First XS650 Build, What to Look For

Hi SM, I've enjoyed your build to date... would love to see a top view of that manifold setup. Looks like it might still be close to your legs?

Have you run it with the extended intake?
 
Hey Oddjob, thanks! I can definitely snap a picture of the intake from the top next time I'm down there. The way the mid controls are set up, the intake does not interfere with my legs natural position.

I've not yet run it with the extended intake, I'll be sure to post an update with the results.
 
That brake rod holding pin is nifty indeed.
Does your clutch setup have any provision to prevent overtravel?

Thanks!

As for the clutch, because of the way the worm gear is welded, it can't rotate backwards beyond a certain point. Which is to say that pressing down on the pedal disengages the clutch and the spring tension pulls it back engaged. The pedal also can't lift up because the spring is still in there and doesn't allow movement in that direction.
 
I think I just had an epiphany as to why the bike wasn't working with the capacitor.

We tried getting it to fire a few times and couldn't make it work, so we switched to the battery. The battery was grounded to the frame and the positive end was hooked up to the same wire that was feeding the red capacitor plug. It ran on the battery, but not on the capacitor and we couldn't figure out why.

Thinking back, I had the capacitor hooked up on the vibration reducing spring, which I assumed was grounding it. However, the coil was grounded to the rear fender mount bolt on the frame, but the capacitor WASN'T GROUNDED TO THE FRAME. Duh! This may explain why it wasn't working with that original setup, as the frame may not be a suitable ground without grounding the cap to it. Unfortunately, I can't run and test this theory overnight as the bike isn't with me at my apartment currently, but I've got a hunch that this might be the fix I was looking for.

In other news, hoping I didn't destroy my pamco because we totally tested for spark with the plug removed and resting against the engine fins, which I read yesterday is a big no-no. It did still fire and run though, so maybe that's a good sign. Either way, hoping for better news when I go back down there to get it squared away.

Wish me luck!
 
Hey guys, quick question for those of you who may know. My 76 has 34mm fork tubes. I noticed that the XT500 (79) also has 34mm fork tubes.

Does anyone know if the XS650 triple tree spacing would allow for a front end swap? I love the dirt bike front wheel look, and I'd love to move the whole setup (forks, axle, wheel) onto my bike, but my only concern is if the XS650 trees are NARROWER than the XT500 trees. If so, that would be a problem. Wider would be less of an issue, as I could just turn some spacers to compensate for it.

If anyone is familiar, please let me know, thanks!
 
Wondered about that too. The auction I'm looking at comes with the triple trees, so if they fit that's even easier. If not, I'll use the XS trees and see how it matches up.

I've got some riserless bars on it now though, so I'm thinking they probably wouldn't work with any other trees. Unless they're also 100mm spacing.
 
She's home! Went back down to Rhode Island for one last session to get her running as good as I could before taking her back to Haverhill with me. Unfortunately, we weren't able to get her running as well I wanted to so no test ride yet. She runs with the choke on, but dies when it comes off. I'm thinking the pilot is too lean, I'll look into that. Also it sometimes wanted to run on one cylinder, even though we've got great compression on both cylinders and have heard it run on both without issue. More investigation is needed, but the good news is she does fire up and the PMA, Pamco, Eadvancer, and capacitor are functioning!

That said, if anyone is familiar with the process for static timing on this engine, I'm all ears! Valves are adjusted on compression stroke, .002 and .006 per the manual. Cam chain tensioner just barely pokes my finger when kicking the engine.

Here's a few shots of how she looks now, before paint and a few more wiring tucks.

iMwfvWr.jpg


7xroQgr.jpg


Ferlc8a.jpg


Also, if anyone was curious to know whether you can fit a whole XS650 into the back of a Honda Civic, the answer is yes. Just take off the front end.
GyLIQuj.jpg
 
I don't think you can static time a Pamco. You do it running with a timing light.

At .002", your intake valves are a bit too tight. Use .003", or even .004" if you can stand the clatter. Don't follow that .002" book value, it wasn't one of Yamaha's better ideas.
 
