Starting XBR600

[timbo]

Ok, so were having problems starting Alisons bike. This has always been the case since we bought it. It has an XL600 barrel. When you hit the starter button, the starter motor just turns over very lazily, even with a fully charged battery. Anyone else suffered the same problem? Have been told that fitting an XL CDI unit makes a difference? Any ideas? I suppose I should try another starter motor? 

[SteveC#222]

I would check the brushes in the starter motor - service limit is 5.5mm - also check the commutors aren't full of crap.  I understood that if you fitted the XL CDI unit you couldn't use the electric starter?

[Moto63]

Morning chaps, can I ask Steve, what difference would it make by fitting an XR cdi unit to the running of the bike ?? Cheers Michael. Ps think I might av one last starter motor in my stock Tim if you find you req one

[SteveC#222]

Morning chaps, can I ask Steve, what difference would it make by fitting an XR cdi unit to the running of the bike ?? Cheers Michael. Ps think I might av one last starter motor in my stock Tim if you find you req one

To be honest I've no idea - I know the XL unit gives a boost to performance as Joolz has fitted one to his bike - probably a bit more advance on the timing - but I don't know if the XR would work.

I don't really see why running the XL unit would stop you using the electric start as I wouldn't have thought the CDI ignition curcuit would effect the starter motor circuit but thats what I'm told. I might try the XL unit myself if I can find one at a reasonable price - they often come up on Ebay from the USA but you need to make sure it's the one with the square connector not the round one.

[Propellor]

Does it kick start ok? This might give a clue as to whether the problem is with the start motor/sprag clutch or not.

What venturi size on the carb?

What happens to the load on the starter as you open/close the throttle?

[blew]

I have an xbr 600,fitted with an xl600 barrel and xbr head.The electric start won't start it when cold-too much compression-but will start it when warmed up.Kickstarting is the only way to start it when cold.I turn the engine over until the kickstart stops,let the kickstart back to the top and then kick.It usually starts after two or three kicks.Adjusting the decompressor correctly is vital,because I cannot kick it over compression without the decompressor.Bump starting is not possible either.

[guest564]

I have an xbr 600,fitted with an xl600 barrel and xbr head.The electric start won't start it when cold-too much compression-but will start it when warmed up.Kickstarting is the only way to start it when cold.I turn the engine over until the kickstart stops,let the kickstart back to the top and then kick.It usually starts after two or three kicks.Adjusting the decompressor correctly is vital,because I cannot kick it over compression without the decompressor.Bump starting is not possible either.

I used a booster battery and jump cables when cold to get some more power into the starter. I don't have the decompressor and I can get it over compression when cold but only with axle stands under the (fixed) footrests and a fair bit of weight on the kickstarter. Bumping must be done in second gear having pushed it backwards to compression - in the old days bump starting was how we started a race, a good push and jump on, drop the clutch as your bum hits the seat.

[guest564]

I wouldn't have thought the CDI ignition curcuit would effect the starter motor circuit but thats what I'm told.

From what I remember the XL setup maxes out the advance a little earlier in the rev range, in the early days of my race bike when it was still 500cc I had the ignition trigger modified to give an extra 8 degrees of advance running super unleaded.

There is a connection from the starter switch to the CDI that gives a big boost to the spark, you can use the XL CDI but you don't get the boost; the later XL units are battery powered rather than using high voltage coils in the alternator. I did once experiment with wiring the boost wire permanently but the coil saturates and it starts missing at something like 2500RPM. It does give a good boost to pick up at low RPM though, I went with a custom Piranha set up and a dyna coil, its not practical for road use though as you can't run it with an alternator.

[guest564]

A little research:

XBR500 (next post)
initial advance 8 degs
Full Advance 29 degs at 5000RPM

from the net:

XL600R 
At idle (F mark aligned with index notch) 
1983 models 6-degrees BTDC @ 1200 rpm
1984 and later models 11 -degrees BTDC @ 1300 rpm
At full advance 31 -degrees BTDC@ 4000 rpm
XR600R 
1985 through 1987 models 
At idle (F mark aligned with index notch) 11-degrees BTDC @ 1300 rpm
At full advance 31-degrees BTDC @ 4000 rpm
1988 and later models 
At idle (F mark aligned with index notch) 6-degrees BTDC @ 1300 rpm
At full advance 31-degrees BTDC @ 3500 rpm
XR650L 
At idle (F mark aligned with index notch) 8-degrees BTDC @ 1300 rpm
At full advance 28-degrees BTDC @ 4000 rpm
XR650R 
At idle (F mark aligned with index notch) 6-degrees BTDC @ 1300 rpm
At full advance 31 -degrees BTDC@ 3500 rpm

