Carburetor help needed

[DBLSHOT12]

Hello everyone, I have a 1980 XS650 special that I could use some help with. I purchased the bike last year and found it was running very hot, so since it has K&N pod filters and 2 into 1 exhaust, I thought it might need re-jetting. I also checked to see if it had a dead cylinder by pulling the spark plug wire, I later found out doing so kills the coils. I always learn the hard way! I also found the wire connection from the regulator/rectifier was burned and melted. So, I replaced the coils and regulator/rectifier and repaired the wiring. Then I adjusted the cam chain and valves and re-jetted and rebuilt the carbs. I changed the main jet from 132.5 to 135and the piolet jet from 42.5 to 45, I set the floats at 27.3mm and set the air mixture at 1 3/4 turns. I have tried starting the bike and it will only run with the choke on, if I give it any gas it dies immediately. What am I doing wrong? Any help with this would be greatly appreciated.

 

[Its been a long time]

Perhaps the first thing is to change the pleated media K&N filters for foam filters. Known to run much better with foam air filters compared to pleated media K&N filters.

 

[Jim]

and set the air mixture at 1 3/4 turns.

Factory setting was to start at 3-3/12 turns out. I suspect your idle mix is too lean, needing choke to run.

 

[DogBunny]

Factory setting was to start at 3-3/12 turns out. I suspect your idle mix is too lean, needing choke to run.

Your first and probably biggest problem is what Jim just said.

Next, with pods and 2 into 1, you need to jet higher. Mains should be 4 or 5 steps bigger -- 142.5 or 145. One up on the pilots might work, but it might run better 2 up to 47.5.

As for the pods, I addressed the heresy according to this forum of using pleated pods in this thread:
https://www.xs650.com/threads/air-filter-heresy.66441/
I sent a pair of pleated pods to 5twins, the person who I'm pretty sure started the whole "K&N pods = bad" thing, and which has been de rigueur ever since. He acknowledged to me in PMs that they worked just fine. They work just fine for me. To specify, not just any pleated pods. The ones I sent to 5twins, and the ones that I've used on numerous XS650s over the years are the XS Performance pods. They are knock-offs of a K&N pod, which would surely also work just fine if you want to pay a lot more. These are the oval style pods. I would be suspect of any other style of pleated pod.
Maybe one day 5twins will get back to the thread linked to above and post his experience with the pods I sent to him.

xs650.com still has limited numbers of the pods I linked to in the first post of my "heresy" thread. They are only $10 each, which is another reason why they are so attractive to me. The other reasons are that they are much more durable and last forever (I've had UNIs fall apart), and they look a lot better than UNIs in my opinion. At one time I bought xs650.com out of them, but they seem to have found a small bunch more.

 

[DBLSHOT12]

Thanks everyone for your input, I changed the main jet to a 145 and the pilot jet to a 47.5, set the air mixture to 3 1/2 turns out, I checked the float at 27.3. With that done I reinstalled the carbs and started it up. It started quickly and ran great. The only thing left is to sync the carbs, I did start it without the pods, it ran fine so I installed the pods and could tell no difference in the way it ran, if anything the K&N filters increase air flow and make the engine run leaner, I have never had a problem with these filters and have used them for years. I have one more question, how hot should these engines run. I checked the temperature after about a five-mile ride, and it was between 280 and 290 degrees. Is this about normal? Thanks again, you guys have been a great help! Now I have 2 more XS650 barn finds to get running and I'm sure there will be more questions.

Thanks, Carl

 

[DogBunny]

Depends on where and how you measured. A 5-mile ride probably won't really get you up to temperature. This is a long thread, but somewhere in it are temps for comparison measured a couple of different ways.

You realize that the 3-1/2 turns out on the mix screw is just a baseline setting to get the bike started. Final adjustment must be made with the bike running. Once you get it the way you want, check spark plugs frequently for a while.

 

[DBLSHOT12]

I realize 3 1/2 turns out is just a starting point and will adjust it when I sync the carbs.
The ride was probably between 5 and 10 miles at different speeds, and I took the temperature on the heads above the exhaust using a temp gun. Is there a better place to check the temp?

 

[DogBunny]

Forgot to add this link earlier:
https://www.xs650.com/threads/xs650-thermometer-dipsticks.14997/
This is a long thread, but somewhere in it are temps for comparison measured a couple of different ways. Been a while since I read it, but I think somewhere in there temp is measured by infrared pointed where the spark plugs screw in.

 

[Jim]

From your link, William...

"This picture was made by the late xsjohn, who used an infrared thermometer for readings. His sump temperature of 140 is extremely low, but note that he is using an external oil cooler AND a big ol' automotive oil filter. Also note the 85 degree difference between the cylinder and the sump. I also have an infrared thermometer, and I intend to conduct my own cylinder temperature tests, which I will be reporting here."

 

[DogBunny]

From your link, William...

View attachment 353229

"This picture was made by the late xsjohn, who used an infrared thermometer for readings. His sump temperature of 140 is extremely low, but note that he is using an external oil cooler AND a big ol' automotive oil filter. Also note the 85 degree difference between the cylinder and the sump. I also have an infrared thermometer, and I intend to conduct my own cylinder temperature tests, which I will be reporting here."

Good find. As noted those temps are low for the reasons stated.
There are plenty of examples of more typical temps in that thread.

 

[gggGary]

Toss the thermometer and keep an eye on your plugs. Watch the right with a two into one. These motors don't run hot unless they are stuck in heat and stop n go traffic.
3 1/2 out is about it, after that hole is wide open. there are 4 idle mix holes on the BS34's, the threaded jet only controls one so you have somewhat limited ability to adjust with the screw. (by design) If you can't get there by 3 1/2 it's time to go up another size on the pilot
The idle mix screw is seated in this pic.