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Installed new cam today, won't start now... (650R)

44 posts in this topic

Made sure everything went back in the exact way it came out, but now I can't get it to even think about firing :thumbsup:

so, suggestions?

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was just out there looking at it, cam timing has to be right, as you are pushing down on the kick starter you can see the intake valves open, then it builds the pressure at TDC that we are all used to, then you hold in the decomp lever and the it goes through its stroke, exhaust opens, etc.

Electrical?

Also noticed that when I was holding in the decomp lever and pushing down on the kick starter that my rear wheel was rotating even though the bike is in nuetral. Doesn't rotate when normally pushing on the kickstarter, just when the decomp lever is held down. Bad clutch?

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pull the plug an look for spark, check gas for on,compression good

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well you stated it built presure used kicking so I guess it has some to start

you could check it with a compression tester I say 110 to 125 lb

what about the gas is the plug wet?

and have you tested the plug to have fire?

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It's been a couple of years since I installed a cam in my 650R. Did you set the valves to spec after the cam install? Is there ANY popping out of the exhaust indicating that it wants to start? Is it possible that the cam was installed 180 degrees off?

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I would be tempted to put the motor back to TDC, and double check the cam timing again.

If correct, recheck the valve clearance specs.

Other than those tips, I am out of ideas.

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Is it possible that the cam was installed 180 degrees off?
I don't see how it could be possible that it is 180° off, it goes to TDC on compression, then as you rotate it the exhaust valves open, then the intake valves open, then TDC again.

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When you installed the cam and had the motor on "T" were the cam lobes up or down? If they were in the down position your gold. Did you maybe bump a coil wire?

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Easy stuff...

Fuel: Hose connected to carb? Petcock on? Tank have enough gas to flow through carb? If you open the screw to drain the float owl, does fuel come out?

Spark: Do you have spark? Can you figure out a way to see if you have spark?

Valve adjust: Did you follow the valve adjustment procedure? If not, your autodecompressor can interfere and make your exhaust valve loose.

http://xr650r.us/tech/valves.pdf

Decompressor lever: Anything interfering and keeping the exhaust valve open?

Cam Chain Tensioner: Did you take out the tensioner? Did you wind the spring back (doesn't matter if you took it out or not)? Your bike will still start if you did not do this, but your cam chain and tensioner will not be happy until you unwind the spring.

Which cam did you install? Did you have to press the timing chain sprocket onto the cam? If so, did you make sure the get the correct orientation on the flange when it went on the new cam?

Did you disengage the timing chain sprocket from the chain? If so, is it possible that it was not put back in at the correct rotation relative to the motor?

Wheel rotation: Is your bike in Neutral? If not, is it in gear and the clutch is pulled in? Sometimes the clutches stick after sitting for a while. I get this when I go to push my bike after it has been sitting for a week.

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When you installed the cam and had the motor on "T" were the cam lobes up or down? If they were in the down position your gold. Did you maybe bump a coil wire?

100% sure they were down. Very well posible I bumped a coil wire.

Fuel: Hose connected to carb? Petcock on? Tank have enough gas to flow through carb? If you open the screw to drain the float owl, does fuel come out?
big IMS tank over half full, everything hooked up, petcock on, gas flowing (as far as I can tell).
Spark: Do you have spark? Can you figure out a way to see if you have spark?
Have tried to check it by myself but didn't have someone else there to help me so it isn't a very good one, will try it with a helper tonight.
Valve adjust: Did you follow the valve adjustment procedure? If not, your autodecompressor can interfere and make your exhaust valve loose.

http://xr650r.us/tech/valves.pdf

checked valve clearances, everything was golden, no autodecomp on a Hotcam
Decompressor lever: Anything interfering and keeping the exhaust valve open?
not that I can see, had to disconnect it to remove the head and now it is reconnected and everything looked like it was working correctly when I pulled the lever with the access ports open on the head.
Cam Chain Tensioner: Did you take out the tensioner? Did you wind the spring back (doesn't matter if you took it out or not)? Your bike will still start if you did not do this, but your cam chain and tensioner will not be happy until you unwind the spring.
This is the one thing I didn't do. How do you do it? I didn't see that page in the manual, I'll go back over it today and see if it details how to do this. I noticed that the tensioner that the chain runs on was cocked a little off to the side when re-assembling but it wasn't bad.
Which cam did you install? Did you have to press the timing chain sprocket onto the cam? If so, did you make sure the get the correct orientation on the flange when it went on the new cam?
Hotcam Stage 1, made sure that the double gap in the teeth lined up with the matchmark on the cam. Then made sure that the flange position on the old OEM cam matched the new hotcam (used a new flange).
Did you disengage the timing chain sprocket from the chain? If so, is it possible that it was not put back in at the correct rotation relative to the motor?
marked it with a paint pen to make sure it went back on the same tooth of the sprocket that it came off of.
Wheel rotation: Is your bike in Neutral? If not, is it in gear and the clutch is pulled in? Sometimes the clutches stick after sitting for a while. I get this when I go to push my bike after it has been sitting for a week.
It is in nuetral, it doesn't rotate when normally rotating the motor with the kickstarter, only when my decomp is engaged. On a whim I clicked it down into first and held in the clutch while using the kickstarter. Same thing, nothing until I pull in the autodecomp. Thats why it stumps me so much, it only rotates when trying to get it just past TDC to give it a good kick.

