FORUM

Notifications
Clear all

Cold temp start issue - '93 GSPD

18 Posts
4 Users
0 Reactions
1,027 Views
Gary Crowell
(@grcrowell)
Posts: 18
Active Member
Topic starter
 

When temps are cold (<55), my GSPD is almost impossible to start.   Attached video is of me trying to start her today.   I ran her around town yesterday, sat in the bike barn overnight.  Infrared thermometer says 42.9 F at cylinder heads.  Heads torqued to spec, valves and rockers adjusted, timing adjusted, carbs balanced.  New plugs, air filter, new Denso starter.  Once I get her started, and she runs for 5 minutes, she runs great.  If I let her sit in the sun to warm up, she starts.   

Any pointers greatly appreciated.  Running older Alpha ignition, carbs rebuilt before I got the bike.

 

This topic was modified 2 years ago by Richard W
 
Posted : 01/16/2022 12:03
David Elkow
(@4949)
Posts: 306
Reputable Member
 

Any history on this?  Since this or that was done, etc?

I couldn’t watch your movie, unfortunately. Hard starting could be due to a myriad of causes.  Based on your info, I would ask if using the enrichment lever makes any / much difference when trying to cold start?  The answer should be yes, it makes ALL the difference.  Should be night and day. If it’s not night and day, then I would think there are enrichment circuit issues.  That’s another list of possibilities. 

 
Posted : 01/16/2022 16:49
Gary Crowell
(@grcrowell)
Posts: 18
Active Member
Topic starter
 

@4949 Since I have owned it, the bike has always been somewhat difficult to start when it's cold weather, or it's not been started for a few days.  All the above maintenance items were performed, in part, to try and rectify the hard starting in cold weather.  

 

Enrichment circuit definitely helps- won't start without it engaged.  Above 60 degrees, second position is only required to start, and first position is only required for about 10 seconds.

 
Posted : 01/17/2022 09:00
James Strickland
(@8053)
Posts: 421
Reputable Member
 

Check and clear the passages in the bottom of the float bowl that feed the brass take-up tubes for the enrichers. A little bit of smutz in only one side can contribute to hard starting. Does the motor seem to run on one cylinder when it does start cold?

former Airmarshal, IL.

 
Posted : 01/17/2022 10:33
Gary Crowell
(@grcrowell)
Posts: 18
Active Member
Topic starter
 

@8053 100% seems to run on one cylinder for a few seconds when starting.  I'll pull float bowls this afternoon and clear the take up tubes.  Will report back- thanks!

 
Posted : 01/17/2022 10:48
Richard W
(@wobbly)
Posts: 2549
Member
 
Posted by: @8053

Check and clear the passages in the bottom of the float bowl that feed the brass take-up tubes for the enrichers. A little bit of smutz in only one side can contribute to hard starting. Does the motor seem to run on one cylinder when it does start cold?

True. Something in the enrichening system isn't working. The number 1 offender is the orifice in the bottom of the float bowl. 

This could also indicate the presence in both carbs of ethanol "varnish". A dark brown coating that closes up all the fuel passages, including the jets. The smaller the jet, the more likely to close completely. What you find in the bottom of the bowls is also in the jets.

Hope this helps.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 01/17/2022 15:35
Gary Crowell
(@grcrowell)
Posts: 18
Active Member
Topic starter
 

I went in and made sure idle jets and enricher jets/passages are good and clean.   Bowls have significantly less varnish that the above.  Unfortunately, it was above 60 degrees before I could get that done- test start will have to wait until the morning.

 
Posted : 01/17/2022 15:38
Richard W
(@wobbly)
Posts: 2549
Member
 
Posted by: @grcrowell

I went in and made sure idle jets and enricher jets/passages are good and clean.   Bowls have significantly less varnish that the above.  Unfortunately, it was above 60 degrees before I could get that done- test start will have to wait until the morning.

The point is that your bowls are supposed to have ZERO varnish. Cold starting is NOT your problem.

Cold starting is a symptom of the problem, which is varnished jets. This is making the bike run lean across the full spectrum. It's simply more noticeable for you during cold starts.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 01/17/2022 16:01
Gary Crowell
(@grcrowell)
Posts: 18
Active Member
Topic starter
 
Posted by: @wobbly
Posted by: @grcrowell

I went in and made sure idle jets and enricher jets/passages are good and clean.   Bowls have significantly less varnish that the above.  Unfortunately, it was above 60 degrees before I could get that done- test start will have to wait until the morning.

The point is that your bowls are supposed to have ZERO varnish. Cold starting is NOT your problem.

Cold starting is a symptom of the problem, which is varnished jets. This is making the bike run lean across the full spectrum. It's simply more noticeable for you during cold starts.

Very true- should have been more clear.  I cleaned off all the varnish I found; a test start this AM (heads reading 45 degrees F) yielded no improvement.  While the throats and slides are nice and shiny, I am reaching the conclusion that jets are plugged in some fashion.  I have a rebuild kit for both, so I guess I know my upcoming weekend project.

This post was modified 2 years ago by Gary Crowell
 
Posted : 01/18/2022 12:00
Richard W
(@wobbly)
Posts: 2549
Member
 

Given:

1. Obviously, 1993 is well into the EPA mandated low emissions era. So you might consider enlarging some of the jets for better performance.

