started well, but running increasingly rough

griennehornette

griennehornette

XS650 Enthusiast
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Sarnia, Ontario
Welp, it's been great getting the bike back on the road. I forgot how much I loved these bikes.

The Hornette didn't run perfectly (after sitting for 11 years, this ain't a big surprise) from the get go; but has slowly been getting more ornery. When I first take off, I get a lot of sputters, backfires and stumbles; worse while accelerating. After it warms up, these things reduce, but don't totally disappear.

I tried switching out the K&N pods for UNIs, as I have a 77D, with the CV carbs. That didn't do much. Reading through other posts, I'm thinking I need to install bigger pilot jets. Started with 27.5 VM22/210 pilots and 127.5 mains. Thinking I should bump up to 30 pilots. If I remember correctly, I set the needles right in the middle; dunno if I should consider going one step richer?

Also gotta do the timing. Been putting that off, as I'm far from a skilled mechanic, and I work 2 jobs so don't have a ton of time. But I got a bit of vacation next week, so it's time. Found a good youtube vid that walks through it.

If all that doesn't solve the problem, would I be correct in thinking that I might have an electrical problem?

This whole PMA thing - which certainly sounds awesome - is out of my budget right now; both the money budget and the time budget. Knowing me, the time budget is the bigger problem, as my projects tend to take a looooong time.

But having resurrected the old bike, I'm finding little treasures that I bought years ago, when last it was on the road. I don't even remember buying it, but I have a Kimpex ignition coil in the garage. I googled it; looks like it might be made for snowmobiles. Why I bought this thing, I can't recall; but I'm wondering if anyone has ever heard of these units, and whether it would be worth trying to install. It's a single coil; the bike currently has 2 separate coils (the original, I presume).

OK, that's enough rambling on for now. Appreciate any and all feedback from you excellent selves.
 
Oh, I guess I should have said I have stock ignition. Points and such. All very fiddly, with tons of room for a guy like me to make errors.

Gotta think positive!

Nah. I hate thinkin' positive. Gotta make me one of those light bulb things, that tell me when the points first open, so I don't just eye-ball it; which I hear is very inaccurate. I think I read an Ohm meter will do the same; but the light bulb seems easier to notice. I dunno. Maybe the multimeter would be fine...

Spinning the engine with a wrench seems like an invitation to grossly inaccurate readings to. It's not like it makes little clicks every millimeter or two. I'm a bit skeptical about how easily I'll manage to stop spinning *precisely* when the bulb/ohm-meter signals.

Hmph. One way to find out...
 
Hi hornette,
From what you describe it ain't your ignition, it's your carbs.
Trust Yamaha for jet sizes on a stock bike, the jets your bike left the factory with should be fine.
It's far more likely that your jets are partially or fully plugged than that they are the wrong size.
Clean the carbs. Clean the carbs. Then clean them again.
Totally. All apart except the butterflies because they are a stone bitch to remove and re-assemble.
Remove every jet, poke it through with a wire and squirt carb cleaner through it to make sure it's clear.
Squirt carb cleaner down every little passage in the carb body to see it emerge elsewhere.
Don't forget the enrichening circuit or the slow running needle.
Clean one carb at a time. Work with the carbs in a cafeteria tray to minimise the risk of parts loss.
And check the gas tank and petcocks that fresh crud ain't coming out with the gas to add new
contaminant particles to your carbs.
 
I beg to differ. It could very well be ignition related. It could be a condenser or condensers gone bad. That can cause all sorts of misfiring. Take the little points cover off and observe the points sets while the bike sits there idling. If they're sparking and arching like crazy then the condensers are bad. Small occasional sparks are normal.
 
5twins said:
I beg to differ. It could very well be ignition related. It could be a condenser or condensers gone bad. That can cause all sorts of misfiring. Take the little points cover off and observe the points sets while the bike sits there idling. If they're sparking and arching like crazy then the condensers are bad. Small occasional sparks are normal.
Click to expand...

