Upping the pilot jets size for stronger idle/better starting.

[Guest]

Anyone With a GS has gone up in pilot jet size to get a stronger idle and better starting in cold weather.

Reason I present this is that my GS's dont do well starting when it's cold out.

I had an Honda 400 single that was like that. The way that I solved it is I upped the pilot jet one or two sizes and the bike would start so much easier it was night and day.

So just curious to know if anyone has tried this on a GS.

[Steve]

Looks like all the bikes in your signature have CV-style carbs, so it's easy to richen the mixture by simply turning out the mixture screw a bit.

How far out are the screws now? In the stock setting they were intentionally lean to meet EPA regulations.

If you richen them up a bit (by just turning the screws), they work quite well, using the stock jet sizes.

.

[BigD_83]

No, but I did up the pilot jet on a CMX250 to smooth out the horrible transition just off-idle with it's Keihin carb, and it made a huge difference. With the A/F mixture adjustability on the Mikuni carb on the 650, I can't see changing the pilot jet on an otherwise stock setup making a huge difference.

P.S. I am curious to see where you go with those components on your rides

[jfman]

How far out are the screws now? In the stock setting they were intentionally lean to meet EPA regulations.

If you richen them up a bit (by just turning the screws), they work quite well, using the stock jet sizes.

.

Well on my 1980 I have never touched the carb since the bike runs well overall. On the 1983, I removed the to clean them out but I counted the number of turns, wrote it down on a piece of paper and reset them the same way after cleaning. cant say I have messed with them.

No, but I did up the pilot jet on a CMX250 to smooth out the horrible transition just off-idle with it's Keihin carb, and it made a huge difference. With the A/F mixture adjustability on the Mikuni carb on the 650, I can't see changing the pilot jet on an otherwise stock setup making a huge difference.

Thanks Ill keep that in mind.

P.S. I am curious to see where you go with those components on your rides

I hope to have the 1980 ready and done for april 2013. If I dont run into major issues. In a way I have to since it is my only mode of transport during the riding season.

The 1983 cafe project is gonna take a little more time I will have to admit.

[BassCliff]

Hi,

My carbs are properly clean and adjusted. The stock intake system is air tight. My bike starts with 1/2 choke, no throttle, and just a touch of the start button. I've had no need to change any carb parts from stock. I can't help but think that if you're really having a problem that you should look for the cause and not just treat the symptom. But, whatever works for you.


Thank you for your indulgence,

BassCliff

[jfman]

Mine is the same way too starts at the hit of the button when the weather is califonia-like. But I am talking about real cold starts when it's 38 outside (soon will be colder) This bike is not garaged.

I should add theat it still starts fine but not as well as I would like. The real test is going to be in a months or so when the weather drops below 32.

Hi,

My carbs are properly clean and adjusted. The stock intake system is air tight. My bike starts with 1/2 choke, no throttle, and just a touch of the start button. I've had no need to change any carb parts from stock. I can't help but think that if you're really having a problem that you should look for the cause and not just treat the symptom. But, whatever works for you.


Thank you for your indulgence,

BassCliff

[hampshirehog]

The choke, or rather on these bikes the enrichener circuit, will swamp anything you do with a pilot jet to help cold starting.

[BigD_83]

Mine is the same way too starts at the hit of the button when the weather is califonia-like. But I am talking about real cold starts when it's 38 outside (soon will be colder) This bike is not garaged.

I should add theat it still starts fine but not as well as I would like. The real test is going to be in a months or so when the weather drops below 32.

I remember November in Montreal...sounds like the start of a new song.

Are you already seeing 38F? September should be warmer than that! I hope that is just at 05h00, and not 12h00.

I have not mined your other posts, so I'm wondering when your last valve adjustment was done.

[jfman]

I remember November in Montreal...sounds like the start of a new song.

Are you already seeing 38F? September should be warmer than that! I hope that is just at 05h00, and not 12h00.

I have not mined your other posts, so I'm wondering when your last valve adjustment was done.

Well just once at night so far. It's warmer than that for now.

For the valves well........ never since 1980 I would guess.

The choke, or rather on these bikes the enrichener circuit, will swamp anything you do with a pilot jet to help cold starting.

You bring a really good point since that other bike had a classic choke and not an enricher.

[Steve]

For the valves well........ never since 1980 I would guess.

Sounds like you really need to read about the Newbie Mistakes and pay particular attention to 1B, 2 and 3.

.

[Thumper88]

I went to 20 from stock 17.5 pilot jets on my GS450....but I have K&N pods and essentially dual open pipes (Emgo "mufflers").
It would stumble at take off, until it warmed up for 5 minutes, now it warms up in 30 seconds. Tried opening the mixture screws, got to 4 turns and it got better but not quite.
Now have 20 pilot jets with 2 turns on the mixture screws.

[tkent02]

Adjust your valves. Leave the carburetors alone until you have adjusted the valves.

[jfman]

Sounds like you really need to read about the Newbie Mistakes and pay particular attention to 1B, 2 and 3.

.

1B and 2 have been done. Sadlu for 3 I will have to outsource this job. But yeah I am overdue.

I went to 20 from stock 17.5 pilot jets on my GS450....but I have K&N pods and essentially dual open pipes (Emgo "mufflers").
It would stumble at take off, until it warmed up for 5 minutes, now it warms up in 30 seconds. Tried opening the mixture screws, got to 4 turns and it got better but not quite.
Now have 20 pilot jets with 2 turns on the mixture screws.

Will keep that in mind

Adjust your valves. Leave the carburetors alone until you have adjusted the valves.

[BigD_83]

1B and 2 have been done. Sadlu for 3 I will have to outsource this job. But yeah I am overdue.



Will keep that in mind

Why outsource adjusting your valves? It really isn't very difficult. Be prepared with a new valve cover gasket, just in case you rip the one that is already there.

[Thumper88]

Before I even tuned my carbs, the first thing I did was adjust the valves (at which point I found they had burned up, and had to do a top end rebuild).
170 psi compression on both cylinders now.