No Start - Voltage Drop While Cranking

[jpdevol]

Can't put two different emojis in the like line, so had to post...... on sorting the sparks....... on the low compression.

Will be looking for your rebuild post

 

[bkellis1]

After a good nights sleep, I got to thinking about the trick of squirting a little oil in the cylinder to see if the compression would come up. It did, which confirms it could use a ring job. But with the new compression reading, it was up to 110 lbs. Not great but not as terrible as it was, and it didn't leak down as I thought it might. I figured that may be enough of an improvement to get that cylinder to fire, and it was. I was able to set the idle mixture on both carbs using the dead cylinder method and it didn't run too bad - well at least as good as it sounded last summer. Now having said that, it's raining in Ole St Louie, so can't give it a proper road test, but I was wondering if I could possibly get another summer out of it before rebuilding maybe over the winter??? I wonder if spraying all of that starting fluid trying to get it to start with my other issues, maybe it washed out the cylinder to the point it wasn't getting enough of a seal at the rings to make the necessary compression. Maybe wishful thinking but worth the question - any thoughts on that, or any tricks to get some more ride time out of this thing before a rebuild?

 

[Jim]

but I was wondering if I could possibly get another summer out of it before rebuilding maybe over the winter???

If it's running OK now, and it sounds like it is, I'd ride it for the summer while you gather the necessary parts for a winter rebuild. It's worth a roll of the dice if you ask me... and you did.

 

[bkellis1]

I'm glad you responded - I have your "XS650 Top End Buildup" thread up right now looking through what's involved. Excellent write-up!

 

[jpdevol]

Sometimes...a bike that's been sitting will re-seat the rings after a few miles (hope so) and the compression will come on up to normal-ish

 

[Jan_P]

Sometimes...a bike that's been sitting will re-seat the rings after a few miles (hope so) and the compression will come on up to normal-ish

And on top of that ..Compression testing is not so Straightforward as one could believe ( Dont ask me how I know that )

Furthermore these machines is in my view not so sensitive to compression I had one with not so good ( Can feel it kick starting ) But it ran like a Scalded cat

As long as the carburetors and ignition is tuned in ---I would believe it to run. If you want to
Perhaps don't get the top OOmmphhh ,,hh But this is not really that type of motorcycle especially when 40 - 50 years old
I am rarely up there after a Rebuild even.

A couple of pictures of the exhaust smoke can help here Or video with sound rattling ...What is on the Odometer ?

 

[bkellis1]

Ha ha, when I first read your message about being 40-50 years old, I thought you were talking about me (I'm north of 55 now), and yeah, I don't like going fast on this thing. I just recently got a back fender mounted, and haven't even ridden it since then. All last summer, I rode around without any fenders and at 60 MPH, just the thought of sliding back off the seat makes my butt pucker. Always felt like I was holding on for dear life, and flapping in the wind like a flag only attached at the handle bars.

Regarding the mileage on the bike - I have no idea. Didn't have any gauges on it when it came to live with me. I only put 500 miles on it last summer, but it was A LOT of fun, which is why I don't want to tear into it with warmer weather approaching. Going to ride and see what happens. I did discover an exhaust leak though that I'm going to address before hitting the road.

 

[Jan_P]

Ha ha, when I first read your message about being 40-50 years old, I thought you were talking about me (I'm north of 55 now), and yeah, I don't like going fast on this thing. I just recently got a back fender mounted, and haven't even ridden it since then. All last summer, I rode around without any fenders and at 60 MPH, just the thought of sliding back off the seat makes my butt pucker. Always felt like I was holding on for dear life, and flapping in the wind like a flag only attached at the handle bars.

Regarding the mileage on the bike - I have no idea. Didn't have any gauges on it when it came to live with me. I only put 500 miles on it last summer, but it was A LOT of fun, which is why I don't want to tear into it with warmer weather approaching. Going to ride and see what happens. I did discover an exhaust leak though that I'm going to address before hitting the road.

I like this type Motorcycles Not perfect and having slight problems Exactly what most had in the early 70 ies
Handle bar is more or less spot on many had up swept Custom mufflers
A bit imperfection gives Authenticity in my View. But is just me ..others have different views.
As you say can always upgrade should . it be a suitable Object T

 

[Paul Sutton]

Just thinking about your wasted spark ignition coil: Remember to wire the ground side of both spark plugs together to complete the circuit when checking to see if there is a spark. This means ensure the threaded bodies of the spark plugs are in contact with each other.

 

[bkellis1]

Just finished installing a new exhaust gasket and was putting on the covers to go for a ride when I encountered my next issue... with the extra washer behind the stator plate, it sits just proud of the case, so now when I try to install the cover, it hits the pickup coils. Now I'm concerned of shorting out or worse, pushing it in toward the rotor and getting the rubbing on the solder issue again. I think I'm going to put some gasket material on the inside of the cover at least to prevent any shorting and then add a washer between the cover and the case to get it back on there. Any other suggestions or thoughts on concerns about shorting?

