Fast Idle Wax Unit Fault?

[Skids]

Guys, a little help please, if able.

 

My 08/72k mile 6th Gen doesn't idle very well when cold. On occasion, it wont idle at all; starts easily but dies unless I hold the throttle open. When it does idle, it's a very low idle, approx. 900rpm. Bike rides fine though, and when warm, idles in the region of 12-1300rpm as it should.

 

I'm suspecting the fast idle wax unit isn't working properly; is that a reasonable diagnosis?

 

Would removal & cleaning be likely to sort it? I have a 72k service to do the weekend after this and I'm replacing the thermostat so I can access the fast idle wax unit when I do that. What should I look for and how do I clean it?

 

Or could it be something else causing the low idle issue?

 

Thanks in advance.

[Auspanglish]

Could be air trapped where the coolant runs through the fast idle wax unit. Could be the long thin metal fulcrum/lever actuating mechanism getting stuck (it often gets bent when synchronizing starter valves or mucking about in the general throttle body area, or it could be gummed up injectors or time to change the spark plugs or bad fuel or... The fact it is when it's cold would make me think wax unit.

Have u lifted tank and inspected fuel lines, air filter, etc?

[Egg on Leggs]

First port of call should be a liberal dose of lubricant on the linkages in the area of the waxstat. Worked on many occasions for me when there have been tick over issues.

[Auspanglish]

Checklist for poor idle performance

[Skids]

But there's no poor performance at low speed, it's just she doesn't idle on occasion! Bike runs beautifully otherwise so I think I can discount ECM/Fi issues.

 

The SVs are balanced every 4k miles and will be re-balanced next weekend.

 

Jim - thanks m8, I'll give them a good clean/lube. I'd like to avoid removing the unit but may need to if it's properly gummed up. I should probably check movement of the actuator as the engine warms too.

 

Thanks guys. 

 

Anyone got any more?

[Auspanglish]

Synchronize your starter valves

[Knight]

Here is a great post with pics of the wax unit disassembled:

 

 

[Auspanglish]

Old thread, but Kaldek's videos have been very helpful for me. Kaldek, I owe you a beer or three. Here's a photo of the internals for reference...I took mine apart (sixth gen) last night to see if it needed servicing, but I honestly can't see how this unit would ever fail. It's just a spring and some metal bits. Mine looked brand new inside.

Now, that said, the coolant passage was almost completely plugged on mine and wasn't allowing the unit to heat up properly:

Before:

 

After:

 

Now to go buy some circlip pliers so I can get the bloody thing back together...

 

I knew I had read somewhere about it getting clogged up.

 

Good find!!

[Skids]

5 hours ago, Knight said:

Here is a great post with pics of the wax unit disassembled:

 

 

 

Thanks Knight. I'd seen that when I searched. A useful video and subsequent post discussion.

 

Cheers. 

[adsrox0r]

Mine does the exact same thing every winter. As soon as the ambient temperature drops below 10 degrees celcius I can guarantee on a cold start she'll need the throttle feeding for about 5 to 10 seconds or it'll bog down to 800rpm and die. Once you let go after a few seconds it dies down a bit and the revs pick up to normal wax idle and then go back down to standard idle as per normal operating temps.

 

Other people have had the same problem over at VFRWorld forum and to date we've never solved it. One guy replaced his wax idle unit and.....yup, still did it. Throttles synced, still does it. Sparks checked and preplaced, still does it. Linkages lubed and checked, still does it. Only happens in winter.

 

Funnily enough mine is the same year, 2008.

 

I've learned to live with it, she runs absolutely fine otherwise.

[Skids]

But it did this yesterday, 24 degrees OAT.

[Egg on Leggs]

There is a brass rod on the status that connects to and operates the throttle linkages to adjust the tickover. This tends to corrode which causes it to stick in its seals. WD40 or GT85 and some manual movement with long nosed pliers can help.

[Skids]

27 minutes ago, Egg on Leggs said:

There is a brass rod on the status that connects to and operates the throttle linkages to adjust the tickover. This tends to corrode which causes it to stick in its seals. WD40 or GT85 and some manual movement with long nosed pliers can help.

 

Thanks Jim, that'll be my first port of call.

 

I have to lift the fuel rail as well to replace the thermostat.

[Auspanglish]

Careful not to bend that actuating rod I mentioned, it's too easy to do.