Jump to content

Need help finding TDC on compression stroke crf100f

Recommended Posts

What is the best way to find TDC on the compression stroke on a crf100f. I need to find it because I am re threading the sparkplug thread an a need the valves closed so I don't get any metal fragments in there.

Also does this engine sound flooded or is there something wrong with it?

 

Share this post


Link to post
Share on other sites

you have to take off the case on the left side so you can see the timing mark, and you can put a screwdriver in the spark plug hole to make sure the piston is at the top (if it's not, the screwdriver will fall further into the spark plug hole)

Share this post


Link to post
Share on other sites

if you are going to rethread your spark plug you need to take the head off the motor and do it.  valves can be closed all they want, but shavings will still get in to the cylinder and that is where the bottom of the plug hole exits to.  TDC is the least of your worries at that point.

 

take the extra time, pull it off, and then thread it.  you will be happy you did.

  • Like 1

Share this post


Link to post
Share on other sites

Oh good. So I assume they also said they would pay for any damages if a shaving didn't make it out with the grease and eventually scored your cylinder walls. Those guys are hard to find. Especially the ones that will also include labor :lol: 

  • Like 2

Share this post


Link to post
Share on other sites
11 hours ago, tranqwhl said:

you have to take off the case on the left side so you can see the timing mark, and you can put a screwdriver in the spark plug hole to make sure the piston is at the top (if it's not, the screwdriver will fall further into the spark plug hole)

Use the little red straw from your can of WD40 or other spray to help find close to tdc.  Use the longer clear straws from other cans on larger stroke engines so you cant drop it in and lose it.

Share this post


Link to post
Share on other sites

Bamboo skewers.
Buy a bag, they have endless uses in your garage/shop.
Drop it in the hole, rotate until you find the highest point.

  • Like 1

Share this post


Link to post
Share on other sites
8 hours ago, MXOldtimer said:

Bamboo skewers.
Buy a bag, they have endless uses in your garage/shop.
Drop it in the hole, rotate until you find the highest point.

 

8 hours ago, hornet10 said:

Use the little red straw from your can of WD40 or other spray to help find close to tdc.  Use the longer clear straws from other cans on larger stroke engines so you cant drop it in and lose it.

I ended up using an Alam key and it worked pretty well. I rethreaded the spark plug hole with a helicoil and even though it was a pain in the ass it seems to work pretty well. I used loads of grease on all the threading bit and that prevented most of the aluminium from getting in the cylinder and the aluminium that did I just shit it out with the air compressor and a vacuum.

One last question though, say there are still a couple small bits of aluminium in the cylinder (I don't think that there are, couldn't see any with inspection camera) will they burn up or get sucked out the exhaust or will they end up in my oil?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×