XS650 Ignition timing revisited - Are we too advanced?

[Bumblebee]

I left the value covers off and started the motor for a few seconds.
Oil went everywhere so I thought everything was good. But one of you mentioned the cam chain slinging oil up to the top and I suppose that's what was happening.
At least now I know why my cam looks like this...

 

[gggGary]

Yes the valve cover off thing is a fooler, it only huffs oil like that when the covers are off. The crankcase of a 360 twin acts like an air compressor, put a window in it and the air comes up through the cam chain tunnel like a hurricane LOL.

 

[Bumblebee]

Finally have gotten time to put things back together.
I checked the float levels with a clear tube and they look good. I changed the pilot jet back to a 45. It starts easy, the idle is better. The mixture screws have more effect.
I haven't changed the main jet or moved the needle yet because I want to try a throttle chop and look at the plugs.
I've attached a Pic of the timing mark with the timing light. It bounced around but more out less the Pic shows where it is at idle.
Does that look about right?
At higher rpm its just to the right of the groove in the side cover... but I don't have enough hands to operate the camera, throttle and timing light all at once lol

 

[Jim]

I've attached a Pic of the timing mark with the timing light. It bounced around but more out less the Pic shows where it is at idle.
Does that look about right?
At higher rpm its just to the right of the groove in the side cover...

Inside the horseshoe marks (red arrow) is where normal idle timing should be.
If you want to be 3-5° retarded, you'll want to be about where the red line is.
When you rev it to about 3000rpm, the timing mark should fall just inside the right edge of the drain slot.
Fyi... the left side of the drain slot is 40° and the right side is 35°.

 

[Bumblebee]

Yeah if I move the mark to the "U", when the rpm climbs it moves a little left of the slot. I will happily sacrifice a little performance/mileage to not have to replace a piston again, lol!
I think I will readjust a little more advanced as, it seems to run better that way.
I'm gonna shoot for the red line you indicated and see where it lands at higher rpm.

 

[Jim]

Yeah if I move the mark to the "U", when the rpm climbs it moves a little left of the slot. I will happily sacrifice a little performance/mileage to not have to replace a piston again, lol!
I think I will readjust a little more advanced as, it seems to run better that way.
I'm gonna shoot for the red line you indicated and see where it lands at higher rpm.

I like the way you think. Advanced (revved) is the more critical value. On any engine where I can't get idle and max advance both adjusted, I'll just set the max and settle for wherever idle winds up.
Yeah... it's the whole, holed piston thing.

 

[Bumblebee]

I can't thank you and the other guys enough for taking the time to share your knowledge! 'Preciate ya!

 

[5twins]

The center of the "U" mark represents about 15° BTDC, the idle timing spec on the later models. The two legs of the "U" would be about 17° and 13°. The vertical leg of the "T" would be about 5° .....

You currently look to be set at about 4° BTDC. I'd consider that to be a little bit too retarded. The early idle timing spec for the 1st few model years was 10°-15° BTDC so I try not to go below that. I run mine over at the right leg of the "U", or at about 13°. Jim's suggestion looks to be about 11° to 12° which would be fine too .....

 

[Bumblebee]

@5twins[USER=156] thanks for the clarification! I'm gonna save that pic and use it for future reference!
What I've done is set it just to the right of the sidecover drain groove at elevated rpm. So the full advance should be in a safe range. That put the idle right around 11-12°, just like you suggested.
Thanks again, fingers crossed she don't burn another hole in my checkbook... I mean piston!

 

[5twins]

That sounds good. The idle deteriorates as you retard it more, getting "lumpy" and rough. A little retard ain't bad, you can compensate for the idle speed drop off by simply turning the idle speed up a little. Yes, it gets slightly rougher, but not to the point where it's gonna up and stall on you. I have the idle timing retarded a little on both mine and they'll sit there and idle all day if I let them, lol. Yes, this is a good little mod, as long as you don't go too far.

 

[Bumblebee]

Do ya think I should run higher octane as added insurance?

