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Discussion Starter #1
A friend of mine has a 2006 650 trailbuck EXT with 5888 miles that the engine started knocking on so I told him I would take a look at it. From everything I have read on it, it is the same as a 650 Quest XT. I started tearing it apart and found that the crankshaft bearing/insert where the rod connects is gone, I can move the rod 1/8" on crankshaft. At this point it looks like I will need a new piston, rings, probably rod and crankshaft to fix it. What are my options for a crank so far the cheapest I have seen is around $700. Also from what I can tell there is no oversize piston for these so does that mean it has a coating on the cylinder and I will have to send it off to be recoated or am I just looking in the wrong place for parts?

Thanks for you help in advance.
 

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Discussion Starter #2
Has no one not had this issue before?

I have it partially tore down and should finish tonight, it is definitely the insert that is gone based on all the metal pieces I have found around the oil screen.

It also appears there may be oversize pistons available, just wanted to confirm with someone that has seen this before.
 

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Discussion Starter #4
I think there is to much scoring on the cylinder walls not to bore, but I will measure it. Hopefully I can find an oversized piston to put in it.

Right now I need a crank, rod, rod inserts, rod end, piston and rings and various seals does anyone know of a good place to order parts from that is reasonably priced?

Also how can I determine if the oil pump and timing chain need to be replaced?

There was a fair amount of metal debris in the bottom part of the engine, only about quarter of the rod inserts were still in the rod, when I got it apart.

The timing chain seemed to have more side to side flex to it then other timing chains from other bikes and quads I have messed with in the past so I was wondering about it.
 

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i just took my jd trail buck 650 apart , i bought it and crank was seized to crankshaft , spun the bearing. the last owner said they ran it through water and then it stopped running. i cleaned up crank of metal stuck to it, bought a new bearing. oiled and installed to to torque spec or if you still cannot turn crankshaft tighten so you can at least rotate crank a couple of revolutions. kinda remember or mark where it gets hard to turn or sticks. then remove rod and look at bearing high spots remember where it was hard to turn and you can pretty much figure out what material you will have to remove on the crank .it might take you a few times to get it right. if possible wrap emery paper around old bearing and then move back and forth to remove high spots so it removes material uniformly . when you are all said and done and torqued up to specs you should not have any binding , if you have i little and i say a little its probably ok. if the rod bearing is to messed up from fitting you can go buy new bearings . the main thing you don't want is an oblonged crankshaft journal. i measured mine and it was at the max limit maybe a hair over when finished. i have done this a diesel engine before which took me quite a while and there were over under bearings available. my 650 does run with no knock. i think continuous oil around the crank is key thats why you don't want any binding. i used mostly 600 emery paper and 320 cloth on a difficult spot oil cloth and paper keeps it cleaner and from plugging up 320 takes it off pretty quick so you do a little and check . it's cheaper than a crank if you have the time. good luck
 

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Discussion Starter #6
Thanks for the response, how long have you been running it since the fix? This one was so bad that I don't think I would want to attempt your method with emery cloth, but instead would have to go to straight rough sand paper to even get it close. I found a place that specializes in rebuilding cranks and have sent it off to them, total cost for the repair will be $400, which is about half what I could get the cheapest new crank for. It just gives me the piece of mind that I did all I could do and since the cost of the oversized piston/rings, rod, rod bearing, head/base gaskets is pushing $400 and that doesn't include all the other engine gaskets and seals that ought to be replaced also. I would rather not spend the money on them and then in a few hundred miles have it knocking again. My dad used to rebuild cranks back in the day and his recommendation was to rebuild this one versus buy a new one especially since these guys know what their doing.

One odd thing I did find when I took it apart was that it was missing the crankcase shim on the cam chain case side. On all the parts diagrams I have looked at it shows one on each side of the crank, maybe this helped attribute to it failing. I do know it took dirt because both intake valves are shot and they told me the small hose coming from the airbox was found to be cracked which they replaced and it ran quite a while after that before starting to knock.

Does anyone know what all comes in the complete engine gasket kit for $278? Does it include all the engine seals too? I would like to replace what I can while it is apart so I don't have issues down the road.

