of the ATU is perfect. When I moved the parts from the old engine to the new I didn't remove the points cam so the error is on the advance side. The photos in my Haynes manual are pretty bad. While I wait for more parts, I'll rotate the ATU.
I think I'll print these photos and keep them in my own notebook. Once this bike is all together, I have a 1978 xs650 for the next project.
Thanks again for the info. There's no substitute for experience.
 
Yes, the hole for the locating pin on the advance end of the rod goes all the way through it, so the pin can be installed sticking out either side. One way is correct, the other is 180° off.
 
Back
Top