strange fuel problem 750

[Skaaning]

Let me start of by appologising. Some words or sentenses my seem incorrect or odd. But the reason being, that I live in denmark and english is not my native language.

I resently bought myself a 89' katana 750 - or in denmark it's called a gsx 750f but should be the same.

I have had some issues with the carbs. But im guessing its lack of proper cleaning in the pilot system?
Its having trouble maintaining a prober idle. It will some times drop, without warning.

But the other issue, that I can't figure out is, that when i turn the handbars all the way to the left, the rpms will drop.
Have any of you had this issue before?

[Court93kat]

Below is the link to THE BEST information you can read about Katana carbs. This is a bit of a long read, but will take care of 90% of all your carburetor issues.

https://katriders.com/forum/service-department/katana-how-to-s-faq-s/14367-carbs-101-long-but-worth-it-carbs101?t=63344

Welcome to KatRiders! The place to learn more about your bike than you thought was possible.

[Skaaning]

I already read it, that’s why I suspect a pilot issue.

but what I’m baffled about is the drop i rpm when turbine the handlebars left♂️

[Court93kat]

Typically if turning the handlebars effects your idle, it has to do with your cable adjustment. I don't know if the European versions are different than the US versions. If you have two throttle cables going to the carbs and the cable that pulls to make sure the butterflies close is too tight, then turning the handlebars full left would tighten that cable even more which would force the butterflies closed even tighter reducing your idle. I have heard on the one cable US version that turning full left would cause the idle to RISE due to the cable being too tight and pulling the butterflies open.

[Skaaning]

This model only uses one cable. That’s why I don’t understand the reason for it. The butterflies have a natural stop on the idle adjuster. So why would the rpm suddenly drop?

[Court93kat]

Well, I am at a loss then. Not real sure I've read anyone having that issue before. Wish I could be more assistance. I'm willing to bet if you tear the bike down and look closely at the cabs while you turn the handlebars, you will see something. I have no idea what, but it's got to be something going on. That just isn't right.

[flyboy]

I suspect the same reason, only I'd check the routing of your choke cable too. Like Court9kat says, this has to be a linkage issue - some cable, somewhere, hits something, sometimes. Either when you turn all the way to the left, or perhaps in every scenario other than left.

Get a few cans of mechanic's lubricant*, pull the tank off, and inspect all cables. You may be able to see what's going on with the tank on, but trust me - mysteries like these are best solved properly lubricated* and with the tank off.

*Just like engines need lubricant, mechanics need it too. My preferred brand is Heineken, straight out of the fridge (look for a green bottle)

[Skaaning]

I found the issue.. And I didn't even need a Heineken.
The problem was a electrical issue, with the harness to the key/lock. It lost a little ground and would try to switch off.
Disconnected the plugs. Cleaned them with emery and contact cleaner. And the problem was solved.

[Court93kat]

Glad to hear your found it, and thanks for letting us know what it was.

[Skaaning]

No problem. There might be others with the same issue one day. That could benefit from this