Starting issues

[AdamX]

('77 XS650)
Working through electrical issues. When I'm using the electric starter, the battery starts to die. Its a new battery and the tender shows that its maintaining. After starting until it sounds labored, the tender show 95%(after reanalyzing). Replaced coils, spark plug wires,caps and plugs. Spark looks pretty weak at the plug, especially on the right side. Sprayed starter fluid in carbs and it turned over briefly.

Previous work done was replacing the 4th gear for the starter. That now sounds fine. All the electrics are working. What gives? Points to the carbs but those have been cleaned and jets replaced.

Thanks

 

[5twins]

Well, there's a bunch of different tune-up specs that have to be set correctly (points, timing, valves, carb adjustments). Have them all just a little off and that adds up to one hard or non-starting bike.

 

[XSLeo]

On the 77's they have a points ignition, Have you cleaned, gapped and timed the points? This may improve the spark. Your repair manual covers the "How To"
Who cleaned the carbs and replaced the jets? Did they do a good job?
Have you read www.amckayltd.com/carbguide.pdf ? If not I would recommend it.
You say "sprayed starter fluid in carbs and it turned over briefly" Does this mean it ran briefly?
When you say turned over that only means the engine turns over, it doesn't mean it started and ran, however briefly.
If it started and ran for a short time then the ignition is working. If the carbs were working then the engine would stay running.
All that you have said indicates the carbs are at fault.
Reading the carb guide and following the steps to tear down, clean, inspect your carbs. Writing down the numbers on all the brass parts Once you have things clean and inspected you know what needs to be fixed.
Now reassemble, adjusting things as you go, like float height, bench carb sync and such will get them pretty close.
The carb guide has a chart were you can find the specs for the year carb you have.
Leo

 

[DanielBlack]

jets replaced.

Did you use a kit? The jets that come in them are often not correct for the year. The kit I got from a reputable dealer for my 77 had incorrect jets, way too rich.

 

[650Skull]

Need some background information before an answer can be given.

In an earlier thread the carbs had a later, (BS34) mixture screw installed, threads were damaged and an attempt to reinstall the correct mixture screw wasn't successful. It was also stated the wiring had been redone.

Without an update on the carbs, an answer is impossible unless more information is forthcoming on what was done to them, (specifically), or were they replaced?

Electrical problems again can't really be answered unless you post a diagram and/or explain what has been done.

 

[AdamX]

On the 77's they have a points ignition, Have you cleaned, gapped and timed the points? This may improve the spark. Your repair manual covers the "How To"
Who cleaned the carbs and replaced the jets? Did they do a good job?
You say "sprayed starter fluid in carbs and it turned over briefly" Does this mean it ran briefly?
Leo

I did the carbs. Completely disassembled and jets replaced. All paths shot with cleaner until a clean exit acheived.
By turned over, yes, I meant it started briefly.
Worked on the points today. First time for me. Reference manual and youtube video. Had to replace the 4 screws as they were chewed up pretty good and were impossible to adjust. Set the points gaps to .014mm on the left and right contact. Moved to the timing. Using a light, was able to statically adjust the right side to light in the fire zone (between the marks) but the left side lights a bit late. Screws for that lower plate loosened fully and was moved counter clockwise as far as it can go. Tried the other direction but the fire point moved to even later in the cycle. Not sure whats happening there. Tested spark tonight. Right plug has a nice blue/white spark, the left plug has more of a yellow but also consistent spark. Perhaps due to the late timing?

 

[AdamX]

Did you use a kit? The jets that come in them are often not correct for the year. The kit I got from a reputable dealer for my 77 had incorrect jets, way too rich.

Yes, the kit from Mikes. The jet sizes were correct for the stock carbs (bs38). I am using pods so I'll play with jetting later. The bike never had the airboxes attached but ran. Last ran on Jan 30 before I replaced the starter gear.
(Found you 77D project thread and am going through that now. Pretty cool.)