Thx
 

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I just went through this with an 05 TrailBuck. The previous owner ran it out of oil, and had a local shop put in a new crank, a year later it started knocking, so they sold it, to me.
I tore it down and found the bearings went bad, I think what happened was that they only replaced the crank, and left the rod, the rod had obviously gotten very hot, and looked out of round.
I sent my crank to CrankShaft Craftsmen in Detroit, they welded, ground, and polished it back to new for $150, plus $10 to ship.
I also replaced the rod, and all bearings and seals.
My piston, and cylinder looked very good, my ring gap was within spec, so I left it alone.
I think I was into it for around $600 or so.
 

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jd trail buck

Thanks for the response, how long have you been running it since the fix? This one was so bad that I don't think I would want to attempt your method with emery cloth, but instead would have to go to straight rough sand paper to even get it close. I found a place that specializes in rebuilding cranks and have sent it off to them, total cost for the repair will be $400, which is about half what I could get the cheapest new crank for. It just gives me the piece of mind that I did all I could do and since the cost of the oversized piston/rings, rod, rod bearing, head/base gaskets is pushing $400 and that doesn't include all the other engine gaskets and seals that ought to be replaced also. I would rather not spend the money on them and then in a few hundred miles have it knocking again. My dad used to rebuild cranks back in the day and his recommendation was to rebuild this one versus buy a new one especially since these guys know what their doing.

One odd thing I did find when I took it apart was that it was missing the crankcase shim on the cam chain case side. On all the parts diagrams I have looked at it shows one on each side of the crank, maybe this helped attribute to it failing. I do know it took dirt because both intake valves are shot and they told me the small hose coming from the airbox was found to be cracked which they replaced and it ran quite a while after that before starting to knock.

Does anyone know what all comes in the complete engine gasket kit for $278? Does it include all the engine seals too? I would like to replace what I can while it is apart so I don't have issues down the road.

Thx
i have only run it about 1 hour ,i have never seen it run since i bought it partially apart and siezed, anyways it smoked pretty bad so i did a leak down test and found rings to be bad .i should have replaced when i had it apart but i did not want to spend alot of money if it was going to knock. i just got parts and will put back together this week hopefully. i'll keep you posted
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i do have another problem, next to the battery there is a box with about 8 wires on 1 plug rectangular shape going into it with 2 additional wires coming out , one goes to chassis ground the other has a ring terminal on it and it went to the round starter solenoid . i don't know which one it went to . what i would really like to know is what it does? and i am pretty sure it is a power wire , but is it only to be powered on start or continually. it started and ran without wire connected. i cannot find a wiring diagram for the trail buck 650, j d is not much help. can am on the other hand is very helpful they gave me a wiring diagram but i'm not sure it's the same. if maybe you could test that wire and tell me if it's hot only in start or run? thanks weldon44
 

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Discussion Starter #9
Is it a larger gauge wire? I have two larger ground wires that run over to the starter, not sure we are talking about the same wire. Send me a pic of it. I have a copy of the JD manual for mine that I could scan the diagram for you if that helps.

I just finally got all my parts last week and the engine back in the quad last night. I started it tonight and it ran for about 25 seconds with my thumb on the throttle and then I noticed there was gas spraying out the vent on the right side of the upper part of the carb and when I let go of the throttle it died. I got it to fire back up again so I could verify for sure where the gas was coming out, but I had to choke it and and hold the throttle to get it going again. It was shooting out a steady stream of gas which I have never seen before. I checked the timing just to make sure it was okay and it was so I guess my next step is to pull the carb off and apart. Has anyone had this happen before?
 

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Discussion Starter #10
I pulled the airbox off tonight and then took a screwdriver and tapped on the float bowl (I tried to tap on it last night, but there wasn't a good way to get to it). I then tried to start it and it started and ran great right away. How much valve noise are these things suppose to have? It seems like to me that it has alot compared to most other motors I have dealt with, but then I have messed to much with hydraulic lifters either. I did have the valve seats recut and had to replace both intake valves, maybe it just needs time to seat everything back in. Even when you turn it over by hand you can hear the springs or rocker arms release.
 

