picked up this bike even trade for something i didnt want anymore but the guy told me it had a timing issue. Can someone tell me or send a picture of the timing marks for this bike. Im just not sure what marks to use, there are 4 marks in the left side cover of the bike and the mark on the cam gear. What mark do i use there is one with an "F" and one with a "T" then 2 unmarked, and is the cam mark supposed to be up or down or sideways or what, please help.
1982 honda xr250r
- Thread starter eskort
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2strokerfun
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- May 19, 2006
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You do use the "T." But if memory serve me right, it is actually slightly before top dead center. There should also be a small circle on your cam gear that you align with a dash on your head. I belive the dash is somewhere close to 270 degrees, or about 90 degrees left of the top of the cylinder.
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Ol'89r
LIFETIME SPONSOR
- Jan 27, 2000
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The 'T' mark is top dead center for cam timing. The 'F' mark is the 'Fire' mark for ignition timing. The two slash marks are the 'Advanced' timing marks for timing the bike with a timing light in the advanced position.
When you time your cams, make sure both lobes of the cam are pointing straight down towards the piston, away from the rocker arms. Put the crank on the 'T' mark and look at the cam sprocket. There should be either two lines on the cam gear or one little 'o' mark. If you have two lines, line them up parallel with the gasket surface on the top of the head. If you have an 'o' mark, there should be a corresponding notch on the gasket surface of the head to line it up with.
When you time your cams, make sure both lobes of the cam are pointing straight down towards the piston, away from the rocker arms. Put the crank on the 'T' mark and look at the cam sprocket. There should be either two lines on the cam gear or one little 'o' mark. If you have two lines, line them up parallel with the gasket surface on the top of the head. If you have an 'o' mark, there should be a corresponding notch on the gasket surface of the head to line it up with.
- Thread starter
- #5
ok, i got the valve timing on the problem was that the guy had it 180 out and the cam gear on backwards. So now my v alve timing is bang on, i cleaned the carb and adjusted the valves. When i kick it over it backfires and just about tears my leg off. It will not start and run. The only thing i noticed is there is some slack in the timing chain but im not sure, you would think it would start at least. Is it maybe an ignition thing ( i have good spark by the way), and if it is ignition timing how do i check it, im new to the small engines in case you didnt notice, but i want to be able to ride this thing. Please help. Thanks!!!!!!
Ol'89r
LIFETIME SPONSOR
- Jan 27, 2000
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I really can't remember if the '82 has points or not. If your bike has points, set them at aprox .012" to .016" and then set the flywheel on the 'F' mark. Your points should break (open) when you reach the 'F' mark.
If it does not have points your ignition timing is pre-set and cannot be changed. You will have a pulse generator coil inside of the right side cover. Make sure your pulse generator coil has not come loose and is in spec as far as ohm readings go.
Also, check your camshaft. Those engine have no camshaft bearings. The camshaft runs directly on aluminum journals. These journals can become worn and allow the cam to move around. This will affect your valve clearance and if you have points, can change the point gap as the cam moves. Put the piston at tdc on the compression stroke and clamp a pair of vice grips on the end of the camshaft. Try moving the camshaft up and down. If you get any movement, your journals are worn out.
If your cam chain is loose, adjust it by backing off the little bolt in the center of the left side cover until you hear the cam chain adjuster 'snap' against the cam chain guide. Then tighten it and tighten the lock nut.
You should get a service manual if you don't already have one. It will give you all of the necessary specs for checking your electrical/ignition components and goes into detail on how to time your cam.
If it does not have points your ignition timing is pre-set and cannot be changed. You will have a pulse generator coil inside of the right side cover. Make sure your pulse generator coil has not come loose and is in spec as far as ohm readings go.
Also, check your camshaft. Those engine have no camshaft bearings. The camshaft runs directly on aluminum journals. These journals can become worn and allow the cam to move around. This will affect your valve clearance and if you have points, can change the point gap as the cam moves. Put the piston at tdc on the compression stroke and clamp a pair of vice grips on the end of the camshaft. Try moving the camshaft up and down. If you get any movement, your journals are worn out.
If your cam chain is loose, adjust it by backing off the little bolt in the center of the left side cover until you hear the cam chain adjuster 'snap' against the cam chain guide. Then tighten it and tighten the lock nut.
You should get a service manual if you don't already have one. It will give you all of the necessary specs for checking your electrical/ignition components and goes into detail on how to time your cam.
- Thread starter
- #7
one last question. The bike starts and runs fine when i bump start it, but when im kicking it it i sbackfiring really bad and i think the last time i cracked a bone in my foot but anyway, i notice the needle valve sticking and gas comes out randomly. This would obviously cause an overfueling issue, but would that make it backfire so much?
dirt bike dave
Sponsoring Member
- May 3, 2000
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I'm not sure if the '82 had an automatic compression release to aid in starting, and also to reduce kick backs. It was very common for people to remove the cable that operated the automatic compression release.
If it never had an automatic comrpression release, I would suspect the spark or valve timing is off. This could be becuase of the issues described by 89er.
If it never had an automatic comrpression release, I would suspect the spark or valve timing is off. This could be becuase of the issues described by 89er.
