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KTM 350 SX-F timing chain slipped is TDC at compression or Exhaust stroke?


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I was doing a valve adjustment on a 2011 KTM 350 SX-F. I put the timing chain tensioner in per KTM repair manual instructions. I pressed the tensioner in after installing it. It seemed to extend / release, but it must not have release all the way. The chain got tight, but then got slack when I turned the motor over. The timing chain slipped. Not sure how much it slipped. Based on marks I placed on the Cam gear and chain, I think it slipped just about 10 teeth. I was able to find TDC on the fly wheel through the crank shaft locking bolt hole. I am able to time up the cams based on TDC and the flat marks on the cam. But I don't know how to confirm if I'm at TDC on the compression or the exhaust stroke.

 

How do I tell if the motor is at TDC on the compression or the exhaust stroke on a 2011 KTM 350? I can't find anything in the repair manual for the bike. I'm concerned I could be 180 degrees out of time.

 

I was very slightly bumping the starter when the slip occurred. I think the motor only rolled over once or twice very slowly. How do I tell if the valves got bent. I've read some people say to force compressed air into the spark plug hole to do a leak down test. Was % is acceptable?  Or is there another way to check without pulling the head?

 

Is it somewhat safe to put it all back together and try to start it?

 

Thanks in advance for the advice!

Edited by kmenzel
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first of all ,it do not matter if it is comp. or exh stroke , the engine fires the spark on both . when you set the crank on tdc ( best check is to take out the sparkplug and see if the piston is up ) and the crank locked set both cams with the flat surface up and your o.k. . take out the oem chain tensioner and trow it away as far as posible (at least a mile) and bay a manual tensioner (sutch as djh ,dave hopkins) make . we even do not start a brand new bike with the oem tensioner , we install a manual one even before we start the bike.

Edited by speedboot
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Thanks for the advice speedboot. After a LOT of searching, I found a web page that said the same thing. It doesn't matter which TDC. The spark plug fires both on the exhaust and compression stroke. They called it a "wasted spark". I was either over thinking it or they made it too easy not to mess up guessing which TDC.

 

What do you think about the Dirt Tricks tensioner? KTM 350 Timing Chain Tensioner – TC2 http://dirttricks.com/shop/ktm-350-timing-chain-tensioner  ?

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I use the dirt tricks tensioner. It's a bitch to install properly however. You actually have to install it without the spring and then push the spring in the hole and tighten the cap on. If you don't follow that procedure, it won't work properly. But it DOES work great once installed. I couldn't find a manual tensioner for my 13' when I bought it, maybe now they have one. 

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  • 2 weeks later...

I had the same issue with my 2011 350. The tensioner slacked and the motor skipped time (while hitting the start button). I have been researching how to get the cams back in time for a few days now. It looks like you need some special KTM tool to keep the cams at the correct location. (see attached picture from another thread.)  I'm still trying to find out where to buy this thing.

 

post-267534-13264041755454.jpg

 

 

to get the piston in TDC we used a small screwdriver and put it in the spark plug hole (after removing the plug) and just turned the motor until the screwdriver started to go back down. This was with one of the master techs at my local shop.

 

if you wanted to see which stroke it is on id suggest looking at the spark plug while turning the motor slowly.   

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dondt need a tool at all . with the piston on top lock the crank with the locking bolt (allen bolt just under the waterpompshaft. remove it ,take the thick washer off and look with a flashlite in the hole to see the v in the crank . install the bolt without the washer and lock the crank . install the cams (intake first) so that the flat surfage just insite the outer cam is in line with the surfage of the cambridge . this is for both cams . now instal the top of the cambridge and tighten it to 12,5 n/m . install the tensioner (take a manual one ,and throw away the oem ) and adjust the cam chain . remove the lockbolt and rotate the engine 2 cycles, and see if the cams ar ok. (flat surfage) .install the lockbolt with the tick washer and you ar ready

Edited by speedboot
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Based on what I just went through, speedboot is totally correct. You don't need the special tool. It is only needed if you are putting in new cams. Looks like I definitely was not the only one with the stupid OEM tensioner problem. Like he said. Throw the OEM tensioner as far as you can throw it. After you smash it. I might add that you remove the cam bridge and Cams before you turn the crank to find TDC. That way you don't have any chance of hitting the valves on the head as you turn the crank looking for TDC. I used a flexible straw to get very close to TDC. When the straw is at the highest point, look for the crank locking hole for the locking slot. Then install the cams with the flat slot up and level with the two dots. I was very concerned of which TDC I was at. Turns out it doesn't matter because the spark plug fires on exhaust and compression TDC. Thanks Speedboot.

 

My piston looked bad when I looked through the spark plug hole. Looked like something might have broke loose. I ended up sending it to the shop for a top end rebuild. Been there 3 weeks already. They lured me in with a quote of only $175 for labor plus parts. Then turned around and said it would be $600 in labor alone. Luckily a call to the owner got it back to a reasonable amount. I will say he was great. Downside is it has be 3 weeks without the bike and I am still looking at a week or two before we get it back to ride. Wish I had just done the top end work myself but I didn't know if it would require a bottom end rebuild too. I'm not touching the bottom end!

Good luck with your bike.

 

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your welkom . i have a motorcycle (repair ) shop of my one , so i do all myself . from crank rebult to instal valve guide,s and seats . most harley-davidson but also mx bike,s .(my son ride one ) . i do a engine repair within 2 day,s (if i have all the parts ) and a bottom end rebult is not diffecult. but you must know what you do and you need some tools. specialy for crank repair

Edited by speedboot
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