Hi 5T,
OK, perhaps it's the hornette's ignition but his post also fits a bike that's been stored long-term and had it's carbs cleaned
but not had it's tank & petcocks de-loused.
The "slowly getting worse" description flags it for me.
You can't do wrong by cleaning up the XS650 fuel system anyway.
Then you'll either have a good running bike or know for sure you have an ignition problem.
 
Ah. It's that careful elimination of all variables thing.

I tend to problem solve by impulsively changing stuff which may or may not be a problem, and/or changing and fixing a whole bunch of things at once, so I can't possibly know what did the trick. But because I respect you, Fred and 5twins, I'll try to behave myself and stick to one thing at a time.

I'm happy to check out the carbs. I did clean them; but I didn't really clean the tank, other than swishing some new gas around a bit. If there was more solid crud in there, it wouldn't have been touched by the quick swirl, and may have since melted and re-clogged things. Serves me right for not storing it properly years ago.

Once it gets dark tonight, I'll fire it up and watch for ze schpitzen-sparken under the points cover. I'm already compiling a second-round shopping list from Mike's North. Can add condenser if needed.
 
I find that once clean jets and float valves often plug a time or two after a wake up may need to do the carbs once maybe twice more. idle and pilot have very fine holes, that "choke" orifice in the bottom of the float bowl will fuggle low speed operation if it plugs. Did you install all new fuel lines. Dip test the floats, or do it again. 2many has a cute little tool that lets you back flush the idle and pilot circuits through the idle screw hole.
 
Last edited:
First gggGary, I love the Adam's Family pics. Classic! Loved that show.

Yeah, I installed new fuel lines. But from what I could see with a flashlight and turning the tank every possible way (don't have one of those dental mirrors, so it was pretty hard to see the far end of the tank well) there seemed to be brown sludge. Can that make it past those inline fuel filters? I put those in; but maybe some stuff gets past them?

Anyway, it doesn't hurt to clean the jets and circuits again.
 
Gary's old gas "wisdom"
New gas with ethanol is great stuff, the ethanol is an excellent solvent and keeps everything spotless clean. The problem is it is also really good at dissolving all the old varnish in the tank left from years of sitting. The varnish heads to the bottom of the float bowls were it kinda re-congeals. Seen this in a lot of carbs. Yes the dissolved varnish is small enough to pass through filters.
 
Hey, I read somewhere that the pod filters can block one of the circuits in the CV carbs (intake?) Looking into the mouth of the pods (both K&N and UNI) there is a pretty substantial - I dunno what to call it, a lip? - which I assume is supposed to stop the pods from sliding on too far. But I could see them blocking a couple of little holes which are really, really close to the outside edge of the carb - uh... mouth? I assume these lead to the circuit(s) which get blocked.

Seriously, they are so close to the edge of the mouth, that I dunno how anything clamped-on would *not* block them.

Has anybody fixed this by cutting/shaving down the lip in a couple of places, and making sure they line-up with the little holes? (In my head, it seems like something that might work. But such mental pictures have failed to translate into reality on a number of occasions in the past...)
 
I didn't cut nothing on my pods and it runs fine. This was both genuine K&Ns to begin with, now genuine UNIs. You have other issues.
 
Okay, fired the bike up in the dark garage, with the points cover off. There were a couple of scattered sparks while it idled for a minute or two, but no real fireworks. And I noticed something again; which it's been doing for the past week. Instead of sparking to life and getting stronger as it starts to warm, it takes 3 or 4 kicks to start (rather than the 1 or 2 when I first got it going), and after a minute of idling, starts to chug slower and slower, needing some throttle blips to keep going.

Hmmmm. I wonder if this sluggish slowdown might be an indication of melted gas goop from the tank making its way into the carbs? Huh. I had them so clean just a few weeks ago!
 
Okaaaay!

