RMZ 450 2009 Cylinder Head thread rounded! HELP PLEASE

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12/2/2018 6:03 AM

Hi guys, I've got a 2009 RMZ 450 and I'm in love with this bike.

Had this bike for a while now and was kept well maintained but decided it was time to do piston and rings just for good measure. As per usual, after replacing the piston and rings the bike would need shimming and timing so I took it to a friend of mine who has done this countless amount of times on all our friends bikes (this is were I f*cked up, should of took it to the shop but there wasn't ever and issue before on any of the bikes he had done before and he actually works for a specialist motocross mechanics so I didnt know the wiser). After a while of him having the bike, I got a call to come round as there was an issue, when we go to tighten the cylinder head bolts, a few of the bolts 3 or 4 of them go to tighten and then they become loose indicating to me that they've heads threads have been rounded from where he was shimming. Everything else is perfect except them so I don't really want to spend £400/500 on an new Cylinder head plus I'm at university so finances are tight! Is there an alternative to this issue like re-threading and getting bolts slightly bigger etc

Sorry if this sounds nooby but I've never come across this issue before so I am kinda lost



Thank you in advance my bros and brolets!

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12/2/2018 6:35 AM

You can look into a thin walled ezlok thread insert or a helicoil insert. The only problem is you have to remove material, and there may not be sufficient material there to do that and still have strength or to not bust into a coolant channel or something.

If it were me id just replace the head and take note to not strip the threads next time.

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12/2/2018 9:21 AM
Edited Date/Time: 12/2/2018 9:21 AM

What bolts are you referring to? The actual head bolts??? or the cam retainer bolts? if it’s the actual head bolts your repair is going to be in the cases, at that point you could probably either A) have the holes welded up and retapped, or B ) put a time-cert in there... I’m quite sure that a time-cert would hold fine as there’s not much torque on them... as stated before I would just pay attention to possible water passages...

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12/2/2018 11:10 AM

Paul_Pitzonka wrote:

What bolts are you referring to? The actual head bolts??? or the cam retainer bolts? if it’s the actual head bolts your repair is going to be in the cases, at that point you could probably either A) have the holes welded up and retapped, or B ) put a time-cert in there... I’m quite sure that a time-cert would hold fine as there’s not much torque on them... as stated before I would just pay attention to possible water passages...

Ahh I wish it was just the head bolts but it’s the cam retainer bolts

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12/2/2018 11:12 AM

kb228 wrote:

You can look into a thin walled ezlok thread insert or a helicoil insert. The only problem is you have to remove material, and there may not be sufficient material there to do that and still have strength or to not bust into a coolant channel or something.

If it were me id just replace the head and take note to not strip the threads next time.

After university when finances free up I’d happily just get a new head but at the moment I’m in a bit of a sticky situation as to why I’m looking for an alternative. It’s the cam retainer bolts

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12/2/2018 11:17 AM

those have such a low torque you may be able to get away with heli-coils if you’re looking for a quick patch

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12/2/2018 11:31 AM

Paul_Pitzonka wrote:

those have such a low torque you may be able to get away with heli-coils if you’re looking for a quick patch

Ahh thank you! That’s perfect news to my ears! I’m going to in research more into heli-coils

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12/2/2018 4:21 PM

I striped one on a crf before and had evo industries east put a heli coil in it. It will be fine.

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12/2/2018 4:30 PM

Polishhammer wrote:

I striped one on a crf before and had evo industries east put a heli coil in it. It will be fine.

I’m going to pick up a kit tomorrow!

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12/2/2018 4:31 PM

Polishhammer wrote:

I striped one on a crf before and had evo industries east put a heli coil in it. It will be fine.

Quick questions, would the bike even start with one of them stripped let alone 3/4?

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12/2/2018 4:54 PM

I definitely would not try to start it with even one striped. Your asking for some serious mayhem if that thing comes loose with the engine running.

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12/2/2018 11:45 PM

Polishhammer wrote:

I definitely would not try to start it with even one striped. Your asking for some serious mayhem if that thing comes loose with the engine running.

Ahh thank you! Luckily I ain’t even bothered trying to start it

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12/3/2018 9:30 AM

Yeah, worth it to have a shop do the helicoils, you can fuck up royally if you do it wrong.

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12/3/2018 8:05 PM

How do you strip a cam bolt. They are 7 ft pounds .

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12/4/2018 2:23 AM

coastlinecascot wrote:

How do you strip a cam bolt. They are 7 ft pounds .

Noobs not using torque wrenches.. thats how

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12/5/2018 8:05 PM

Like it was stated I would go with a time-sert not a heli coil. Helicoils are more of a band-aid and fine to use on non crucial areas, they're basically just springs...cam bolt threads are pretty crucial. Time-serts are designed for EXACTLY what you're describing. Plus time serts are a little thinner than heli-coils and although im not positive on the suzukis you typically dont have a ton of material to work with and the bigger the insert the thinner and weaker you make that wall where the threads are going in to. Just do a little research on them before you buy.

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