CR250 intermittent bogging issues

carl-h
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GB
8/16/2016 10:22am
I'm hoping someone here can help, I've been having a nightmare recently with my CR. 10 hours ago it had a full rebuild including genuine crank and wiseco piston. It's on a Lectron carb which has been running great for 6 months. Bike has felt great after rebuild until now.

All started after I took the flywheel weight off. Fired it up at home the day before riding and it had a slight hesitation or bog every now and then when blipping. I checked the needle in the lectron was seated right fired it back up and it was fine. It did it again the next day at the track after running for a few minutes. Then it was okay till I got out. 1 and a half laps in to my first session it died coming out of scorned at low revs. Fired straight back up and did it again just as I was coming to the track exit. Got it to the van and it had no spark and wouldn't fire back up. Got it home and it fired straight up.

The stator was sent off and found to be reading low so that was rewound, but the problem is still there. I replaced plug cap HT lead spark plug and cleaned the electrical connections. Running fine on the stand, went to the track and it died after half a lap but fired straight back up. Put my old carb on and it was the same so it rules out a feeling issue. Also, it's not the tank vent or feed pipe as the lectron has a clear float bowl which is still full when it cuts out.

Just replaced the coil, fresh plug and HT lead and it's still doing it.

I took the powervalve cover off with it running and that's working as it should even when the bike bogs/cuts out and closing at lower revs so it's not a problem there.

Only thing I noticed that's different is that it seems to be leaking a lot of splooge out the front where the flange sits on the cylinder. I cleaned it up Sunday and after running for 10 mins just its spewed enough out to run down the engine. But the bike isn't really running rich, I was wondering if a leak there could make enough of a back pressure loss to make it cut out? Doesn't explain why it's only intemittent though.

Does anyone have any ideas to try next?

Thanks for reading, sorry it's a bit long winded.
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Steely Dan
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Fredericksburg, VA US
8/16/2016 10:35am Edited Date/Time 8/16/2016 10:37am
The splooge is because a misfiring bike is 100% rich when its not firing, so that's to be expected.

Your problem is indicative of a loose flywheel wobbling around. the small metal strip where it's supposed to pass beneath the magnet on the stator will "miss" the magnet and cause misfires. It will be ok on the stand because the bike is flat and motionless. but on a track, it will cough and sputter when the flywheel wobbles.

But I trust you've tightened it. So that's probably not the problem. I'm typing this to jog the next guy's mind who reads this.

the only other solution is the CDI box itself, and if im not mistaken, those 02ish CDI boxes did have issues. Have you tried replacing it with a buddy's? That's what I'd try next. then when I got done with that, I would replace the rectifier that's on the left side frame spar under the rad shroud. those are the two things within the electrical system you haven't tested/tried, so go out in the garage and do it.
carl-h
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GB
8/16/2016 10:57am
Thanks for your reply! Makes perfect sense with the splooge. I'll stop worrying about that now haha.

I bought the bike with the flywheel weight fitted and the box with the original nut in. I've just had a look at the diagram in my manual and it appears I'm missing a washer between the flywheel and nut. The flywheel felt completely tight with no movement by hand but do you think this could of caused the problem? I'm going to put the fly wheel weight back on and try it asap!

At the minute I don't know anyone with a Cdi I could borrow but my mechanic thinks he does. Do you know if the years are interchangeable? I'm guessing if so I'll be able to use 02-04 on mine? Also, is there any risk with me using someone else's cdi? I'd hate to break theirs too and have to buy 2 of them.
Steely Dan
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8/16/2016 11:01am Edited Date/Time 8/16/2016 11:03am
carl-h wrote:
Thanks for your reply! Makes perfect sense with the splooge. I'll stop worrying about that now haha. I bought the bike with the flywheel weight fitted...
Thanks for your reply! Makes perfect sense with the splooge. I'll stop worrying about that now haha.

I bought the bike with the flywheel weight fitted and the box with the original nut in. I've just had a look at the diagram in my manual and it appears I'm missing a washer between the flywheel and nut. The flywheel felt completely tight with no movement by hand but do you think this could of caused the problem? I'm going to put the fly wheel weight back on and try it asap!

At the minute I don't know anyone with a Cdi I could borrow but my mechanic thinks he does. Do you know if the years are interchangeable? I'm guessing if so I'll be able to use 02-04 on mine? Also, is there any risk with me using someone else's cdi? I'd hate to break theirs too and have to buy 2 of them.
No real risk. It's 02-03. 04 had a different Mikuni TMX with a TPS sensor.

Well I'll be damned, your flywheel is installed incorrectly...imagine that...

Report back, let us know what you find. Good luck.

one more thing, when your flywheel is off, make sure your keyway isn't buggered. little halfmoon piece of metal that keeps your flywheel securely on your crankshaft.
carl-h
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8/16/2016 11:13am
First this I'll do is put the weight back on. If it solves the problem I'll order the correct washer from Honda. I'll fit the weight tonight but here in the UK it'll be too late to fire it back up with the neighbours lol so it'll be tomorrow before I know. I've found a used cdi off a 2003 so that's an option if it's still playing up

The Shop

Steely Dan
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8/16/2016 11:28am
don't forget to check the key way.
carl-h
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GB
8/16/2016 11:35am
I don't have a puller so I'll run it to my mechanic to check it!
AHRMA361
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Fantasy
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8/16/2016 11:40am
Steely Dan wrote:
No real risk. It's 02-03. 04 had a different Mikuni TMX with a TPS sensor. Well I'll be damned, your flywheel is installed incorrectly...imagine that... Report...
No real risk. It's 02-03. 04 had a different Mikuni TMX with a TPS sensor.

