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Cold Blooded Gs

  • Thread starter Thread starter GS750GUY
  • Start date Start date
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GS750GUY

Guest
Me again. GS750Guy here.
My newly restored 78 GS750EC with 11,000 original miles has been a blast to ride since early September and performs great. That is until I rolled it out of the garage yesterday morning in 50 degree weather and fired it up. It seemed to start o.k. if I babied the choke and finally got it stabilized and warmed up a bit. However, when I attempted to take off on the bike it bogged and coughed, had no power and I kept it running by playing the choke. Finally after five minutes or so, and I assume when the bike got up to full running temperature it smoothed out and ran beautifully through my three hour ride.

I have the point gap and plug gap set at right in the middle of the specified range of gap. Should I adjust these gaps any to the closer or wider end of the range? Would that help any?

I ran into the prior owner today and I asked him if the bike was cold blooded during his 10 years with the bike and his response was .......O YEA!!!!!! And he said it was a characteristc of those bikes. He said he had the bike in the shop for tune ups periodically while he owned the bike.

Another biker friend told me these bikes were engineered to be ridden in 70 & 80 degree weather not 50.

Also, would a slight fuel leak from a float bowl cause these symptoms. I noticed just a drop of fuel on the bottoms of two bowls after riding yesterday. No puddles anywhere just a drop of fuel hanging from the draing plug screw on two bowls. Would this cause any engine performance problems?

I thougt I would throw this out to my trusty GS family for your experience with this bike.

Thanks!

GS750Guy
 
Sounds like your ready to clean the carbs and check float levels and or valve adjustment.That's the same thing Im going to do this winter.
 
tconroy said:
Sounds like your ready to clean the carbs and check float levels and or valve adjustment.That's the same thing Im going to do this winter.
Click to expand...

I know the carbs are clean and the float levels are right on. I just completely rebuilt them.
Could be valves. I've not touched them. Would they be ready for a check after only 11,000 miles?
GS750Guy
 
Check your jetting. Lean bikes are cold blooded bikes. You shouldn't have to have the bike on choke for more than a minute or so if it's jetted right.

Also check for anything that could lean out your mixture - intake boot leaks, exhaust leaks, intake o-rings, etc etc.
 
Last edited:
GS750GUY said:
I know the carbs are clean and the float levels are right on. I just completely rebuilt them.
Could be valves. I've not touched them. Would they be ready for a check after only 11,000 miles?
GS750Guy
Click to expand...

You should check your valve clearances every 3,000 miles or 5,000 km. So yours are definately overdue for a check and I would think some adjustment after 11,000 miles. I would also try and richen up the idle circuit on the carbs too. If you have VMs half a turn in on the air screws.
 
On these engines the valves usually get tighter as they wear, and the engines get hard to start when the valves are too tight. You friend is full of it, these bikes are from Japan, and Japan is a cold place. They run fine in cold weather. It's all in proper maintenance.
 
GS 750 GUY,dont feel like the lone ranger because i have the same problem with my 77'gs 750B.[im sure the b. stands for beast]. ive cleaned my carbs last winter and had my valves ajusted this spring and i still need to finesse my choke for at least 3 minutes to get the old girl to run on her own after that.Then everything is fine. Up here IN M.N. its been in the 40's but i ride till the snow sticks or my nads get frostbite. I run b7s' in my bike with great results. I also been reading about irridum plugs. NGK has been claiming they provide faster warmups and quicker acceleration if this is true then im all for it. Has anybody else have tried these plugs in there gs's? Let us know.For your other problem, the o-ring is dried out and a small amount of fuel is geting past it .What i did was go to my local ACE hardware and pick up a similar sized o-ring. GOOD LUCK. "AND KEEP THE SHINY SIDE UP."
 
tkent02 said:
On these engines the valves usually get tighter as they wear, and the engines get hard to start when the valves are too tight. You friend is full of it, these bikes are from Japan, and Japan is a cold place. They run fine in cold weather. It's all in proper maintenance.
Click to expand...

