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highcam

wr426 kick starter wont move, but can turn from crank

45 posts in this topic

Hi all,

Was having a rough night and decided to take the bike for a ride... usually helps...not today..

I own a WR426 [(supermoto trim) (incase u didn't know after the title, lol)] anyways when i was out riding the bike started hesitate and began bucking a bit... the engine felt like it was dieing, so I pulled in the clutch... engine stalls.

I go to try and kick start, and the kick starter won't budge. I'm thinking great, the engine is seized up ***.

So I got my friend with a truck to come pick me up and bring the bike home. I drain the oil and there is some metal in it but nothing like I expected. I pull out the two big plastic screws on the case and take a socket wrench to the crankshaft nut... and it turns the engine like butter. If i play with the kick start eventually it will seize but will always turn easy from the crank shaft...

I am kind of lost.. I guess I am happy my motor isn't 100% grenaded but has anyone else experienced anything like this?

Suggestions?

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I would pull the valve cover and take a look. Broken timing chain maybe?

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ok, so I pulled the valve cover... Timing chain is fine. I also noticed that the position of the crank/camshafts don't appear to have anything to do with when the engine seizes via the kick starter.

I am open to suggestions. I think next I will pull the casing off of the right side of the engine and see if I can see anything transmission related...

any one have this problem before?

Edited by highcam
updated

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Check the kick starter gear. It should be under the right side engine cover, the cover that the clutch cover attaches to.

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take a socket wrench to the crankshaft nut... and it turns the engine like butter
How easy is "butter"? Were you able to turn is over w/o holding the compression release?

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Check the kick starter gear. It should be under the right side engine cover, the cover that the clutch cover attaches to.

That's my suggestion too

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How easy is "butter"? Were you able to turn is over w/o holding the compression release?

i mean easy enough where it does not feel seized. I can feel it compress, and then i can hear it suck air through the air box... In other words no I do not have to hold the compression release lever... But it is not turning so easy as if the crank is not attached to anything....

Once I have time (hopefully this weekend) I will be pulling the case off of the kick starter side. After looking at the exploded diagram in the service manual, I am very surprised that the kick starter assembly consists of 23 parts!

I will update as soon as I know something new...

In the mean time I am still open to any other suggestions.

Thanks so far everyone

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The kick start stopper is known to fail and the resulting pieces like to get caught in other gears and ruin them. It is possible for it to bind up the gear on the backside of the clutch basket.

The easiest thing to do is pull the clutch basket and look up at the kick starter parts. The stopper is bolted to the case in front of the kickstart shaft

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Its been a whole but I finally had a chance to do some work on the bike. Pulled the clutch basket kick assembly is fine. All the gears behind the clutch are in really good shape, however there is definitely quite a bit of metal shavings/particles on the bottom of the engine, and when i turned the engine over a few times the oil that started dripping out of the drain looked to be about half dissolved/small particle metal... Good thing i just bought a new full exhaust :thumbsup:

So as more time frees up (after Thursday) i will be pulling the engine and starting to tear it down.... see what I find.

Keep the good comments/suggestions coming I know it could be about a million things at this point but would like to hear things to look for etc.

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fwiw..

theres going to be some metal shavings, particulate as these bikes dont have a real filter element other than a wire mesh screen.

if you can get some pics of the "shavings"

with the clutch side cover off, remove the spark plug and install the kick lever.

rotate it down a few times(by hand) to see if everything is functioning correctly.

just my .02 though its prolly worth -10.00

good luck tomorrow.

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so I pulled the motor last night. Pulled the cams and head... cams were within tolerances. The cylinder is scored up pretty bad, so that will need to be replaced. I also noticed that the crankshaft is discolored on one side I am assuming it is from heat as it has that rainbow/heat discoloration color... so I am guessing that will need to be replaced as well.. also the cam chain is pretty stiff so gonna need a new cam chain as well!! Haven't taken a good look at the valves yet so but i do know titanium valves aint cheap. Sooo its not looking good so far... I guess I will see what else is wrong as I keep getting it taken apart

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so I pulled the motor last night. Pulled the cams and head... cams were within tolerances. The cylinder is scored up pretty bad, so that will need to be replaced. I also noticed that the crankshaft is discolored on one side I am assuming it is from heat as it has that rainbow/heat discoloration color... so I am guessing that will need to be replaced as well.. also the cam chain is pretty stiff so gonna need a new cam chain as well!! Haven't taken a good look at the valves yet so but i do know titanium valves aint cheap. Sooo its not looking good so far... I guess I will see what else is wrong as I keep getting it taken apart

The rainbow color on the crank is normal.

