Cr250 not starting after rebuild

Storey867
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13
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4/8/2024
Location
Roy, UT US

I have a 2004 Cr250 I just did a full frame up rebuild on with a 05-07 crank, wiseco piston, vforce reeds being the main changes to the motor. I noticed the slide in the stock mikuni was cracked so I replaced it with a keihin pwk out of a yz im guessing? I bought it and the power jet is already plugged. I replaced the stator and flywheel due to corrosion and happened to get the ‘03 part number which I was told would work. I am getting fuel to the cylinder, I pulled the plug and laid it on the pipe. I can get spark with my hand on the kickstart. It seems to die out after a few kicks. I cannot get this thing to start. Any ideas? 
170 main jet

48 pilot

N3EW 3rd clip

2 turns out on the as

at 4300ft elevation

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4/18/2024 12:17am

I had a similar issue when I first installed a PWK, but it would start with a partially open throttle.

I adjusted the throttle stop screw until it would run with a high idle, before adjusting the air screw and pilot size and turning the idle down.

Storey867
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Roy, UT US
4/18/2024 7:01am
I had a similar issue when I first installed a PWK, but it would start with a partially open throttle. I adjusted the throttle stop screw...

I had a similar issue when I first installed a PWK, but it would start with a partially open throttle.

I adjusted the throttle stop screw until it would run with a high idle, before adjusting the air screw and pilot size and turning the idle down.

Okay this relieves some of my worries. I was beginning to worry it’s electrical. Spark is strong and I know it has to be a pretty hard kick for the cdi to generate spark. 

1
Storey867
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Roy, UT US
4/18/2024 5:36pm

I still can’t get it to start. Tried a 40-48 pilot, tried adjusting the idle, nothing. Still getting spark, tried swapping the spark plug. 

The Shop

crc245
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Yorba Linda, CA US
4/18/2024 8:27pm

What temp at 4300’ elevation? SoCal sea level I’m usually 48/50P, 178/180M, 1.25-1.75 AS with similar setup. Keep us updated

Storey867
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Roy, UT US
4/18/2024 8:33pm

Is it flooded, did you try full throttle?

Is the TPS disconnected?

Pulled the plug on a few occasions and it would be wet. Tried a fresh br8eg as well. TPS is disconnected. Have tried giving it some gas

Storey867
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Roy, UT US
4/18/2024 8:34pm
crc245 wrote:

What temp at 4300’ elevation? SoCal sea level I’m usually 48/50P, 178/180M, 1.25-1.75 AS with similar setup. Keep us updated

I’m in Utah so right now we’re anywhere from ~40 F - 70 F. Soon it will be much warmer though

Storey867
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Roy, UT US
4/18/2024 9:19pm

I have tested primary and secondary coil resistance and alternator coil resistance. All is good and getting spark with a solid kick. 

4/18/2024 9:37pm

Is the pulse generator is the same position on the 2004 and 2003 stators?

Have you tried 2 or 3 slow priming kicks, to charge the crank, before the solid kick?

Is there any fuel on the spark plug after the solid kick?

Storey867
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4/18/2024 9:45pm
Is the pulse generator is the same position on the 2004 and 2003 stators? Have you tried 2 or 3 slow priming kicks, to charge the...

Is the pulse generator is the same position on the 2004 and 2003 stators?

Have you tried 2 or 3 slow priming kicks, to charge the crank, before the solid kick?

Is there any fuel on the spark plug after the solid kick?

The part numbers are different. The wiring is the same. I am using a flywheel and stator out of an ‘03. The guy I bought it off assured me that it would work and he has had many CR’s. I can’t speak to this confidently, but I did throw in my 04 stator and flywheel. Same result. I replaced it after originally cracking open the stator cover, water pouring out and the stator and flywheel having some corrosion. One of the inner case bolts had also come out at some point, doing some damage to the flywheel and it was resting in the bottom of the case.  
I have tried a process similar to putting a 4 stroke at TDC with a few slow kicks and then one swift kick. There is a small small amount of fuel on the plug following that.

4/18/2024 9:56pm

You may have an air leak between the cases, to reduce air leaks, Honda increased the bolt size in the 2005 CR250 from M6 to M7.

Have you done a leak down test?

Storey867
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Roy, UT US
4/18/2024 10:02pm
You may have an air leak between the cases, to reduce air leaks, Honda increased the bolt size in the 2005 CR250 from M6 to M7...

You may have an air leak between the cases, to reduce air leaks, Honda increased the bolt size in the 2005 CR250 from M6 to M7.

Have you done a leak down test?

I have not done a leak down test. I don’t personally have one but I could likely get my hands on one. That’s good info!

Chance1216
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Federal Way, WA US
4/19/2024 2:11pm

Try starting it like a 500 when cold. 


Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it back up and, you should see fuel coming out of the overflow tubes. Put it in third gear. Rock the bike back and, forth 5-6 times. Throw it back into neutral. Find TDC and, give it a solid kick. 

captmoto
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Rancho Cucamonga, CA US
4/19/2024 8:02pm
Chance1216 wrote:
Try starting it like a 500 when cold.  Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it...