My old bike was running on one cylinder and couldn't figure out why. Turns out the cap and wire became disconnected inside (not visible to the eye). Once cut and a new cap put on it ran on two cylinders fine. Not saying that's what your problem is, but it's the easiest, cheapest route to start with. Good luck!
 
Great tips! I'll adjust those valve settings and also check on the caps and wires. I made these out of VW beetle spark plug wires per the advice of others on this forum and while I don't doubt that their advice was solid, it's certainly possible that my worksmanship wasn't. I wouldn't have thought to check that but I will now.

Any other ideas, I'm all ears. And for whatever it's worth, the carb tends to spit gas as I try to get it running. Not sure what's up with that. I'll go play mechanic on it again later in the week.

Thanks!
 
You're kinda in uncharted waters with that single carb and convoluted manifold. The best manifolds give a straight shot into the engine. Yours has a U turn and a Y split. The fuel/air mix may be condensing, fuel dropping out of suspension, before it even reaches the cylinders. By all means, play with different jetting and needle settings, but that stuff may not be the root of the problem.
 
Yea, definitely a lot of unknowns with a setup like this. Reached out to Joe Wiseguy who recommended a 22.5 pilot for a setup with a similar runner length. All his other jetting recommendations mirror what I've already got in there.

Wondering if a SMALLER pilot would help this issue. I would think that if it dies when it comes off choke, a BIGGER pilot would be needed. Am I off base here? Could always order both and see what happens.
 
When using the normal set up with 2 carbs, if the engine dies when coming off the choke, it means the pilot circuit is restricted somehow and not delivering enough fuel/air mixture. Usually the pilot circuit (pilot jet) is partially plugged up and needs to be cleaned.
 
Who knows, maybe the pilot jet is gummed up since there's no fuel filter on it currently. I'll take it out and have a look at it first, then decide whether or not I need to order anything additional.
 
Hey guys, question for those who are familiar. With the hunt for drum brake font wheels proving unsuccessful, I was considering keeping my single disc setup with one condition. Keeping the bars clean. I found a master cylinder that I thought could be a great candidate for a remote setup, operated via a cable. Here's the master cylinder in question https://www.mikesxs.net/yamaha-xs650-master-cylinder-assembly-rear-2.html

If I were to mount that behind the headlight, slim down the reservoir by adding a small piece of tubing, and find a way to attach a cable to that 8mm threaded hole, I could essentially operate it via a simple cable on the bars.

It's a 12.7mm bore as well, I believe my 1976 came stock with a 13mm, but I'm not sure if it wouldn't still work. I still have my rotor, caliper and brake line, and I would only need the lower portion of the brake line, as the master cylinder would then sit where the old t joint to the upper line originally was. So in theory, it would bolt right onto my lower setup.

Thoughts? Advice? Anyone done this before?
 
If you don't follow him, look up member rut31 on IG. He did something similar, mounted the MC under thank and operated it via cable. He might be able to help you out.
I just tagged you in one of his pics to see what I'm talking about.
 
Thanks Figure8, chatted with him and it was definitely helpful!

Next step is to eliminate any chance that the poor idle is coming from rust in the tank. I took the cap out to see what the inside looks like and that shit is spotless. Super clean bare metal. That said, I want to be extra careful so I'm thinking of doing a red kote liner inside and installing an inline fuel filter.

My question with the red kote is how do you empty it without getting sealer all in your petcock mounting threads? People seem to pour it out the bottom holes of the tank. My tank has two, one is plugged with a brass hex cap, the other with the petcock. It seems like the method is to remove both those items, and put painters tape over the hole itself, swish the stuff around in there, and drain it. But like I said, I feel like this is gonna gum up those threads badly. Is that supposed to be the case? Does it not matter?

Any advice would be appreciated. Same goes for any prep steps you'd recommend. Like I said, my tank is pretty damn clean, and it's been sitting with gas in it for a while if that matters. Was gonna drain that out, maybe let it sit with some simple green then clean water to wash it out and let it dry for a day or so. But I'll take any precautionary steps you think are necessary.

Thanks!
 
Back
Top