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HELP - Head has stripped threading where Cam Tower bolts on

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My CRF450R was hard to start, so I took it to a shop for Valve inspection

They found the valves were way off, and they have now been set to: 222 on Top 2, 179 on Bottom 2

But they warned of a very big problem - the Upper Right Cam Tower bolt is stripped in the threading, and said that would require a new Head replacement

They also said the Tensioner has no tension

So I am wondering how serious of a problem the Stripped Threading is on the Head, because it seems to be very expensive fix. But they also said when the Cover is on, the bolt cannot escape.

 

Some Question:

1) If I do ride it like this, can the problem get any worse - or has the damage been done and I may as well keep riding until it stops running if an  entire head is to be replaced anyways

2) What parts will I exactly need in the replacement - because if I search for CRF450R HEAD, there are multiple parts packages and they are so pricey I want to ensure I get only what I need - seems like I may want to replace Valves too if they are close; and is the Tensioner a part of that package?

3) Should I try to get a Big Bore kit or something, so the large expenditure of time and money at least puts me to a point of better than stock?

 

Thanks in advance - let me know if any pics or anything can help - really a sad day

 

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It sounds like they're the cause of all the issues. i.e. Nobody in their right mind would say what they said about the bolt not going anywhere because the valve cover was on. That would be the least of your problems. And a tensioner with no tension is broken. Wow. I bet during their efforts, they stripped the head threads and f'd up the tensioner.

Edited by Eddie8v
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Yeah... any reputable shop would of stopped the second they found a serious problem like that. Bolts do not strip on their own. Either the PO did it or the shop did it. It needs to be fixed. A decent shop would install a Time-Sert or a HeliCoil. Done. They also would of contacted you during the tear down and not just gone ahead, done work and casually mentioned a serious defect like that.

A cam chain tensioner that is maxed out means the engine needs a new cam chain, not a big deal and again, something they should of picked up on during the original inspection. Chains cost about $35.00, tensioners, $50 top $75 and should be done every 75 to 100 hours (unless replaced by a manual one, then they last forever).

 

No need to do a barrel/piston though I'd not trust that shop at all.

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So it sounds like the Tensioner problem is no big deal

As for the Threads, they said it was too deep to repair with a Heli-Coil, but could possibly be Heli-Coil'd if going from the bottom direction - but that would have been a larger engine tear-down

They did contact me during the job to let me know, but I wasn't sure what the best solution might be, since they said Head replacement would be like $1500 - so I said just fix the valves and let me think about best solution for Stripped-Thread on Head

 

12 minutes ago, William1 said:

No need to do a barrel/piston though I'd not trust that shop at all.

When you say no need to do barrel/piston - are you saying the Piston is fine so I don't need to shop for a "Big Bore Kit", and instead just a smaller piece?

Do I need something like this for the Replacement part:

https://www.ebay.com/i/172815176837?chn=ps&dispItem=1

Or should I try to Heli-Coil from the bottom and not replace any parts, except the Tensioner 

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No self respecting shop would of gone further if there was a cam cap bolt failure. Had I had the bike, I would of told you to come get it. Way too irresponsible to do what they did.

Cam caps bolt to the head, a real pro might be able to do the repair 'on bike', worse case, you remove the head and do it on the bench. Drain coolant, six bolts, carb and exhaust off. One hour of labor to R&R, another 1/2 hour to rep[air the threads.

Check with a place like FastHeads or BigBoreThumpers for head cost. $1,500 is insane!

For example: http://www.bigborethumpers.com/newheads.html

Under $600 for a complete head. An R&R is a two hour job, start to finish.

Cam chain and a tensioner (you need to do BOTH) are an additional 30 minutes shop time. Again, no shop would let bike leave if they were shot.

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Thanks William

So my plan will be to try and repair the Threads, and consider a completely new Head to be worst-case-scenario/Option-B

But seems the Chain and Tensioner need to be replaced as NEW , so I will plan on purchasing that

 

Don't know much about that area of the engine, so it may be a fun adventure to take everything to the Bench and try to repair myself

But most likely I will run into something confusing and post some more questions - like how to do the Heli-Coil-thread-repair

 

 

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Get the thread fixed first - if you can, and go from there

What makes you think it needs piston and rings ?

Replace the cam chain - get a manual tensioner

What year 450 is it ?

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It is a 2005 450r

I don't think it needs Pistons or Rings; I may have indicated that when mentioning complete Head replacement and not knowing what goes with that - but everything should be fine minus the top right bolt thread + tensioner/chain

Will look for Manual version of Tensioner and replace Cam Chain

 

Just not sure how to fix the threads, worried if the shop could not do it - I am much less experienced

Only different approach I would have is taking the time to remove it completely and have it on the Bench, whereas they just had it opened up still on bike

 

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Before you do anything, get a service manual. Read it. A lot. While working on one of these engines is simple, if you are not aware of what you are doing, you can make a small problem, a huge one. You need tools, space and time to learn. Barring that, you need a competent shop or better still, a freind who actually knows what he is doing and will look over your shouldedr while you do the work.

All the work you want to do is easy on the bike and actually a lot less work.

