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Snow Drift

Clutch Adjustment and General Running Where to Start?

30 posts in this topic

Hi Everyone

 

This is my first post. I have been reading around this forum and can see so much information that I need to learn. I have just bought (4 weeks ago) a 2007 WR450. The bike has only done 400 miles but hasn't been maintained to the highest of standards during those miles. The bike hasn't really been ridden for 18 months.

 

I haven't has a chance to ride the bike really since I bought it as I wanted to check things over and sort the air filter first. I have taken off the airbox and filter, cleaned the airbox thoroughly, and bought a new twin air filter. I took the bike out around my garden this evening and found the following.

 

1. The clutch isn't fully disengaging, when I pull the clutch in the bike still wants to go slighly and this means that unless I keep the revs up it will put load on the engine on tick over and stall the bike.

 

2. The bike doesn't like to be ridden slowly. When I go into first gear and slowly take a corner at a fast jogging pace without pulling in the cluch the bike almost wants to stall.

 

3. When I restart it after it has stalled I have to open the throttle literally a fraction as when completely closed it doesn't want to start.

 

The bike pulls strong once going. The bike seems standard, grey wire still connected, air box still standard, AIS still there. I didn't want to start messing with things yet as I wanted to get a general feel for the bike and ride it a few miles first. I don't know what the best way of sorting the bike is as it clearly has an issue with the clutch and possibly carb.

 

I don't know whether the 18 months not riding means the clutch just needs to be used for a bit to free up. I don't know if I need to adjust the clutch and how to. I don't know if there is also a problem wiith the carb, TPS, etc. What is the best way forward to get the bike running properly?

 

thanks

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Sorry maybe that was a bit of a long and demanding post.

Basically I just wondered if there is a specific procedure for setting up the clutch if it is starting to drag and not disengage properly.

The second question is about starting and the bike running at very low rpm. It seems to need the throttle to be open about a milimetre otherwise it doesn't like to start. It seems to stall when you try and ride it very slowly. When I try and start it again the compression seems so high that the start often gets stuck and I have to try and kick it over a little before I can then try the starter again. I am just wondering then if this suggests that the TPS is not good, the carb settings are all wrong etc. I presume that it should roll out the factory working without the need to fiddle, rejet, modify etc. What is the starting point for elminating the problem and then next steps?

any advice would be appreciated

thanks

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All normal symptoms with a stock bike.

You need to read the pinned posts at the top of the forum about your specific year and model.

Essentially, you need to un-cork, re-jet, and it will run fine.

The WR clutch plates will warp very easily with the bike in stock jetting, as it runs way to hot, and the clutch gets too hot.

Even then, the clutch will never completely disengage properly with a cold motor, and will always drag a little.

Adjust your clutch cable to get the cable slack down to 5mm when hot.

If that puts the clutch lever in a bad place for you, then you can get an adjustable lever.

 

YOU NEED A SERVICE MANUAL

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Also check you idle speed. These bikes don't like to idle slow. Its needs to be 2000 + - 100 rpm.

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1. The clutch isn't fully disengaging, when I pull the clutch in the bike still wants to go slighly and this means that unless I keep the revs up it will put load on the engine on tick over and stall the bike.

 

2. The bike doesn't like to be ridden slowly. When I go into first gear and slowly take a corner at a fast jogging pace without pulling in the cluch the bike almost wants to stall.

 

3. When I restart it after it has stalled I have to open the throttle literally a fraction as when completely closed it doesn't want to start.

 

 

1) Adjust the clutch so there is aprrox 5mm free play end of lever, when the engine is hot

 

2) The bike is geared too high as std. First is too high to use without the clutch. drop down to a 13T or even 12T front sprocket (with 50T on the back) and it will feel like a different bike (I run a 12T front, and my bike had a 14T on as std from Yamaha )

 

3) Are you pulling in the the hot start lever on the left handlebar (sounds like you are not) - this allows extra air into the engine to allow the bike to start when hot. opening the throttle (like you  do on a two stroke) actually puts more fuel into the engine coz it activates the accelerator pump

Edited by GuyGraham

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Thanks for the replies.

 

1. Can you explain what you mean when you say 5mm free play end of lever when the engine is hot. For some reason I'm having a little trouble understanding how to adjust and measure this.

 

2. Right I was hoping that someone would say something along these lines as I was starting to think that something was really a miss. I mean in the standard gearing I don't know how anyone could do slow technical sections on their rides. How do I decide between 13T and 12T? I suppose I'm going to be doing quite relaxed riding compared to others till I get used to it.

