2013 wrr bump starts and runs but won't button start or idle

Hi gang,
Looking for input on what I think is an electrical gremlin. Just limped home from a 5k mile loop on part of the TAT.
I got covid the last night of camping and maybe my 2013 wrr does too?? Almost 23k on the odometer. Ive had it for years since 1800 miles and it has always worked flawlessly on everything from Baja to black diamond singletrack.
800 miles ago the bike didn't want to idle without dieing. It just started one afternoon. Next morning it wouldn't start on the button so I got it going on a hill bump start. Runs fine on the throttle with same power as always. So I got really good at sprinting with the fully loaded bike across flat gas station parking lots to bump start it (works great) and rode it home. In addition to this primary issue, every once in a while under lots of heavy throttle, the power will cut out completely for a split second, then come right back to life after rolling off the throttle, almost as if the fuel pump can't keep up with demand
Things I've checked:
1. Obviously not bad gas since I put another 5 tankfulls in.
2. New spark plug 600 miles ago. No difference.
3. Shorai lithium battery reads 12.7v and 10.5v when cranking. Also tried another battery with no difference.
4. I can hear the fuel pump do it's thing when switching on the ignition. I assumed this is not a fuel pump issue since it runs with good power at 60 mph.
5. Checked for the "loose connector behind the radiator" but I don't see the same type as in the sticky. Anyone know if this was updated by 2013?
6. The kill switch is on run mode. Every time, button start won't work but 2nd gear bump start does.

Any advice? Electrical? Possibly valves or piston?
Thanks for any advice, Matt

[url=https://servimg.com/view/20456281/1]

Also,
7. Fresh air filter 900 miles ago.
8. No error codes listed on the diagnostic.

When you push the start button, does it crank but does not start, or it won't even crank?

John, cranks just like normal on the button start. Engine turns over fine. Just no boom.

Did you try giving it some throttle while cranking? You should at least hear some change in sound.

Yep, tried that. There is a change in sound and I can smell unburnt gas.

matthepp wrote:

Yep, tried that. There is a change in sound and I can smell unburnt gas.

And not even a hint of detonation?

Not a hint.

Aftermarket tank?

No difference whether engine is hot or cold?

Given the mileage, I would check two things:
1. Engine compression (Harbor Freight has a set that fits the WRR)
2. Valve clearances. When I checked mine at 22k, both exhaust valves were out of spec, one by a lot.

The above though do not explain the other issue you are experiencing with random cutouts at high RPMs, so there may be additional troubleshooting that needs to be done.

Thanks John. I already dug out my compression teste and will try that tonight. I pulled the plug again, checked the gap, verified good spark, no change.
Then I'll dig into checking valve clearance. I've done it once on an older WR400f. Know of any good videos for this for wr250r? I couldn't find any on youtube.

Sorry, also, it has had the ims 3.1 gal tank for the entire time I've had the bike. No difference hot or cold.

No difference between hot and cold points away from valve clearance, but it doesn't hurt to check. I never found a specific video for the WRR, but the check clearance is straightforward, the most difficult part is removing the valve cover: it can be done, you have to be patient to find the right angle and the right sequence; unfortunately I didn't make a note of what I did, so I'll have another miserable time when I try it again in a few years. Don't forget to clean the area thoroughly (easier said than done on a dirt bike) lest debris falls into the motor.

Something that just occurred to me: have you taken your bike to the dealership for the stator recall?

I did the valve check and all 4 seemed in spec (but honestly I'm not that confident with my feeler skills beding around the cams). I'll have to get a different compression guage that fits this size.
Meanwhile, I broke the fuel line nipple off the pump assembly so I my hand is forced now to replace the pump.
I'm 90% sure that the stator recall was done way back before I got the bike but I will verify. Since the battery is still going strong 800 miles later I assumed it has been getting good charge from the stator (while revved at least). John I appreciate your i sights.

For the valves to be the root cause of the problem, the clearances would have to be way off; plus/minus 0.02mm won't make much of a difference, so your measurements are fine.

Bummer with the fuel line nipple; the silver lining here is that you will eliminate one of the variables, although it doesn't seem likely that this is the culprit.

Diagnostic Mode 09 allows you to monitor the system voltage; at idle you should be seeing around 13.4V, and about 13.7V at higher revs.

Harbor Freight offers a few different compression kits, the one I linked above is the only one that fits the WRR (and unfortunately is the most expensive one).

I believe the stator recall was issued in early 2016, so if you got the bike before that time it probably doesn't have it.

