XR650L Dying When Warm

[Jsmoot]

Hoping for some help before I throw in the towel and end it all!

Engine starts fine, runs and idles well for +/- 10 minutes, but cuts out while riding once the engine warms up (175 - 185) and intermittently cuts out thereafter (any speed/gear). It will start up after 30 seconds or so (but won't run for long before dying again). No spurting or surging.. just dies.

I've replaced CDI (twice), Spark plug, spark wire and coil, and most recently pulse generator. I do have a 41mm Flat side carb from a CRF (and it has more power than the old carb setup), breathing through a Uni filter. Also, sealed battery tender battery (hasn't shown low when trickle charged).

What's next on the test/replace list? Stator maybe? Please help...

[creeky]

Check the pulse generator. Resistance should be 360-440 ohms. If it is shot, Honda part # is 30300-MY6-671

Edited March 7, 2018 by creeky

[Jsmoot]

Thanks Creeky, I replaced the pulse generator this weekend (thought that was the issue), didn't solve the issue.

[DoubleP]

Sounds like vapor lock. Check your fuel vent. Or rule it out by reproducing the problem...then unscrew the fuel cap...if it is vapor lock...unscrewing the gas cap will allow fuel to flow again.

[ScottRNelson]

9 hours ago, DoubleP said:

Sounds like vapor lock. Check your fuel vent. Or rule it out by reproducing the problem...then unscrew the fuel cap...if it is vapor lock...unscrewing the gas cap will allow fuel to flow again.

This.

I would be looking at a fuel delivery issue of some sort.  Follow the fuel system all the way through, checking the flow at each point.

[Jsmoot]

Thanks guys. I'll double check the petcock screen and vent/hose. I'm wondering if the fuel line I swapped when I had the old/OEM carb has a smaller diameter than the CRF250 (41mm) carb needs? Or is that over-thinking it?

[DoubleP]

Not sure a smaller fuel line would cause so drastic a reaction. A bad vent would not allow any air in the tank....so as the engine consumes fuel, whatever volume of air that is present in the tank will become more and more of a vaccum till the suction of the engine is not great enough to draw more fuel....starving the engine. You will still see fuel in the filter, at a regular level. But there is an unseen pressure preventing the fuel from flowing...potentially

[Jsmoot]

Thanks Double! I'll take her out today with a loose cap and see what she does!

[ScottRNelson]

54 minutes ago, DoubleP said:

Not sure a smaller fuel line would cause so drastic a reaction. A bad vent would not allow any air in the tank....so as the engine consumes fuel, whatever volume of air that is present in the tank will become more and more of a vaccum till the suction of the engine is not great enough to draw more fuel....starving the engine. You will still see fuel in the filter, at a regular level. But there is an unseen pressure preventing the fuel from flowing...potentially

Minor correction - it is purely gravity that gets the fuel from the tank to the float bowl, engine vacuum, or suction, has nothing to do with it.  I agree with everything else.

[XR650L_Dave]

The carb might be not well seated in the head side boot/manifold.

The boot on the head side might be cracked.

The enrichment plunger ('choke') might be stuck and not closing all the way.

[Jsmoot]

Sure enough.. dried crap in the nipple of the gas cap vent. Running like a champ now. So sad I replaced all the other components before realizing such a simple 'fix.' Oi.

Next time I'll be sure to ask you fellas before all the bonehead replacement$. haha.

Thanks a bunch, gents!

Here's a pic from the maiden (no stall) voyage.

[RevyRoamer]

Glad you got it fixed.

In my spare parts kit on all rides is a piece of new gas line and clamps as well.

Even if you don't need it, likely one day someone who rides with you will.

[Foiler]

awesome! I love reading posts like this.

[Jsmoot]

8 hours ago, RevyRoamer said:

Glad you got it fixed.

In my spare parts kit on all rides is a piece of new gas line and clamps as well.

Even if you don't need it, likely one day someone who rides with you will.

Good advice, Revy. What else is in your spare parts kit? Thinking about putting one together (now that I can ride more than 4 miles without the engine dying, haha).

[ScottRNelson]

1 hour ago, Jsmoot said:

Good advice, Revy. What else is in your spare parts kit? Thinking about putting one together (now that I can ride more than 4 miles without the engine dying, haha).

I have a clutch cable, a spare CDI (because I had it), and a couple of spark plugs.  I've never really needed a fuel line out on any ride.

[RevyRoamer]

I can some basic tools of course.

But as for parts, 2 types of wire electrical and mechanics wire, black tape and duct tape, fuel line, 2 master links for the chain, a jump start batrery if its an electric start only bike,  tube patch kit, 3 shorty plastic tire irons and small pump, spare clutch and front brake levers.

Remember a screwdriver can makea great splint across a broken part with enough tape and wire on it. 

 

Also running a clear fuel line can let you see if you have fuel flow or not.

Branches tend to rip fuel lines off as I ride. 

I am also a big fan of manual petcocks not vaccuum style.

Removing side stand safety switches, because they could fail which means you cannot start the bike.

Please note that I am not easy on my bikes.

So this may not apply to you.

Edited March 10, 2018 by RevyRoamer

[lrbest4x4xfar]

I saw you got rid of air box and went to UNI filter. How has that worked out for you and what differences did you notice? Any cons seen to-date?

[JoeRC51]

15 hours ago, lrbest4x4xfar said:

I saw you got rid of air box and went to UNI filter. How has that worked out for you and what differences did you notice? Any cons seen to-date?

You can't park it in the rain.   It'll run fine in the rain , but the filter will get sopping wet while parked , then it won't start.

[Jsmoot]

Not sure about parking in the rain Joe, but I've driven through it without issue. I'm East of the Cascades in WA, so not much rainfall here.

I did put on an Outerwears pre-filter that is supposed to repel water (not sure how much it helps). Pic attached..

[lrbest4x4xfar]

I love what you did and will do to my bike. The problem is I only see it 1 week a year so time is tight. Maybe the dealer will do it all for me. I'm just worried about the filter...I get into muddy and dusty conditions a lot.