Sticking carburettor slide

[Sculptor55]

Hi All,
Any tips for preventing sticking carburettor slides on Mikuni CV carbs?  My brothers Virago XV535 recently went onto one cylinder, the slide had stuck closed. It freed off easily enough but he’s concerned that it it may happen again. Diaphragms are fine, both were replaced some time ago.  I cleaned the slide and bore with carb cleaner and it now feels fine, but is there anything else that I can do, or things that I definitely shouldn’t do?  I’d guess that using metal polish in the bore would be fine, but am wary of doing anything to the plastic slide that may damage it.
Thanks, all thoughts appreciated.

[kwackboy]

It sounds like you've fixed it .   

As long as the slide is clean and the bore has no obvious damage you should be fine.

Just as a precaution, I'd make sure the needle is smooth with no major wear or damage.

[Sculptor55]

Thank you, wanted to be able to reassure him that it should be OK now.

I didn’t think to check the needle condition, that’s a good suggestion so will take a look.

[Hugo Magnus]

When servicing my DRZ carb. I found that the slide was quite gummy which set me wondering if this E10 was responsible for it?

[Sculptor55]

That’s a good point.  I’m pretty sure that the bike is always used with V-Power E5, but maybe even this lower ethanol content is enough to degrade 20 year old fuel lines.  Perhaps that’s the next task....

[Brockett]

Some float jet needles have some sort of plastic or rubber tip and these are being eaten away by E10. So my mechanic friend says.

[kwackboy]

Maybe I misunderstood...

I'm no guru on fuel and have experienced the reduced power in my old CB500 but, I thought E10 only affected fuel systems when stood idle for long periods...?

Happy to be corrected 

[Mr Nick]

It's a two-fold problem for us older bike owners:

There are two big issues with ethanol fuels and older cars. The first is that ethanol can have a corrosive effect on metal, plastic and rubber parts in the fuel system. The results of this can range from inconvenient, like sticking carburettor floats, to dangerous, such as when fuel lines perish.

Crucially, not all vehicles will have problems and rather like the introduction of unleaded fuel back in the ’80s, some will be perfectly happy on the new fuel and some will need modification.

The second issue with the E10 fuel and something which is more of a problem for classic cars than everyday modern vehicles is that the ethanol is hygroscopic, meaning it tends to absorb water. Clearly the longer a car is left standing idle, the bigger an issue this will be, with any moisture in the fuel only adding to potential issues.

https://classicsworld.co.uk/guides/e10-fuel-a-classic-owners-guide/

[Joe Rocket]

Before a whole misplaced discussion is held on E10 and sticking slides E10 is OK to use on Yamaha models from 1990. Start from here and venture deeper if you think your concerns warrant it.

https://www.yamaha-motor.eu/gb/en/information/e10-fuel/#/

I do not put E10 in my 1987 GPX.    (Yes, I know it's not a Yamaha, just saying)

[kwackboy]

I don't use it in my 2000 cb500, it runs OK but there's a noticeable difference ...

I happen to have a tesco petrol station local and they sell 99 octane super.

It's rocket fuel for my little Honda,  it loves it .. 

[Joe Rocket]

No 10% ethanol in that then kwackboy. No more power either, I've read/seen. https://www.bing.com/videos/search?q=Octane+and+power+in+motorcycle+engines+youtube&view=detail&mid=C4D7148DB17E75B26B9FC4D7148DB17E75B26B9F&FORM=VIRE

[kwackboy]

Sorry .. turn of phrase ...

No more power , just runs a lot better on 99 octane.. 

[Mojo-Jojo]

The key sentence from that video, 'The higher concentration of detergents will help keep the engine cleaner, and sustain power, mileage and throttle response', so it is beneficial in all ways.   

[Joe Rocket]

Yes Mojo-Jojo, that's what he said. That's ignition, timing and tuning levels to benefit from premium fuel. It's just a waste putting it into mediocre robust and general market motorcycle engines, unless you want to pay more for your petrol.

Sorry, I've digressed.

BOT

[Mojo-Jojo]

I always used the higher octane fuel in my Varadero 125cc, it just seemed to run better. Maybe it was psychological.