I got a cheap harbor freight compression tester that fits. Cranked the engine over WOT and only measured about 15 psi??? Added the oil down the spark plug hole, rested and got 30 psi?? Can an engine even run at all with measurements this low? I am starting to think that the valves need adjusted and that the top end needs done altogether,  maybe more?
Once I get the new fuel pump in I'll give it a whirl. If nothing, I guess Ill have a winter project to keep me busy dinking around in the garage

That is really low compression, I don't think I have seen lower numbers on a working engine.

The fact that the compression increased when you poured some oil into the cylinder indicates that this is a piston ring problem, not a valve problem.

It's probably a good idea to do a leak down test to confirm the above and quantify the leaks.

Hey John,  fyi, I put in a new fuel pump and put everything back together. Same exact condition. Button start turns engiine over but no combustion. Got the bike going at least with a spirited hill bump start but it ran terribly. I blew air into the cylinder at TDC with the compression tester hose and I could feel air flow at the exhaust.
I'm gonna lower the engine once dark dark November arrives to take the top end apart, adjust valves, maybe more. Will report back.

The fuel pump was a long shot, so no surprises there.

The exhaust valve leakage is an encouraging sign because it points to something easily fixable: when you checked the valve clearances, did you also check the valve timing to make sure that the cam chain had not jumped teeth? It may be worth taking the valve cover off again and checking valve clearances and valve timing.

BTW, was the engine warm or cold when you did the leak test?

Is it possible to get a good compression test on a WR? I've tried on mine but figured the auto compression release
(holds an exhaust valve open) kept me from getting a decent result.

fwiw, the two times mine would only bump start the fix was a valve adjustment (tight intake).

on2wheels52 wrote:

Is it possible to get a good compression test on a WR? I've tried on mine but figured the auto compression release
(holds an exhaust valve open) kept me from getting a decent result.

The auto-decompress feature is never mentioned in the service manual, so apparently it is irrelevant to the compression measurement. Just keep the throttle wide open and crank until compression stabilises.

Update: I dropped the motor out of the bike and took apart the top end. I wasn't accurately reading valve clearances when I tried to check them on the bike. Both exhaust valves measured equally slight tight (0.15mm). While the left intake valve was still in range, the right was zero! I pulled the valve and it's heavily worn. I got a shim kit, 2 new exhaust valves, and 1 intake valve. This is my first time tackling valve adjustments so fingers are crossed. There was a lot of carbon built up on the piston and head but it all looks a lot better after cleaning. I pulled the cylinder (cross-hatching still looks good) and checked the ring end gaps so I'm just gonna put those parts back together. Anything critical that I might be missing? I am hoping that it's really just the intake valve making the biggest fuss here. I've learned a lot and it's so dark in November so I'm glad to have something to do in the evenings.

Such a discrepancy between intake valve wear is cause for concern. Did you measure the valve seat area? You need to establish which one wore out more: the valve, or the valve seat.

I don't see the reason for changing the exhaust valves, but now that you have them, I would change all four (I actually thought that valves are sold in pairs). If you do that, I would suggest that you change the valve stem seals too.

Since you have already taken the cylinder apart, why not change the piston rings? They're inexpensive, and you are ensuring that you don't have to remove the cylinder again for a long time.

You had previously mentioned that you had felt air escaping through one of the exhaust valves, did you find a reason for that?

Cool, I'll do the rings too. I think the exhaust valves were not sealing well from the carbon build up. The one intake valve was definitely worn thin while the other is totally fine. Seats looks good as far as I can tell. After extensive noob google research, I understand that lapping with new valves is a major non-no and even laoping the seats with old valves is questionable. What I assume has happened is that the 1 intake valve wore through the hard coating then zeroed to the cam causing poor sealing, poor compression, and allowing carbon buildup. I am content enough to put it all back together and learn from the process even if it means I have to try again this winter, or even send off the head to a pro like many suggest. But if I don't even try, I won't learn from my mistakes.

That extreme wear of the intake valve is weird, but it is what it is.

You may want to look at page 5-21 of the service manual where they say that if you are installing new valves, you need to lap the valve seat with the new valve; they also give instructions on how to measure the valve seat width, and ensure it is within specs.

I would say that if you can take valves and cylinder apart, you don't need to send the engine to a mechanic, you can perform all these tasks yourself.

Good news: I got the motor back together the other evening. I swapped out the offending worn intake valve and shimmed everything to middle of spec. First time for me so it was fun learning. I put the bike back together yesterday morning and it fired right up via butt9n start on the 3rd crank and is purring like a kitten.
Bad news: a few hours later I blew out my knee crashing an orange bike deep in the bowels of Monster Ditch. It'll be a few days or maybe more til I can road test the 250r. Anyhow, I should have checked valves clearances well before the 26k recommendation. Any recommendations for this mini break-in period?
John thanks for your guidance.