 

3. I honestly don't know how often and when I am safe to use the hot start lever. I don't know if it damages the engine to use it too much. I thought that you were only suppose to use it to decompress the engine then let it go and then start the bike. Are you saying I should actually keep it open until the bike fires?

 

 

I really am suprised that the bike doesn't run okay even with out doing the mods in the pinned posts. I thought. I am wondering if there is crap in the carb or if there is any problem with the TPS, because I really do come off the bike thinking "that bike isn't happy". Also when I open the throttle a little bit too much when trying to get it to fire, it backfires. I don't know if that is normal.  I have read some of the pinned posts but not in detail about the jetting. I hope that it is stated what jets I need as I have no idea how to choose jetting.

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When you put your hand on the clutch lever , how much does it move before you feel resistance (taking up the cable slack)?

That is the 'free play' and you measure it right at the gap between the lever and the lever perch.

It is not critical, as long as it is not tight.

Many people add in more slack  to position the lever closer to the bar, but that prevents full disengagement.

 

You need to go through the carb because no it should not backfire.

If the carb has not been brought back to new specs, it will act strange, period.

http://www.dirtrider.com/features/protips/141_0707_keihin_fcr_carb_rebuild/

 

Hot start just adds cool air to the combustion chamber for easier HOT starting.

It has nothing to do with decompression.

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I tried 13T first but found that I was still having to used the clutch too much in first, in the tight stuff, so I dropped down to a 12T which isjust baout right (for me anyway). the bike will still do well over 70mph with a 12T so no concerns there about running out of revs on the fast stuff

 

As you are in the UK, you can get front sprockets hear for £7.68 each

http://www.motorcycleproducts.co.uk/sprocket-yamaha-wr450-2007-09-front-12t-p-179589.html

It will wear faster, but the trade off is worth it

 

 

As Krannie says above, Hot start just bleeds extra air into the engine.

You can pull on that lever all day long and it will not damage your engine.

You need to use it when trying to start the bike with a hot engine (ie after a fall or a stall) - think of it as a reverse choke (the choke adds extra petrol for cold starting, the hot start lever adds extra air for hot starting - easy)

 

TPS doesn' too much - don't worry about it, its not causing your problems.

 

Where bouts in the UK are you?

 

As regards jetting

Start with

168 main jet

The std needle as the bike comes form Yam (NNHU) is there for emissions reasons only (the bike barley runs with it). They supply another needle in a little bag with the bike (GDDUQ) - put the clip in the middle groove to start with

Leave pilot jet as std (48)

Pilot screw - 1.5 - 2 turns out from fully seated

 

Have you replaced the throttle stop screw?

Edited by GuyGraham

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Ok thanks I think I understand about the hot start lever now and also the clutch adjustment so that is good to know.

 

Understood about the front sprocket, I think I will go for 12T as I want to be able to ride some slow woods or trail sections without having to use the clutch so much.

 

I live in Dorset/Somerset and close to Talon so I will probably get a sprocked from them soon.

 

Although I'm probably coming across as someone with no mechanical knowledge I usually have a go at sorting things and only like to do things when it is done properly. However, I really don't understand about carbs and how they work with the different jets. To my knowledge the throttle stop screw hasn't been done, but then again it doesn't seem too badly restricted when I rev the engine.

 

I see that people talk about JD jetting kits, is this what I should be buying and can you buy them anywhere in the UK at a decent price. I don't mind getting the slightly better kit as long as I can sort the bike out and not have ongoing hastle as I really want to get on it and ride now. Do you buy jet kits or buy them individually?

 

Krannie what do you mean when you say "If the carb has not been brought back to new specs, it will act strange, period."? The carb is as it came out the factory to my knowledge.

 

I also guess that I need to get an AIS removal kit, I can't seem to see if the Yamaha GYTR kit is sold in the UK. If I ring my Yamaha dealer in Bristol should they be able to source this?

Edited by Snow Drift

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The bike will run just great with the jets/needle quoted above

The FCR carb is highly tuneable and lots of different needles are available

 

This shows you the difference in throttle stop screws

No need for the AIS removal kit (you can't get it in the uk anyway)

 

http://www.thumpertalk.com/topic/370721-2007-wr450-performance-mods/page-15

 

If the carb has been put back to how it came from Yamaha then it will run like asthmatic pensioner - get the jets/ needle quoted above (you can buy them as Yamaha spares)

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I just went out to my bike and checked the throttle. When I twist it it turns a quater of the way round, so I'm guessing this means that it has the original stop screw.