Japan didn't have tough emmission laws as early as some other countries.
The later VM carbs were deliberately jetted lean to meet more stringent emmission laws in other countries. With temperatures approaching zero C (32deg F), full choke is needed with longer warm ups. In winter months, usually around or just above zero C, my 850 takes 3-4 minutes to warm up enough to pull away cleanly with partial chock. When I richen the pilots to correct the cold lean condition, the engine slightly fattens off idle when hot. This causes a slight stumble off idle when the throttle is opened. Re-tuning to clean running on the pilot when hot, results in the engine becoming cold blooded again. Plug chop tests and throttle response through the rev range indicate that my pilots are set correctly.
Give it adequate time to warm up and ride. You'll definately need to check those valve clearances as well!!
 
Cold weather does make a difference. Any manual I have ever read and studied and any carb I worked on always takes longer to warm up on a 40 degree day than on an 80 degree day.

Infact, we wouldn't tune any snow blower until we hit November to properly set the idle and main mixtures.

My old super sport takes longer to fully warm up but once it is it runs great. Carbs aren't fuel injection where they compensate and a bike that takes less to warm up in the winter probably runs a little rich in the hot summer.

I've had people ask me why it takes a few minutes to have the choke out, and I said well it's not fuel injected and when you ride it for 5 mins you no longer need to have the choke out on a 40 degree day. On an 80 degree day I'd let the bike warm up for about 2 mins before taking off and within a block the choke was off completely or it would start to run rich and stumble. I tuned the carbs after a good hour ride to ensure the bike is fully warmed up.
 
I'd definitely check valve clearances. That slight leak from your carbs might make a difference to ease of starting (level of fuel might be slightly down on your first spin) so I'd sort it (apart from the obvious bit that you don't really want petrol dripping on your motor).

As for the need for a long spell on the choke - it goes with the territory of running an aircooled motor. If it runs fine when warm and at any time outside winter then it's running right.

Wally
 
RICKV. said:
GS 750 GUY,dont feel like the lone ranger because i have the same problem with my 77'gs 750B.[im sure the b. stands for beast]. ive cleaned my carbs last winter and had my valves ajusted this spring and i still need to finesse my choke for at least 3 minutes to get the old girl to run on her own after that.Then everything is fine. Up here IN M.N. its been in the 40's but i ride till the snow sticks or my nads get frostbite. I run b7s' in my bike with great results. I also been reading about irridum plugs. NGK has been claiming they provide faster warmups and quicker acceleration if this is true then im all for it. Has anybody else have tried these plugs in there gs's? Let us know.For your other problem, the o-ring is dried out and a small amount of fuel is geting past it .What i did was go to my local ACE hardware and pick up a similar sized o-ring. GOOD LUCK. "AND KEEP THE SHINY SIDE UP."
Click to expand...

Thanks RickV! What are b7's?
I'm pretty sure my fuel leak is at a couple of bowl gaskets. When I put a mirror and light under the carb bowls and look at the under side I can see wet gasket material between the bowl and carb body. I probably just did not get a good fit with the gasket. I avoided putting some kind of gasket sealant on these for fear it would get into the fuel system and plug something up.
GS750Guy
 
b7ES NGK spark plugs. I initialy ran b8ES plugs in my 750 but even after a long 100 mile ride.And my plug were not running at the right heat range [ burning more blackish gray than brown] So i started running the b 7's that i was telling you about.And now my plug run a nice cinnamon color.And no fouling. also it seem to warm up and start more cleanly tha it did with the other plugs. HOPE THAT THIS IS SOME HELP TO YOUR COLD BLODDED BIKE. R.V. ROCHESTER MN.
 
aside from some of the more effective and actual fixes suggested here :wink: just to help it start right off the bat, there's a great tip to blow gently into the vent tubes before starting. it won't really mean you don't have to warm up the engine, but it might help some getting it "primed"

I usually don't even start putting on all my gear until the bike's started, so it gets a few just in that process and I can hear it hit different stages. I didn't used to have a choke lever, so I got used to unscrewing the throttle adjuster and tightening it just till it held its idle. after less than a minute it hits a high 4K rev and I back the adjuster off, then a minute or so more it does it again, and then I can set the adjuster back where it should be.

just to help illustrate the effects of a little warm-up
 
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