Classic Hard Starting / Poor Running FAQ

compiled & edited by Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 31 December 2006, by Winter #1935

For other related FAQs:


When you experience problems starting or running your F650, it could be related to any number of other smaller problems. So sometimes it can be very difficult to find what is wrong. This FAQ aims to help you identify what is wrong and redirects you to more appropriate FAQs with more detailed answers. Start with the troubleshooting table and see where you end up.


Attempting to start your bike with a low or failing battery is a really bad idea because there is a real risk of the starter solenoid contacts welding closed due to low voltage arcing. If this happens you will have to disconnect the battery (because the permanently closed solenoid contacts will crank your battery dry) and either replace or repair the starter solenoid.

[From the BMW Dual Spark Rider's Manual (Australian Version)] If you attempt to start the engine when the battery is flat, you will hear the relay chattering. Further attempts will damage the starter relay and starter motor. Before trying again: recharge the battery.

If you have a Classic

If you have not already done so, replace your plug caps with NGK plug caps, replace your spark plugs, and think about replacing your battery / performing the VR flay. This will deal with 99% of problems encountered.

Diagnostic Tables

Please note: some of the entries in this table are sorta jokes - they are easy to spot (humor is the best medicine, but it will not fix your bike). There are also some stupid things in there such as leaving the bike switched to the "on" position. These are easy to spot as well... The table is symptom based, and for any one symptom there may be multiple causes. The possible cause/solution list is in order of what is fairly fast and easy to fix through to more difficult things. If you come across something that is incorrect or have something to add, please let us know. (Note: Items marked as FI are relevant on the Fool Injected (GS/CS/Dakar) models only. Items marked Carb are relevant on the Carb (Classic/ST) models only. Everything else is relevant to both bikes).

Also note that this table does not cover everything - it is a guide only. There are heaps of other FAQs that should help you out.

