Can you bump start a modern bike?
Discussion
I feel I should know this but I don't! My newest bike is a 2003 so I'm not really up with modern stuff.
The background is that when I stopped for petrol a couple of weeks ago the guy at the pump next to me couldn't start his R1250RT. It had enough battery to power up and to do a slow turn over but not enough to fire. It had been ridden 20-30 miles already before stopping for petrol so should have been an easy start. I offered a push to try a bump start and we got it up to a good enough speed but it didn't fire. The owner admitted he didn't really know how to bump start and I refused to try on a bike of that size on a potentially oily garage forecourt. When he let the clutch out the bike of the bike didn't drop at all and it slowed in a few feet rather than locking solid. Maybe he didn't let the clutch out quick enough?
So, is there something that stops them bump starting? Does an R1250 have a slipper clutch for example? Would a slipper stop a bump start? Is there something else in the electronics that would stop a bump start (e.g. engine braking control)?
The background is that when I stopped for petrol a couple of weeks ago the guy at the pump next to me couldn't start his R1250RT. It had enough battery to power up and to do a slow turn over but not enough to fire. It had been ridden 20-30 miles already before stopping for petrol so should have been an easy start. I offered a push to try a bump start and we got it up to a good enough speed but it didn't fire. The owner admitted he didn't really know how to bump start and I refused to try on a bike of that size on a potentially oily garage forecourt. When he let the clutch out the bike of the bike didn't drop at all and it slowed in a few feet rather than locking solid. Maybe he didn't let the clutch out quick enough?
So, is there something that stops them bump starting? Does an R1250 have a slipper clutch for example? Would a slipper stop a bump start? Is there something else in the electronics that would stop a bump start (e.g. engine braking control)?
Crudeoink said:
Yes you can. Good luck bump starting anything 1000cc and above though. I'm sure it can be done, but I've never managed it
I've manged to bump start a 1000cc FI bike, although to be fair I had some downhill assistance, nearly killed me pushing it uphill in the first place though!I don‘t think it‘s possible to bump start most modern bikes. Many sensors und ecus need a minimum amount of voltage to work properly.
Tried bumpstarting my fathers V-Rod. No chance really, as it wouldn‘t disarm the immobilizer and ignition wasn‘t working either.
Tried on a R1150RT, did kind of work, but ABS got messed up and it really didn‘t sound healthy to do so.
Tried bumpstarting my fathers V-Rod. No chance really, as it wouldn‘t disarm the immobilizer and ignition wasn‘t working either.
Tried on a R1150RT, did kind of work, but ABS got messed up and it really didn‘t sound healthy to do so.
If it's got enough battery to prime the pump etc but just not enough to turn over the engine you can get away with it sometimes. In reality trying to bump a large, high compression twin is just going to lock the wheel unless you have good technique.
And I think modern BMW have something in them to prohibit anything that isn't hideously expensive at the main dealer
And I think modern BMW have something in them to prohibit anything that isn't hideously expensive at the main dealer
Steve_H80 said:
If it's got enough battery to prime the pump etc but just not enough to turn over the engine you can get away with it sometimes. In reality trying to bump a large, high compression twin is just going to lock the wheel unless you have good technique.
And I think modern BMW have something in them to prohibit anything that isn't hideously expensive at the main dealer
Really would need 1 person on it and 2 pushing. I suspect it needs a higher gear.And I think modern BMW have something in them to prohibit anything that isn't hideously expensive at the main dealer
Jump start is the best way.
The batteries on bikes are small so they really need trickle charging regularly and if the batt isn’t 100% health I would bung another on there.
Some years back when I had a knackered battery, I managed to bump start my 916, rolled it down my drive and onto the road and down the hill.
However, I've also done the same and it not start and then had to push it back up again so I wouldn't try it again, unless on a more significant hill.
There can be enough battery to run systems but when the starter's spinning it drops too low to get any fuel pressure/spark.
However, I've also done the same and it not start and then had to push it back up again so I wouldn't try it again, unless on a more significant hill.
There can be enough battery to run systems but when the starter's spinning it drops too low to get any fuel pressure/spark.
Hungrymc said:
You need plenty of battery voltage for the ECU / injection / ignition.
You have to get quite lucky to have enough life in the battery for the bike to run when it won’t start off the starter. And you can foul plugs.
Better answer is to jump start.
Given that it had ridden the 20-30 miles to the petrol station I'd guess it had enough to run the systems needed. Also there would have been some warmth in the tire to help grip. I'd never even try to bump start a cold engine/tyre as I've never had that work. Unfortunately the owner said the battery is buried pretty deep on an R1250RT (it was around a 2016 if I remember correctly). Luckily there was a Quik-Fit next to the petrol station due to open 30 minutes later, so I didn't feel I was completely abandoning him when I only gave it one go!You have to get quite lucky to have enough life in the battery for the bike to run when it won’t start off the starter. And you can foul plugs.
Better answer is to jump start.
Tango13 said:
Good luck bump starting anything with a slipper clutch...
Does an R1250RT have a slipper clutch though? I was guessing it might as it didn't slow quick enough or drag the rear when the clutch was let out...but maybe the owner wasn't aggresive enough with the clutch?stang65 said:
Does an R1250RT have a slipper clutch though? I was guessing it might as it didn't slow quick enough or drag the rear when the clutch was let out...but maybe the owner wasn't aggresive enough with the clutch?
2019 onwards R1250rt have a slipper clutch in them which will make it almost impossible to bump start itSeveral issues here.
First, slipper clutches won't let the bike drive the engine
Second, big high compression engines take a lot of turning
Third, the ECU may not be providing fuel and sparks in various scenarios. The fuel pump may be shut off because the ECU thinks you've crashed and stalled or something. Different bikes may vary.
If the battery volts are down, all sorts of things are possible, or not.
AIUI, some bikes will start if you use the starter motor to assist a bump start.
Other bikes e.g. BMW k1100 will have none of it. But that's only 'modern' if your other bike has a magneto.
First, slipper clutches won't let the bike drive the engine
Second, big high compression engines take a lot of turning
Third, the ECU may not be providing fuel and sparks in various scenarios. The fuel pump may be shut off because the ECU thinks you've crashed and stalled or something. Different bikes may vary.
If the battery volts are down, all sorts of things are possible, or not.
AIUI, some bikes will start if you use the starter motor to assist a bump start.
Other bikes e.g. BMW k1100 will have none of it. But that's only 'modern' if your other bike has a magneto.
I’ve bump started my Tiger Sport before. There was just enough juice in the battery to prime the fuel pump and power up the ECU; without those working, you’re wasting your time anyway. Luckily I was on the first floor of a multi storey car park so had a ramp to go down - it started on the third and final attempt, just before I reached the bottom!
So it can be done, but carrying a Noco jump starter pack in the top box is a lot easier! And having used it in anger, I speak from experience of both methods…
So it can be done, but carrying a Noco jump starter pack in the top box is a lot easier! And having used it in anger, I speak from experience of both methods…
Thanks everyone, concensus seems to be "you'll be lucky". I don't think I'll be trying again. Shame they don't make the batteries accessible like they used to - they were under the seat on my CB500 and VFR750, no tools needed for a jump start.
Still odd that it didn't drop the back/lock up the wheel when dumping the clutch, maybe he was too gentle with it, but maybe that made no difference......
Still odd that it didn't drop the back/lock up the wheel when dumping the clutch, maybe he was too gentle with it, but maybe that made no difference......
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