My 1980 XS650SGR - Looking for Help

[JeffMc]

Hi all - new to the forum usage, this is my first formal post. In short, bought this 7200 mile bike a couple yrs ago, when it was running pretty well. In 2 years, I haven't put but ~100 miles on it. Now, it’s not running right and I'm confused where to even start.
The only thing I have done (engine wise) is completely disassembled carbs and cleaned them, replaced gaskets…and discovered it’s wearing BS38s (vs 1980 34’s). I probably coulda/shoulda replaced the right diaphragm as it did drop faster than left side. Also changed plugs 20 miles ago and they already have carbon. Last thing, I’ve always thought it ran rich…lot of gas smell. Attached are two movies I made. The first is overall pics of the bike, the second documents how it's running right now.

Hoping all these online mentors can give me a starting place.
Thank you!

 

[Kevin Werner]

My thought initially is carb sync. Solve that and move to next issue.I say that because you said "cleaned the carbs" which may have included separating the linkage.

 

[JeffMc]

My thought initially is carb sync. Solve that and move to next issue.I say that because you said "cleaned the carbs" which may have included separating the linkage.

Thanks @teamWicked ! I used two gage pins to set the butterfly alike. I probably should also mention, that right after reinstalling the carbs and changing the plugs, it ran very well. It just quickly degraded after that.

 

[jpdevol]

Sorry, it does appear I missed the thread on Monday. I agree with TW that there is a synch issue, but I suspect more issue as well.

So, in the video, it does appear to have BS38 carb tops. Perhaps a better and closer still pic would verify. If there's BS34 jets in a BS38 - or vice-versa. There is a problem mismatch. Any pics of assembly process?

Also, right plug likely fouled at this point

What manufacture date is on the white sticker on steering head @ front of frame?

 

[jpdevol]

https://www.xs650.com/threads/xs650...workshop-manuals-and-other-information.30569/

 

[Kevin Werner]

If somebody dropped BS38s into this b8ke you will need to figure out which 38s went in. There is a carb section in the "Tech" thread that outlines which jets and needles go in what years. You can find pilot and mainjet #s by dropping the bowls and you can find the needle jet by removing the diaphragm caps. All without removing the carbs from the engine.

 

[650Skull]

the petrol marks on the sidecover shows the carbs have been leaking. Vacuum operated petcocks should not allow the fuel to leak like this.

leak from bowls/carbs when the bike is running. I assume that was why the gasket were replaced

The float valve is stuck on................The floats cant do their job and shut off the fuel and this can allow fuel to get into the oil..........need to check the oil by smell...........this will cause the bike to run poorly if at all

vacuum petcocks are faulty and need an overhaul.

Checking the jets buy bowl removal will not tell you what set of BS38's you have. Need to take the air filters off and look at the carb intake. This will tell you what set you have. 76/77 or 78/79.

 

[gggGary]

A fast slide drop and rich running can be a choke slide not closing fully or with a damaged rubber end seal.
Was your carb overhaul before or after the two years of low use.
Two years of sitting can gum up a lot of tiny jet and orifice holes.

 

[Kevin Werner]

As many wise men on this forum have said, all sorts of problems can cause you to blame carbs. If valves, cam chain adjust and charging are right, look at carbs. But fix any of those other deficiencies first.
I had black fouled plugs. I went down in main size a number of times with no improvement. It turns out that my pilots were too small and the idle (butterfly) adjust had to be open so far that the needle jet was supplying fuel (too much) at idle.

 

[Raymond]

My bike had terrible running problems, such as refuse to rev or accept much throttle. It was due to a small tear in one of the carb diaphragms - could only see the tear by gently stretching the diaphragm. Replaced that and it solved that problem. But as others have said, old fuel goes gummy and plays havoc with pilot jet, etcetera. And need to check cam chain, timing, etc.

 

[JeffMc]

Thank you for all your replies. I have answers for many of the questions - particularly the carbs. They are the '78/'79 version BS38s. And in my disassembly I verified all the jet sizes were correct from the same chart @teamWicked showed above.
I reworked the carbs most specifically to clean them up (I'll send before/after pics) and it's worth mentioning that it ran great after i'd reassembled. This was nearly 10 mos ago now.
I have also realized now @Raymond , one big mistake is that I've never managed the fuel. I've only put 100 miles on it since I bought it and I have only added a splash of gas...I have no idea how old the gas is and what kind of crap I may have dragged into the clean carbs. So, I'm going to start there and report back to the group....as I start working through your other recommendations!
Give me a couple weeks...work/personal travel will delay work.
Thanks again!

 

[Kevin Werner]

If the carbs sat for 8 or 9 months with fuel in you may have to clean out the idle, pilot and main circuits. The chart I posted was posted by @5twins in the tech section carburetor thread. There is a wealth of information there in the tech section .

 

[Jan_P]

100 miles is not much
Heard that about 1000 miles a year is needed
How long time have you tried to run it .. Have there been a full temperature cycle ?
It idles fairly good and stumbles a bit but That is not uncommon after a standstill.

I would check the battery so it is OK and measure charging Voltage across battery .
A running bike going in ..Should run again Mostly .
I would use the pri position --- switch to on and perhaps restrict the fuel flow getting the
float valve to get some movement.

If already done please disregard