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-   -   WR250F issues (http://www.dirtbikeworld.net/forum/showthread.php?t=124073)

dieseldude 29-01-2017 07:06 PM

WR250F issues
Hi all.

I have an '01 WR250f (which I've had for about 5 years).

It has always been a bastard to start - as are all from that era with the manual decompression etc etc.

Long story short. I have persevered with it for years because it's a great bike. Last June / July at the Murphy's Creek ride was the first time I had ridden it for a while due to house renovations. I fitted a new filter, new spark plug, fresh service etc etc and it was impossible to start with the kick starter. I could clutch start it only.

It was put back in the shed until the Xmas holidays just passed.

I sourced an exhaust cam from an '03 model with the auto decompression and fitted that. I still can't start it.

I just fitted a new plug, new filter and gave it another crack and still no go. It occasionally sounds like it's close to starting, but seems to then flood easily.

I have checked the valves and the exhaust valves seem ok (don't ask me to quote figures though - I didn't write them down as it was purely for trouble shooting purposes only).

Intake valves all seem tight. I couldn't even get the thinnest feeler gauge in my kit between the cam and valve hat.

I had the valves checked a few years ago by Bayside Yamaha - which wasn't that many kms ago in reality, and they were apparently within spec.

My question is: Will tight intake valves likely be my problem?

There are vids on YouTube of blokes who have done this mod starting their bikes with their hand only. I don't expect this kind of result, but I'd like to at least be able to kick start it on uneven ground without dieing from heat exhaustion.

Any feedback by those who are mechanically minded would be much appreciated.



normanator27 29-01-2017 07:45 PM

I will pass comment on this because I have had a similar experience. However, please note that I am mechanical novice at the very best, and I have no doubt that there will be others on this forum who may offer better advice. But, I had a similar experience with an old XR 400 that I had. It went really well then all of a sudden the only way I could start it was by clutching it. A quick trip to the mechanics revealed that the valve clearance wasn't what it should be. The problem was fixed and I had no more starting trouble.

dt200rg 29-01-2017 08:58 PM


Originally Posted by dieseldude (Post 2000883)
Intake valves all seem tight. I couldn't even get the thinnest feeler gauge in my kit between the cam and valve hat.

No gap? There's your problem right there....intake should be about 0.15 and exhaust 0.25 from memory...if you gave no gap then the buckets will be riding on the cam and holding the valves open = minimal to no compression...and causing excess wear on your cam....

arrow 29-01-2017 11:39 PM

intake .10-.15 exhaust .20-.25mm not being able to get a feeler gauge under your valves provided you have the cams in the right position is 100000% your problem in my opinion.

dieseldude 31-01-2017 09:38 PM

Thanks guys.

I'll book it in for the valves to be adjusted.

For those in the Brisbane Northside (Burpengary) area, are there any recommendations for reputable workshops to do this job? There is a Yamaha dealer at North Lakes that I know of.............

We've just moved up this way so need to establish new contacts for stuff like this.



Pygmygod 31-01-2017 09:42 PM

You're almost there. (Having replaced the exhaust cam and checked valve clearances)

You just need to buy a shim kit and one of those telescopic magnet tools.

dt200rg 01-02-2017 10:39 AM

Des Roberts Motor Cycle Performance
Address: 120/193 South Pine Rd, Brendale QLD 4500
Phone: (07) 3205 7911

Des is a really good bloke, great rates and honest quality work.

Not sure of Caboolture Yamaha....they might have changed in the last few years but I've seen / heard mixed reviews. But grab a hot shims kit, a magnet tool and a set of verniers and you can do the job yourself.

dieseldude 07-02-2017 06:23 AM

Thanks very much.

arrow 07-02-2017 03:26 PM

go and see Quinton and Marty at Brisbane Dirt Bike Services in Capalbar, Quinton is a mechanical god team mechanic for multiple ISDE's and a ex factory endure rider, Michael Marty was the head mechanic at the Serco Race team and Kawasaki race team you cannot go wrong, awesome people and masters of their craft. I worked with Quinton at Moorooka Yamaha in the mid 2000's (now Team Moto Yamaha/KTM) he has ran most workshops in QLD focussing mainly on dirt bikes

dieseldude 15-11-2017 09:57 PM

Soooooooo, I had the valves adjusted to be within spec and it now starts but runs like crap.

It was starting but only running or revving with the choke out. As soon as the choke was pushed in, it would conk out and stop running. It was also backfiring really badly.

I cleaned all of the jets in the carby and then had it checked over by a motorcycle shop. A couple of o-rings needed attention (air fuel screw and the needle and seat on the main jet). The bloke had the carby only and reckoned there was nothing wrong with the carby after sorting the o-rings.

I have just fitted the carby back in the bike and it will start and idle with the choke pushed back in, but as soon as the throttle is twisted, it bogs down and usually conks out.

Any idead guys? What was once such a great bike has all of a sudden become a massive headache.

Very keen to hear thoughts on what it might be.........

I'll note that changing the timing on the accelerator pump and moving the air fuel screw (1.5 - 2 revolutions out) seems to make no difference at all.

I have just pulled the carby back out and tested the squirt pattern. It seems fine to me.

I have also checked the timing and it is extremely close. When the cams are aligned with the hemishpere of the case, the timing TDC mark on the flywheel is slightly off the mark to the left. Skipping a tooth on the chain will make it worse, so I reckon the timing is ok.

Thanks very much.


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