Hard start when cold/after sitting awhile

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xs400newbie

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Hi all,

So I went to start up the bike yesterday after it sat for a couple of weeks and I had some difficulty again. It took about 12-15 crisp kicks before it came alive. The electric start won't cut it in this situation. I've kept the battery on a tender so it's not the battery. I had experienced this before so yesterday I went ahead and adjusted the valve clearances before I attempted to start it. The bike seems to run and idle great once fully warmed up. Now the weather was a bit cool also, around 8 degrees celcius, which I'm sure didn't help much. Over the last few weeks I've cleaned the carbs, added a new fuel filter, drained the old gas, new plugs, and reconditioned the air filters. The ignition is electronic so there is nothing to adjust. Timing not checked as I believe on this model it's also non adjustable. It's an 81 special II. I wasn't able to remove the pilot jets on the carbs as they were stripped but everything inside look pretty clean upon first inspection. Like I said it runs fine when warmed up, so can we eliminate the carbs as the problem? The carb boots have some cracks but it appears to only be on the surface but I should probably check for any leaks. The spark plug caps and wires have not been replaced, so this is my next purchase. Could this be a situation where the spark is a bit weak? Once the bike is warmed up I can start it with the electric start. Is it likely a lean condition? Guess I'll have to remove the plugs and have a look at them again. I have yet to balance the carbs. Anything else I need to consider?
 
too bad those pilot jets are stripped as those should prolly be bumped up for this cold'er weather. You can try giving the AF mix screws a turn or two and def get some new plugs and wires in there.
 
AF mix screws are at 3 turns out. I was already experiencing the hard start in the summer though. New plugs, but will be ordering caps and wires. When I looked inside the carb boots I didn't see cracks. I'm going to be checking for air leaks this week though. If the carbs are not perfectly balanced, can this cause a hard start also? Will be making my own carb sync tool also.
 
xs400newbie said:
AF mix screws are at 3 turns out. I was already experiencing the hard start in the summer though. New plugs, but will be ordering caps and wires. When I looked inside the carb boots I didn't see cracks. I'm going to be checking for air leaks this week though. If the carbs are not perfectly balanced, can this cause a hard start also? Will be making my own carb sync tool also.
Click to expand...
I have a dohc, but sometimes experience a similar phenomenon now that it's colder and sometimes below freezing overnight. From one day to the next, even with a weak battery, it will start. But if it sits for a few days, it can fail to catch and then needs to be turned over numerous times to catch.

Being a novice when it comes to real mechanicals, I theorized that my petcock works perfectly and completely shuts off fuel when it's not running. After only one day there is plenty of fuel in the carbs to let the engine catch on the first crank. After several days though, I imagined some of the gas in the carbs either settling, evaporating or seeping - thus causing it NOT to catch on the first crank.

After having this dream, I tried setting the petcock to PRI for a few minutes before trying to start it the next time it had sat idle a few days. Started right up.
Coincidence, placebo effect, psychic powers, correct diagnosis using out-of-the-box thinking? I have no idea. :shrug:
It's worth a try though as I don't think it can hurt.

My go-to cold weather starting procedure now involves an old 12v car battery and jumper cables should it not catch on the first crank - with or without petcock-on-PRI. Once warmed up (even after sitting for an hour at the coffee shop) it will fire up instantly - even without any choke.
 
The carbs will always be a problem. My standard answer is that they are not jetted correctly and are dirty. I know many will want to dispute this statement, but carbs are that bad. The best we can hope for is to get close, and then the weather will change. :banghead:

Now, if it is just hard starting, without other major performance issues (by your description, running lean like most bikes), I'd be doing a compression test on the cold engine. I'm thinking you will find it low. By kicking it over so many times, you are wetting the cylinders with gasoline and helping the rings seal. And getting enough fuel in the cylinders to have a combustible mixture. :)

You may also want to check your engine ground wires back to the battery. It should be easier to start with the starter than kicking, simply because the starter can spin the engine over faster for longer than one could kick it over. Or at least it should... :shrug:

Dave
 
well funny enough, I just had the same problem as you. I have no kick start, hadnt started the bike in a week, and it took ages to start, to the point I thought something was wrong. finally started with choke full on and giving a little throttle!

p.s got new airfilter in mail (old one looks bad, and ill do the plugs at the same time), hoping that might help.
 
jayel said:
tight intake valve clearances make for hard cold starts too, better to run them a little loose
Click to expand...

The range is 0.003" - 0.005" so I went with .004". This was my first time adjusting clearances but I'm pretty sure I did it right. Maybe I should try going 0.005"?

I've also read about people adjusting their startup procedure a bit as the bike ages. I was just opening the choke and kicking it over. Maybe I can try going back to the electric start and blip the throttle as it cranks, maybe hold in the clutch?
Thinking about taking the carbs to a shop and having them extract the pilot jets, just to be sure everything is nice and clean.
 
.004 should be fine, if the pilots haven't been out and they and the passages cleaned that may be the problem, have you tried removing the air/idle mix screws and spraying carb cleaner back thru them? if you do decide to have the jets removed have new ones ready for replacment as they will likely be destroyed in the process
 
jayel said:
.004 should be fine, if the pilots haven't been out and they and the passages cleaned that may be the problem, have you tried removing the air/idle mix screws and spraying carb cleaner back thru them? if you do decide to have the jets removed have new ones ready for replacment as they will likely be destroyed in the process
Click to expand...

Would definitely have to have new jets as I would not be wanting to put the stripped ones back in. I have not removed the air/idle mix screws but I can try that also. With regards to the pilot jets, I believe stock are 42.5? I know there are two different types. Not sure which type I need.
 

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My bike will start 1st kick no choke when its warm and idle high enough it will stay running.I read these bikes are very cold natured and my experience with mines proves that to be correct.When its cool half choke it start right up.Realy cold full choke Im sures thats about normal.My bike had alot of carb issues when I 1st got it.I ran sea foam through it and alot of carb cleaner and its seemed to get better over time.I plan on doing a complete overhaul this coming winter or early spring.
 
I had been having the same issue for a year I took the carb apart again for the tenth time lol and cleaned all the ports for the choke really well and it works perfect now
 

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