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trail buck 650

i don't know how much noise they are suppose to make, i still have mine apart .when it was running i thought it was pretty quiet hopefully next week i'll get back to it.i 'll try to get a picture of that wire i am talking about. some other person posted that they sent crank and rod and had it spray welded and fitted to specs i'll see if i can send to you i'm not to handy when it comes to computer and sending things i'll try . nice talking to ya
 

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Discussion Starter #13
I replaced the intake lifter arm and it is much quieter now. It actually runs pretty decent not sure it will take my 650 Prairie though. At idle it has a lope (over cammed kinda sound) that reminds me of what the 700 Polaris Sportsmans sound like, once you get above the low end throttle it smooths out fine. I probably need to do some adjustment on the low end to try to smooth it out but other then that get it broke in good and return it to my friend. I will say I do really like the box on the back, kinda handy for throwing stuff in, but the seat setup isn't to kid friendly, my 3 yr old is always falling off the front of the seat onto the little luggage area.
 

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just something to think about,

i reciently dumped a bunch of "Sea Foam" into the crank case of my 500 and after riding it for maybe 25kms or so i've noticed that there seems to be a lot less noise coming from the lifters. also i noticed that the shift procedure seems alot smoother and maybe the clutches are grabbing better 'cause now i can fish tail the bike and get it going sideways and that wasn't happening before.

if you can still hear your lifters maybe give it a shot. if you do tho, make sure that you only run the "Sea Foam" in the crank case for maybe 100kms or so then change out to your regular oil of choice.
 

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Discussion Starter #15
Then thing keeps randomly leaking gas out the carb like it did the first time I started it after the rebuild. I thought it was a vacuum type system so I shouldn't have this issue especially with it just sitting there. Sometimes it will leak just sitting there and other times it will start to leak once you start it up, beat on the side of the carb and it quits. Anyone had this issue before? I am wondering if the float level is to high or maybe the needle seat in the carb needs replaced.
 

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Discussion Starter #16
I took the carb apart and the seat for the needle is out of round and it never shuts the gas off via the float. The antifreeze leak is from the leak hole, and when I tore it apart it was the waterpump seal that was the culprit.

I also had a torn boot on the front drive shaft that was leaking oil. What is the right way to reinstall the front drive shaft on this? It is just a straight shaft and I don't see an easy way to do it. Not sure why then couldn't of done it like my Kawi, it would of been so much easier. You can break all the motor mounts loose, but your still fighting the rear drive shaft at that point. The front differential doesn't look like it would move the 1 1/2" that I need to make the shaft fit back in, but that is probably the direction I am going unless someone tells me differently, pretty sad when you have to tear the whole quad apart for simple maintenance.
 

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trail buck 650

i don't work on these to much and kinda glad i don't. i pulled the engine on mine, there is a bolt right where the universal is and is attached to the shaft coming out of the engine .i had to take the swing arm pivots on the rear out and slide it back far enough to get it off the shaft then lifted the motor and slid it off the front shaft after i removed the bolt . i supported the swing arm with a small floor jack. the carb on mine i never took apart. even though you said you took carb apart and cleaned , i have seen fuel tanks with so much crap in them ,the only way to keep the carb from messing up is to remove and clean tank completely. it sucks but you have to do it if you want to run it dependently for any length of time . if fuel lines are hard or extremely soft replace them also . sometimes the cheap fixes are the ones we hate to do . good luck
 

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Discussion Starter #18
They are definitely no fun to work on. Thanks for the recommendation on the removing the swingarm, that worked great as compared to trying to remove the front differential. I got the water pump seal in, the front drive shaft boots replaced and the new carb needle and seat installed. Now I need to pull the left front drive shaft out and replace the outer CV boot, I noticed it has a small tear in it, just as well fix that now and I should be done with it.
 

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I got a 500 buck and i just did new piston,rings,gaskets and it wont start at all.I have spark and fuel but im wondering about timing because the manual is not all that good for these motors...
 

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John Deere 650&500 CVT

I have a John Deere 650 and 500 CVT and one has 600 miles and the other has 1400 miles on it and for some reason both have the same problem that I can not figure out. They both backfire constantly I have cleaned both carbs numerous times does anyone on here have any advice you'd be willing to give me?
 
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