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2007 WR450F Valve Help



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10 replies to this topic
  • Simsy

    TT Newbie

9 posts
Location: Australia

Posted October 01, 2016 - 02:15 PM


Hi all, Sorry for the long winded post. I purchased my WR second hand. The previous owner said that the valves clearances had been recently checked and were within spec. After around 400Ks riding i found that it was getting harder to start and was beginning to stall when the revs got low. I checked the clearances and found that the 2 exhaust valves were out of spec so i re-shimmed and was back in business, the bike was running great again. After approx 500 Ks riding since the re-shim again it was having similar problems. When cold it starts and idles fine but when warmed up it wants to stall. 

I rechecked the valve clearances and are still within spec, I have removed and cleaned out the carb, new  spark plug, i always keep the air filter clean and not that it should matter but i put new oil and filter in.

I have found that when the bike stalls it nearly always stops rotation at TDC so the Estart cant turn it over and the kick start is locked up. I can free it up by rocking it in gear.

I'm definitely no expert but i think it may be a sticking valve which is why the engine always stops in the same position. I'm going to pull the head off and take a look. Should i just replace all valves? The bike has done around 6000Ks.

Any help or input would be greatly appreciated.

 



  • Krannie McKranface
36,208 posts
Location: California
Garage View Garage

Posted October 01, 2016 - 02:53 PM


The locking up senario is typical, and normal.

 

Define 'cleaned out the carb' please

 

Have you put in brand new pilot jet

 

What is your current jetting



  • Simsy

    TT Newbie

9 posts
Location: Australia

Posted October 01, 2016 - 03:35 PM


I did not replace any of the jets nor did i check what jets were actually in it as it was running fine with them previously. I think the carb has been rejetted by the previous owner as he put on a GYTR pipe, Throttle stop was replaced with shorted YZ stop so i think he probably used some form of carby kit.

I pulled the carb completely apart and cleaned all ports by spraying carb cleaner and compressed air through. All jets were cleaned in an ultrasonic jewellery cleaner followed by blow out. I also soaked all parts in a carby dip for 4 hours followed by final blow out and re assembly.

I am aware of the TDC lockup problem in the WRs and have experienced it on occasion but it now seems to lock up almost every time.

Thanks for your input



  • Krannie McKranface
36,208 posts
Location: California
Garage View Garage

Posted October 01, 2016 - 05:22 PM


I did not replace any of the jets nor did i check what jets were actually in it as it was running fine with them previously. I think the carb has been rejetted by the previous owner as he put on a GYTR pipe, Throttle stop was replaced with shorted YZ stop so i think he probably used some form of carby kit.

I pulled the carb completely apart and cleaned all ports by spraying carb cleaner and compressed air through. All jets were cleaned in an ultrasonic jewellery cleaner followed by blow out. I also soaked all parts in a carby dip for 4 hours followed by final blow out and re assembly.

I am aware of the TDC lockup problem in the WRs and have experienced it on occasion but it now seems to lock up almost every time.

Thanks for your input

 

Put in a brand new pilot jet

Replace the slide plate seal and emulsion tube as they wear out 

If you put in a 12ah Li battery instead of the 9ah lead acic you will get less of the TDC lock up



  • Simsy

    TT Newbie

9 posts
Location: Australia

Posted October 01, 2016 - 07:00 PM


Cheers for the reply, i will pull the carb off again and replace parts as suggested. 

I have attached the carb blow up. Just to be certain i will need to replace parts numbered

 

19 (Pilot Jet)

17 (Needle Jet) or Emulsion tube

and i think the slide plate seal must be number 11. Can you please confirm or point me to the correct part.

 

Is this a common cause for hot stalling, i thought that once warmed up it must be slight expansion of valves etc that must be causing the problems, do you think i can rule this out? It would be great to leave the head alone for now.

 

Thanks again.

Attached Thumbnails

  • carby.JPG


  • Krannie McKranface
36,208 posts
Location: California
Garage View Garage

Posted October 01, 2016 - 07:11 PM


Part numbers are correct.

 

Either the valves have the correct clearance, or they don't. You have confirmed this.

Either the valves are leaky, or they are not. Confirming this requires a leak down test....but typically, leaking valves only show strong symptoms when cold, as in hard starting.

 

More common is corrosion on the stator harness, a stator that is dying (poor running only when hot),  a bad battery cell that is sensitive to heat, a poorly venting gas  cap,  or corroded grounds.



  • Simsy

    TT Newbie

9 posts
Location: Australia

Posted October 01, 2016 - 11:12 PM


So i have pulled the carb back off, the current setup is as follows

 

Main Jet - 175

Pilot Jet - 50

Starter Jet - 65

Pilot Air Jet - 70

Leak Jet - 45

Needle - GDDS Q 3rd clip from top

 

I ride close to sea level in warm but not too hot conditions.

 

Bike mods are

GYTR Exhaust

AIS Removed

Throttle stop removed

Grey wire mod done

 

Does this setup seem ok? the bike was running fine until recently.