Try starting it like a 500 when cold. 


Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it back up and, you should see fuel coming out of the overflow tubes. Put it in third gear. Rock the bike back and, forth 5-6 times. Throw it back into neutral. Find TDC and, give it a solid kick. 

None of that is necessary in a healthy CR250.

OP, was it running before the rebuild? Put the stock Mikuni and electronics back on to see if you get anything out of it. I know you said you get spark but I would disconnect the kill button. Check your throttle cable routing, make sure the it isn't hung up somewhere. Do these things one at a time to isolate the problem.

4/19/2024 8:14pm
Chance1216 wrote:
Try starting it like a 500 when cold.  Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it...

Try starting it like a 500 when cold. 


Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it back up and, you should see fuel coming out of the overflow tubes. Put it in third gear. Rock the bike back and, forth 5-6 times. Throw it back into neutral. Find TDC and, give it a solid kick. 

I agree with @captmoto, the only thing I do with mine when it is cold is pull the choke, do 2-3 slow priming kicks, and it starts 1st or second kick, when warm it starts first kick.

1
Storey867
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Joined
4/8/2024
Location
Roy, UT US
4/19/2024 10:16pm
Chance1216 wrote:
Try starting it like a 500 when cold.  Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it...

Try starting it like a 500 when cold. 


Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it back up and, you should see fuel coming out of the overflow tubes. Put it in third gear. Rock the bike back and, forth 5-6 times. Throw it back into neutral. Find TDC and, give it a solid kick. 

captmoto wrote:
None of that is necessary in a healthy CR250. OP, was it running before the rebuild? Put the stock Mikuni and electronics back on to see...

None of that is necessary in a healthy CR250.

OP, was it running before the rebuild? Put the stock Mikuni and electronics back on to see if you get anything out of it. I know you said you get spark but I would disconnect the kill button. Check your throttle cable routing, make sure the it isn't hung up somewhere. Do these things one at a time to isolate the problem.

Fairly certain it’s an air leak. I made a leak down setup. Had a pretty good leak below the around the reeds. At this point I think I may just split the cases one more time, get a fresh gasket kit and seal the space around the reeds very well. Prior to doing that I might put my mikuni together and try that. As far as I can see electrical is working well. I tested the coil and have two different flywheel/ stator setups. 

4/19/2024 11:31pm
Chance1216 wrote:
Try starting it like a 500 when cold.  Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it...

Try starting it like a 500 when cold. 


Turn the gas on, pull the choke up and, lay the bike over on it’s side. Stand it back up and, you should see fuel coming out of the overflow tubes. Put it in third gear. Rock the bike back and, forth 5-6 times. Throw it back into neutral. Find TDC and, give it a solid kick. 

captmoto wrote:
None of that is necessary in a healthy CR250. OP, was it running before the rebuild? Put the stock Mikuni and electronics back on to see...

None of that is necessary in a healthy CR250.

OP, was it running before the rebuild? Put the stock Mikuni and electronics back on to see if you get anything out of it. I know you said you get spark but I would disconnect the kill button. Check your throttle cable routing, make sure the it isn't hung up somewhere. Do these things one at a time to isolate the problem.

Storey867 wrote:
Fairly certain it’s an air leak. I made a leak down setup. Had a pretty good leak below the around the reeds. At this point I...

Fairly certain it’s an air leak. I made a leak down setup. Had a pretty good leak below the around the reeds. At this point I think I may just split the cases one more time, get a fresh gasket kit and seal the space around the reeds very well. Prior to doing that I might put my mikuni together and try that. As far as I can see electrical is working well. I tested the coil and have two different flywheel/ stator setups. 

They are prone to leaks below the reeds, sucking air and gearbox oil, making jetting problematic...
image-20240420163016-1

If you are splitting the cases, face the gasket surfaces between the cases, assemble the 2 halves and face the base gasket and intake gasket surfaces.

 

Storey867
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Joined
4/8/2024
Location
Roy, UT US
5/1/2024 5:54pm

Tore the engine back apart. The cometic gasket kit i had seemed to not cover a lot of area around the reeds. Not sure if it was a manufacturing issue, but I had no material on the top section of the case where the reeds sit. I set the cases together with just dowels to ensure I was getting proper contact between gasket surfaces and resealed the engine up. the bike will not start still though. I have tried the stock mikuni carb, pulled my keihin apart several times and checked nearly every electrical item with the service manual other than peak voltage output. I am fairly certain my plug cap is not staying seated on the spark plug as one side of the "clip" is broken so to speak. I ordered a new coil and plug cap, which will be here shortly. If that fails, its pointing to a CDI. I can get a nice blue spark, but it seems to fade or get more intermittent the more it's kicked. When i am attempting to start the bike, usually the first kick is the most promising and then it fails to start. Have thoroughly inspected the harness

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