Warped intake valves

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany
One Benjamin Franklin got me a 1979 XS650 and a whole lot of work! It didn't take long to get it up and running, so I set out to summons a high pipe street tracker out of it. Only 3200 original miles on the clock, the engine was tight with a lot of compression. Not so much now...The engine cases show absolutely no signs of prior owners greasy little fingers molesting the internals in any way shape or form! I cut excess weight off the machine and replaced everything with plastic. I removed the stock air filters and put a set of TC Brothers high pipes with 16" cones on it. When I got into the carbs, which you will read, did not go well. one BS 36 carb had a 2.5 fuel needle and seat. The Other had a 2.0. So I ordered carb rebuild kits, and the both came with 2.0 fuel needles and valve, which I used. I rejetted the primaries with 30 jets. (original 27.5) The high speed jet went up one size as well I believe 135. On my tuning ride the right carb had alot of gas spitting out the idle jet into the air pod. So I thought my float was set too high. I adjusted the float from 24mm to 25mm. A 10 mile ride to work seamed to cure the spitting of fuel into the air pod, and it ran strong across the range of acceleration. So, I took a chance and rode it to an inspection station. Another ten miles. I then rode 20 miles home. I got a little bit of a stumble going up a long hill. I made it all the way home. After it cooled off, I went to start it (It was a two kick machine) turning over with electric start I heard a metallic ping in the top end, and it would only fart out the intakes thru the carbs. Putting it up on TDC, I blew compressed air into the cylinders. It comes out past the intake valves. The head is already off. Both intake valves are warped. The number one so much it kissed the piston. ( hence metalic ping) Head gasket and new oem valves are already ordered. My thoughts are the 2.0 needle seats and the adjusted 25mm float height are the culprit.
This is my first carb rejet rodeo, and I've been kicked in the teeth hard! Welcoming anyone's constructive thoughts and criticism's...Also offering up a slightly used set of intake valves...
 

5twins

XS650 Guru
Top Contributor
Messages
23,850
Reaction score
20,314
Points
813
Your main jets may be too small as well. 135 is the stock size for the '78-'79 carb set. I would go 140 or 142.5 if it will take it. With the larger mains, the needles will need to be leaned a step.
 

gggGary

Just call me squirrel brain
Top Contributor
XS650.com Supporter
Messages
28,219
Reaction score
46,963
Points
813
Location
Baraboo, WI, USA
You don't mention;
checking oil for gas,
changing oil,
looking for rust on valve stems.
Stuck valves on wake up motors happen, my best guess; that's the root cause here.
piston.jpg

could have been worse......
 

joebgd

XS650 Junkie
Messages
567
Reaction score
310
Points
63
Location
NY
I don't see how changing float height or adjusting jets and needle in any way would cause damage to a valve. Maybe if the bike was set to run very lean and ran hard to the point of over heating.
 

jpdevol

Hacker of Frames,Wires and other things
Top Contributor
XS650.com Supporter
Messages
2,109
Reaction score
4,942
Points
263
Location
26187
You're into it now....might be good to check everything while it's apart: valve guides (in & ex), cam chain, guide & tensioner, etc.

If too lean jetting was the cause, one would think the exhaust valves would or pistons would be damaged before intakes. Do you have a pic of spark plugs to assess jetting as cause?
 

Jan_P

XS650 Guru
Top Contributor
Messages
1,915
Reaction score
3,416
Points
263
Location
Sweden
I am with joebgd as first thought
I have heard of one person fumbling up the jetting and overheat the engine.
But I believe it manifests itself in poor running. Giving a warning to stop and fix.

But this being a very low mileage machine there can be tight play and old Oil restricting oil flow
Clogged oil pump
fex Valve stem sticking ..and then ..problems.
Is there any blueing visible. Scratches on piston skirts ? Piston Pins ?
Was oil flow to the top checked as per startup procedure for a newly rebuilt engine.
Turning over many times before starting.
 

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany
When I originally started this machine several years back, I put about a teaspoon on trans fluid down the spark plugs and let it set for a week. Then engine was ran several times at idle, and had good top end oil flow. It was stock from factory then. I had the intake valve cover off while running to verify oil flow last week. There is no scuffing in the cylinder walls. I can still see the factory honing patterns. The bent valves seemed to have happened with in one block of my house. I rode it into the garage and shut it down. Two hours later it would not start. There was no gas in the oil. I'll try to get pictures of plugs and piston tops tomorrow. Anyone know which fuel needles seats I need? 2.0 or 2.5? Thanks in advance...
 

jpdevol

Hacker of Frames,Wires and other things
Top Contributor
XS650.com Supporter
Messages
2,109
Reaction score
4,942
Points
263
Location
26187
The original valve for '79 "2F0" carbs is 168-14190-20 (available) that I think is a 2.0
 

Miker Vee

XS650 Member
XS650.com Supporter
Messages
15
Reaction score
58
Points
13
Location
The Netherlands
Had this neighbor once, who asked me to have a look at his car.
Parked it one day, wouldn't start the next. Made funny sounds, too.
Lifted the valve cover; all push rods were bent like bananas.
Turned out, one of his little sons wanted to show off to his friend that he knew how to start the car, and rev it till it sounded like a race car ready to leave the starting line. Unfortunately, it wasn't a race car but just a petty Peugeot family vehicle.
Imagine what an inspiration revving a real motorcycle would be for a young boy.
You have young sons?
 

