Shakedown ride - three issues

[Incubus]

I just got back from Succubus' first significant ride. It was not overly extensive, maybe 10 miles. I was just trying to find out how everything was fitting together. Overall the bike runs pretty darn well, but I have discovered three issues:

1. In first gear, coming off the line, the bike jumps and rattles soon after the clutch grabs. It almost feels like the front end is jumping up and down. It smooths out after I'm moving and hit about 2,000-2500 rpm. I suspect it is the God-Knows-how-old clutch plates, but it doesn't really feel like a clutch slipping. It feels like the front end jumping around. It smooths out as the bike accelerates. The bike also grabs well when I pound it in the other gears. Second gear is very strong.

2. The bike does not consistently return to low rpm on its own. It will stick around 3,000 or so - it's hard to tell the way the tach gauge jumps around. My first suspicion would be throttle cable, but the throttle seems to move smoothly and the return springs on the carbs are strong. The throttle stop screw doesn't seem to addess the problem. If I back it off the bike just drops to lower rpm when it finally winds down. Vacuum issue?

3. Succubus doesn't always want to downshift to second and first gears. Sometimes it's fine, sometimes it seems to bottom out on third. It upshifts great and downshifts from fifth to fourth to third just like it is supposed to. I can get it to downshift if a turn off the bike and mess with the shifter. Could this be related to issue no. 1 or am I looking at a tranny problem?

Suggestions on any or all of these issues would be appreciated.

Patrick

[Dragonrider]

# 2 is often fixed my a carb sync. Check thoroughly for vacuum leaks first.

[Snow]

Could #1 be warped steel clutch plates or perhaps at least steel plates with unequal deposits?

When I did my clutch rebuild, I went ahead and got all new fiber and steel discs just to get it all over with...they weren't that much more for all oem from bikebandit.

[Incubus]

Hey, DR, other than around the intake manifolds, where are vacuum leaks most likely to occur? I synched the carbs yesterday, so I don't think that's the issue.

Patrick

[Snow]

The XS doesn't have that complicated of a vacuum system. Is this an F or SF?

On Specials, the octopus can be a source of vacuum leak. On the standard, the fuel petcocks can leak vacuum. I suppose the vacuum advance can also leak. Of course, all the hoses that connect all of these to the vacuum ports could leak also, and that would be more likely.

You could spray some WD40 in the suspected areas while the bike is running and note increase of idle speed to find the leak(s).

[TopCatGr58]

Hey Patrick,

Other sources for vacuum leaks is around the butterfly shafts on the carb bodies, the synch ports(but you've already fitted those with NEW caps ). A hanging idle is quite often the synch!
But folks have had the throttle plate hang up on the filter intake mounts...the C-clamps. You'll want to clean up the charging system wires(see Snows recent post ), the tach gets it's signal from the charging circuit.

No aspersions to your riding ability, I see you've had other machines, but many folks try to run these at too low rpms, especially when starting out from 1st. IF you're letting the clutch fully out at 1krpm, then it's going to stutter, lug even.

Although more rare but can occur, the 1st gear can jump out just like the 2nd gear problem. Mine started acting up in 1st gear, then a few months later 2nd gear went! Had to do the Dremmel!

The downshifting problem is probably the return spring not returning the shift lever back up to the full ratchet reset. Instead of turning the engine off, just use the side of your foot to GENTLY pull up on the shifter, not enough to shift back up a gear, but just enough to allow the shift pawl to reset to grab the next dowel pin on the shifter drum, and then it should downshift just fine.

IF this fixes the downshift problem, then you'll need to get a new spring and replace it, about $10.00 still available from Yamaha!
T.C.

[motoman]

#1....The 'dogs' that keep fisr gear engaged most likely worn(have the original motor out of mine sitting on garage floor with same problem).............#2...Remove carb assembly, remove bowls and give it a good cleaning with spray carb cleaner to make sure all orficies are clear for a start, then set cam chain slack adjuster as per procedure(out of adjustment can cause it to not idle down as it should).........#3.....the spring on shift shaft is getting weak. They are still available from Yamaha for $3.40, as I have bought two extra recently just to have. Also check alignment dots on shift pawl with tranny in second gear, adjust at set screw and lock nut on shift shaft assembly. All instructions are here in the tech section and in the manuals. Also, if you already haven't, spend the $65 for Motion Pro mecury stick to sync.the carbs(which you have to re-do, even if just removing carb assembly and re-installing), trust me, they'll be way off.........Sure this will get you started in the right direction.

[Incubus]

That would make sense on the downshifting problem, TC. And yes, what you have described is exactly how I get it to downshift after I turn off the engine and mess with the shifter. Guess I'll call my local Yamaha dealer and invest in a spring. I need that rubber stopper for the cam chain adjuster anyway.

The high idle is what is bothering me most. Nothing I can do about clutch plates today. Shudder does describe what the clutch is doing off the line, but it isn't for lack of rpm, especially in light of my idle issue.