GB500
I found this here:
http://www.hondagb500.com/index.php?option=com_fireboard&func=view&catid=8&id=890&Itemid=81#890

The GB500 cdi box has a 5 deg idle and a 21 deg full advance. I've read that Honda did this as the GB500 was built to Europeon specifications. The 21 deg advance was due to the 8.9 to 1 compression ratio and the low octane Europeon gas. The idea was to
 avoid detonation. I had read where some people had tried to install the XR600R cdi box in the GB500, but when they pressed the starter button the starter relay 10 amp fuse would blow. I've solved this problem and now have an electric starting GB500 with an XR600R cdi box with 6/31 deg advance.
 In the 4 pin cdi box harness plug remove the G/W wire and slip a short piece of small diameter tight fitting plastic tubing over the bare end to protect it from shorting out. Move it out of the way as it is no longer used. The pins are removed by sticking a straight pin down the side of the harness pin to release the hook.
 The only thing I can tell that this wire (G/W) does is kill the motor if you try to put it in gear with the side stand down. You still get the side stand is down light, but the engine will not quit if you put it in gear. No big deal I can live without that.
 Next, swap the 2 pin cdi box harness plug BL/W and BL/R wires. They are the wires in the 2 pin plug.

 I purchased an after market cdi box for an xr600r. http://www.powersportsuperstore.com/Ricks-Motorsport-Electric-CDI-Boxes-15-601-p/4078330.htm?CartID=1
 for only $40. They have great prices on other things too.
 After making the wire changes to the harness the new cdi box correctly plugs right in.

 It has an 8,500 rpm red line, a more aggresive advance curve
 and has some double circuitry for better reliability. Of course it has the 6/31 deg advance.

 I put it all together and to my absolute amazement it fired right up and runs great! It seems to rev up more quickly and
 doesn't cause any detonation so far on low octane fuel.

 I also rejetted the stock carb. I now have a 150 main jet, a 50 slow jet, 1 1/2 turns out on the screw for best idle.
 I also added a .002 inch thick shim under the needle. I also drilled out the vacuum hole on the bottom of the carb slide to 1/8th inch. This is supposed to make the carb more responsive at full openings. I read about this on several blogs about xr600's. (I ride from 5,000 to 10,000 altitude)

 All of this seems especially to have helped the mid range. It pulls hard and runs clean from low rpms when opening the throttle full. It just accelerates great and doesn't bog down. I think I've got the jetting about right.

 The jetting and cdi box change have made a noticeable performance
 difference and was worth doing. I use low octane fuel. No detonation.

I don't have the XBR handbook or FSM to hand so maybe someone can check the specs and the minimum recommended octane rating. My experience was more advance and a good fat spark gave a very noticeable improvement.

[blew]

I have an xbr manual downloaded from the internet.It gives the initial ignition advance at 8 degrees @1,200 + or - 2 degrees. Full advance is 29 degrees at 5,000 + or - 2 degrees.

[timbo]

Thanks for all the info folks. Have kickstarted her ok, but havnt got round to looking any further at the starter motor yet.

[timbo]

Finally got round to taking starter motor out, stripping, cleaning, and put back in. No difference. Still won't turn over enough with a full battery. So stuck another starter motor in, exactly the same. So, I reckon, as suggested, that the compression is just too much. However, she seems to start on a kick no problem, so no worries  Have fitted  tails off the battery, and will carry mini jump leads just in case. (Note to self, always reconnect oil lines before starting bike, or you end up with a lot of oil were it shouldn't be, ie, outside of the engine!) 

[guest564]

Have you tried changing the earth strap from the battery? I've had one go bad without any obvious signs. A voltmeter across it during starting showed up the problem.

[timbo]

I would never have thought of that in a million years. Will swop it over sometime, but for now, the bike is starting easily on the kick, so im happy enough