 

[5twins]

I've always run high test in all of my bikes over the years. On some, the 650 included, some people said they ran regular with no issues, but mine always pinged. On my 650, it started happening once the weather got hot. That was the whole point of this slight retard of the timing, to "fix" that, which it did. But, an added bonus was I found the bike runs and performs better, mainly at higher RPMs and speeds. The very early models made a few more HP than the later ones. Part of that was no doubt due to the little bit hotter cam they had, but some of it could be due to their more retarded timing setting as well. If you think about it, firing the cylinder closer to TDC means the piston has risen more and possibly increased the compression a tad. Higher compression usually means more power.

 

[Bumblebee]

Gotcha! Higher octane it is!

 

[Bumblebee]

Well, been on a few test rides. So far all seems good. There are 2 things I'm unsure of... I know, it's always SOME thing! Ha!
The first is... the cam chain seems kinda noisy. I was messing with it and found if I unscrew the cap and hold some pressure on the rod as it moves in and out, it quiets right down. The rod is adjusted so it's in and out about 1 mm.
The other is... I did a plug check yesterday. Best I could do on the roads around me was 3rd gear at sort of high rpm. Like you'd really wanna shift to 4th and then held it for 1/2- 3/4 mile. Shut it off and coasted into a parking lot. Here are pics, left cyl then right.
Any thoughts?

 

[motorbikerx]

Thinking of retarding the timing on this TX650, engine is a '77 US import according to eng no.
It has Boyer Bransdon ignition.
As I'm still waiting on the correct RR35 unit to come from England to Aust , I'm intending to do some daytime rides on total loss.
Just topping battery up now on trickle so I start with full volts.
Wanting to not use electric start ( which actually functions due to an upgrade according to P.O.)
I figure a kickstart will not waste valuable volts.
This bike feels a little over advanced on kick-starting it tries to fight back against my boot.
As it's got the usual lame sidestand which leans the bike to the left a lot, and no centre stand I'm wanting it to fire up first kick without a fight.
Also been reading up o Two many XS1B's thread on timing and fuel qualities vs comp ratios etc and I tend to agree after running my first Victory on Premium Unleaded for 100,000 kms prior to pull down for big bore kit and big cams,
The carbon crust on the pistons I removed evidenced the slow burn of higher octane fuel was leaving deposits behind.
Also I refuse to believe the fuel company propaganda of supposed cleaning effects of higher octane...

So long story short I'm gonna back off the timing, unsure right now which way to turn the baseplate but with my timing light hooked up I'm sure I'll work it out visually.
Looking forward to a ride back in time to scratch the itch till the correct RR unit arrived and I can ride after dark.
Also it'll let me know if the stumbling midrange is due to lack of volts for the Boyer or more likely the carbs letting it down.
Oh yeah I've changed the handlebars to ease the strain on the ol lower back, they feel good and look great IMHO

 

[Jim]

unsure right now which way to turn the baseplate but with my timing light hooked up I'm sure I'll work it out visually.

Turn the plate counterclockwise to retard the timing.

 

[motorbikerx]

Turn the plate counterclockwise to retard the timing.

Thanks Jim...timing mark seems to be gone since the rewind on the rotor, but took it back a few degrees by guesswork / ear and it's not fighting the Kickstarter so I'm off for a ride.
Guess I'm gonna need to find TDC and mark a line on the rotor for future reference, anyway I'll see how she rides

 

[5twins]

The timing marks on your '77 motor will have a slightly different "look" if the stator is original, being cast into it's housing .....

But the same degree range applies (13°-17° BTDC). The long slash mark in the middle of the "range", just to the left of the "F", is 15°. Yes, you will want/need to mark your rotor. The long slash to the right of the "T" is the TDC mark .....

 

[Bumblebee]

I found out the hard way that a timing light is crucial and correct timing is more important than just how it starts or sounds.

 

[motorbikerx]

The timing marks on your '77 motor will have a slightly different "look" if the stator is original, being cast into it's housing .....

View attachment 229842

But the same degree range applies (13°-17° BTDC). The long slash mark in the middle of the "range", just to the left of the "F", is 15°. Yes, you will want/need to mark your rotor. The long slash to the right of the "T" is the TDC mark .....

View attachment 229843

It's the mark on the rotor that's not there anymore
Also rotor year and stator years are unknown.
Somehow in the rewinding process the mark is now gone