GS700E won't start when cold runs rich on choke

[maysha17]

I'm hoping someone can give me some insight. I recently became owner of a 1985 GS700E and have been working on it non-stop over the last couple months to get it ready for summer.
I will put a list of what I've done to get to where i'm at now at the bottom of the post. Here's my issue:

The bike is very difficult to start when cold. After it sits for about 6 hours or more, it takes me going full choke and giving it 1/4-1/2 throttle to start. Once it does start (if it does) it seems to run very rich (smelly exhaust, white smoke out of pipes). The bike will run fine once it's warm. Has power through all rev-ranges and idles where it should after it's warm.

List of what i've done:
Adjusted valves
Thoroughly cleaned carbs (dipped for 24-36 hours, de-racked, washed, compressed air, and carb cleaner before reassembly)
vaccum synced carbs
Checked air and intake boots for cracks (none and are still flexible)
Replaced spark plugs
Replaced air filter
Replaced petcock and fuel lines
Checked for vacuum leaks

Any advice would be great. I just want to be riding down the road care free!

 

[zed1015]

The white smoke is excess oil burning off.
Most likely the valve stem seals are shot and need replacing.

 

[tom203]

Sounds like your “ choke” circuits aren’t enriching …each carb body has to scoop fuel off bowl bottom thru a little pipe which can easily get clogged and carry it to carb throat .. sounds like you did a good cleaning though.
opening the throttle during cranking defeats the “ choke” designed intent.

 

[maysha17]

Thanks for the input. To be clear, the bike runs off choke until it’s warm like normal so it’s getting fuel once it’s running. Just that initial cold start (only cold starts) often requires me to be cracking the throttle while turning it over and then I let off the throttle completely while it fast idles and warms up.

 

[Grimly]

Thanks for the input. To be clear, the bike runs off choke until it’s warm like normal so it’s getting fuel once it’s running. Just that initial cold start (only cold starts) often requires me to be cracking the throttle while turning it over and then I let off the throttle completely while it fast idles and warms up.

Just to clarify - when you set the cold start device (choke) and leave the throttle alone, it won't fire, is that correct?
It will only fire when you crack the throttle?

 

[zed1015]

Thanks for the input. To be clear, the bike runs off choke until it’s warm like normal so it’s getting fuel once it’s running. Just that initial cold start (only cold starts) often requires me to be cracking the throttle while turning it over and then I let off the throttle completely while it fast idles and warms up.

As advised in my earlier post..
One or more of your plugs are oil fouling due to valve stem seal leakage which will cause the hard starting and the need for excess use of the throttle to fire..
The white smoke is the oil being burnt off and clearing the fouling.
Depending on the severity of the oil leakage engines with this problem will then generally start and run ok as you describe for the rest of the day until the next prolonged period of inactivity which allows sufficient oil to again pool in the cylinder and foul the plug.

 

[rphillips]

I'm with tom203. Starting a cold GS, come from the choke tubes. You should "never" even touch the throttle when starting a GS., If the carbs are right it "should not" start if you turn the throttle at all.. Did you assure the stock size pilot & main jets were in your carbs...Just an opinion from a non carb mechanic.