weird cold idle issue

[maim]

sled is 07 rs vector. this was my 2nd attempt at fixing the cold idle issue. sled will not idle on cold start up but idles fine once it is warmed all the way up. stalls out unless on the throttle once it comes off higher idle and choke does not help keep it running at all.

as it came to @kirkswim and i not running at all, we went through the entire fuel system to get it running including, draining gas out and new fresh, discovering pumps failing to prime even off of gravity feed bottle of gas (replaced with good used) as well as repairing fuel leak in line at pump, cleaning all the carb jets and passages 2x along with making sure cv slides are not sticking and clear all before we synched the carbs on it. discovered it was over filled on oil as well as having gas in oil as well as fouled plugs. over filled oil stuck the valve they have mounted to right frame that goes to air box. fixed and corrected all of this and is still doing it. did discover that the check valve on frame was still sticking as oil tank was being pressurized witch when ran with dipstick out did straighten out some.

gave it back to guy and reccomended new valve and he go through and check the ground blocks on sled as it does have 15000 mi on it.

did i miss anything or pretty much covered it?

 

[RobX-1]

I remembered reading this post last year about the thermowax causing idle issues during cold starts. Might be something to look into/consider:

Yes that is the thermowax, the 2 lines that hook up to it are coolant lines. When the engine is cold it allows more air to bypass the throttle plates through the IAC. As the coolant warms up the wax, it slowly closes off this extra air, then your idle adjustment screw takes over. Your throttle plates should be completely closed when at idle, If they are open slightly then your issue is either the linkage holding them open (ie) cable is tight, or the shaft that your throttle plates are attached to are starting to get stiff (usually caused by corrosion) and not allowing the plates to close. If the plates are completely closed, then the engine is getting too much air from another source such as the thermowax or cracked TB boots, gaskets or loose clamps. I am referring to the rubber ones that connect the TBs to the engine. The thermowax has been an issue with motorcycles that have the same setup. With the symptoms you are describing it sounds like the thermowax is causing it, but I would check the boots to rule that out.

 

[MrSled]

Did you clean pilots or get new ones? If it has piles of miles it could need a valve adjustment or have a sticky valve.

 

[Stubbs]

The pilots on those three holers are SOOO tiny, if they’re gummed up at replacement is the best option, although it’s strange half choke won’t keep it running. New plugs were on the list? I’ve had carbed 973’s that act very strange when cold out of storage come around 100% after a good long ride as long as the fuel system/carbs are absolutely clean, adjusted to spec and synced. When that’s the case I chalk it up to a bit of rust on the valve seats and move on with my life.

 

[Fast Lane]

Once my high speed idle comes off, it will try to stall. My trick is to make sure the choke is off before the high speed idle comes off and give it a few braaps. Then its fine. Its always been like this. I think the fuel pumps are lazy in the cold or maybe the fuel bowls are not quiet full yet. Not sure but its always been like this. I even bought all new jets and it made no difference.

 

[maim]

plugs where new.


pilots where new last year and verified clean. new fuel filters where installed by me last season. did have to fix where the throttle cable attaches as the last local guy they had try to fix it bent the bracket and it was rotating on the screw messing up the idle.

robx-1, didn't know about that. might need replacing.

sled only has 15000 mi and was purely lady driven for most of it. runs fine and smooth when valve 8es-13520-00-00 is not sticking as we did clean it out as it was full of oil. ran it up to almost shut down temp while spinning track 2x before i gave it back.

added k100 to tank for water residue and reccomended that he take it for a boys ride as his wife doesn't ride hard. might just need a good hard agressive ride to blow the crap out of it.

 

[MrSled]

plugs where new.


pilots where new last year and verified clean. new fuel filters where installed by me last season. did have to fix where the throttle cable attaches as the last local guy they had try to fix it bent the bracket and it was rotating on the screw messing up the idle.

robx-1, didn't know about that. might need replacing.

sled only has 15000 mi and was purely lady driven for most of it. runs fine and smooth when valve 8es-13520-00-00 is not sticking as we did clean it out as it was full of oil. ran it up to almost shut down temp while spinning track 2x before i gave it back.

added k100 to tank for water residue and reccomended that he take it for a boys ride as his wife doesn't ride hard. might just need a good hard agressive ride to blow the crap out of it.

Might need valves adjusted.

 

[Clintww]

Once my high speed idle comes off, it will try to stall. My trick is to make sure the choke is off before the high speed idle comes off and give it a few braaps. Then its fine. Its always been like this. I think the fuel pumps are lazy in the cold or maybe the fuel bowls are not quiet full yet. Not sure but its always been like this. I even bought all new jets and it made no difference.

Mine too 2005 Rx 1 will do this sometimes as well. Never caused a problem otherwise, just annoying.

 

[pdiddy]

Three possibilities: 1. Pilot Jets plugged. 2. Pilot Jets plugged. 3. Pilot Jets plugged.

 

[Stubbs]

Normally I’d agree but usually you can find a “happy place” with the choke and keep it running ish. Doesn’t sound like that’s the case here. I still say take it out and flog it for one/two hours, see what happens after that.

 

[Clintww]

I also tend to keep the idle speed on the low side. Both sleds stumble slightly or die just as the timing changes from the warm up period. I take them off completely off the enrichment as soon possible also. If I don't stand by and blurp them they will die at that point. One throttle blurp and good the rest of the day. I have never fouled a plug in either sled. I agree with Stubbs. They always run better on the second tank of gas.

 

[Metallicat]

I also tend to keep the idle speed on the low side. Both sleds stumble slightly or die just as the timing changes from the warm up period. I take them off completely off the enrichment as soon possible also. If I don't stand by and blurp them they will die at that point. One throttle blurp and good the rest of the day. I have never fouled a plug in either sled. I agree with Stubbs. They always run better on the second tank of gas.

I used to follow the same warmup procedure as you outlined until someone on this forum suggested a different approach a number of years ago. The suggestion was, in order to reduce stalling and potential plug fouling, to keep the choke on and the engine idling high until it has warmed up enough to idle smoothly on its own with the choke off. So now I practice that routine and will even drive it for a short ways with the choke on before I back it off. Inthink either way is fine, really, but I just about eliminated cold stalls leaving the choke on longer. Then again, I am also using slightly larger pilot jets in mine which also helps.

 

[Stubbs]

The “get the choke off ASAP” thing with the carbed sleds started with the RX-1. I ran an RS Nytro for years and NEVER fouled a plug leaving the choke on for as long as it took for the sled to idle decently. If it started to stumble sliding it off I’d give it some more for a while longer, never had any issues with plugs or anything else for that matter.

 

[maim]

it cuts out with choke on or off. the only thing that keeps it running is getting on the throttle.

 

[Fast Lane]

I put NGK iridium plugs in a few years ago. Highly recommend them.