XR kicking back?

[keith500r]

Im having some trouble with an XR200 after a top end rebuild. I used the Honda service manual, and this is not the first XR top end ive done. Well anyways on the third warm up cycle of breaking it in, I noticed the kickstarter would kick back in the up direction every once and a while. I started to check the timing, but when I tried to start it, it kicked back REALLY hard and messed up my foot, throught my Astar boots.. I couldnt even walk on my foot last night. I dont think the timing is all that far off, cause the bike was running. it didnt sound perfect but it ran and idled fine. there does seem to be a little extra slack in the timing chain even with the tensioner all the way out. Does anyone have any idea what could cause this? Is the bike just out of time and firing too soon, or could there be a problem with the kickstarter mechanism?? anyone had this happen before?

and i thought i was going to hurt myself starting MY bike, not my girlfriends :(

 

[cr25096er]

could the cam timing have nething do do w/ it?

 

[Humai]

Check the cam timing. If my memory serves me correctly, the XR200 is one of the few dirtbike engines that registers its ignition timing from the cam rather than the crank. If the cam is one tooth too advanced, this will affect cam and ignition timing adversely and may cause kickback.
HTH

 

[Highbeam]

I rebuilt an xr200 and dorked up the cam timing a couple times before I got it right. Mine would blow the head gasket though.

 

[keith500r]

I'm pretty sure I did have the timing off, I went back thru everything starting with the cam sprocket and now it seems to be ok. hasnt kicked back so far and it runs much better now. Im just glad I only had it off a little, I could have done some real damage if it were really off.

thanks everyone!

 

[cr25096er]

i have an xr80 engine all apart right now and i have a manual but what do u do to set the cam timing? put it at tdc then place the cam in so the lobes are down and not compressing the valve then line up the little dot on the cam sprocket n put the chain on?

 

[karlp]

That's about it on the XR80. I don't think you can put the cam sprocket on wrong; the two bolts are not straight across from each other. The flywheel should have a "T" and an "F" marked on it. As I recall, the "T" points straight up, the piston is then at TDC, and the cam will only go in the right way if the mark on the sprocket points straight up. I like to put them together and then turn them over gently by hand and watch the valves and timing marks and check it all out.

 

[keith500r]

doh! it still seems to be kicking back, but not nearly as bad. The timing has been set with a timing light, but I dont have a tachometer to get the rpms exactly right so I suppose it could be off a little still. does anyone have any idea if this could be a problem with the kicker mechanism? it seems to kick back when the motor sputters but does not start(like the first kick when the engine is cold or something), it fires once or twice then throws the kicker up.

 

[Battered Sav]

Hmm, a friend has a very similiar problem with an old Honda 4st. trials bike, really looking forward to the answer, might help him as well!

 

[Battered Sav]

Hmm, a friend has a very similar problem with an old Honda 4st. trials bike, really looking forward to the answer, might help him as well!

 

[keith500r]

Im going to replace both cam sprockets, the timing chain, and the spring for the timing chain tensioner since there seems to be excessive slack in the chain at all times. I'll post if that fixes the kicking problem.

 

[keith500r]

just thought id post to this in case anyone is still having trouble, the kicking problem was completely solved by replacing the two sprockets and timing chain it also eliminated the engine noise from the slack in the timing chain so the bike sounds a lot cleaner now.

 

[Myke]

i always thaught kickback had to do with the de-compresion release? o well, beats me

how much did it cost to replace the sprockets and chain?
im sure mine could go for it, since its quiet abit older than yours

 

[keith500r]

it was about $70 bucks all together, from mail order. I did have some trouble getting the correct flywheel puller- the one from the Honda service manual wasnt the right one for my bike. Funny thing was I happened to try using the rear axle bolt as a puller, it was the exact fit! using a strap oil filter wrench to hold the flywheel back I had the flywheel off in 2 mins.

the only bad part was I had left the bike sit for like two weeks waiting on the puller to show up before i figured out i could use the axle :uh:

 

[smb_racing]

a buddy of mine was reassembling a '95 xr200 and it was doing the same thing, it recoiled very voilently but wouldn't start. Turns out he left the cam sprocket bolt out :silly:
Problem solved after he replaced the bolt though.