Another thing I just remembered, before doing this cam swap, it was getting hard to start for some reason. I had never had this issue until just the last few times of kicking it over. It would act like it was super lean, requiring just a bit more throttle english then before with the quicksilver. I will check the compression today and see how bad it is. Might actually have to rip the cylinder off of it, not looking forward to doing that since its full of new coolant and new oil.

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Cam Chain Tensioner: Since it is jammed in there, you will have to loosen it. First remove the center bolt. Then loosen the two outside bolts on the flange ears. Back the thing out (Loosening the flange bolts) to relieve the pressure on the mechanisms from the cam chain. Now use a small flat blade jewelers screwdriver (the cheap ones usually are silver handle with a rotating knob on the top and a black shaft/blade). You want to rotate counter-clockwise I believe. This reverses the ratcheting mechanism and winds up a coil spring. If you can't turn the screwdriver, then there is still too much pressure on the cam chain tensioner from the chain and you will have to back out the flange bolts more.

After you wind up the coil spring in the tensioner, keep one hand on the screwdriver and use your other hand to tighten the flange bolts. Just get the tenstioner to snug up against the head before you release the screwdriver/coil spring. When the flange bolts are finger tight, you can release the screwdriver, tighten the flange bolts and replace the center bolt on the mechanism. As the chain gets loose, the mechanism unwinds and ratchets to keep proper cam chain tension.

Compression: I think your bike is probably good on compression.

Spark Plug: How is your spark plug? Black? White? Brown (Light Dark)? Can you get a new one?

Decompressor Lever: That is weird. I can't figure that one out where it makes your back wheel rotate.

It sounds like you were thorough in marking the components and reassembling everything.

Other starting troubleshooting:

Does the bike ever backfire (out of the exhaust or intake) when you are trying to start it? If so, then at least you are getting fuel and spark.

Perhaps you can turn up the idle 1-2 turns on the adjustment screw and then try to start without turning the hand throttle.

My hotcam went in really easy and the bike fired right up with the stock carb and uncorked jet kit.

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Compression: I think your bike is probably good on compression.
going to check it tonight anyway.
Spark Plug: How is your spark plug? Black? White? Brown (Light Dark)? Can you get a new one?
here is the old one:

a939be9a.jpg

already tried a brand new one in there as well as the old one.

Decompressor Lever: That is weird. I can't figure that one out where it makes your back wheel rotate.
yep :thumbsup:
Does the bike ever backfire (out of the exhaust or intake) when you are trying to start it? If so, then at least you are getting fuel and spark.
no backfiring anywhere, it sounds like it has always sounded when trying to start it without an air filter in.
Perhaps you can turn up the idle 1-2 turns on the adjustment screw and then try to start without turning the hand throttle.
didn't think of that one.

I started taking pics of the project, then pretty much gave up, here are some of the others:

ccc2f848.jpg

think my thermostat is junk?

d6cd8029.jpg

the cams.

20f21373.jpg

the head without a cam in it, notice the mark on the chain.

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One other thought, I don't think was covered. It is possible to bolt the cam sprocket onto the hub incorrectly. I almost did this when installing mine. With those two bolts out, you will see that you can rotate the sprocket on the hub and you need to pick the right orientation.

Hope that helps...

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One other thought, I don't think was covered. It is possible to bolt the cam sprocket onto the hub incorrectly. I almost did this when installing mine. With those two bolts out, you will see that you can rotate the sprocket on the hub and you need to pick the right orientation.

Hope that helps...

yep, noticed that myself. There are two lines on the sprocket that you line up with the top of the head, with the side that says "EXH" towards the exhaust side. :thumbsup:

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I have spark. Wouldn't even try to fire when I poured gas into the cylinder. Checked compression, only have 50psi after three kicks. Time to replace the piston?

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I think 50 lbs compression is too low. Maybe this information will help?

Address to compression release adjustment:

http://www.4strokes.com/tech/honda/decomp.asp

You already know this but here it is again. If engine has these at the correct time:

(1)Intake, Good compression, exhaust ,

(2)Strong spark,

Then

(3)Fresh gas

Then it should at least attempt to fire. If it will not then at least one of those three is missing. I would check each item carefully until one or more of those 3 is identified as being wrong or bad.

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I have spark. Wouldn't even try to fire when I poured gas into the cylinder. Checked compression, only have 50psi after three kicks. Time to replace the piston?

50 PSI is WAY low! I think it is a cam timing issue where the valves are opening /closing out of phase.

With spark and fuel, you should at least get a backfire or a couple enginer turn-overs with 50 PSI.

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50 PSI is WAY low! I think it is a cam timing issue where the valves are opening /closing out of phase.

With spark and fuel, you should at least get a backfire or a couple enginer turn-overs with 50 PSI.

okay... so how do I go about re-doing cam timing on it? Rotate to TDC and the pull the cam chain from the sprocket and reset the cam? :thumbsup:

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