2008 won't cold start

Well, I had loaded up the bike, which was running perfectly fine during the 4 day dualsport trip, then drove home. Where I preceded to unloaded and tried to start it for a much needed bath. All it did was crank over and over and over. Hmmmmm? No hiccups at all on the trip, other me with than two mild get offs, one day two and three. No starting or running issues other than it took a couple extra seconds of cranking on day 3. So I preceded to put a new fancy plug in it and nothing. I tested the fuel pump and it would run steady gas through it also. I ohm'd the starter coil and it was good. The Lithium battery shows 13.5 volts resting and 11.8 volts while cranking. So I figured with the stator recall never preformed that I would take it in to a authorized dealer that said they'd get it quickest. Plus an additional 3 weeks due to sturgis. After installing the stator at S.E. HARLEY DAVIDSON yamaha and it still didn't start. The "tech" went on a trouble shooting expatiation. His findings were that the compression was low, 30 psi, and stated that it was probably leaking down the intake. Curious. He also said it was probably had a bent valve or, huh, the piston had a hole in it. Seriously. They quoted me and additional $500.00 on top of the $200.00 they had in labor already to check the valves. They figured it would be another $900.00 in labor and $800.00 in parts above that due to the probable catastrophic failure. I went ahead and picked it up. After getting some advice on the ADV forum I tried to give it a bump start. It took a couple runs but she finally bobbled then fired up with a little throttle manipulation. I held the throttle just past the point of tension to keep it running till it warmed up. Once warmed up i took her for a ride out back for about 10 minutes and the thing ran like a WR that only has 15000 miles on it. Great. With the machine warm, 160 degrees or above it'll fire right up and idle fine. If I let it cool down to as low as 130, I have to massage the throttle just a tad to get it to fire and it will idle with a little attention needed to the throttle occasionally. If it cools down completely, it wont fire at all. But I can bump start and run it again with no problems. I'v since put a new fuel regulator in it, checked the cam timing and am waiting for a new coil. Anyone have any thoughts on the issue. Thanks.

Once you successfully bump start the bike, and while the engine is still cold, does it hold idle without any throttle input?

Compression of 30 psi is crazy low. Sure, the shop may have screwed up a bit, but are you sure they completely botched the measurement? Don't you want to check it yourself?

I haven't. I was told them motorcycle runs decompressed at 30 lbs until started. And the only way to check it is to bring it up to operating temperature and then check the running pressure. They never did get it running so I assume that pressure is correct. I've been quizzed on me intake temperature sensor which owns out at 2. That's .21 below the acceptable value.I've also been told to check the intake air pressure sensor on the other forum. Looks like I'll be running out and buying a couple gauges today. Both sensors have never throw a fault code. I'll get it running and check the compression.

Nominal compression is 120 psi; minimum is 105 psi, so even if 30 psi is half-accurate, you are way outside specs.

Do you have a service manual? Is that how you checked the intake temperature sensor, or did the shop do it?

The intake air temperature sensor and intake air pressure sensor would be suspects if the bike wouldn't start at all when cold; but it bump-starts fine, so if these two sensors negatively affect starting via starter, they would have equally affected bump starts.

I have the service manual. And discussing the cylinder head pressure on the forums and other owners they all stated that cold it will read 30 PSI because of the decompression doohickey.

Decompression is not being mentioned in the Service Manual, which means that if you crank according to the instructions, the decompressor is not affecting compression measurements.

Moreover, the decompressor is independent of engine temperature (it's only RPM-dependent), so it seems you have received some less than stellar advice.

Follow the instructions on pages 3.9 and 3.10; make sure you run the test both with and without oil.

OP, was there any resolution to your issue? The exact same thing happened to my 2011. After a 1k mile dual sport ride the bike will only bump start. 25k miles. Runs great when bump started. I put in a new spark plug, ohm tested the ignition coil, checked the timing, did a compression test showing 20psi. I’m stumped.

As I said above, compression should be 120 psi, not 20 psi. Do a compression test as prescribed in pages 3-9 and 3-10, making sure you run the test both with and without oil.

Seeing that you're at 25k miles, it may very well be that the valves need to be adjusted.

Thanks I got 2 loaner compression testers from oreilly’s. 1 read 0psi. I added oil and it continued to read 0psi. I thought must be a faulty reader then I got a 2nd compression tester from another oreillys and it read 20psi. I’m thinking I might need to bring it into a mechanic to get a reliable compression test or leak down test.