I'm guessing it's something in your tranny/ kickstarter gear if the crank turns over easily. What is the cylinder damage from? How does piston look? Lower crank bearing?

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the cylinder damage appears to be from the piston... maybe the ring was out of spec?? I'm not sure. As far as the kickstart gear- its fine. I pulled the clutch basket first, and all of the gears behind it and on the clutch basket its self looked near brand new. I figure I may as well go through everything at this point anyways....

As far as the bearings I am not sure yet, I need to take more apart, it is rather difficult to spin the engine right now as the timing chain wants to bind up.

The discoloration is normal? I am assuming it is from heat but why would it be only on one side of the rod if it is not from a failing bearing or other fault?

sorry for the cell phone pic but this is the cylinder

IMG_0407.jpg

There was also some slight grooving on the opposite side of the cylinder but it was worse on this side. These are the two sides were the piston has the longer flanges if you know what I mean...

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Rainbow discoloration on the crank is normal, but not the rod. Would help if you had a good pic. How does the bearing feel at the bottom of the rod? Any up and down play?

The cylinder damage could be from pieces of the rods needle bearing...

Timing chains on this bike are there weakest link. Needs replacing every year or two depending on how much you ride.

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Rainbow discoloration on the crank is normal, but not the rod. Would help if you had a good pic. How does the bearing feel at the bottom of the rod? Any up and down play?

The cylinder damage could be from pieces of the rods needle bearing...

Timing chains on this bike are there weakest link. Needs replacing every year or two depending on how much you ride.

I will get a good picture of it asap. I have to first get the decent camera back from the girl-- I tried to snap a pic with my phone but the quality is not high enough to tell what is going on inside the case. But for now to try and get the point across:

http://www.partforyamaha.com/pages/OemParts?aribrand=YAM#/Yamaha/WR426F_-_WR426FN_-_2001/CRANKSHAFT_PISTON/WR426FN_%282001_MOTORCYCLE%29/CRANKSHAFT_PISTON_%28WR426FN_-_2001%29

the discoloration is on part number 3.

There is definitely some side to side play, as far as up and down its hard to tell....

The needle bearings from the rod damaging things is good point, I did find what looks like a piece of a needle bearing... I set it aside as I was not sure what it was from....it looks kind of similar to a spoke nipple(about the size of one for a mountain bike).

Thanks for your help so far.

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I will get a good picture of it asap. I have to first get the decent camera back from the girl-- I tried to snap a pic with my phone but the quality is not high enough to tell what is going on inside the case. But for now to try and get the point across:

http://www.partforyamaha.com/pages/OemParts?aribrand=YAM#/Yamaha/WR426F_-_WR426FN_-_2001/CRANKSHAFT_PISTON/WR426FN_%282001_MOTORCYCLE%29/CRANKSHAFT_PISTON_%28WR426FN_-_2001%29

the discoloration is on part number 3.

There is definitely some side to side play, as far as up and down its hard to tell....

The needle bearings from the rod damaging things is good point, I did find what looks like a piece of a needle bearing... I set it aside as I was not sure what it was from....it looks kind of similar to a spoke nipple(about the size of one for a mountain bike).

Thanks for your help so far.

Well thats probably normal. These bikes come with a rainbow discoloration there that many will mistake for damage. Would have to see a good pic to be sure.

Some side to side in the rod bearing is normal, check the side clearance via the manual. Any up and down play is a no no. How about a pic as well of the piece you found.

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I will get some pictures up asap, however it will probably not be until Thursday.

I have had a really busy day today, and will again tomorrow and Wednesday.

Once again thanks for the help, and I'll get some more stuff up on Thursday.

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Got some pictures today... tore a bit more of the engine down. I am in the process of making a part so I can pull the CDI Magneto wheel off.

Look through things closer, the crank shaft has too much play in it.

Anyways here are the pictures of the discoloring and of the part I found that I don't know where it came from. Once again sorry for the cell phone pics- I have not been able to get the other camera yet.

IMG_0410.jpg

IMG_0411.jpg

IMG_0413.jpg

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Well thats definately your culprit. That's not normal, heat induced for sure, and that piece looks suspiciously like a piece of a needle bearing.

I don't know on the older models but for my 07 I can get a new OEM crank for $225. You'll want to replace the main bearings as well. And since you have the cases split, all the tranny bearings and seals.

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The crank does look a bit suspicious...though that IS where they are blue from the factory. It's just usually more uniform. It's from locally heating the crank halves to enlarge the pin holes. That makes it easier to put the crank together.

Looking at that pin, it actually looks like the plunger that goes in the shifter drum for the neutral switch. The mushroom head on the right side looks to consistant to be displacement type damage...

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