XS750 headshots

[fredintoon]

My son took his XS750's top end apart to investigate an oil leak.
Here are shots down the exhaust ports:-
#1 valve is bone white



#2 valve is sooty black



#3 valve is oily black



And yes! Those are all from the same engine. Ideas anyone?

[DGXSER]

Is it possible number one is also processing oil only it is getting burned up to be dry looking due to XSive heat from running so lean?? (yeah a bit of a reach really.)

Otherwise, dunno.

[Guy_b_g]

Goldilocks diagnostic method,

1 is too lean.

3 is too rich.

2 is Juuuust right.



Time to pull the carbs, maybe check on the ignition for #3 too.

[fredintoon]

Update

Hi list,
our boy phoned today. Seems that if he will do a day's worth of splitting firewood for a former schoolmate's mother the lady will give him her Ex's '78 XS750 in exchange.
Trouble is, this bike will be stored in our garage and as a loving mother my wife ain't mad at him, she's mad at me.
There Ain't No Justice.

[rpgoerlich]

Yea, but that 78 was the one to have. A bit more Hp and torque I believe.

[Rickrod3]

Hi list,
our boy phoned today. Seems that if he will do a day's worth of splitting firewood for a former schoolmate's mother the lady will give him her Ex's '78 XS750 in exchange.
Trouble is, this bike will be stored in our garage and as a loving mother my wife ain't mad at him, she's mad at me.
There Ain't No Justice.

Yea but, some things are worth the punishment.

[fredintoon]

Further update

Well, the extra XS750 deal fell through, seems that not all of the parties involved were OK with it.
But Eric's own XS750 is back together with re-lapped valve seats, new valve stem seals and it seems to be running OK.
No road test yet, the stock exhaust has rotted to the extent that we had to cut one muffler off (the other had already broken off) and we are transferring the long reverse cones off his XS650.
Then he gotta make a 3-way aquarium tube manometer to balance the carbs. Better yet he can make a 3 & 4 way manometer and balance my XS11 with it, he needs the experience.

[rpgoerlich]

You really only need a 2 port manometer(easier to make) as #2 is the fixed one. You'll be syncing #3 to #2 and #1 to #2.

It should have MIC II's on it which are easier to sync. MIC I's you have to go in from the bottom to get to the sync screw(a real PIA ).

[fredintoon]

You really only need a 2 port manometer(easier to make) as #2 is the fixed one. You'll be syncing #3 to #2 and #1 to #2. - - - -

Hi Richard,
the manometer is just aquarium tubing and plastic tees, a few more won't hurt. And besides, he needs to be able to switch it to a 4-way to balance my XS11, don't he?

[fredintoon]

Latest update

The triple is running like a train now that we found #3 coil was 95% dead and put an XS650 coil out of the junk box in it's place.
The exhaust looks and sounds great with the ex-XS650 mufflers on and no oil leaks neither.
But my son says the road test shows the outfit will go 120+kph in 4th but is hard to get above 100kph in high gear.
So what is involved in putting an XS11 rear drive into an XS750 to put the gearing to where it needs to be for sidecar work?
Just see the posts on putting an XS750 rear drive into an XS11 and do it backwards or is there some unforseen little trick to it?

[3Phase]

So what is involved in putting an XS11 rear drive into an XS750 to put the gearing to where it needs to be for sidecar work?
Just see the posts on putting an XS750 rear drive into an XS11 and do it backwards or is there some unforseen little trick to it?

Fred, the XS750 coupler uses a wet coupler, no grease. The gear oil from the pumpkin lubes the inside of coupler and drive shaft splines and there's a seal on the '750 drive shaft that fits inside the '750 coupler.

You might be able to just remove the seal from the '750 drive shaft and grease it like an XS11. Let us now how it works out and take lots of pictures.


Regards,

Scott

[petejw]

Hi Fred,
is he running stock main jets,
he might be running rich on the mains
that could prevent it revving out in top gear.

[rpgoerlich]

If you haven't already I'd check the plug caps.
What year is this one? 76/77? Still had points unless it was converted. 78/79 had electronic ignition.