Cold Starting Issues

[silverslp]

First off, I understand that the GS500 is cold blooded. This phenomenon has just recently occured. Idle is set at 1400.

All of a sudden, I am having cold start issues. If I pull the choke lever to about half open and crank the bike, it won't start. I'll even open the choke fully, and the bike still won't start. I have to have the choke open and give it a liberal amount of throttle for the bike to start, and keep the throttle open or it will die. Previously, I'd pull the choke and the rpm's would soar and I'd dial it back perfectly until the bike was warm enough to shut it off.

I know the choke is working because I can see the slider working on the carbs, and it will raise the rpm's a slight bit when open.

Any ideas are greatly appreciated. Thanks in advance for the help.

[EdChen]

I'm no expert, but I believe out of adjustment valves can hinder cold starting. When was the last time the valve clearances were checked?

[silverslp]

I'm not sure if the valves have ever been checked. I just bought the bike in May of 2014. Thanks.

[HPP8140]

I'm no expert, but I believe out of adjustment valves can hinder cold starting. When was the last time the valve clearances were checked?

I agree. Tight exhaust valve.

[bombsquad83]

Definitely check your valves, but could also be a clogged choke circuit jet in the carb.  The jet for the choke is integrated into the float, and it sits near the bottom of the float bowl.

Did the bike sit for long time without use?

[gsJack]

Dirty air cleaner.

[silverslp]

As far as I know, the only time the bike sat without use was during winter months; and was stored respectively. I put a brand new air cleaner in last fall. There also seems to be "dead spots" in the bike when I am at wide open throttle. Not sure if this is more clutch related or not?

Additionally, once the bike is warm, it runs beautifully and has absolutely no problem starting thereafter. If my problem was due to a tight exhaust valve, wouldn't the valve expand once up to temp and make things worse? Thank you all for the help.

[gsJack]

Valve clearances increase as the engine warms up.  A tight valve cold will free up and the engine will smooth out.  The aluminum head expands more than the steel valve lifing the camshaft away from the valves.

[silverslp]

Ok, so more than likely its the exhaust valve out of spec versus the choke jet? Thanks.

[bombsquad83]

Ok, so more than likely its the exhaust valve out of spec versus the choke jet? Thanks.

Seems like the first thing to check.

[DoktoroKiu]

Ok, so more than likely its the exhaust valve out of spec versus the choke jet? Thanks.

I wouldn't rule it out, though.  How quickly did this set in?  Was it like this after the storage period, or did this just happen overnight?  When I got my GS with 9k miles I had a hard time starting cold, but I never had to use throttle to start.  It just took a lot (lot) longer to warm up to where the choke could be off, and it died when coasting to a stop with the clutch in unless I manually de-revved the engine more slowly.  IIRC this has something to do with there being very low compression at low RPMs with tight exhaust valves, because they end up opening too early and staying open too long (tight valves means the cams push the valves open sooner and release contact later).  My bike had unmeasurable clearances on both exhaust valves, and very tight clearances on the intakes (all were factory valves), and I had virtually no valve noise.  My GS is a lot throatier and has a lot more valve noise now, with slightly wide clearances on the exhaust.

It is probably at least worth checking the clearances no matter what (I believe it's every 6000 miles in the manual, or was it 4000...).  While you're there the carbs are more accessible, so you could check your cabling and possibly try cleaning the carbs.  Don't do this before you get JIS screwdrivers, an impact screwdriver, and a hacksaw.  Those ***** carb screws can be a major headache if you try to use a phillips head to go at them.  I took mine apart and cleaned the jets, but everything was pristine as far as I could tell.

[bombsquad83]

Great advice on the JIS Screwdrivers if you are digging into carbs.

[DoktoroKiu]

Great advice on the JIS Screwdrivers if you are digging into carbs.

They are worth every penny - just like the hex-head screws you buy to replace the stock screws 

I only wish they sold JIS bits in the US/online.  They have to exist, but apparently (at least a year ago) you can't buy them anywhere where I can read the language.  It's hard to use an impact screwdriver without proper bits...

[silverslp]

Ok, so more than likely its the exhaust valve out of spec versus the choke jet? Thanks.

I wouldn't rule it out, though.  How quickly did this set in?  Was it like this after the storage period, or did this just happen overnight?  When I got my GS with 9k miles I had a hard time starting cold, but I never had to use throttle to start.  It just took a lot (lot) longer to warm up to where the choke could be off, and it died when coasting to a stop with the clutch in unless I manually de-revved the engine more slowly.  IIRC this has something to do with there being very low compression at low RPMs with tight exhaust valves, because they end up opening too early and staying open too long (tight valves means the cams push the valves open sooner and release contact later).  My bike had unmeasurable clearances on both exhaust valves, and very tight clearances on the intakes (all were factory valves), and I had virtually no valve noise.  My GS is a lot throatier and has a lot more valve noise now, with slightly wide clearances on the exhaust.

It is probably at least worth checking the clearances no matter what (I believe it's every 6000 miles in the manual, or was it 4000...).  While you're there the carbs are more accessible, so you could check your cabling and possibly try cleaning the carbs.  Don't do this before you get JIS screwdrivers, an impact screwdriver, and a hacksaw.  Those ***** carb screws can be a major headache if you try to use a phillips head to go at them.  I took mine apart and cleaned the jets, but everything was pristine as far as I could tell.

When I got it out of storage, the bike wouldn't pop off like it would previously, but I just assumed that was normal from storage. My bike will also stall when coasting to a stop with the clutch in, when cold. I have recently noticed that if I start the bike on the side stand, versus vertical, the bike starts easier. However, the choke still does not make much difference in RPM as it used to. Last year I had to replace my float bowl gaskets as they were leaking heavily, and the carbs looked extremely clean to me. I have zero experience working with carbs or jets so detailed information is very helpful. Thank you.