Symptoms Possible Cause Possible Solutions Reference
No power Key in off position Turn key to on position Doh!
Key left in on or park Turn key to off or lock position when bike not in use Doh!
Blown fuse(s) Check/Replace fuse(s) Ummm?
Continually blown fuse(s)? Short circuit / bad wiring Electrical Misc FAQs
Battery flat or missing or damaged Recharge or replace battery Battery FAQ
Battery cables loose or damaged Check cables are secure + rust free Battery FAQ
Ground cable loose or damaged Check the ground cable is secure Battery FAQ
Broken / Damaged ignition (key) lock Check / replace lock Ignition Switch FAQ
Lights dim when starter pressed Battery Voltage Low Recharge battery Battery FAQ
Headlight globes continually blown Voltage Rectifier failing Test/Fix VR VR FAQ
Relay chattering when starter pressed Battery Voltage Low Recharge Battery Battery FAQ
Battery failing (voltage becomes low when starter pressed) Check / replace battery Battery FAQ
Battery Continually Flat/Low Voltage Key left in on or park Turn key to off or lock position Doh!
Battery is failing Check/Replace battery Battery FAQ
Too many accessories Use fewer accessories
Turn coffee maker off before stoping
Voltage Rectifier failing Check/Fix VR VR FAQ
Battery Continually Low on Water Voltage Rectifier failing Check/Fix VR VR FAQ
Bike starts in Neutral, but fails/dies when:
  • Starting in 1st with clutch in
  • Putting bike into 1st after starting
Side stand down Retract side stand OR
Select Neutral
Side stand switch broken or wires shorted Check / fix switch and wires Classic Elec Misc FAQ
GS Elec Misc FAQ
Sidestand Kill Switch FAQ
Clutch switch broken or wires shorted Check / fix switch and wires GS Clutch FAQ
Strange dash behaviour (FI) Unknown BMS-C / ECU problem Reset BMS-C / ECU
Test using BMW diagnostics
Upgrade BMS-C firmware
Fuel Injection FAQ
(FI) BMS-C / ECU connector damaged Fix/Replace connector Fuel Injection FAQ
(FI) Battery Voltage very low Check voltage / replace battery Battery FAQ
Engine does not turn over Broken starter/ignition button Check / fix ignition button
(and contacts)
Broken kill switch Check / fix kill switch
(and contacts)
Low battery voltage Check / recharge battery Battery FAQ
TDC bolt left in place! Remove TDC bolt after service Doh!
Water in engine (after creek crossing) Remove water (see FAQ) Riding Tips FAQ
Engine turns over, but does not start No fuel Check fuel warning lamp
Ensure fuel in tank
(Carb) Is the fuel tap (petcock) on?
Clogged fuel screen or filter / Bad fuel Clear fuel screen
Check / replace fuel filter
Change fuel
GS Fuel Pressure FAQ
Classic Tank Removal / Replacement
(FI) Insufficient Fuel Pressure Check fuel pump Fuel Pressure FAQ
(FI) Clogged fuel injector / bad fuel Check / replace fuel injector
Change fuel ASAP
Check / replace fuel filter
Fuel Injection FAQ
Fuel Pressure FAQ
Hard to start / puking petrol (Carb) Float related problem Clean / Fix carbs? Carb Misc FAQ
Generally Hard Starting Air Intake Blockage Check / Clear Intake (remove mouse nests)
Check / Replace Air Filter
Classic Air Filter
GS Air Filter
Spark plug fouled / old Check / replace Spark Plug(s) Spark Plug FAQ
(Carb) OEM plug caps Replace plug caps with NGK Plug Caps 'n Coils
(Carb) Split Carb Diaphrams Check / replace carb diaphrams Carb Clean FAQ
Valve clearance incorrect Check clearance / change valve shims Classic Valve Shim Check
GS Valve Shim Check
Bike starts but:
  • Has idle problems (until warm), OR
  • Bike starts but fails within seconds
Unsuitable Oil Type for ambient temperatures Use appropriate oil Oil FAQ
GS Oil Change FAQ
Loose Battery Connections Check Battery Connections Battery FAQ
(FI) Unknown BMS-C / ECU problem Reset BMS-C / ECU
Test using BMW diagnostics
Upgrade BMS-C firmware
Fuel Injection FAQ
(Carb) Idle Speed incorrect Adjust Idle Speed to 1400rpm Idle FAQ
(Carb) Idle Mix incorrect Adjust Idle Mix Screw Idle FAQ
Bike will not rev above 1.5-2k RPM
(when cold)
Possibly voltage rectifier failing Test / fix the VR VR FAQ
Flaying the VR
Will not rev above 4-4.5k
(once warm)
Voltage Rectifier failing Test/fix the VR VR FAQ
Idle Problems (once warm) (FI) Throttle used when starting Do not use throttle when starting GS Hard Starting FAQ
Loose battery connectors Check / tighten battery connectors Battery FAQ
(FI) Hole / missing bolt in rear airbox Check for missing bolts
Check for missing oil drain plug
Air Filter FAQ
(FI) Unknown BMS-C / ECU problem Reset BMS-C / ECU
Test using BMW diagnostics
Upgrade BMS-C firmware
Fuel Injection FAQ
Exhaust gasket problem Check / replace gasket Exhaust Gasket FAQ
Valve clearance incorrect Check / adjust valve clearance Classic Valve Shim Check
GS Valve Shim Check
Misfiring and Power Loss above idle Voltage Rectifier failing Test/Fix VR VR FAQ
Valve clearance incorrect Check / adjust valve clearance Classic Valve Shim Check
GS Valve Shim Check
Surging while riding (FI) Surging and Stalling See Reference! S&S FAQ
Rider twisting throttle Stop twisting throttle ;-P
Throttle cable damaged Check cable moves freely Cable FAQ
Loose Battery Connections Check Battery Connections Battery FAQ
Clutch adjustment Check clutch adjustment
Check / Replace clutch plates and springs
Clutch Adjustment FAQ
Clutch Misc FAQ
Clutch Plate / Springs FAQ
Stalling (engine dies) while riding (FI) Surging and Stalling See Reference! S&S FAQ
Inappropriate (low) engine speed Select more appropriate gear
(ie keep RPM over 3k RPM)
Riding FAQ
Loose Battery Connections Check Battery Connections Battery FAQ
Stalling below 3k RPM
(after long trips)
See Stalling Problems below
Cracked Inlet Manifolds Replace inlet menifolds Carb Misc FAQ
Idle mix screws too rich Check / replace screws Idle FAQ
Black box failing (Check by placing icepack on it for 5mins) Electrical Misc FAQs
VR failing (Again, check with an icepack) Voltage Rectifier FAQ
Plug related problem Have you done a plug chop? Spark Plug FAQ
Piston rings need replacing Run a compression test Compression Test
RPM not dropping once stopped Throttle cable damaged Check / replace throttle cable Cable FAQ
Throttle return spring ineffective Check / replace return spring Cable FAQ?
Very high (7k+) RPM when starting
(After winter storage)
(carb) Fuel left in carbs over winter Replace or rebuild carbs Carb Cleaning FAQ
Carb Misc FAQ
Increased RPM at steering lock Insufficient throttle play Adjust throttle free play Cable FAQ?
Engine dies when steering turned
(Dash / lights also die)
(Carb) Choke play insufficient (when engine warm?) Adjust choke free play Cable FAQ?
Ignition switch wiring Check / fix damaged wiring Ignition Switch FAQ
Lurching / Jumping Problems (Carb) Fuel getting low Switch fuel tap to reserve! Doh!
Clutch adjustment problem Check / Adjust clutch free play Clutch Adjustment FAQ
Clutch Misc Problems
Clutch routing problem Re-route clutch cable Cable FAQ
Chain/Sprokets worn or needs adjustment Check / adjust chain tension
Check chain and sprocket wear
Chain Replacement FAQ
(Carb) The Petcock is on See FAQ Fuel Petcock FAQs
Blocked Fuel Filter Check fuel filter Carb Misc FAQ
(Carb) Carbs Dirty? Check / clean the carbs Carb Clean FAQ
Bike acts like fuel is low
(switching to reserve no help)
(Opening gas tank helps for a bit)
(Noticable in the rain)
Canister related problems Perform canisterectomy
Fix vacuum lines
Check fuses
Canisterectomy FAQ
Poor throttle response Canister related problems Perform canisterectomy
Fix vacuum lines
Check fuses
Canisterectomy FAQ
(carb) Carb diaphragms Check carb diaphrams Carb Misc FAQ
Carb Clean FAQ
(FI) Throttle cable in restricted position Move cable from 25kw to 37kw position
(Check your license restrictions!)
Poor Gas Mileage Spark Plugs / Caps related Check / replace spark plugs
Check caps
Plug Caps and Coils
General poor mileage All sorts of causes Poor Mileage FAQ
Bike Backfiring Many causes See FAQ Backfiring FAQ
Temp Light comes on
(when bike cold)
Broken sensor or thermostat Check thermostat operations
Test Sensor (how?) / Replace Sensor
GS Coolant Change FAQ
Classic Coolant Change FAQ
Overheating FAQ
GS Radiator FAQ
Fan not working Check / replace fan Cooling Fan FAQ
Cooling circuit blocked Check thermostat operation
Flush coolant system
Check / Replace coolant pipes
GS Coolant Change FAQ
Classic Coolant Change FAQ
Overheating FAQ
GS Radiator FAQ
Bike gets very hot Insufficient coolant Check / replace coolant Classic Coolant Change
GS Coolant Change
Oil level low Check / top up oil Classic Oil Change
GS Oil Change
CS Oil Change
Failing water pump See FAQ Pump repair FAQ

