2016 CRF 250R not kick starting

chanersMX
Hello everyone, so my partners bike is being such a pain right now. He’s recently brought it 2nd hand and it will not kick start... it really does struggle. It bumps with no problems and runs smoothly when bumped.
It’s had...
*new spark plug
*new cylinder
*new piston
*new valves (valves cut)
*re-shimmed
Its all timed correctly, it’s got plenty of compression, timing is fine on everything, the top dead centre line is lined up to the cam.
He has spent a lot on this bike already and he’s only rode it twice.
I have a 2014 and mine starts 2nd 3rd kick with no problems at all... his will just not start from a kick and we are running out of thoughts on what could be causing this bike not to start. Please any help or suggestions would go a long way for us to try.
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FGR01
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FGR01 11/7/2020 5:23pm
11/7/2020 5:23pm
Will it kick start after it is warmed up?
Paw Paw
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Paw Paw 11/7/2020 5:48pm
11/7/2020 5:48pm
Sounds like it still has a valve sealing issue.
It should have had new intake valves installed with either new valve seats or the seats cut.
Just because parts are new does not mean much if they are not correctly installed.
Was the cam chain replaced? If not the timing can be off enough to make it hard to start, but the marks can show to be close. In this case close is not good enough, it has to be exactly right or it's wrong.
It is time to do a leak test.

Paw Paw
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Jaybird67k
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Jaybird67k 11/7/2020 6:55pm
11/7/2020 6:55pm
I had the first year model KTM 350 do this to me after sitting up a few months from a injury. It wouldn't start with electric but would bump start.
Long story short, after finally doing a leak down test I had 80% leak by at TDC.
Turns out the ring at the gap was carboned up and not freely moving in the groove.
Bump starting would supply enough pressure to release it.
chanersMX 11/7/2020 8:03pm
11/7/2020 8:03pm
Paw Paw wrote:
Sounds like it still has a valve sealing issue. It should have had new intake valves installed with either new valve seats or the seats cut...
Sounds like it still has a valve sealing issue.
It should have had new intake valves installed with either new valve seats or the seats cut.
Just because parts are new does not mean much if they are not correctly installed.
Was the cam chain replaced? If not the timing can be off enough to make it hard to start, but the marks can show to be close. In this case close is not good enough, it has to be exactly right or it's wrong.
It is time to do a leak test.

Paw Paw
His valves are cut in already. What we had to do was, when we took it apart he had 2 valves that were not cut in at all, and they have to be cut in to be seated so no air escapes obviously so my father cut those in and he’s a master mechanic on bikes, he’s never ever been puzzled with bikes and he doesn’t understand why this isn’t kicking up. He had to buy a compression tester, and was only getting between 20-25psi and that isn’t enough to be kicked off. So then my father brought a leak down test because he was losing compression somewhere, when testing with the leak down he had a hiss from the left side (gear changer side) so we then went to the barrel as that was chipped and scored so he replaced that. Now he has absolutely no air escaping, none from the exhaust, none from the air filter even at TDC he has no air escaping at all now.

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chanersMX 11/7/2020 8:06pm
11/7/2020 8:06pm Edited Date/Time 11/7/2020 8:07pm
FGR01 wrote:
Will it kick start after it is warmed up?
No, they’ll bump it... let it get warm/hot let it rest a couple mins and try and kick and it does not go... when it’s a warm it should go 2nd to 3rd kick and your there kicking it over 6-7 times and even then it doesn’t kick up. It backfires quite a bit also when it’s trying to be kicked so they’re thinking now summit with the throttle body I think? Something that can be turned to let a certain amount of fuel and air in? Someone before may have turned that too much and it’s pushing too much fuel through which is why it’s backfiring?
DF313
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DF313 11/7/2020 9:43pm
11/7/2020 9:43pm
Might be a long shot, I had trouble starting my 2006 similarly, turned out my cam chain tensioner had gone bad. Just throwing that out there, would be easy to look at
mtl
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mtl 11/7/2020 10:08pm
11/7/2020 10:08pm
Shims might be off.
walent215
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walent215 11/8/2020 1:48am
11/8/2020 1:48am
chanersMX wrote:
Hello everyone, so my partners bike is being such a pain right now. He’s recently brought it 2nd hand and it will not kick start... it...
Hello everyone, so my partners bike is being such a pain right now. He’s recently brought it 2nd hand and it will not kick start... it really does struggle. It bumps with no problems and runs smoothly when bumped.
It’s had...
*new spark plug
*new cylinder
*new piston
*new valves (valves cut)
*re-shimmed
Its all timed correctly, it’s got plenty of compression, timing is fine on everything, the top dead centre line is lined up to the cam.
He has spent a lot on this bike already and he’s only rode it twice.
I have a 2014 and mine starts 2nd 3rd kick with no problems at all... his will just not start from a kick and we are running out of thoughts on what could be causing this bike not to start. Please any help or suggestions would go a long way for us to try.
Cam gear possibly spun just enough to be out of time. Been down this road before. I’d replace cam chain and tensioner as well.
Fuel filter will cause similar issue as well. Our 13 and 15 crf250 showed similar symptom when filter needed replacing.
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davis224
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davis224 11/8/2020 3:23am
11/8/2020 3:23am Edited Date/Time 11/8/2020 3:28am
Make sure you have spark first, then you're getting fuel, then check for mechanical issues. Could be a weak spark. I had an 04 KTM 125 with the same issues and it ended up being the CDI, after I mistakenly figured it would be the stator.
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chanersMX 11/8/2020 4:30am
11/8/2020 4:30am
davis224 wrote:
Make sure you have spark first, then you're getting fuel, then check for mechanical issues. Could be a weak spark. I had an 04 KTM 125...
Make sure you have spark first, then you're getting fuel, then check for mechanical issues. Could be a weak spark. I had an 04 KTM 125 with the same issues and it ended up being the CDI, after I mistakenly figured it would be the stator.
We have spark, it’s a nice orange colour and looks very strong. It’s getting fuel as we’re getting a lot of backfire, plus the spark becomes wet after a few kicks. He’s just took the left crank case off and checked the stator and made sure everything was aligned at TDC, he’s currently putting it back together again.
chanersMX 11/8/2020 4:50am
11/8/2020 4:50am
At this moment in time, we currently have a new noise when kicking it, a hissing air noise so now we’re gonna check the shims again and make sure they’re what they’re supposed to be.
chanersMX 11/8/2020 5:02am
11/8/2020 5:02am
So my dad has just checked this hissing noise, it was burning fuel out the exhaust which was good but then a big flame came out the exhaust so now my dad knows he’s gotta do the valve clearances again. Hopefully fingers bloody crossed this will fire up! Kicking it now it is trying you can hear the bike nearly going but isn’t enough to start. I’ll keep you guys posted. Thank you all for your suggestions and help!
Paw Paw
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Paw Paw 11/8/2020 5:03am
11/8/2020 5:03am
An Orange color spark is a BAD spark. you need a bright Blue spark for it to be correct. You need to do an Ohms test of the ignition coil on the the primary and secondary sides. You could have dirty or rusted coil mounts or connections or a bad spark plug boot.

