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Need help with timing!

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Hi guys, I have a 2004 rmz250 and I just replaced piston and rings. I have a shim kit coming soon also.. But I was wondering how to get the timing down? If I put it at tdc and put it on the pins the manual says the cams do not line up with the top of the head very well. So is there a something that I'm missing? Bike will not start and backfires a lot when I kick it. Thanx in advance for the help!

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Take out tensioner spring. Get left cam marks at 9 and 12 oclock and right cam marks at 12 and 3 and crank at TDC. Tighten tensioner spring. Should be good. Check valve clearances. Theres a good thread in the kx250f section(same bike) with good pics and detailed process. The guys problem ended up being an old stretched chain.

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Take out tensioner spring. Get left cam marks at 9 and 12 oclock and right cam marks at 12 and 3 and crank at TDC. Tighten tensioner spring. Should be good. Check valve clearances. Theres a good thread in the kx250f section(same bike) with good pics and detailed process. The guys problem ended up being an old stretched chain.

That's what I'm afraid of.. The chain.. I just got the shims today so valves will be out of the equation once I'm finished. And I'll look up the thread ty

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Can you post pics of your shim job please? Gotta buddy that needs motivation to do his top end.

Ok this is my first time tho so I don't think he should learn from me lol.. But I don't mind taking pics. What do you want pics of? Step by step or just the cams and so forth?

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His first time too. But hes outta state and my motor doesn't need anything anytime soon so i wont have it apart to take pics. I think timing is covered well in kx250 post. Maybe just a better pic of the cams lobe positions at tdc and an intake shim and exhaust shim pictures. Like a pic of you measuring. The math, the shim install and measuring again. Heck, i could even use the torque specs if you list them. I showed my buddy pics of a sohc 4 valve motor, but i want him to see the rmz motor. Thanks. Here if you need any help

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Ok here's my first question again

ImageUploadedByThumper Talk1369348777.020223.jpg

I put the engine at TDC. Then I go to the exhaust cam hole [D] and put them on the second pin [A] on the cam chain as the manual says...

ImageUploadedByThumper Talk1369349120.171408.jpg

But my cam hole [D] does not line up with the top of the head?!

ImageUploadedByThumper Talk1369349402.225555.jpg

So my question is, should I follow the manual and put on the pins it says or should I just move down one tooth on both cams so the cam hole lines up with head?

Edited by dirtnastydosuno

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Here is a photo if I don't follow the manual and line the cam holes with the head 28 pins apart.ImageUploadedByThumper Talk1369349826.771956.jpg

Lines up perfectly just not on the same part of the chain as the manual..

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Ok. I am a self taught mechanic. So get second opinions. I think pin numbers is like a guide to how long or placement of cams or whatever. But a brand new chain will have closer pins than a used old stretched one. I have the same year bike. I just bought a new one and held it up to the old one and was like oh shit. It stretched for sure. With that being said.

I say forget about pins. Focus on chain and tensioner. If you put cams in properly a tight chain will keep it tru with the crank. If chains good, check tensioner. Take off assembly. Take out middlep bolt. Push on extenioner arm. (That kx250 post has pics of this)

Either your chains loose or the cam gears skipping. Im not too experienced with this but some have welded their gears to not skip. In my opinion its chain first before this happens.

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Ok i did some digging. You said you didnt follow the manual and have chain at 28 pins? That second pic is from manual? The manual says 28 pins.

Anyway. To rule out stretched chain i guess it would close in on 27 pins head level to head level. Or less pins. Thatd be super stretched.

So if its correct. The culprit may very well be gears spinning on cams.

Hit a nice spot of weld at a 12 and 6 oclock pattern and itll stay put. ill find a pic

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Eric was kind enough to invite me over, so let's see if I can help. There is no issue with the spacing of the chain. The easiest thing to remember is 12 pins from top dot to top dot. That is what your pictures show, so good.

The next step is to be sure you are at TDC. The easiest way to do this is to insert a screwdriver into the plug hole and turn the crank gradually to see when the piston is at tdc. This should correspond with the TDC mark on the rotor, as you pictured.

If at exact TDC, it looks like your marks on the cam gears are not lined up, even if you have 12 pins from 12:00 dot to 12:00 dot, it just means you have to rotate each gear a tooth (relative to the chain) in the same direction. Simple. At TDC, the 9:00 and 3:00 dots must line up with the top of the head, the lobes will face out, you need 12 pins from dot to dot on top, and time is correct. At this point all of the tension should be on the left, or front, or exhaust cam side. When everything lines up, you insert your chain tensioner body, which has been RE-SET by you, as you always do before putting in the tensioner. Torque down the tensioner holder bolts to 87 INCH pounds, then insert the spring (with spacer) and torque the cap to 14 or 15 foot pounds (whatever the manual says). The tensioner should click out to take up chain slack. You should rotate the crank counterclockwise a few revolutions with a wrench, just to make sure everything seems smooth. The tensioner may click a couple more times to take up slack. You should be good to go after that.

If you want to take a pic after all of this is done and you are on TDC for reassurance, we will look at it. Hope this helps!

Edited by Dragon67

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Hey dirtynasty. Im wondering. Was pic 3+4 taken at the same time? Without cycling motor... so in pic4, does the sight window look like pic1? Im curious how your cams bumped up a tooth. Unless thats just how you pit it back together. Tensioners out during all this right? Dragon gave top notch timing advice. Thank you

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The forth pic is following your guys advice and the bike starts great! Ty for the help. I was just confused if it had to be exactly on the chain like the manual showed. It's just not the same as the manual, mine is on a different chain link. But I guess it just has to be lined up with the head 28 pins apart at tdc.

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Hello I have a 2004 rmz 250 there are 3 timing mark on my fly wheel there should be 2 mark close together and 1 mark about a 180 deg the first timing I set my up out of time I use the 1 mark it would kick over but not start set it up with the 2 marks and started after that. Hope this may be of help.

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I took a picture of my stock flywheel I have have heavy flywheel on my bike now

IMG_1495.JPG

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