FIrst bike I couldn't push start

J

Jack the Smack

Well-known member
I've push started a triumph bonneville t-100, sv 650/1000s, sport bikes, 500s and 250s.

But I went on the fattest hill I've ever been on and tried to push start a Harley Sportster (800ish cc engine) that had been sitting for weeks and it didn't even turn over. :wtf I charged it for a day and it works now, but it would have been nice if my mom could ride her Harley that day.

Does it have something to do with the belt drive? Or compression ratio?
 
K

K-dog

Well-known member
I think it's a bit of both. It's a real summabitch to do. I think I got it work twice, and it works if you're at real moving speed okay, like 30+. but yah, they have bad compression ratio for it, and the belt drive doesn't help the situation.

I don't know if this is common, but I couldn't get it to jump off a prius either. (the one time I was really desperate to get it moving again. lol) Went and got a real car, and it worked fine. :twofinger
 
QuaiChangKane

QuaiChangKane

Anathema
Jack the Smack said:
The engine wouldn't even spin, the wheel just locked up, or the bike stopped nearly instantly if I let off the clutch slower.
Click to expand...


Did you try a higher gear, like 3rd or 4th even?

Some fuel injected bikes won't start at all if the battery is completely dead, as well. I don't think the engine design or compression ratio would have mattered in whether or not the bike would have bump-started; rather, the trick would be to get the engine to turn over at all due to the compression ratio - hence using a higher gear...


Try it again with a cold engine whith a charged battery - that might help figure out if the fuel injection is battery-dependent. If it's carbed, then it's likely just finding the proper gear to get the engine to turn over without dragging the rear tire. Maybe a shot of ether in the air filter would help, as well...


-Q!
 
Sidewalk

Sidewalk

My bikes have pedals now
I push started high compression HD engines before, you were probably in the wrong gear.

The belt drive has nothing to do with it.
 
Skim325

Skim325

Well-known member
Can you guys tell me what gear a the gsxr 750 would need to be in? Cause I swear I tried like 5 times to push start that down a hill one day and it just wouldn't turn. I was sweating up a storm and was super pissed! Lol definitely wasn't funny at the time though.
 
ST Guy

ST Guy

Well-known member
What kind of alternator do Harley's use? If it's the kind that doesn't use a permanent magnet, but instead uses a field coil powered off the battery to generate the magnetic field, then if the battery is really shot, there won't be a strong enough magnetic field to generate the juice to make a spark. This holds true for any bike using an alternator without a permanent magnet. You must have some juice left in the battery.
 
QuaiChangKane

QuaiChangKane

Anathema
Skim325 said:
Can you guys tell me what gear a the gsxr 750 would need to be in? Cause I swear I tried like 5 times to push start that down a hill one day and it just wouldn't turn. I was sweating up a storm and was super pissed! Lol definitely wasn't funny at the time though.
Click to expand...

Second or third should work - I never bump anything in 1st gear...


Rule of thumb is that if it just slides the rear and won't turn over in whatever gear you're in, just try higher gears until it will. :thumbup


Most bikes will turnover by hand in top gear on a rear stand when checking the valves, but YMMV depending on bike (like big thumpers).


-Q!
 
russ69

russ69

Backside Slider
To get a big single or twin to turn over, back it up in gear until you back up onto the compression stroke. get a little speed and click it into second gear. That should get it going unless the battery is flat on a fuel injected bike. The injectors need good voltage to open. Pushing an injected bike usually doesn't work too well.

Thanx, Russ
 
Var

Var

One Track Pony
We had problems push starting an R1 with race tires cause they had no grip at all. We deflated the rear tire a bit and jumped/pushed down on the footpegs right when releasing the clutch to put more weight on the rear tire at that instant.
 
PunkRockMonkey

PunkRockMonkey

Wild in the Streets!
Interesting re: fuel-injected/big bore bikes. I've tried push-starting the Superduke ONCE and gave up after the 3rd push. :laughing

So long ago I don't even remember what gear it was in. Oh well. Next time I'll try 8th gear. ;)
 
brichter

brichter

Spun out freakshow
My BRP will not push start (in the dirt) if you use the clutch, due to big piston and high compression. Use the compression release in place of the clutch and it's a piece-o-cake.

T3h Sportster will need 2nd or even 3rd to push, and you'll need to bounce down on the seat when you pop the clutch. Lowering the rear tire pressure will help as mentioned earlier...
 
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