Now please explain " the valves were cut". The only thing that should be cut are the valve seats in the head.

As already stated, check your cam gears as they can spin on the cam.

Also with the auto decompression cam in your bike your compression will be low, but the reading you posted is just way too low. You should have between 65 and 90 psi.

If the cam chain was not replaced then do so now.

What do you have your valve clearances set at right now.

Paw Paw

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chanersMX 11/8/2020 5:32am
11/8/2020 5:32am
Paw Paw wrote:
An Orange color spark is a BAD spark. you need a bright Blue spark for it to be correct. You need to do an Ohms test...
An Orange color spark is a BAD spark. you need a bright Blue spark for it to be correct. You need to do an Ohms test of the ignition coil on the the primary and secondary sides. You could have dirty or rusted coil mounts or connections or a bad spark plug boot.

Now please explain " the valves were cut". The only thing that should be cut are the valve seats in the head.

As already stated, check your cam gears as they can spin on the cam.

Also with the auto decompression cam in your bike your compression will be low, but the reading you posted is just way too low. You should have between 65 and 90 psi.

If the cam chain was not replaced then do so now.

What do you have your valve clearances set at right now.

Paw Paw

Hang on then, I’ll get him to check the spark as I brought summit to tell me if it’s a strong spark or not. Yes buddy as you said, the valves were cut into the seats in the head that’s what I was saying. Erm... right his shims
-right exhaust is 0.012
-left exhaust is 0.011
-right inlet is 0.004
-left inlet is 0.005
So they are within spec.
I’m not sure about the spark atm the light it’s giving off the spark tester isn’t very bright so bare with.
Paw Paw
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Paw Paw 11/8/2020 5:59pm
11/8/2020 5:59pm
On this bike, .004 on the one intake is too tight. May I suggest using .006 on both intakes? Any thing tighter than .006 on the intakes will cause starting issues, show the compression to be low and fail a leak test and a weak spark will add to the problem.
And again... the valves should not be cut, but the valve seats will have to be cut for new valves.

Paw Paw
nascarnate326 11/9/2020 5:00am
11/9/2020 5:00am
I had a 2014 and even after adjusting the valves my self several times I took it in and had a shop do it. They found I was off just a tiny bit and it ran great after they changed the shims.
chanersMX 11/9/2020 5:16am
11/9/2020 5:16am
nascarnate326 wrote:
I had a 2014 and even after adjusting the valves my self several times I took it in and had a shop do it. They found...
I had a 2014 and even after adjusting the valves my self several times I took it in and had a shop do it. They found I was off just a tiny bit and it ran great after they changed the shims.
How much did they charge you all together? Cuz we’ll probably end up taking it to a shop stripped to where they can see the shims so they don’t charge us so much labour.
nascarnate326 11/9/2020 6:28am
11/9/2020 6:28am
nascarnate326 wrote:
I had a 2014 and even after adjusting the valves my self several times I took it in and had a shop do it. They found...
I had a 2014 and even after adjusting the valves my self several times I took it in and had a shop do it. They found I was off just a tiny bit and it ran great after they changed the shims.
chanersMX wrote:
How much did they charge you all together? Cuz we’ll probably end up taking it to a shop stripped to where they can see the shims...
How much did they charge you all together? Cuz we’ll probably end up taking it to a shop stripped to where they can see the shims so they don’t charge us so much labour.
I want to say it was 200 to get it top notch. Ive got a old school very very small honda dealer that does great work and is awesome to support. They take good care of me.
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kibby
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kibby 11/10/2020 8:45pm
11/10/2020 8:45pm
Just to be sure this isn't your problem, check this:
Remove the vacuum hose from the MAP sensor to the throttle body and spray contact cleaner / compressed air through the orifice into the throttle body to confirm there is a clear passage.That orifice is less than 0.7mm and blocks easily.
It is necessary for that to be clear in order for the MAP sensor to get a signal when the intake valve opens during initial kicking (below 1500 RPM).
A signal from the crank angle sensor paired with the signal from the MAP sensor indicating which is the firing stroke lets the ECU know critical first injection timing points.
This can cause poor and/or non kick starting issues.
Good Luck.
Also .004-.006" valve clearances all around are fine.
I would actually tighten your exhaust clearances a little maybe.006-.008" the looser the ex lash is the less effective the exhaust valve decompression device is too.
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