Warm start perfect but cold start hard

[Guest]

I'll try to help you help me the best

1982 GS650GL 32kkm (~20k miles)
All stock (airbox, carbs, engine, exhaust)

Before you ask, here what's been done so far:

- Carbs totally disassembled, dipped, thoroughly cleaned and rebuilt using most NOS parts.
- NOS air intake boots
- new petcock
- new gaz
- new oil and oil filter
- new spark plugs
- thoroughly cleaned the air filter and airbox
- choke lever cable cleaned (choke pronge move freely)

Not done yet:
- Valve adjustment
- Valve stem seal replacement on cylinder #1 and/or 2 (white smoke at cold start out of left exhaust)
- Compression test

Here is a video of a warm start.
https://photos.app.goo.gl/LKKWH7BHHckP6Cxa7
(seems perfect to me).

The Problem
Need almost 1 min of starter to get the cold engine running.
Here is a video of cold start.
https://photos.app.goo.gl/MiUhJpD6Nh1DzR3S6
Test conditions:
- the engine has not run for a couple of weeks.
- engine is at "room temperature"
- Outside temperature is about 5C / 40F.
At 0:22 I put the petcock at Prime, and waited for ~60 seconds before trying again.

The question
Where should my time be worth the most for the next steps?
(yes, I read the "Help! Your Bike Won't Run Well" sticky)

Thanks for your help

 

[chuck hahn]

I would do the valves first. but my question is has the bike sat a few days before trying to start? if so gas evaporates from the bowls. if its sat a while switch petcock to PRIme and try it after 20 seconds or so. remember to switch back to the ON setting once it starts.

 

[Guest]

I would do the valves first. but my question is has the bike sat a few days before trying to start? if so gas evaporates from the bowls. if its sat a while switch petcock to PRIme and try it after 20 seconds or so. remember to switch back to the ON setting once it starts.

Thanks chuck hahn. Yes, that was mentionned: "At 0:22 I put the petcock at Prime, and waited for ~60 seconds before trying again."

 

[Nessism]

You might want to check the Newbie Mistakes thread linked in my signature to see if anything applies. There are some red flags in this thread but it's best if you decide for yourself...

 

[Guest]

What was your right hand doing BESIDES pushing the starter button?

It should be doing NOTHING. Do NOT move the throttle while you have the "choke" engaged.

You did engage the "choke", didn't you?

 

[Who Dat?]

Yep, adust the valves should be the first course of action for your hard-start situation.

A properly-done compression check seldom hurts, but is probably not necessary in this case.

Hopefully you realise that replacing the the valve seals will also have you removing the cylinders to replace the base gasket?
It is mandatory to remove the head to do that job. Removing the head usually disturbs the base gasket, so it is highly suggested that the base gasket also gets changed. Please do yourself a favor and only use OEM gaskets.

 

[Guest]

What was your right hand doing BESIDES pushing the starter button?

It should be doing NOTHING. Do NOT move the throttle while you have the "choke" engaged.

You did engage the "choke", didn't you?

Yes I did. Thank you.

 

[Guest]

... Hopefully you realise that replacing the the valve seals will also have you removing the cylinders to replace the base gasket?
It is mandatory to remove the head to do that job. ...

I didn't realize that. I though valve stem seals could be changed without removing the head using this method:
https://youtu.be/n_9Y8Y2vEXw
Doesn't this apply to a 1982 GS650?

 

[Nessism]

I didn't realize that. I though valve stem seals could be changed without removing the head using this method:
https://youtu.be/n_9Y8Y2vEXw
Doesn't this apply to a 1982 GS650?

Personally, I would use that technique (hammer.) There are guys here that have used lever arms and such to depress the springs and release the retainers before with the head installed. Searching the archives should turn up the photos. I saw one guy on KZ Rider who made a special tool that bolted to the head and then a big screw to push spring down. The idea came from an automotive tool specific to the purpose. At any rate, there are ways...

 

[Guest]

I have never seen that tool before, it looks like I need to do some research on it.

 

[alke46]

His old stem seals sure came out a lot easier than mine did. I suspect they had been changed recently and not the originals.

 

[Gorminrider]

I watched your cold-start video I don't see a 'cold start" problem .Given that the bike's been sitting a long while, after :22 you did the right thing. Turned to prime and waited. My 650 is the same. Good mileage, because it runs leaner than my looser bikes...You don't really need to turn it back to "run" by the way, but you are likely smarter than me and know you'll forget if you don't ! so Next,...apart from suggesting another error I make ("Choke/Enricher not pulled the whole way, or cable not pulling it the whole way) I can only nag: adjust the valves, seals or not. If you really don't want to go there at least check compression that might prove the valves need adjusting. There's no escape from valves for a home-mechanic. Rings, gear box? ok throw the bike away. but adjusting valves? No.
Are 1+2 spark plugs fouled? Are you sure the seals are bad? Maybe they are but that seems an advanced diagnosis you can live with awhile...

Nice farkling by the way!

 

[Guest]

Getting back to this old post; here is the end of the story after that episode.
I just pulled the vaccum tube from the petcock and let it the engine run until it ran out of gaz. Then, I stored the bike until about 2-3 weeks ago.
I put the the petcock at prime for a minute, pulled choke and pressed the starter button and guess what: it started right away!
I was then able to start it cold perfectly at any time. Maybe last fall I was unconsciously touching the throttle.
Thanks chuck hahn, Nessism​​​​​​​, phydeauxmutt , Who Dat? and Gorminrider​​​​​​​ for your help.

 

[rphillips]

Congrats man, hope it keeps doing well.