90 xr600-Hot Start Problem

Just this past month or so the bike suddenly is very difficult to start when hot. Kicked it cold this morning and she started right up. Later in the day, each of 3 hot starts were problems and I had to bump it to get going. Also stalls occationly. (Usually at the worst time like at an intersection or in a water crossing .)

Motor has probably 30k and is stock except a Twin Air filter that's been on there for years. Seems to run normal otherwise.

When was the last time you serviced the air filter, set the valves, change the spark plug? The fact that it doesn't idle well is most likely the same reason why it's hard to start.

What's the tip of the spark plug look like?

Tight valves or rich float setting..

Most likley tight valves.

Actually it idles well once running and starts fine when cold. No backfiring on decell to speak of.

All maintenance items are done routinely and specifically within the past two months. Actually the spark plug change was right around the time it started acting up. I pulled the carb and blew out the passages and jets to no avail. Air cutoff is still good however I didn't check the float level.:thumbsup:

Could California gas be part of the problem as it seems to noticeably ping more also.

my xr600 started doing that when my stator was going out. I would replace the plug again, check the float and comp. if that does not fix it replace the stator or try a friends stator and see if that does it. B

All the above^^^

Also do a ohms check on the stator while heating it with a hair dryer. This will really show you a 'bad stator'.

Even if it's good it will still increase a little on the ohms when heated.

The ping could be due to using too low of octain fuel.

However, it could also mean you're running lean, which would make it run hot, which would also make it hard to start after running it hard. You should recheck the spark plug's color to see if it's white. If it continues to ping, you'll shorten the life of the motor.

Had time to check most of the electrical components and they were with in spec except the coil wire resistance after the plug cap fluctuated. Seems the connection to the cap may have been loose.

I could not find the information in the manual to check the stator though. Any help would be appreciated: thumbsup: as are all of the comments here.

While the tank was off I checked the valves and they were OK. Still need to check the floats which leads to this...

The plug is a medium grey after -1/4 throttle cruising home to the garage. Messed with the air screw by adding a 1/2 turn out to 2 turns total. It resisted stalling better but the idle was up a bit too.

Turning the gas off resulted in worse idle and response very quickly. Overall I think it is running lean. Chopping the throttle to idle seems to cause the stall in the motor.

I need to do a days ride to get a better feel for the hot start problem though. Again thanks for the help!

Today I checked the voltage regulator and it is out of spec. Does it affect the ignition system or simply the lighting?

Also noticed the bike is an A/C system. Are the 600L's regulators compatable or are they D/C? It appears I will need one.

Did an Ohms check on the stator. 313 cold vs. 240 hot. Does that indicate a bad unit?


your still within spec though(230-320)but that is a big gap, you can rewind the stator exiter coil or buy a new ricky or baja designs stator...

Im about to rebuild my engine again, along with a new ricky stator, hopefully that along with a new ignition and cdi will cure my issues with sooty plugs and seemingly rich symptoms on my 88xr600, despite lean carb settings...

lets hope, good luck too!

edit. forgot to add that heat and oil is what destroys these stators and that's what usually is the culprit is that the epoxy on the winding breaks down and you get shorts when the engine is warmed up...

If youve got the money just buy a new stator, I REWOUND mine TWICE and they eventually failed or ran badly...,my second rewind broke down badly on the epoxy front!

oh well


Edited by elsalvadorklr
more info
A friend of mine said the resistance should go down as the wires heat up as the electrons transfer easier at higher temps.

It's actually the opposite of that for conductors like copper. Electrical resistance increases with temperature because the atoms in the conductors vibrate more vigorously as temperature increases and more electrons collide with them(being dissipated as heat) instead of passing through. Imagine a game where you have to throw tennis balls(electrons) through a board full of holes. Now imagine someone is waving the board around.

In your case, the resistance went down with heat because there is breakdown of the winding's enamel insulation somewhere that is causing a partial short.


good luck!

I have a stator on order. Seller says it is the same as others sold by name brand. Hopefully that's the end of this thread.:confused:

Thanks All.:thumbsup:

Had to add a post scrip. The new stator solved the problem. It even starts without using the "find TDC" routine.:smirk:

thats so awesome man! such good news!

good to know that the stator worked for you, let us know how that ebay stator works out as its a good deal more economical than the competition...

really congrats!

Cant wait for my install and engine rebuild now...



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