 

Ok so if I ring up Yamaha dealer I need to ask for the following:

 

  • 168 main jet
  • needle jet GDDUQ
  • YZF throttle stop screw

 

Looking at the pinned posts about the mods etc, there is mention of the fuel screw on the bottom of the carb bowl and punching out the plate in front of it. Do I need to have anything to do with this? Also it mentions replacing the leak jet for a smaller size?

 

Basically I don't want to have to take the bike to bits again a week or two after doing the above jets as it is quite time consuming to do all this learning as I go.

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I just went out to my bike and checked the throttle. When I twist it it turns a quater of the way round, so I'm guessing this means that it has the original stop screw.

 

Ok so if I ring up Yamaha dealer I need to ask for the following:

 

  • 168 main jet
  • needle jet GDDUQ
  • YZF throttle stop screw

 

Looking at the pinned posts about the mods etc, there is mention of the fuel screw on the bottom of the carb bowl and punching out the plate in front of it. Do I need to have anything to do with this? Also it mentions replacing the leak jet for a smaller size?

 

Basically I don't want to have to take the bike to bits again a week or two after doing the above jets as it is quite time consuming to do all this learning as I go.

 

You'll need the parts numbers

  • 168 main jet - 4MX-14943-91
  • needle jet GDDUQ - 5TJ-14916-91
  • YZF throttle stop screw - just cut it down if it is still the original one - dimensions are in the link above (its horrifically expensive from Yamaha, for what is basically a screw)

 

When I twist it it turns a quater of the way round, so I'm guessing this means that it has the original stop screw

Hard to tell - take the screw out to confirm - you can get it out with dismantling anything. Its a bit of a fiddle but it can be done

 

there is mention of the fuel screw on the bottom of the carb bowl and punching out the plate in front of it. Do I need to have anything to do with this?

No, this is an American thing - the UK bikes do not have this

 

Also it mentions replacing the leak jet for a smaller size?

The std #50 is fine

 

You may want to check the AP squirt timing (use a dgiital camera) ,and also do the O-ring mod on the AP linkage. Also, pull the snorkel out of the airbox if it is still there (it comes out by undoing 4 screws), and chuck it in the bin.

Edited by GuyGraham

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Krannie what do you mean when you say "If the carb has not been brought back to new specs, it will act strange, period."? The carb is as it came out the factory to my knowledge.

 

?

My point is that unless you KNOW the inside of the carb is all working properly you must assume it is not, especially the trouble spots: 

- accelerator pump diaphragm, cavity, leak jet, 

- pilot jet

- air jet (inside intake bell)

- float height

- float needle (needle tip is not grooved)

 

A sitting bike it the hardest thing on a carb. 

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GuyGraham

 

Thanks for the part numbers. When you say check the AP Squirt timing, is there a thread explaining how you do this? Also I couldn't see in the free mods section anything about O-ring mod on the AP linkage?

 

When I took the airbox off to clean thoroughly I thought of leaving off the snorkel but then thought that the design of it probably stops dirt and water from entering the box too easily. Although a little restrictive do you not risk chuncks of dirt and water running off the seat/mudguard and going directly into the box with the snorkel off?

 

Krannie

 

I see your point. I guess when I take the carb off to replace the jets I need to give it a good clean. I hope that the float level isn't an issue as I starting reading about that once and thought it sounded quite tricky.

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You should re-jet the main, pilot, jet needle, replace the needle jet, open the air box, buy a remote fuel screw, and you will be done.

 

162 or 165

45

NCVS or JD Red

stock

4 x 4

R&D Racing

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GuyGraham

 

Thanks for the part numbers. When you say check the AP Squirt timing, is there a thread explaining how you do this? Also I couldn't see in the free mods section anything about O-ring mod on the AP linkage?

 

When I took the airbox off to clean thoroughly I thought of leaving off the snorkel but then thought that the design of it probably stops dirt and water from entering the box too easily. Although a little restrictive do you not risk chuncks of dirt and water running off the seat/mudguard and going directly into the box with the snorkel off?

 

Krannie

 

I see your point. I guess when I take the carb off to replace the jets I need to give it a good clean. I hope that the float level isn't an issue as I starting reading about that once and thought it sounded quite tricky.