Got home, and my wife told me the kids are over at their friend's house, and she was going out. I was changed and working on the bike in seconds. Managed to pull the carbs off, and drop the bowls. The bottom of the bowls looked clean. But, the gas which leaked out as I removed the carbs was almost orange, and felt a wee bit more viscous than I think gas is supposed to feel.

Not having a lot of time, I sprayed out the jets with carb cleaner, cleaned the goo off the outside of the bowls, and reinstalled. I'll do a thorough clean next week, when I have more than an hour to work with.

Oh, on an embarrassing side note, I not only dropped the bowls, I dropped the bike. Sigh. Trying to grunt the carbs back in, I pushed it off the centre stand. Didn't quite catch it as it rolled and toppled. At least I caught hold enough to sort of ease it down. Wow. I'm just smooth as silk. There's some trick to getting a bike up when you drop it. I used to know it. Now I don't. Somehow I grunted it back up. Wasn't pretty.

Anyhoo. Shaking my head at myself, I turned on the gas, jumped on the kick starter... and continued to jump on the kickstarter for awhile. Worked up a sweat. Tried the electric start, which promptly drained the battery. Kicked again for a time, and finally it chugged to life.

Not the results I was looking for. But I did notice that it sounded wrong. Sure 'nuff, only the left pipe got hot. Right is cold.

Crap. Looks like maybe both Fred and 5twins were right. Soupy gas, and electrical something-or-other.

At least I assume electrical for the right side... I suppose the right carb might be gummed up enough to not work. But the bowls seemed fairly clean inside. Maybe.

And now that I think of it, I've been riding around thinking that the exhaust sound was leaning mostly to the left. 'Cept I did try touching both pipes the last time I was out, and the right one seemed good and hot.

Guess I'll be spending some of my vacation next week working on the bike. (I don't really mind at all. I may be an ignorant, fumbling mechanic. But I enjoy it. I might enjoy it almost as much as I enjoy riding!)
 
OK, managed to get an hour of carb cleaning in this evening. Started with the right carb, as that's the cylinder which weren't firing.

Gotta say, the inside looks fairly clean. Although maybe I'm looking for clogs that seem like chewing gum. Used a guitar wire, and poked around as well as spraying cleaner. The little o-ring holding the main nozzle to the upper body was already showing signs of corrosion. I installed it mere weeks ago. Gonna have to try to find gas resistant o-rings.

Speaking of gas... I'm now quite confident that I did not clean the crud out of the tank well. Fresh gas has done that job for me, and polluted gas has therefore been running through the bike for a couple of weeks. I assume I need to empty the tank. Wondering if that gas is fit for lawnmowers? I'm not really sure how to dispose of bad gas, if it's not. I assume pouring it down the storm drain is eco-unfriendly ;-)
 
Try to get your hands on ethanol free gas (If you can find it) the Ethanol is horrific to rubber parts...especially non-fuel resistant o-rings.

I may have missed it, but I think you stated you are running non-stock air filters....but are you running stock exhaust? If so, re-jetting is needed. If not, then maybe fuel/air mixtures need to be tweaked with the airflow you're getting...I doubt you'll need to address new jets with just using pods...unless there were different jets in there to begin with.

However, From the sound of it...only real way to know what's going on is to eliminate the obvious and work towards the challenging things. I'd look at your battery first...does it hold a charge? Have you had a load test done on it? A bad battery can do funky stuff to your bike and make for lots of interesting assumptions. If good...then I'd look at your charging system...does it keep your bike around 12v's when idling...when you rev it, does it go up to 14.5 or so? If good, then I'd look at your fuel flow... carbs/petcocks, issues, etc... cleaning your carbs and setting the floats, etc. is very worthwhile...and you're already doing that, so that's good. After you do that and it's still having issues, I'd get into the ignition system, etc. And if you're there, might as well do a complete tune-up, valve adjustment, set timing, and all that jazz. Good luck :)
 
Yup my poor old B&S eats a lot of gas deemed unfit for motorcycle service. I tend to use only about 30% crap gas, the rest fresh, done that for years with no problems.
 

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