Table: Hard Starting / Poor Running Diagnostics

StateClassicGS/FI Models
Bike in gear, stand down, clutch in No noiseNoise but no starty,
Bike in gear, stand up, clutch in starty
Bike in gear, clutch out no noise
Bike in gear, bad clutch switch no noise whether clutch is in OR out
Bike in gear, stand up, clutch in, bad sidestand switch no noisenoise but no starty

Table: Differences between the Classic and GS (starting in gear) - dinskeep

Misc Stuff

Hard Starts/Poor Running

Q. My bike is hard to start/runs poorly. What should I look for?
It depends very much on the symptoms. The FAQs below might be able to help you out, they are in no particular order, but do the simple things first.

Warm Non-Starting

Q. Trouble restarting when warm. Hi I've got a 97 F650ST and when its been for a run and the engine is lovely and hot if I park up for a short while (5 -15mins) when I try to restart it the bugger needs 'choke'. Is this normal because its bugging me! Cheers from the Isle of Man.

Cheers & Rgds. Thanks to Flash, HsN, Andy UK and 1001 others.


Cold Non-Starting


Andy Leeds UK #982
November '01


Slow Starts on Cold Mornings - Oil Related & Engine Warm-Up

Various, January '02

Engine warm-up

Generally BMW says start it up and ride off. Not like a maniac, but get going. You don't have to "allow it to warm it up", like in the old days, so long as you don't redline it past Mrs Jones House on the first straightaway.

I don't have a Canister and still have "I can't be Outta Gas Symptoms"

Stalling Problems

For the GS/Dakar, see This FAQ.

Q. After riding constantly for around 100 miles my bike stalls below 3k rpm.
The oil in the tank is also full of bubbles. It is a 1995 classic with 14k miles on the clock. I put up a message about this before and was advised to run a compression test to see if I needed new piston rings. Well I've just done this test as described in the FAQs. With a warm engine, decompressor restrained, the compression read 12.5 bars, with a teaspoon of oil in the cylinder it read 13.5 bars. This seems to indicate the compression is fine. Bike has been fully serviced by me at 12k. My local BMW parts supplier has said to me that they have come across this problem before and they are suggesting that I replace the alternator. If this doesn't cure the problem I can give it back to them and get a refund. Any ideas?

As it's a 1995 model F650 could it be a fuel or a fuel-mixture problem?
I've changed inlet manifolds as they were cracked, but to no effect. The idle mix screws are stuck fast, but if this were the problem would it not cause rough running at other times. The problem only occurs on long trips (100 miles +) and goes away when the bike is cooler

Have you done a "plug-chop" at various revs?
I'll have to look up what this is!

Have you tried riding with the choke lever in various positions when it happens or when it is about to happen?
No. But I did increase the idle to 1500rpm, with no effect. If I keep revs over 3k it doesn't stall

Do you get any warning that it's about to stall and just it just die? or splutter first?
The idle starts to falter, then dies, usually standing at the lights. No spluttering

Lurching/Jumping Problems

  1. Check the Clutch Adjustment. See Clutch Adjustment FAQ or the Clutch Misc Probs FAQ.

  2. Check Routing of Clutch Cable. See Cable FAQ.

  3. Check the Chain/Sprockets. See the Chain Replacement FAQ.

  4. Check the Petcock is on. See the FUEL PETCOCK FAQs

  5. Check the Fuel Filter is Not Blocked. Carb Misc FAQ

  6. Check the Carbs. See the Carb Clean FAQ.