XJ650 Seca 1980 Not working right

Hello.
I need help from this forum. I have a 1980 xj650 seca that has been giving me problems. Right now I have a lot of difficulty getting the bike to work and when that happens, working is not ideal. I already measured the ignicion coils and they were good, I changed the spark caps. The battery is fine and I replaced the fuse box, but it still doesn't work. Any suggestion?
Thanks for everything

 

Sidestand switch, handlebar cutoff switch would be something to look at - you need a good clean feed to the coils.
Once running if it is still not good can you confirm valve clearances are good? Then its carburettors - you will need to strip and clean.

 

thanks.
I will see all that ... I will start with the easiest and then the valves. Sometimes when I hit the rear brake the bike would shut down. Maybe it's an electrical problem. thank you again

 

Also change the fusebox if you have the original Yamaha one. The clips break that hold the glass fuses and they are old. Get a blade type fuse box.

 

I already changed the fuse box. Thanks

 

You need to test the battery when cranking the engine (testing under load) with a multimeter as you need ten volts to operate the transistors in the TCI unit. There are also small jets in the carburettor float bowls which supply extra fuel for cold starting. If these are blocked the fuel air mixture will not be rich enough when you operate the choke lever.

 

Please add more detail to what the issues are. "Not working" could be due to literally anything.
According to your post in another thread you have a starter issue. Is there anything else that isn't working right?

 

Sorry, I will try to explain it better.
When I try to get the bike to work it shows great difficulty. But if I clean the sparks it starts to work more easily, but after a few minutes it shows great difficulties to keep working. When I take the sparks out again they are black and full of fuel. The battery is ok, the resistance of the spark coils are also within the values, I changed the spark caps (NGK xd05f), I also changed the fuse box. What can I see next? Thanks for all the help.

 

Good advice here ^^^

Likely a good indication of excessive fuel from leaking float needle valves or improperly assembled carburetors. Be sure to check your oil level in the inspection window to be sure it is not too high from gas contamination - take a sniff of the oil to make sure it does not smell like gasoline. Don't continue to run the bike if the oil is contaminated with gasoline until the cause has been corrected and the oil changed.

When I try to get the bike to work (run) it shows great difficulty (it cranks but it is hard to start). But if I clean the sparks it starts to work (run) more easily (better).

Fouled plugs can be difficult to clean even when just fuel fouled, so if you haven't tried new plugs recently that would be in order, but odds are the carburetors likely need a refresh as suggested above.

Some helpful links if you have not found them:

https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

https://www.xjbikes.com/forums/threads/airhead-valve-adjustment-with-pics.14827/

http://www.xj4ever.com/setting fuel levels.pdf

 

Sorry, for my English. I will check the carburetors.
Thank you all

 

Your English is better than most native-speakers in the U.S.. No lie.

 

Hi. I think I have fuel in the oil. Does anyone have any useful advice. Thanks

 

Fuel in the engine oil is due to a faulty petcock. Here is a guide how to repair it.

https://xjbikes.com/forums/threads/rebuilding-the-yamaha-vacuum-fuel-valve-w-pics.25058/

 

AND faulty float needles. The petcock can be left on prime all-year-long and fuel won't overflow into the engine if the float needles are doing their job. The only exception being a perforated vaccum diaphram in the petcock.

 

Good point I forgot about those.

 

Why would that make a difference? Fuel flow is fuel flow...float needles should always block. BTW my petcock had a bad diaphragm (rubberized coating worn to the mesh) and leaked out onto the carbs when running but still didn't allow gas to flow out to the fuel line with engine off like prime would. Maybe a tear would.

 

What should I do now? It is obvious that I must change the oil but in relation to the fuel that is in the combustion chamber? can i use the air compressor to blow the fuel out? Any idea?
Thanks

 

Pull the plugs and crank it. Maybe place a rag over the top first, and watch your eyes.

 

Viton tipped needles age/harden and no longer seal. Rust or other detritus from the fuel tank can cause a needle to not seat. The washer or o-ring (depending on model) that seals the needle seat to the carb body can age and fail.
Owners (and even shops) can set the float levels incorrectly. Floats can stick. The wrong float needles can be installed, causing them to bind in an open position. Floats can be installed upside down. etc, etc.

In short, float needles do not always prevent fuel from overflowing into the engine, which is why overflow tubes were added to some carbs in the mid 80's by the carb manufacturers.

 

OK, you interpreted my question wrong. Assuming the float needles are doing their job, the question is in regard to this: The only exception being a perforated vaccum diaphram in the petcock.