Well I'll be damned, your flywheel is installed incorrectly...imagine that...

Report back, let us know what you find. Good luck.

one more thing, when your flywheel is off, make sure your keyway isn't buggered. little halfmoon piece of metal that keeps your flywheel securely on your crankshaft.
Actually, the flywheel key is just used for proper alignment of the flywheel to the crank for timing purposes.

The mating tapers on the crankshaft and corresponding flywheel, held together by the flywheel nut, do all the securing.
JW381
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8/16/2016 5:12pm
Wow, I'm almost at a loss for words as to how similar your problems are to mine on my 04. I don't have any solutions at the moment, but I feel your pain brotha. I also got some good info here, more things to check. Ugh. If the handling on those last gen CRs weren't so great and sturdy, I'd have a different bike already. But I want mine to work. Blink

Good luck mate.
8/16/2016 6:00pm
Is there an ohm/voltage spec on the CDI and rectifier that you could test for with a multimeter?
carl-h
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GB
8/16/2016 10:07pm
I've put the weight back on so the flywheel is secured the same way it was before any problems started. I'll give it a run when I'm home from work later.

I'm sure the cdi can be tested needing a reading of 0.7 volts while kicking the bike over. I'm not sure if this test will show any problems though as mine only plays up after a few minutes of running.

JW381, hopefully I'll get mine sorted soon. It's frustrating isn't it? I've literally put so much into this bike now. Every bearing has been replaced suspension is sprung and valved for me, SM pro wheels 2015 restyle kit the lectron carb 280mm brake kit. I've literally improved every single bit of the bike since buying it and now it does this to me. It's made me start considering the new crf a lot more now. It's a shame as this bike has been good to me right up till now and it probably will be once I've sorted it out.

I think cdi will be the next thing to try if the flywheel hasn't made any difference?
carl-h
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8/17/2016 9:07am
After fitting the weight the bike is still the same, ruling out any flywheel issue. I think next will be the cdi and see if that helps. Any other ideas?
ratonmacias
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Guadalajara MX
8/17/2016 9:14am
Try to borrow a cdi fom a buddy it gets expensive just buying stuff.
ratonmacias
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Guadalajara MX
8/17/2016 9:20am
My bike a 04 had the capacitor cut off from the rectifier. It was really difficult to kickstart. After i got the correct part it kickstart 1st or second kick. According to my mechanic the capacitor can make the bike run bad.
carl-h
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8/17/2016 9:40am
I'm gonna see if anyone has one I can borrow. At the moment I can't think of anyone with a cr but I'll ask about.

And that will probably be the next thing to replace. This will start really well pretty much all the time. First kick and it doesn't even need a proper kick really. When it's playing up it sometimes starts back up with a bit of throttle but instantly dies again, other times it will start and run fine for a few more minutes.

I've found a used cdi for £80 delivered and I may see if he has a regulator too and if it's not much get it thrown in so I can figure it out once and for all
Steely Dan
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8/17/2016 10:15am
Then it's the CDI or rectifier.

But, I still wouldn't ruin out the stator. You had it re-wound, correct? Try swapping it out with a known good.
carl-h
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GB
8/17/2016 12:37pm
Just tried a CDI off a mate of my mechanics. No joy. Still doing the same thing, only thing left to try is the rectifier. I'll get one ordered as soon as I'm home.

If it's still no good were gonna send the stator back for a bit more testing.

My hour metre reads rpm too and just to confirm its a spark problem it cuts down to around 6-700 when the problem occurs, even though the engine is obviously spinning faster than that. The fact it drops to 6-700 and not 0 until the bike actually dies means it's still getting spark albeit not enough I imagine? This doesn't really mean anything to me but someone else may recognise the symptoms?
8/17/2016 12:43pm Edited Date/Time 8/17/2016 12:47pm
this may sound a little stupid, but worth checking there is no vacuum lock in the fuel tank, make sure the air breather is clean. The way you explain the issue is exactly what a blocked air breather will cause.
and another thing if i remember correctly those models needed a resistor in the sparkplug or they had problems
carl-h
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GB
8/17/2016 1:29pm
this may sound a little stupid, but worth checking there is no vacuum lock in the fuel tank, make sure the air breather is clean. The...
this may sound a little stupid, but worth checking there is no vacuum lock in the fuel tank, make sure the air breather is clean. The way you explain the issue is exactly what a blocked air breather will cause.
and another thing if i remember correctly those models needed a resistor in the sparkplug or they had problems
Thanks for your reply, I've tried it with the tank cap off and it's still there, also wouldn't explain the Rev counter behaving unusually. I'm 99% convinced it's a spark issue rather than fuel. The float bowl remains full at all times too, it's a clear bowl on the lectron so you can see the level.

I've ordered a rectifier
Paw Paw 271
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Benton, LA US
8/17/2016 1:39pm
Did you check the coil by doing an ohms test on the primary and secondary sides? If the primary side reads too low it will quit firing when it heats up. Then it will refire and repeat.
I must state that it sounds like a fuel issue, but a bad coil will do the same thing.

Paw Paw
carl-h
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GB
8/17/2016 1:47pm
Did you check the coil by doing an ohms test on the primary and secondary sides? If the primary side reads too low it will quit...
Did you check the coil by doing an ohms test on the primary and secondary sides? If the primary side reads too low it will quit firing when it heats up. Then it will refire and repeat.
I must state that it sounds like a fuel issue, but a bad coil will do the same thing.

Paw Paw
I've replaced the coil with a brand new one and still the same problem. Is it still worth taking a reading from the new coil?

I'm running a BR8ES plug. I assume the R means a resistor is fitted?

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