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Hi everyone,

I bought an 09 CRF250R with a blown bottom end. I split the cases and replaced everything with OEM parts. I had the head rebuilt with new OEM valves by a local machine shop. This included springs, valves, seats lapped and surface faced. Every single bearing and seal was replaced.

The bike started and did a total of 2 hours riding. It stalled when an inexperienced rider stalled by dumping the clutch. It has never started since.

Valves
I've checked the valves as below, both are marginally loose:
Intake - 0.09 to 0.15mm. An 0.18mm feeler gauge won't fit, an 0.15mm will fit fine.
Exhaust - 0.25 to 0.31. I can 'force' a 0.33mm feeler gauge in, any bigger won't fit.
I've left the valves loose as I understand it will tighten up relatively quickly on a newly built head. The plan was to check at 5 hours.
Attempted the decomp pin mod, without pictures it was difficult, though only kept a small 'nib'

Carb:
I live in Perth, Western Australia at sea level. Currently Summer and has been mid 30's (86 to 104 F)
Idle: #40
Main: #180
Choke: #68
3rd clip from top
I've disassembled and fired compressed air all throughout. I've replaced all jets except choke.

Spark:
First kick is nice and bright, subsequent sparks look 'normal'. I don't know what a weak spark looks like

Air:
I've been trying with no air filter - direct open carb intake
I've sealed the airbox boot liberally with black silicone.

I've sprayed starting fluid down the throat of the carb, not even a burp.
I've used fresh 95 octane. I don't know what equivalent that is for the states

What in the world do I look at next? I'm about to throw this damn thing in the bin -- But I've spent an obscene amount of money on it as a fun project.
It's not fun anymore

Any help leading to the bike starting, I will honestly buy you a beer.

Hi Chaddles101 and welcome to the site.
Do you have the service manual?

I would be checking the valve timing first off in case the timing chain has jumped a tooth. What sort of condition was the tensioner in at the time of the rebuild?

See how you go with this first.

Hi Chaddles101 and welcome to the site.
Do you have the service manual?

I would be checking the valve timing first off in case the timing chain has jumped a tooth. What sort of condition was the tensioner in at the time of the rebuild?

I do have the service manual.

Brand new chain and brand new tensioner. I've reset it several times to make sure. I was an idiot and was lazy. I tightened down the tensioner full extended, I think it ran for about an hour afterwards. Would that be enough to stretch the chain?

When the valve lines are parallel, with the cams up and back, the RIGHT side dots line up. However, on the flywheel side the case pointer is between the two lines -- which apparently is correct?
A lot of googling says it should line up with the second line?

Attached are pictures of the timing.

When I lined up the dots by eye on the RHS, I found the marker was in between the flywheel marks. I removed the valve cover gasket and the cams was slightly askew (pictured), I rotated it to be dead on and the rest of the timing marks are absolutely dead on now

Is the cam pointing backwards at 2 o'clock position?

Intake cams are point up and back

Ok pull the plug and pour say a teaspoon of fuel into engine replace plug and see if it fires when you start it. I would expect some reaction unless there is low or nil spark at the plug. Is plug new?

I have had faulty new plugs( old stock) just recently.

I've been spraying ether down the throat of it without any results.

If I ground the sparkplug to the head, it does spark, but I don't know what a strong or weak spark looks like

I get intermittent spark when cranking the kickstarter by hand -- I'm guessing by hand I'm not spinning it fast enough??

edit:
Scratch that, spun the motor with a drill by the RHS bolt - sparked perfectly

Following the proceedure in the manual do a compression test.
If only to take it off the list of things required to run.
Compression
Fuel
Spark at right time

Did the bike fall over when it was stalled?

Not at all, the bike was upright and stalled by the clutch.

There's plenty of sparky. I pulled out the spark plug, shot some starter fluid down on top of the piston and cranked it over - absolutely nothing.

I'm going to take it to a shop next weekend - I think I've hit my limit of trial and error and have to move on to a pro

Well be interesting to know what they find.

I'm starting to think it's the head.

The invoice I had from a machine shop is
"250R strip head, cut seats, machine valves, lap face & assemble".

I did tell them the intakes were titanium. I'm going to pull the head and pour some kero and see if it leaks through

Titanium vavles and the seats shouldn't be lapped and does cause problems. Wouldn't have thought this quick though.

Did you do a compression test?

You can put compressed air with a spark plug attachment and see where the air leaks out.
Have piston at TDC on compression of course.

I was going to go to supercheap and buy a compression and leak down tester -- but they don't come in 10mm spark plug sizes. For a automotive store, they have next to nothing for bikes
The online bike specific testers are heinously expensive, rather spend that money and pay a pro