XS2 Rustoration Build

[gwallis]

Many hardware store bolts are fully threaded, so you can just cut a bolt to length to make a stud.

Went to a local Ace Hardware and they had the 8 X 1.25 in a 31mm length. Worked great. I double nutted the stud and drove it home... good as new.

QUESTION: The bike starts within a couple of kicks; but the left side cylinder is backfiring on acceleration as well as decel. Do the Air Mixture screws meter air or gas? Does turning the screw counter-clockwise increase air or gas?

 

[gggGary]

left side cylinder is backfiring on acceleration as well as decel. Do the Air Mixture screws meter air or gas? Does turning the screw counter-clockwise increase air or gas?

A pretty much iron clad rule is;
mix screws on the engine side; meter gas, out is richer
mix screws on intake side; meter air, in is richer.

I'd be looking for an air leak... spray carb cleaner, engine running is my goto.

 

[gwallis]

A pretty much iron clad rule is;
mix screws on the engine side; meter gas, out is richer
mix screws on intake side; meter air, in is richer.

I'd be looking for an air leak... spray carb cleaner, engine running is my goto.

Your Iron Clad Rule has always been what I assumed... however, everything I have read always referred to it as an Air Screw. I should have also mentioned that it does not look like the offending cylinder is firing all the time. Almost like it fires every second or third time. I have checked the timing and it is spot on.

I will check for any air leaks. I currently only have foam air pods on the carbs as wells the new cone mufflers... should I be looking at increasing the pilot jet?

 

[gggGary]

I'm too lazy to dig back through the thread, points? what year are the carbs from?
swap everything you can side to side. See if the problem follows a component.
plugs, caps, wires, coils, condensers, dirty worn, pitted points all can cause misfires. so can weak charging, ground issues, dirty ignition switch, bad wire/connector somewhere in the harness.
Carbs synched? floats dip tested. fuel levels correct?
Then yeah open air filters, low restriction exhaust likely to need a bump up in jetting main and pilot.

 

[gwallis]

I'm too lazy to dig back through the thread, points? what year are the carbs from?
swap everything you can side to side. See if the problem follows a component.
plugs, caps, wires, coils, condensers, dirty worn, pitted points all can cause misfires. so can weak charging, ground issues, dirty ignition switch, bad wire/connector somewhere in the harness.
Carbs synched? floats dip tested. fuel levels correct?
Then yeah open air filters, low restriction exhaust likely to need a bump up in jetting main and pilot.

New Coils, Points and plugs. The one thing that I did not replace was the condensers. As far as the year of the carbs... I just assumed that they are the original 1972 '38 carbs' that cam with the bike.

I am going to trim a little off the spark plug wire and see if that could be a cause for a weak spark. I will report back when and if I figure this out. 'Thanks' for your comments.

 

[gggGary]

Quick no tools condenser check; in a "darker" room watch the points while it's running, big sparks = bad condenser. It's a common problem. Ohm out your spark plug caps they should read close to 5K ohms.

 

[Jim]

Back in the stone age before computer controlled everything..... was common practice to change condensers along with the points. Like Gary sez... look for big sparks.

 

[gwallis]

Back in the stone age before computer controlled everything..... was common practice to change condensers along with the points. Like Gary sez... look for big sparks.

Well Jim you were correct... it was a bad condenser. The way I found out is that I had an old condenser off a 1975 Honda CB350 Four that had the same Piggy Back configuration as the dual coil XS650. For kicks I installed it... bike started right up with both cylinders this time. So... I tried to buy a new set from MikesXS and they are sold out at this time. QUESTION: Are all condensers the same? Or do they have very different specs... particular to the bike?

On a very different subject... I removed the oil screen (not filter) and replaced it with a new one. After seeing pics of ones that were absolutely trashed I figured I better do this. Here are pics of the one that came out of the bike:

The screen was in surprisingly good shape... no holes... just a lot of gunk attached to the two magnets. The gunk did not feel like it had a lot of metallic material.

 

[gwallis]

Quick no tools condenser check; in a "darker" room watch the points while it's running, big sparks = bad condenser. It's a common problem. Ohm out your spark plug caps they should read close to 5K ohms.

GGGGary... you were also correct... one of the plug caps was out of spec.

Thanks for the help!

 

[GLJ]

Condensers are specific to the coils. I'm sure there are other places to get condensers than Mikes. I use Boyer ignitions so I've never searched for condensers.

 

[GLJ]

Condensers for coils are rated by MicroFarads.

 

[Jim]

Well Jim Gary you were correct... it was a bad condenser. The way I found out is that I had an old condenser off a 1975 Honda CB350 Four that had the same Piggy Back configuration as the dual coil XS650. For kicks I installed it... bike started right up with both cylinders this time. So... I tried to buy a new set from MikesXS and they are sold out at this time. QUESTION: Are all condensers the same? Or do they have very different specs... particular to the bike?

Did you try Ebay? Look for an OEM there. Condensers have different ratings but most are close enough to work OK. Although I wouldn't run the wrong one long term... might burn up the points.

 

[Jim]

First hit on Ebay.

 

[gggGary]

First hit on Ebay.

View attachment 182610

Jim is an NOS condenser a wise buy?
sez the wiseguy....
Yes they are matched to the coil primary so's about any motorcycle condenser is going to be pretty close.

 

[GLJ]

I have 2 sets of NOS points and what looks like a NOS condenser, can't be sure on the condenser. Do not know how old the condenser is.
PM me if interested.
What Gary alluded to is condensers "dry" out with age, especially if not used.

 

[Jim]

Jim is an NOS condenser a wise buy?

What Gary alluded to is condensers "dry" out with age, especially if not used.

All else bein' equal, I'd still take the NOS over the Chinese knockoff.

 

[gwallis]

Ok... I got the bike running pretty good. I have a new set of condensers coming and now I want to move onto the front of the bike. I was thinking of going with slightly wider tires.... maybe make the tires the same size (18 inch ). Any comments on if I should do this? Please keep in mind that this build is not going to be an original 'restoration'.

I will also be replacing the front fork tubes. Is Mikes the best place to buy the tubes?

 

[jetmechmarty]

If going wider, go smaller. 18/18 or 18/17, although I don't know how much room you get with an XS-2.

 

[gggGary]

18 or 19 2.1 2.50 are good. 3.00 is prolly too wide for the front. on a 72. stock fender will look like crap with an 18...

 

[gwallis]

18 or 19 2.1 2.50 are good. 3.00 is prolly too wide for the front. on a 72. stock fender will look like crap with an 18...

Gary,

'IF' i were to go with an 18 front... Would buying 36 18 inch spokes work with the original front hub?