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany
Timing was spot on. Slipped timing was my first assumption. No young sons in the house, and I wasn't beating on the poor thing. There are no marks on the pistons showing the valves touched them. The number one valve is bent more then the number two. This is a true mystery for me...I am ordering new intake manifolds to go with the new valves. Tending to think it ran hot and warped from the signs I am seeing.
 

Jan_P

XS650 Guru
Top Contributor
Messages
1,915
Reaction score
3,416
Points
263
Location
Sweden
You sure nobody ever replaced the valve guides? Sounds like stuck valve stems.

Kind regards christian

That is what I am also thinking Others here have more knowledge
No need replace any Valve guides if that is true

Only 3200 original miles on the clock

Beginning eighties there was a revival and many bikes was parked and garaged.
The Valve stem seals dried up and upon starting there was smoke.
1500 km / year needed

My theory
Tight fit Valve stem / Dried Oil down under the valve stem seal / Hesitant Not Sufficient lubrication
 

GLJ

Never go faster than your guardian angle can fly.
Top Contributor
Messages
3,371
Reaction score
13,897
Points
513
Location
Dixon IL USA
I bought a parts bike that had a running engine it. It ran but only on left cylinder. Long story short the right intake valve was bent. Not a mark on the piston. Also found the valve guide was broke.

If I were you I would take a good look at the valve guides. Also the cam chain, chain guides and chain adjuster.
 

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany
It's certainly unusual to "warp" intake valves - in-time - without hitting pistons. Got any pics?
I am not the right model for a photoshoot! You want to see someone better looking! The heads are at work. I took them in so a coworker could take a look, and lend a hand removing valves. We got busy on Friday, and didn't touch it. I will try to get in the garage tonight with a camera. This weekend was last weekend for hunting deer in Germany...Spent yesterday stocking freezer.
 

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany
That is what I am also thinking Others here have more knowledge
No need replace any Valve guides if that is true

Only 3200 original miles on the clock

Beginning eighties there was a revival and many bikes was parked and garaged.
The Valve stem seals dried up and upon starting there was smoke.
1500 km / year needed

My theory
Tight fit Valve stem / Dried Oil down under the valve stem seal / Hesitant Not Sufficient lubrication
I believe, I am buying into your theory. That makes the most sense. The left cylinder bent further then the right. More restricted oil flow? The top end had plenty of oil going to it. It was lying pretty thick in the cam valley when I took it apart. As stated earlier, all timing was right on. All nuts, bolts and screws appeared factory fresh, and unbuggered... I examined the points plates pretty close, and I am willing to bet, no one ever adjusted anything there either...Except for sitting in a barn for the last 30 years of its life, I think it had a relatively leisurely lifestyle. It's poorly mistaken, if it thinks it is bound to go back in the barn...
 

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany
That is what I am also thinking Others here have more knowledge
No need replace any Valve guides if that is true

Only 3200 original miles on the clock

Beginning eighties there was a revival and many bikes was parked and garaged.
The Valve stem seals dried up and upon starting there was smoke.
1500 km / year needed

My theory
Tight fit Valve stem / Dried Oil down under the valve stem seal / Hesitant Not Sufficient lubrication
I doubt the valve stems got replaced. The bike had all its original hardware. The frame didn't show any signs for the engine ever being removed. I was impressed with what $100.00 got me...I think it got parked after a couple seasons uses...Then it came to me...Poor thing....
 

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany

Attachments

  • IMG_20230129_142835_802-1.jpg
    IMG_20230129_142835_802-1.jpg
    410.2 KB · Views: 17
  • IMG_20230129_142504_745.jpg
    IMG_20230129_142504_745.jpg
    277.4 KB · Views: 18
  • IMG_20230129_143738_513.jpg
    IMG_20230129_143738_513.jpg
    250.7 KB · Views: 17
  • IMG_20230129_142938_203.jpg
    IMG_20230129_142938_203.jpg
    333.9 KB · Views: 17
  • IMG_20230129_142745_176.jpg
    IMG_20230129_142745_176.jpg
    349.9 KB · Views: 17

olewahrhorse

XS650 Member
Messages
15
Reaction score
19
Points
3
Location
Germany
Allow for some artistic representation here. I put a teaspoon of oil in each cylinder trying to bring the compression up, hence the sweaty look. The plugs were new, maybe 80 miles. They were black\brown and sooty. I wiped some of the soot off with my finger.
The most interesting photo is of the carb, which was clean. I noticed a lot of tar or schelac on the secondary needle. I am guessing the bottom of the tank has residue. The tank top looked clean, I didn't etch the tank.
 
Top