[Skyguyz]

I have a 750 SEI and although it runs fantastic it has a “Sometimes issue.” If I run it for a bit on a ride and then stop the engine and let it rest for more than 10 minutes, sometimes it won’t start at all. I know it is getting spark and fuel ??? Could it be a case of the fuel getting too hot or what?
*I always turn the petcock off when I shut the engine off.
If I let it sit for over an hour it starts right up???
Thanks in advance for any helpful opinions.

 

[R Powell]

I had the filler cap air breather blocked and it did the same as your bike. Check it lets air through it otherwise it creates a vacumn and stops the fuel getting through.

 

[DenH]

I had the filler cap air breather blocked and it did the same as your bike. Check it lets air through it otherwise it creates a vacumn and stops the fuel getting through.

Why do you turn the fuel off if you're only stopping for ten minutes ?the fuel in the carbs might be evaporating with the heat of the engine !

 

[Lotus54]

an easy test for tank breather is to try to start when generally a ‘no-start’ condition. Then open fuel cap, wait 20-30 seconds and try again. If it fires right up the cap is plugged.

I’ve never seen it on a sei, but coils getting hot after sitting is a very slight possibility. Have you tested for spark when it does not start? Some ignitions can have issues after a heat soak- although I would expect issues when running also.

Do you still have stock ‘pointy ended German fuses’? Those are awful, the sei I bought new in the 70s has issues with it from the first day I had it. I tossed it and put one off a Datsun back then. For my current sei, I run a modern blade type fuesbox.
I also run relays for things like the coil and lights. All the power goes through the handlebar switches and those were not that great when new. But they work just fine if just triggering a relay.

I have aftermarket coils and electronic ignition, so I especially wanted to make sure I had good power.