Sounds like the valves need to be adjusted.

BTW, leak down testers are not that expensive, although they're not as trivial to use as a compressor gauge.

Ok I’ll check the valves. I didn’t think it was the valves sinceI did the valves 20k miles ago and I set it to the the most loose spec per Bigdogadventures that valves always get tighter. Will report back.

Hold on, you said the bike had 25k miles, now you say you adjusted the valves 20k miles ago, does this mean you adjusted the valves at 5k miles? Why? Did something go wrong with the engine?

You're correct, valve gaps tend to tighten up, so if you set them up at the looser end of the range you should be fine for at least 26k miles. But low compression is either worn piston rings, or valves out of adjustment, and the latter is easier to check than the former.

Yeah. I bought my WRR with an Athena Big Bore kit. I was having issues with oil consumption so I changed the top end back to a 250cc and while I was there I shimmed the valves. That taught me a lesson to modified motorcycles.

Update I checked the valves and the exhaust was in spec but the intake was wayyyyy off. I couldn’t even fit a .04mm feeler gauge so I have no idea what the measurements were. I patiently sanded the shims and in the end I removed 0.20mm and 0.30mm from the intake and put everything back together. Still no start. It won’t bump start now either so I’m going to recheck everything I’ve done to see if I missed anything. I’m not even sure how it went out of spec so quickly? . I don’t think oil changes affect the valves too much and even then I replace the oil on or before 2000 miles. I’m sure riding a lot at WOT doesn’t help but geez. It looks like I should’ve checked it 10k miles ago.

I’m now bummed I did major damage.

Rustyenduro wrote:

Update I checked the valves and the exhaust was in spec but the intake was wayyyyy off.  I couldn’t even fit a .04mm feeler gauge so I have no idea what the measurements were. I patiently sanded the shims and in the end I removed 0.20mm and 0.30mm from the intake and put everything back together.

Sanding down the shims is a really bad idea. The shims are surface-hardened, and by sanding them down you removed the hardened surface, so the shims are going to wear out very fast.

Before you do anything though, I would suggest that you check the compression to see if it's back to normal levels. If it's still very low then the cams may have not been aligned properly during installation? In any case, you need to open the cover again and install new shims.

BTW, this is not the first report I've read about the Athena kit wearing out very fast.

Thank you johnkol for all your help. After I reset the valve lash and timing and it still wouldn't start I gave up. I dropped it off at a mechanic since I didnt want to deal with another untrustworthy autozone compression tester to test the compression.

Mechanic checked the compression and did a leakdown test and found that there was major leaks in the intake valves and minor leaks in the exhaust valves. Compression test showed 50psi on his gauge. He tore into the engine and found the valves and valves seats were toast. 25000 miles on the clock and he's going to send it off to get the head reworked with new seats and new valves.

I'm surprised to see the valves wear out that quickly, but maybe i got the lemon WR250R off the factory line or perhaps the previous owner did some odometer trickery. Who knows.

Given that the valves needed so much adjustment, it makes sense that they and the seats were burned out. The mystery, as you point out too, is why they tightened up so early.

When you adjusted the valves at 5k, what shims did you use, OEM or aftermarket ones?

I don’t think that the shims has anything to do with valve wear. The valve slaps the valve seats 9000 times a minute or so when you’re riding spiritedly where the valve shim is more of a spacer used to set how much your valves open per rotation of the cam shaft. I would expect the valve and valve seats to wear first then the camshaft and buckets then the shims

When I asked the mechanic he says the valve wear is solely a function of the material quality. He said Yamaha will make 10 Wr250r and one may have impurities in the valve material that causes premature wear. I was thinking maybe poor air filter maintenance even though I have 3 air filters and swap them fairly frequently but he squashed that idea. Also he said titanium valves fail quite often and allow the engine to rev faster at the cost of durability compared to stainless steel.

Rustyenduro wrote:

When I asked the mechanic he says the valve wear is solely a function of the material quality. He said Yamaha will make 10 Wr250r and one may have impurities in the valve material that causes premature wear.

No, that's not how manufacturing and quality control work. To make a long story short, the probability of having two intake valves so out of spec is astronomically small, so an external factor must have contributed to their early demise.