I've sprayed WD40 around the intake manifolds and had no effect. I've replaced all the vacuum lines and put on new vacuum caps (storebought, TC, the drilled acrylic plug solution was an abject failure - couldn't get the inside walls smooth enough). I'll plug the other vacuum connections off the manifolds and run on prime to see if that eliminates the petcocks as the problem.

Patrick

[prometheus578]

"Jumping clutch... groovey, Man!"

In first gear, coming off the line, the bike jumps and rattles soon after the clutch grabs. It almost feels like the front end is jumping up and down

Interesting thing I encountered recently.. Similar effect on the bike. Only happens in first gear, as the load is required to get the bike initially moving.
This may, or may not be the problem, but is worth looking for when doing clutch jobs.
Check the clutch basket and inner clutch hub for gouges.
Hard to explain without photos, but shall try.
The friction plates have "tabs' on their outer edges which ride between "fingers" on the clutch basket. After years of use(and abuse), these tabs wear grooves into the aluminum basket. The friction plates tend to stick in these grooves, and not slide nicely back and forth as the clutch is engaged and disengaged.
I had this guy's bike running for a while, and then attempted a short test ride, but soon returned back to the shop and tore open the clutch cover and disassembled the clutch.
The clutch plates were bone dry!
By sticking in their "grooves"... they wouldn't separate enough to let oil get between them and the steel plates. Hence, they would grab and stick intermittantly until the forward momentum of the bike eased some of the load.
Skillful work with a file on the fingers of the clutch basket can smooth out those grooves and all should be well. (there were grooves on the inner hub where the "teeth" of the steel plates engage, as well.)
Like I mentioned, this may or may not be the problem, as I've only encountered this once... to this extreme degree. (most clutches will show wear in this area, but not deep ruts.)
$750 just for parts!(new hub and basket), but then again, that's a "Victory" fer ya. Nice bikes, but expensive parts
If it were my bike... I'd pull out a file.

[Dragonrider]

You switched the carbs...but did you sync them?

Also check the vacuum pot for the vacuum advance and make sure:
1) It's not blown
2) The mechanism isn't sticking

[Incubus]

How do you check the vacuum pot?

I synched the carbs yesterday and it showed 9.7 to 9.8 inches of vacuum on all four carbs and had a nice smooth idle at 1,000. That was with the petcocks on prime, as opposed to run. The only change between synching the carbs and running this morning was reconnecting the petcock vacuum lines and sealing off the vacuum connections on Nos. 1 and 4. I thought the clamps I put on the fuel lines might be binding, but they're not. It's got to be vacuum.

I haven't gotten back to the carbs yet. I actually found a dealer in town that had the shifter spring, cam tensioner blind plug and the upper dampers for the side covers in stock! The owner told he he keeps one item in stock for all of the things known frequently to go wrong with all the old bikes he's sold over the years, including the XS11. I probably should have bought everything he had for my '79F.

Patrick

[chopwatchagot]

Sounds like that dealer is a man you want to become friends with!

[TopCatGr58]

Patrick,

I don't have my manual handy, but IIRC, the pot should traverse it's full distance at about the vacuum levels you synched at!

The basic way is to apply some suction is simply by mouth, see if the vacuum actuator moves to it's full retraction, and then pinch the hose or put your tongue in the end of the hose to maintain suction, and verify that the actuator doesn't release=leak!

Regrettably, IF you do find a leak, you'll have to hunt down an NOS or used one, cause they are no longer available from Yamaha. Or...you might do us all a favor and find an automotive equivalent?
T.C.

[Goin Commando]

The bike does not consistently return to low rpm on its own. It will stick around 3,000 or so - it's hard to tell the way the tach gauge jumps around.

The only change between synching the carbs and running this morning was reconnecting the petcock vacuum lines and sealing off the vacuum connections on Nos. 1 and 4.

Looks to me like you have solved one of your problems, your self.

Check the clutch basket and inner clutch hub for gouges.

If your clutch has a problem in first gear, it will have a problem in every gear. The problem that Promepheus has described, would cause your clutch lever to feel hard and cause the clutches to slip. The problem you are having is the first stages of first gear being blown.

Succubus doesn't always want to downshift to second and first gears. Sometimes it's fine, sometimes it seems to bottom out on third. It upshifts great and downshifts from fifth to fourth to third just like it is supposed to. I can get it to downshift if a turn off the bike and mess with the shifter.

TC could be right on this one, but if your motor will not idle lower than 3000rpms, "consistantly", then it will be hard to down shift when this is happening also. The "sometimes"down shifting problem could be related to your "sometimes" high idle problem.

Just my opinion

[Incubus]

I hope you are mistaken about first gear, Commando. But assuming you are not, I've read the stuff in tech tips about repairing fifth and second gear with the transmission still in the case. Since the parts fiche seems to indicate that first gear is on the other end of the drive axle, can first gear be attended to this way also? Can the whole drive axle be removed from the bottom? Or would I need to pull the engine and split the case?

I won't know the extent of that issue until I finish addressing the idle. That is tomorrow's project.

Patrick