 

There's a thread on here somewhere explaining AP squirt and the O-Ring mod - I think its in the FAQ. Use the search function and you will find your answers

Basically you  are checking the timing of the squirt is such that it just misses the slide

Hang carb off side of bike, and with a digital camera film the squirt as you rapidly open the throttle. Duration needs to be less than a second (controled by the leak jet) and the squirt should just miss the slide as it lifts. You can check both of these by replay the film clip on your pc frame by frame

The o-ring mod improves the reaction of the the AP squirt so you don't get a bog when you twist the throttle. anothe ralternative is to fit a stronger springs to the AP linkage but I don't know where to source one in the UK

 

 

Removal of the snorkel allows more air in. No need to worry about dirt or water it makes no difference. The snorkel reduces intake roar which helps the bike pass noise emission tests so it can be registered for the road - get rid

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OK thanks lots of useful information there and I found the FAQ about the AP linkage. It is a shame that we don't have all the mod bits that the US seems to have.

 

I don't mean to insult anyone but what is the deal with jetting is it an individual opinion as to what jets to use or is Krannie suggesting different jets because he is in California with different climate and altitude. Or is it the case that each bike is different and i'm going to have to try different jets to get the right size for my carb?

 

I just want to make sure that if I'm going to have to play around with the jets that I've got all the jets I need before I start. Would it be cheaper/sensible to buy a set of jets or do I really only need to change the main and needle jet.

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OK thanks lots of useful information there and I found the FAQ about the AP linkage. It is a shame that we don't have all the mod bits that the US seems to have.

 

I don't mean to insult anyone but what is the deal with jetting is it an individual opinion as to what jets to use or is Krannie suggesting different jets because he is in California with different climate and altitude. Or is it the case that each bike is different and i'm going to have to try different jets to get the right size for my carb?

 

I just want to make sure that if I'm going to have to play around with the jets that I've got all the jets I need before I start. Would it be cheaper/sensible to buy a set of jets or do I really only need to change the main and needle jet.

There is no way to know exactly what jets you need because of the condition of your carb, motor, pipe, aircleaner, valves, etc, but the jetting I present will get any WR450 up and running  pretty well if you do it all at once.

A mere change of the needle jet position should handle most situations, unless you are always above 8,000 ft. Then you just go down to 42/160 and drop the needle.

 

Four strokes are not like two strokes where very specific jetting is required, and it provides only a very small window of operation.... so you will be fine.

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I bought a 12T front sprocket and tried to adjust the clutch before beginning down the path of rejetting. Interestingly the bike was running on a 13T front sprocket, the change has helped though I think. Now that I'm utilising the hot start lever properly I think the bike is actually running not too badly.

 

However, there is still a big problem with the clutch. When cold the clutch isn't too bad. Once warmed up the clutch really refuses to properly disengage. I mean with the clutch fully in I'm barely able to hold the bike still with my feet on the ground. By adding any free play to the clutch it just seems to mean that it is even less likely to disengage.

 

The bike has only done about 400 miles so I really don't want to have to start pulling the clutch to bits and changing plates if I don't have to. The bike hasn't really been run properly in 18 months. I have only really ridden it a couple of times round my garden. Do I need to give it a good long ride before the clutch will free up or is there likely to be a bigger problem do you guys think?

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I bought a 12T front sprocket and tried to adjust the clutch before beginning down the path of rejetting. Interestingly the bike was running on a 13T front sprocket, the change has helped though I think. Now that I'm utilising the hot start lever properly I think the bike is actually running not too badly.

 

However, there is still a big problem with the clutch. When cold the clutch isn't too bad. Once warmed up the clutch really refuses to properly disengage. I mean with the clutch fully in I'm barely able to hold the bike still with my feet on the ground. By adding any free play to the clutch it just seems to mean that it is even less likely to disengage.

 

The bike has only done about 400 miles so I really don't want to have to start pulling the clutch to bits and changing plates if I don't have to. The bike hasn't really been run properly in 18 months. I have only really ridden it a couple of times round my garden. Do I need to give it a good long ride before the clutch will free up or is there likely to be a bigger problem do you guys think?

 

Your clutch is always going to drag a little.

A 2007 with hours is going to have glazed fibers and slightly warped steels.

If you want more disengagement with less lever through, you will have to put on new fibers and steels.

...and it will still drag a little. It's the nature of that clutch.  All Yamaha 's do it to some degree. That's one reason the shifting is not buttery smooth like a honda.

All you can do to make it better is to modify the clutch lever at the case, to be 5mm shorter, which will make it possible to be puledl farther when properly set up, but harder to pull.

Do you know if you have the stock clutch lever on the bars?

If someone replaced it with the wrong one,  that might be the problem....not enough leverage and throw.

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