Centrifugal Noise?

[80mdnt11]

Hi Y'all,
Yep, still around........Well IL. weather got the bug going last week, 85* and sunny.....now 60* and rain. Gotta love IL. weather!
Anyway, doing some spring prep....oil,filter,fluids,pressures,etc....
Planned on some off season maint/repairs that, well just didn't get done...i/e....cam chain replacement & head work, no sig. prob with valves & comp. good. Chain does need replaced, tensioner plunger 3/4 in & some slight noise.
Issues:
Slight "cough" back through intake off idle (intermitent)
Timming/Carb tweak?? Yes, poss. int. valve?
Extended crank to start when hot
Seems to be running somewhat rich........could this cause the ext. crank?
Centr. unit noise
So, during cam chain adj. thought would check timming....in spec. However did seem to notice a bit more noise in there. IIRC....seemed someone posted something on this. Search came up empty.....
Thanks for any input,
Jim

[3Phase]

Mdnt, have to take it one thing at a time and mechanical noises trump carburetor and ignition adjustments so I'll start with the mechanical parts of ignition itself. There isn't a whole lot to the vacuum/centrifugal advance setup on the 1978-1980 XS11s. It basically works just like any common, garden variety, distributor but it's stuck on the end of the crankshaft instead of geared to run off of the camshaft.

What kind of rattling noises is it making and what was the pickup coil plate/vacuum advance pot doing while you had the side cover off to check the ignition timing?

If the rattling is coming from the mechanical advance weights under the pickup coil plate there could be a broken spring or something that would make a rattling sound when the centrifugal advance weights began to misbehave.


Is the vacuum advance moving the pickup coil plate back and forth really fast at idle and rattling it? If so, where is the vacuum advance line connected? The vacuum line should be on the brass nipple on the #2 carburetor, not the one on the rubber intake boot. There is supposed to be a small restrictor pressed into the carburetor nipple that keeps the vacuum advance pot from moving too quickly and pulsing at idle and low speed but still allows the advance to react to the engine load.

[80mdnt11]

Scott, Thanks for the reply.......
Vacume adv. is smooth & conn. to correct port, will be taking a look in there at mech. adv. unit.
Howevever, mine has not been into, has the "fixed" rivits on the timming plate with bell looking things......
Do I drill & tap? Think that is plan of attack......just want to make sure.
Thanks

[80mdnt11]

Pic

[80mdnt11]

Oh Well.......Off to work...............

[3Phase]

Midnight, you have to use a third-party picture hosting site like Photobucket to post images but thanks for the invitation to view the contents of your C: drive!

The 1980 timing assembly bolts had breakaway heads that came off when they were torqued at the factory to prevent tampering with the ignition timing. To remove them, use a round, flat-face punch to flatten the broken stub, then a pointed punch to mark the bolt center so you can drill out the remains of the bolt head. The timing assembly should come off and the shanks of bolts can be unscrewed fairly easily once the broken heads are drilled out. A left-hand drill bit worked really well for me and no EasyOut was required.

The special breakaway bolts are no longer available from Yamaha and they were a dumb idea anyway so unless you're doing a full-on restoration for a museum you don't need to worry about it. Just go to a hardware store and pick up a couple of stainless steel Allen bolts to replace them and be sure to use some Loctite/antiseize when you put them in.

[80mdnt11]

Thanks Scott,
Good tips!
Jim
Oh, and thanks Ken for pic fix.

[SFerinTEXAS]

Been a while since I had mine off but I would think just removing the center bolt and removing the timing plate should give a good view of whats going on in there.

[crazy steve]

The 1980 timing assembly bolts had breakaway heads that came off when they were torqued at the factory to prevent tampering with the ignition timing. To remove them, use a round, flat-face punch to flatten the broken stub, then a pointed punch to mark the bolt center so you can drill out the remains of the bolt head. The timing assembly should come off and the shanks of bolts can be unscrewed fairly easily once the broken heads are drilled out. A left-hand drill bit worked really well for me and no EasyOut was required...

If you use a 13/32" drill bit, you won't even need to centerpunch the old bolt. This is big enough that the 'tamper collar' will keep the drill centered. Works great...

[cywelchjr]

If you use a 13/32" drill bit, you won't even need to centerpunch the old bolt. This is big enough that the 'tamper collar' will keep the drill centered. Works great...

Yep, pops right off. And if you have them, if you keep the tamper collars, a couple of valve cover bolts work just right as replacements, looks close to stock and easy to tighten and loosen.

[3Phase]

Brilliant! Use a 13/32" bit instead of center-punching it! The next sweet little 1980 that I find with its original anti-tamper device intact gets the big drill treatment!

I kept the collars too but at the time I didn't have any spare valve cover bolts (part# 91311-06035-00). Of course I have a jar full of them now but at the time Yamaha wanted ~$1.25 each for new ones with the usual wait for shipping so it was off to the local Ace Hardware/Discontinued-Or-Just-Insanely-Expensive-To-Buy-From-Yamaha motorcycle supply store.

[CaptonZap]

If you use a 13/32" drill bit, you won't even need to centerpunch the old bolt. This is big enough that the 'tamper collar' will keep the drill centered. Works great...

Might be a good idea to use a split point drill bit, if you have one.
I live at 5280 ft elevation, and we always advanced the timing on our cars to get better performance at this altitude.
I would assume that the same would apply to this engine, but the question is, what timing marks do you use?
Do you take a reading stock, and then give it four or five degrees advance, or do you advance it till it pings on hard load at slow RPM's, and then retard it a few?
(That was my method with the hopped up 235 Chev 6 when I was a kid. )
Thanks for any ideas, CZ

[bikerphil]

I run both of my XS motors a few degrees advanced down here at sea level. It makes for a snappier throttle off the line, YMMV. Gotta run the mid grade gas though. Set by trial and error, retarded back a bit from pinging.

[SFerinTEXAS]

I do not suggest taking off the timing plate, And agree with everyone else. Not.

[80mdnt11]

Thanks guys...............Will be looking into Fri./Sat. will let you know how it goes.
Jim