2. The smaller the jet, the greater the effective closing will be, given that a carb has accumulated a fixed amount of varnish throughout. (The smaller jets are more adversely affected. Smaller jets also do the Starting !!)

3. Due to the intake pulse, the needle and needle jet get physically hammered to death. So they need replacing every 10 years anyway.

 

Result:

A. You'll want to replace both Pilot jets with the same size. The orifice are too small to effectively clean, and Starting happens with these jets.
B. You'll want to go to the next size Needle Jet, 2.66 up to 2.68. (That's the latest info I have.)

C. Replace the needle with the same size.

D. Increase the Main Jet from 165 to 170. (That's the latest info I have.)

If you can find more up-to-date info follow that. I'm basically just suggesting you re-jet the carbs to European jetting standards. 

E. You'll want to research Top Tier Fuels AND start running a brand of fuel with a built-in cleaner. https://www.toptiergas.com/licensed-brands/

F. May I suggest you start turning your fuel completely OFF when you are 1/4 mile from your home. This will empty a greater part of the fuel from the carbs, and help with the storage issues.

Hope this helps.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 01/19/2022 07:50
Gary Crowell
(@grcrowell)
Posts: 18
Active Member
Topic starter
 
Posted by: @wobbly

Given:

1. Obviously, 1993 is well into the EPA mandated low emissions era. So you might consider enlarging some of the jets for better performance.

2. The smaller the jet, the greater the effective closing will be, given that a carb has accumulated a fixed amount of varnish throughout. (The smaller jets are more adversely affected. Smaller jets also do the Starting !!)

3. Due to the intake pulse, the needle and needle jet get physically hammered to death. So they need replacing every 10 years anyway.

 

Result:

A. You'll want to replace both Pilot jets with the same size. The orifice are too small to effectively clean, and Starting happens with these jets.
B. You'll want to go to the next size Needle Jet, 2.66 up to 2.68. (That's the latest info I have.)

C. Replace the needle with the same size.

D. Increase the Main Jet from 165 to 170. (That's the latest info I have.)

If you can find more up-to-date info follow that. I'm basically just suggesting you re-jet the carbs to European jetting standards. 

E. You'll want to research Top Tier Fuels AND start running a brand of fuel with a built-in cleaner. https://www.toptiergas.com/licensed-brands/

F. May I suggest you start turning your fuel completely OFF when you are 1/4 mile from your home. This will empty a greater part of the fuel from the carbs, and help with the storage issues.

Hope this helps.

1) Agree- bike was desmogged when I got it, and came from sea level.  I'm at 5k feet, so it needs rjetting for a variety of reasons.

2) Cleaning/rebuilding Saturday- will report.

3) On order

 

A) Thanks for pointer!

B) Bueno!

C) That was my plan for sure

D) I found the attached chart that shows suggested main jet at 135?

E) I do run a top tier premium.  Bike has shaved heads, so...

F) Had not thought of this, but good call.  The bike does get ridden regularly- it's my "around town" bike in addition to being my "around Big Bend" bike (I live in Far West Texas).

 

Thanks for the pointers (and time!)

 

 
Posted : 01/19/2022 20:54
Richard W
(@wobbly)
Posts: 2549
Member
 

Glad to help. Some additional thoughts...

• The Pilot jet and enrichener circuit will have the largest effect on starting, cold or otherwise.

• The Needle Jet will mean more to general riding.

• The Main Jet will have the lowest effect on all areas of engine performance.

• You will also want to check the adjustment on the "Choke Cable". Due to its Y-cable construction, it's easy for one carb to be way out of adjustment.

• If the cold starting problem persists... then disassemble the rotary valve for the enrichener circuit. These can be found under the small squarish cover on the side of the carb. The disk is different for LH and RH carbs, and if they get swapped by mistake, cold starting becomes very, VERY difficult.

Hope this helps.

This post was modified 2 years ago by Richard W

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 01/20/2022 10:30
Gary Crowell
(@grcrowell)
Posts: 18
Active Member
Topic starter
 

I have now rebuilt both cabs, reinstalled, and set idle mixture and synched the two.  Once warm, idles very nicely at about 1000 rpm, and runs really great.

The cold temp start issue remains, and it alternates on which cylinder is running when it starts.  Sometime left, sometimes right- wondering if there is some sort of ignition issue.  Older Alpha installed.

 

Any pointers appreciated.

 
Posted : 02/10/2022 13:59
Richard W
(@wobbly)
Posts: 2549
Member
 

• There are ignition analyzers you can use. I've seen hand-held tubes about the size of your index finger to can hold against the plug wire and a small lamp inside tells you when the coil is firing.

• I see where you have installed new plugs, but I see no mention of plug wires and plug caps. It's very important that you use the older METAL core wires, and not the new high-resistance "suppression" automotive cables.

That's all the help I have.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 02/11/2022 05:01
Richard W
(@wobbly)
Posts: 2549
Member
 

One last idea... Have you looked at the condition of the 3-pin ivory-colored connector coming off the bean can ? If there is any crazing, cracking, crumbling... any degradation in that connector at all, then these type things start to happen.

Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.

 
Posted : 02/12/2022 06:47
Page 1 / 2

Advertisement

Scroll to top