What The? Vac line popping off boot on kick start.

OdysseusXS

XS650 padawan
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Good morning all,

Had a weird engine/carby event happen yesterday, warmed the bike up for a few minutes (3 or so) choke out. Once she was purring smoothly I took off on a short errand. Got to my destination (about 2 k's down the road) and parked her at the shops. When I returned to ride her home I attempted to kick start my bike (a one kick starter too). As the bike started up there was a pop and the vac line explosively popped off the vac barb. I pushed it back on and rode home. The plugs are beautifully clean, no fouling, light tan/ biscuit colour. Just wondering if this is something to be concerned about. Any suggestions welcome fellas.

Cheers, Odysseus:confused:
 
Small hose clamp. I use zip ties. I have tool that pulls them tight and trims off the extra. Works well on fuel lines too.
Depending on what the vacuum hose is made of it can soften as it warms up. This can let it pop off.
Leo
 
cheers XSLeo,
Just wondering if it was just a backfire and I'm being paranoid. I've just got this bike running perfectly, one kick starts but I believe that the idle is still set too high. Once the engine is at running temp she sits at 1500 rmp. I'd be happier if she idled at 1300 or so, should I back the idle screw off a bit next time I've got her properly warmed up?
 
You can, some run it even lower. Too low and it might start stalling unexpectedly at stops. I keep mine in the 12-1300 range. If I do a lot of around town riding I turn the idle up a bit, 1500 rpms, this help keep the battery charged better.
Leo
 
tried idling at around 1100-1200 with a sick left carb, that didn't end well. She'd up and quit at the ights etc... kind of embarrassing. Is it normal for the indicators to cause the headlight to fade a bit when the indicators are flashing?
 
tried idling at around 1100-1200 with a sick left carb, that didn't end well. She'd up and quit at the ights etc... kind of embarrassing. Is it normal for the indicators to cause the headlight to fade a bit when the indicators are flashing?
yeah 1100 is about as low as you would want if your a kick only, flashers yes they will dim the headlight a lower rpms... 30 year old charging systems a funny that way ha ha ... there are things that can be done to help, LED signals, electronic flasher, up-graded charging system (PMA $$$) or up-grade Reg/Rec cheap and works well
 
Cheers Jayel, I'll do some thread searching and see what I can find on those upgrades/mods. I love the bike, NEVER selling it. It has an fully functional electric starter too, I just like using the kick for the nostalgia...
 
I see you have an 1982 model. A simple way to reduce the bike's wattage is to replace the rear taillight with an LED taillight. The double light bulbs used on the 80 to 83 years draw a very large current.
 
Thank you for the suggestion retiredgentleman, I took the cover off while cleaning the rear brake light lens and was amazed at the size of those bulbs, could almost warm your lunch up on them. I'll try to find the appropriate LED option to replace them.
 
To the original question an occasional hiccup at idle isn't unusual, A lot of guys (me included) have had the carbs blown out of the holders from an idle backfire.
 
Stupid question, and I know that another member has already raised the question in another thread, but why do these curious engines occasionally 'hiccup' even when they are idling happily? Is this a universal trait with these engines? Why? I thought that my 82's TCI would have made the idle smoother than it is.
 
In the US the EPA regs had them very lean. When that lean an occasional misfire is common. I will concede a points system is more susceptible to misfires. All the usual carb and ignition gremlins can make it worse.
 
Stupid question, and I know that another member has already raised the question in another thread, but why do these curious engines occasionally 'hiccup' even when they are idling happily? Is this a universal trait with these engines? Why? I thought that my 82's TCI would have made the idle smoother than it is.

You can achieve a smooth idle but it takes some detective work searching around the carb inlet area. When I bought my bike from the PO, the idle rpm would wander up and down at random and occasionally hang up at 1600 to 1800 rpm.

Any small air inleakage will change the idle rpm, and I mean even very tiny openings.
A few leakage places that I found:
1) Butterfly shaft seals..................they may sound like a bird "chirping".

2) The machine screw on the side of the carb, that can be used to measure vacuum or sync the carbs. Normally does not have a washer, but I had to use a phenolic washer and some Threebond 1104, in order to get an air tight seal.

3)The rubber carb manifolds would leak air, due to a very poor fit. Why did they fit poorly? They fit poorly because I had bought then from Mikesxs.com, and as with many of their parts, they just had no quality control during manufacture in Taiwan/China. I re-installed my 30 year old stock manifolds (Japanese quality,perfect fit), and no more air leakage.

Besides the air inleakage, I also had worn out rubber O-rings on my carb needle jets
(1970 to 1979 years). Extra unmetered fuel was being drawn past the outside of the needle jets, and caused the idle to hang.

My idle is now very smooth.
 
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