 

[40north]

After a good nights sleep, I got to thinking about the trick of squirting a little oil in the cylinder to see if the compression would come up. It did, which confirms it could use a ring job. But with the new compression reading, it was up to 110 lbs. Not great but not as terrible as it was, and it didn't leak down as I thought it might. I figured that may be enough of an improvement to get that cylinder to fire, and it was. I was able to set the idle mixture on both carbs using the dead cylinder method and it didn't run too bad - well at least as good as it sounded last summer. Now having said that, it's raining in Ole St Louie, so can't give it a proper road test, but I was wondering if I could possibly get another summer out of it before rebuilding maybe over the winter??? I wonder if spraying all of that starting fluid trying to get it to start with my other issues, maybe it washed out the cylinder to the point it wasn't getting enough of a seal at the rings to make the necessary compression. Maybe wishful thinking but worth the question - any thoughts on that, or any tricks to get some more ride time out of this thing before a rebuild?

I use a pump-oiler from napa with 16:1 twostroke mix to squirt into the tooters on rebellious engines. I like the smoke, and starting a dry motor is wear-intensive. Actually running 100:1 or 200:1 for the summer might even improve things. Another trick is to try to reseat the rings by reving her up WOT and letting the old gal suck some bon ami... I've done that on 6000 hp ship engines. Don't use comet, only bon ami, if you want to try this trick...maybe a teaspoon. I'd think about it as a last try prior to tear-down. A last resort.

Also, rings can get tight in the lands when a scooter sits...I'd pull the plugs and put in a few cc of kroil ever day, kicking her over several times a day. I've had that loosed frozen rings. It smells great too. That might be a smart first step... Try not to do stuff that can't be undone. Remember that the cylinders have taper, if the rings are frozen, they'll be compressed to the smaller end size, and not spring back. The small end is the bottom end, Kroil plus oil of wintergreen. Or wintergreen by itself.

Best!

 

[Jan_P]

Just finished installing a new exhaust gasket and was putting on the covers to go for a ride when I encountered my next issue... with the extra washer behind the stator plate, it sits just proud of the case, so now when I try to install the cover, it hits the pickup coils. Now I'm concerned of shorting out or worse, pushing it in toward the rotor and getting the rubbing on the solder issue again. I think I'm going to put some gasket material on the inside of the cover at least to prevent any shorting and then add a washer between the cover and the case to get it back on there. Any other suggestions or thoughts on concerns about shorting?

I am taking this out of Memory not read through or checked Boyer installation. Instructions .
But If I recall right there is an all thread with the Boyer system .. please use that one --It can have been cut to exact length -- And ensure everything is tightened .. the rotor with magnets is fully on
And Boyer bushings and washers is in ..

 

[bkellis1]

I threw some cork gasket material under the cap to keep it off of the pickup coils, screwed it down with some blue loctite, then after that dried, I backed it off until it had some wiggle room and put a large o-ring seal left over from the valve covers to fill in the gap to keep it from rattling. Worked pretty good. Just got back from my maiden voyage of the year. Here's a pic of the cap, and the bike from the other side with the new Avon tires and the brand new rear fender which used to be the front (standard chopper mod). I'm pretty happy with it - at least it didn't leave me stranded

 

[jpdevol]

Lookin' good...

IDK if it would solve the issue, but these Mike's points covers do have more room.........
https://www.mikesxs.net/yamaha-xs650-alloy-engine-advance-points-cover-set-oem-256-11158-01-00.html (without logo $80)

 

[Jim]

Remember that the cylinders have taper, if the rings are frozen, they'll be compressed to the smaller end size, and not spring back. The small end is the bottom end.

Just so we're all clear, there's no taper on XS cylinders. It's a straight bore.

 

[Jim]

I threw some cork gasket material under the cap to keep it off of the pickup coils, screwed it down with some blue loctite, then after that dried, I backed it off until it had some wiggle room and put a large o-ring seal left over from the valve covers to fill in the gap to keep it from rattling. Worked pretty good. Just got back from my maiden voyage of the year. Here's a pic of the cap, and the bike from the other side with the new Avon tires and the brand new rear fender which used to be the front (standard chopper mod). I'm pretty happy with it - at least it didn't leave me stranded

'67 LeMans?

 

[bkellis1]

Jim wins the prize... You are correct sir! Good eye

 

[bkellis1]

Here's one of the things that I like most about that car - it's the same age as I am

 

[Jim]

Well, you could say I cheated.... I owned a '67 LeMans back in the 70's.
I still miss it.

 

[40north]

Just so we're all clear, there's no taper on XS cylinders. It's a straight bore.

Yes indeed Brother. I'd use a bore gauge or snap gauges and mic to verify that, if the engine has hours and low compression. I am sure that they are bored without taper, obviously. Equally sure that they are tapered after they're old and tired...just like all piston engines. I have honed cylinders to take out taper...takes all day, and usually you have to 10 over what you started with. They wear at the hot end, less so at the oily end that's cooler. Thanks.

Best!