 

Should i still just replace pilot and needle jets or replace the lot.

 

Opinions appreciated.

 

Cheers



  • Krannie McKranface
36,208 posts
Location: California
Garage View Garage

Posted October 02, 2016 - 06:00 AM


So i have pulled the carb back off, the current setup is as follows

 

Main Jet - 175

Pilot Jet - 50

Starter Jet - 65

Pilot Air Jet - 70

Leak Jet - 45

Needle - GDDS Q 3rd clip from top

 

I ride close to sea level in warm but not too hot conditions.

 

Bike mods are

GYTR Exhaust

AIS Removed

Throttle stop removed

Grey wire mod done

 

Does this setup seem ok? the bike was running fine until recently.

 

Should i still just replace pilot and needle jets or replace the lot.

 

Opinions appreciated.

 

Cheers

 

First off, lets make sure which version WR you actually have.....

 

Looking at the left side of the carb you will see either this: a blank 'casting' spot

 

DSC05838.jpg

 

..or one which is not blank, with a thing installed on the carb body....known as the ACV (air cut valve)

 

 

Either way, you jetting is waaaaay off.   I am assuming you are at 1000' elevation or below....

 

Main Jet - 175 - should be 165 with aftermarket pipe. 175 if backing off the throttle at wot makes run better (not rich enough)

Pilot Jet - 50 - should be 45. It will never run well with a 50

Starter Jet - 65 - should be 85, but 65 will work

Pilot Air Jet - 70 - this means you probably do have the ACV; lets ignore this for now

Leak Jet - 45 - a little big (smaller is bigger) but again not a huge deal

Needle - GDDS Q 3rd clip from top - this is a very odd needle. You are better off with the stock 2005/6 YZ needle or a NCVS aftermarket needle. Not sure what this needle actually is....

 

You make no mention of the fuel screw....which is critical for your issue, idle and off idle repsonse.

 

I would suggest getting an R&D remote fuel screw, a 45 pilot, an NCVS needle (3rd).

The Remote fuel screw is really not an option with these carbs. Adjust for highest idle when motor is HOT. Then drop the idle if too high with the idle screw.

 

Further, you should consider removing/blocking the ACV system on the side of the carb. This requires changing to a 110 pilot air jet. This will remove the vaugeness at idle/off idle. 

 

Search ACV in the WR section for details. Essentially, you pull the cover, cut the pointy part of the plastic thing, and re-install. Some just fashion a complete gasket and remove the plastic thing.

One this is done, you become too rich, hence the larger pilot air jet. This gets you pretty close to standard YZ spec (at idle at least).



  • Simsy

    TT Newbie

9 posts
Location: Australia

Posted October 02, 2016 - 03:50 PM


Mine has the ACV.

95% of my riding would be below 1000ft with occasionally just above, up to 1100- 1200ft.

Fuel screw is currently at 2 turns out i will definitely be changing the screw after having to adjust this last time (i actually made myself a super stubby screwdriver for adjustment but it was still a real pain to adjust)

 

I will change setup to the following:

 

Main Jet 165

Pilot Jet 45

Starter Jet (Leave at 65) Parts catalogue only ranges from 60-70 with 65 being standard, not sure where to get an 85

Pilot Air Jet will leave with 70 and ACV for now, having trouble finding a 110 jet

Leak jet probably leave at 45 for now unless suggested to change

The GDDSQ needle is listed in the 07wr parts catalogue im using but i will try to get a YZ needle anyway. 

Replace emulsion tube and slide plate seal.

 

Hopefully this will sort out my problems.



  • knuckleduster271

    TT Bronze Member

222 posts
Location: Ohio

Posted October 04, 2016 - 05:44 AM


Im at roughly 1200' asl.
With similar mods i ran a jd "blue" needle at the 3rd notch, 170 main, 48 pilot and fuel screw between 1.75 and 2 turns out. The other jets were stock- Bike ran perfect.

Edited by knuckleduster271, October 04, 2016 - 05:48 AM.

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  • Simsy

    TT Newbie

9 posts
Location: Australia

Posted October 13, 2016 - 05:34 PM


So i have made the changes to the carb as per post #9.

I have been trying to setup fuel/idle screws however think I still have the original stalling problem once hot.

 

The bike fires straight up on choke, better than it ever has so im happy with that. Again I have to keep the bike running above 3000rpm to keep it running.

I have adjusted the fuel screw to 1 3/4 turns out which has the bike running at its peak revs of a 3800rpm. I then try to adjust the idle screw to get the revs down to around 1800rpm however the bike stalls below 3000rpm.

 

I set the bike to the lowest possible idle of around 3100rpm, while sitting idling the rpm surges between 2900-3400 on its own and will still stalls out at times.

 

The bike shop who sold me the carby parts said i was was probably wasting my money on emulsion tube and needle however were still happy to take my money. They suggested that it was probably a faulty coil pack however said since it was only failing when hot it couldn't be tested. Im running out of options and money does a coil pack seem like the next thing to try?

 

Any help appreciated.

 

Cheers






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