YZ250F 2017 valve clearance specs?

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3/1/2018 11:27 AM

Hi there this my first post.
I'm new to the forum.
Noticed my yzf getting harder to start last couple of sessions and after washing it Sunday now can't get it started.
Would like to rule out the valve clearances as being the problem, dose anyone know the specs?
I don't have the 2017 owners manual, I have downloaded a 2016 manual but dose anyone know if the clearance specs are the same?
Any help or advise would be much appreciated, as I've searched the internet with no luck.
All the best, joff

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3/1/2018 11:44 AM

Check your spark plug for spark yet? Whats the condition of it too? Also when the bike was washed, did water find its way to a place it shouldnt be and or create a shorted or grounded out condition? Check the air filter too, and fuel condition. If all that checks out then move on to valve clearance stuff. Seems kind of early for a 2017 250f to have worn enough for a valve adjustment... Anybody know specs? Btw, i could be completely wrong. Good luck and keep us posted ☺

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3/1/2018 11:45 AM

Also, Welcome!

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3/1/2018 12:06 PM

Thanks for the advise.
I've checked sparkplug getting a nice blue spark each kick.
I've emptied the fule and replaced with fresh.
I also suspect it's an electrical issue but just want to check and rule out the valve clearance.
I have dried and cleaned all the connections coming off the harness with electrical contact cleaner and a hairdryer and re assembled but still no luck.
The exhaust bung was in when I washed it.
Just occasionally backfires when attempting to start it at moment, I give up after 20 or so kicks it use to start up within a couple attempts.
ATB, joff

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3/1/2018 12:09 PM

Im kinda thinking electrical too... Fuel injection wiring. Can you smell gas?

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3/1/2018 12:24 PM

The valve specs are the same between the 2 years for what it’s worth, I don’t remember them off hand though

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3/1/2018 12:52 PM
Edited Date/Time: 3/1/2018 12:54 PM

kruspy378 wrote:

Im kinda thinking electrical too... Fuel injection wiring. Can you smell gas?

I can smell/see small amount of fule on the plug when I remove that. I have a multimeter here just little experience using it, have visually checked the harness and connections but haven't tested anything yet.
ATB joff

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3/1/2018 12:54 PM

murph783 wrote:

The valve specs are the same between the 2 years for what it’s worth, I don’t remember them off hand though

Ok great, thanks for that, much appreciated.
I can get on and check them now.
ATB joff

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3/2/2018 3:56 AM

Quick update, I've managed to check my valve clearance.
Exhaust clearance is within spec
Inlet clearance is very tight, not even remotely close dose anyone know what would cause this?
No wonder I can't get it started.
I've only owned the bike a couple of months and done approx 8 hours on it, the bike was pre owned but in good condition and almost original so don't think it's racked up that many hours.
Something dosent seen quite right here?
Thank and all the best
Joff

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3/2/2018 4:37 AM

Joff_Palmer wrote:

Quick update, I've managed to check my valve clearance.
Exhaust clearance is within spec
Inlet clearance is very tight, not ...more

??? Strange...

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3/2/2018 5:19 AM

When the intake valves start getting tight, it is a sign of the valves beating against the valve seats. Either the valves get longer or the seats become damaged and thus the clearances tighten up and it becomes hard to start.
This is normally caused by some one bouncing the rpms off the rev limiter for periods of time. It is very hard on the valves. It is also a sign of normal wear over a long period of time.
I would also suggest looking at the cam chain for wear.

Paw Paw

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3/2/2018 5:45 AM

2014-2017 YZ250F have electrical issued when wet. 1st step it to remove all connectors, clean them, and reinstall with dielectric grease.

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Race Bike: 2018 KTM 350SXF

Other Bikes: 1985 CR80R, 1990 CR250R, 1998 PW80, Yeti SB130LR.

Sold: 2016 YZ250F, 2012 CRF250R

3/2/2018 6:02 AM

Paw Paw 271 wrote:

When the intake valves start getting tight, it is a sign of the valves beating against the valve seats. Either the valves get ...more

Thanks for your reply and the interesting information.
I haven't ridden it that hard, hit the limiter few times but very short periods. Might of been raced hard from new?
I want to get it checked out properly now due to the fact the clearance is so far out of spec has me slightly concerned.
While it's there I'll get him to check the piston,rings,camchain,valves etc etc
Thanks for your input everyone.
Atb- joff

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3/2/2018 6:06 AM

c0ncEpT wrote:

2014-2017 YZ250F have electrical issued when wet. 1st step it to remove all connectors, clean them, and reinstall with ...more

I did try that, didn't work unfortunately then I checked valve clearance and the inlet is not even close to spec think that's my problem but cheers anyway.

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3/2/2018 9:01 AM

Paw Paw 271 wrote:

When the intake valves start getting tight, it is a sign of the valves beating against the valve seats. Either the valves get ...more

Joff_Palmer wrote:

Thanks for your reply and the interesting information.
I haven't ridden it that hard, hit the limiter few times but very short ...more

Remember that bouncing off the rev limiter is not a good thing, ever. I know we all see some very good pros doing all the time, but remember they don't have to worry about engine life or that cost. In the real world we do have to worry about such things as the cost of repairs comes out of our pockets.
Every time you bounce off the rev limiter you shorten the engine life. I read some where, but don't remember were but it does seem reasonable, that every time the revs hit the rev limiter it shortens the engine life by about an hour.
So in a 15 minute MX race with the engine being bounced off the rev limiter many times per lap, the engine life will be reduced greatly. Do that over a season and you can see that the engine life becomes very short.

Paw Paw

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