Total Timing

[Crazcnuk]

Anyone out there check their timing lately?

The procedure in the manual says the timing should be on the F mark at idle, and about 36deg at 5200rpm

I was checking mine the other day, and it was going up to nearly 50deg at 4000rpm.

[jmnjrpa]

S$1t fuzzies

It runs so good I never thought about it!

[bikerphil]

I run the timing on my 79SF probably 5+ deg. higher, but with half the vac. advance travel. It seems to pep up the lower RPM range. YMMV

[Crazcnuk]

How do you limit the vac adv travel? Better yet why? It has nothing to do with performance, or drivability.

[bikerphil]

I drilled a hole in the arm and added a screw to limit the travel. It seems to help with that knocking noise the specials are prone to in the 4K range under light load.

[Crazcnuk]

Which is what I am getting right now. It never did it until this year, but now I have a major noise that used to start right at 4000 when accelerating. Now it starts at 3000rpm, and can be heard from time to time at even lower speeds.

[Geezer]

I had a similar problem on the Mongrel. I drilled out the screws and retarded the timing 5 degrees. After that it wouldn't ping at full throttle when climbing steep hills.

Geezer

[Crazcnuk]

Mine doesn't ping at full throttle. the noise it makes used to start at ~4000rpm when under moderate load, ie; accelerating or climbing a hill.

Once it starts making the noise then I can make it, at will, with any opening of the throttle at all, but less if I crack it wide open, at almost any rpm up to 5000or so.

it doesn't seem to make it i the upper rpms.

[Geezer]

Mine doesn't ping at full throttle. the noise it makes used to start at ~4000rpm when under moderate load, ie; accelerating or climbing a hill.

Once it starts making the noise then I can make it, at will, with any opening of the throttle at all, but less if I crack it wide open, at almost any rpm up to 5000or so.

it doesn't seem to make it i the upper rpms.

I would set the timing so that at full advance stops at the full advance timing mark or a couple degrees further retarded. These bikes were designed to run on good quality fuel. I don't know if the quality of gas up north is as bad as the crap they sell us down here in the US but what we get won't support full advance on most older bikes and even more advance is just asking for trouble.

Geezer

[Guy_b_g]

Could also be carbon build up in the combustion chamber causing this.

A good way to knock off the carbon is to take filters/airbox off, warm up engine, then use a spray bottle of water (set to a fairly fine spray) and hold the throttle at mid rpm range while spraying water (enough to cause it to start to bog), You should see a pretty good cloud of black come out the tailpipe..don't worry, it's carbon.

Repeat for each cylinder.

I've used this procedure for years...I do it about twice a year.

[XSokieSPECIAL]

craz....

If you disconnect the vac advance and check the timing it should read the 36 the manual talks about.

That is how it is supposed to be checked, with the vac disconnected. 50 degrees + is normal with the vacuum line connected.

Fuel IS most likely why the detonation is different now, the formulas change from season to season and it's probably just not matching the current running conditions. (i.e. temperature/humidity)

Try some Seafoam engine treatment in the fuel, that usually helps a lot.

[Guy_b_g]

Here is a PDF describing carbon removal (in a car engine) using TEC and water...I've had good luck just using water.

http://www.motorwatch.com/automotive...bonRemoval.pdf

c. The shock of the relatively cool water and steam should dislodge the carbon adhering to the piston faces, valves, and
combustion chamber.
d. While keeping the engine at 2,000 RPM introduce 2 quarts of water into the engine slowly enough to prevent it from stalling.

[XSokieSPECIAL]

The Seafoam will take it off too.

[perurider]

Could also be carbon build up in the combustion chamber causing this.

A good way to knock off the carbon is to take filters/airbox off, warm up engine, then use a spray bottle of water (set to a fairly fine spray) and hold the throttle at mid rpm range while spraying water (enough to cause it to start to bog), You should see a pretty good cloud of black come out the tailpipe..don't worry, it's carbon.

Repeat for each cylinder.

I've used this procedure for years...I do it about twice a year.

huh. I always thought you do this by running the crap outta it, least that's what my dad told my mom he was doing in his '69 Mach 1...

[Crazcnuk]

I've already run Seafoam through it. And I doubt it's carbon, I just redid the top end last spring. It only has maybe 6,000 miles on it since.

I have no idea what this stupid noise is. As I have said numerous times inthe past, this bike is cursed.

If I can't figure it out before the 78 is ready to ride, I will transfer all my mods and upgrades to the 78, strip this one and push it into the river where it can't bother anyone else.

I just find it coincidental that it started making the noise when I decided to sell it.

In fact, I am selling all of my XS11's. Going to pick up a bike that will run for morte than 3 months w/o needing repairs.

Anyone want to trade 4 xs11's and a GT750 for an ST1100A?