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jbyo

2000 XR650l Top End Rebuild problems

30 posts in this topic

Hello,

I just rebuilt my top end, over heated bike originally. I went .5 over I believe. I put every thing back together. A freind and I spent quite some time on the cam/chain/TDC alignment, we triple checked it b4 we closed it back up. Now I got everythng back in the bike. Tried to fire her up and just turning turning turning. I know I set the indicator mark exactly the way the honda service manual says with the three marks lined up with top of the head/ and the cam lobes in down position with the Flywheel indicator right where it needed to be with the line and the T......any one have any ideas b4 I go taking this thing back apart again please?

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Do you have a spark? Getting fuel? Kill switch/kickstand checked? Have you read the trouble shooting section in your manual?

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Got spark, plug comming out dry but I poured gas right in there, then put plug back in, nothing happend. I read the trouble shooting section....just still trying to figure it out. But I spent 6 hours putting motor in getting it all back together, tommorrow I have at it again.

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Did you recheck your valve adjustment? I would also like to know if it has good compression and if there needs be adjustment at the manual decompresser or the cable is hung up under the tank.

On my first start up on a fresh rebuild I always take out the air cleaner and use a little starting fluid, I am worried with that much kicking why the plug was dry and not wet.

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First thing, I have to disagree with xr650rhonda, never use starting fluid on a MC engine, they are tough but not that tough, if you use to much you can blow the head right off. But I have to agree with him about the plug,and it being dry, if you are getting gas and have spark you should fire, even if its out of time, you will at least get a back fire or a pop. How long was the carb sitting? maybe you have a clogged jet? I would go over the fuel system and make sure you are getting fuel. Pouring fuel into the spark plug hole is not a sure thing, you most likely put in to much and will not ignite a real rich mixture, especially with estart. I would verify timing first, again I know,put a degree wheel on it and make sure you have spark on the recommended btdc of the compression stroke, compression, valve lash,and fuel delivery, even if you have to take the carb apart. These items are a lot easier than taking that motor out and apart.

Good luck and let us know.

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I have compression just stuck my finger over the plug hole and turned her over(good bit of wind), I don't think the valves are moving. I see the cam spinning but no movement on the valves....didn't want to take the motor out again....anything special you have to do when you put the valve cover back on?

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I got compression. 2 things I notice valves not moving, and no suction at intake port.

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your cam timings got to be 180 degrees off or woud at least geta backfire. When you have it on TDCC makes sure the cam lobes are not touching the rocker arms at all

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I broke afeeler guage off in my old 650 while adjusting valves and she still runs good lol

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The top end should be able to be rebuild with the engine in the frame, it's a little tight getting the head off, but it should come off. When the bike was at TDC on the compression stroke and you installed the cam, most people would back out the valve adjustment screws all the way out, install the rocker cover and then set the valve gap, if you failed to set the valves I could see how excessive valve gap could keep the valves from opening and explain the dry plug.

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So you got some compression but valves not moving Norcal could be right and you got wind both ways on the stroke ,in and out i mean.

Simple from here if so.

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So do you think if I loosen the valve adjustment screws and set them proper they might open and take in fuel?

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Mate if you are at TDC and your intake valves are at 6 thou and your ex valves are at 8 thou or there abouts ,then it should be game on.

If as you say the engine turns over and your valves don't open then read as above and try again.

One of these guys will probably jump in and help if that don't work.

Mate unless you are there looking at with you it's sorta join the dots territory to me.

Hope i have helped though.

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I see the cam spinning but no movement on the valves....didn't want to take the motor out again....anything special you have to do when you put the valve cover back on?

If it was me, I would set the bike at TDC on the compression stroke, pull the rocker cover and recheck my work and make sure the cam marks are right on, I would also pull the plug and make sure the piston is at the top of the cylinder.

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Well this sounds strange. First question, did you have any parts left over when you finished up?

Take the valve adjustment covers off. Hit the starter. You should see the rocker arms move and push down on the valves. If you don't see those move, then there is something really wrong.

One thing that I can think of is the cam chain can fall off the sprocket on the crankshaft. Then there is nothing driving the cam and it will not move. Another possibility is that some of the rocker arms are missing. The RFVC head uses a unique two part rocker arm. The only other things that I can think of that would cause something like this is no cam chain at all, the bolt on the top sprocket were not installed, no cam. I think that you would have noticed these, so I think the chain off the lower sprocket is a good chance.

To get it back on, the easiest was is to take off the right side cover. Otherwise it's really hard to get it back on correctly.

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One thing that I can think of is the cam chain can fall off the sprocket on the crankshaft.

.

I'd say this is a good bet.

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I have compression just stuck my finger over the plug hole and turned her over(good bit of wind), I don't think the valves are moving. I see the cam spinning but no movement on the valves....didn't want to take the motor out again....anything special you have to do when you put the valve cover back on?

In this post he says the cam is turning?

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Is it an L i thought it was an R,disregard anything i've said about valve gap never been inside an L.

My bad .

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If the cam is turning and the rocker arms are not, I am totally mystified. Please let us know what you find.

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