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If you need a new head, check out big bore thumpers. You can get a complete oem head(new) with ss valves and springs for about $600, ready to bolt on. Do the cam chain at the same time. Whether you do the work or not, get the manual.

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As for Manual - I found this .pdf and printed it:

http://owners.honda.com/assets/OWNERLINK/model/own_man/powersports/2005/2005_CRF450r.pdf

 

 

13 hours ago, William1 said:

 

All the work you want to do is easy on the bike and actually a lot less work.

If it were possible to repair the damaged threads while Head is still on the bike, I would imagine the shop would have done so

But they said it was not possible to Heli-Coil because the threads were deep down; but also said maybe if you came from the bottom of the Head 

Can it be Heli-Coil'd from the bottom - and then the bolt comes in threading from the top?

 

 

 

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What they're describing is the cam tower bolts that run down through the locating dowels. Ive got four heads in the garage right now that are like that. You can try this: get a longer bolt and see if you can get it to bite. The main issue is the torque spec honda gives for that bolt is way too much for that size bolt, in a location that's going to going on and off several times. The spec is like 11ftlbs. And even with a 200% thread engagement, it's still not enough for any kind of longevity into the soft casting. Ive been working on a fix for this issue. Once i get it nailed down, I'll probably offer it as a service.

what really sucks is when the threads pull out of a head with a really nice port job.

But, try a longer bolt. The hole is deeper than you'd think. But make sure the bolt isn't too long and bottoms out before it pulls the tower down tight.

The problem with putting a helicoil in is that the outer diameter of the helicoil is larger than the dowel. Once you've helicoiled the hold, you now cant locate the tower and it NEEDS that dowel.

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Good stuff Shawn, it would be awesome if a longer bolt did the trick

If you have 4 heads with same problem, it seems unlikely I can fix it and more likely that I need to purchase another head - but I am definitely going to try all options before buying new

Let me know if you have a great bolt spec for the longer bolt option, and let me know if you have any other theories that could work

I am in California too, so if you are close to a breakthrough on solving this, I can come to you and be your 1st customer (I am in Central California)

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On 8/13/2017 at 10:23 AM, Casey Pudwell said:

Good stuff Shawn, it would be awesome if a longer bolt did the trick

If you have 4 heads with same problem, it seems unlikely I can fix it and more likely that I need to purchase another head - but I am definitely going to try all options before buying new

Let me know if you have a great bolt spec for the longer bolt option, and let me know if you have any other theories that could work

I am in California too, so if you are close to a breakthrough on solving this, I can come to you and be your 1st customer (I am in Central California)

Every time I fixed one with a longer bolt, I measured the total depth of the hole to find out how much room was actually there and cut a custom bolt to take advantage of every single thread I could bite. Pull the bolt that's stripped, stick something down to the bottom, subtract about .020" of an inch and make sure your lead thread is good and clean on your new bolt after you cut off the new bolt. The bolt is going to stretch, quite a bit because of it's length. That's why you cut it off a bit short. When selecting a bolt, it needs to be a 8.8 at a minimum, better if it was a 10.9 (metric hardness scales)

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On 8/14/2017 at 10:23 PM, Shawn_Mc said:

Every time I fixed one with a longer bolt, I measured the total depth of the hole to find out how much room was actually there and cut a custom bolt to take advantage of every single thread I could bite. Pull the bolt that's stripped, stick something down to the bottom, subtract about .020" of an inch and make sure your lead thread is good and clean on your new bolt after you cut off the new bolt. The bolt is going to stretch, quite a bit because of it's length. That's why you cut it off a bit short. When selecting a bolt, it needs to be a 8.8 at a minimum, better if it was a 10.9 (metric hardness scales)

THANKS!!

Generally how much longer have your repairing bolts been?  Believe the bolt in question here has stock spec: M6 72

Will try to measure the depth of the hole as soon as I can figure out how to safely open up the Cam; planning to replace Chain and install Manual Tensioner, so trying to get those parts ready first

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I don't remember how long it was. I believe I ended up finding one that was longer and cutting it exactly to length the last time.

What do you mean you need to safely open up the cam? To replace a cam chain, you'll need to pull the flywheel usually unless the guide on the bottom is bent. Which means you'll need that puller, and a stator gasket too. But pulling the valve cover is just a matter of taking off the bolts and lifting it up...

 

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I read that when changing Cam chain / tensioner - you can really screw up timing if not done correctly, something about a flat head screwdriver with vice grips to hold tension

Just not sure on that whole process, and I am waiting for the Manual Tensioner to arrive before starting - hopefully it has instructions for how it replaces stock tensioner

Did not know I needed flywheel puller, I should probably order that now then + Stator gasket

 

Will look for 10.9 hardness bolt, measure and subtract 0.02" - and when cutting bolt for most perfect leading thread - any tips? (was planning to use Hacksaw...)

 

 

Thanks,

Casey

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In my experience Ive been lucky with shawns advice. If it was stripped out with the factory bolt then chances are a longer bolt will work. Its when someone strips it out with a longer bolt that your in trouble. I don't use a torque wrench on these for that reason. 1/4inch ratchet and a good feel by hand and I haven't had any issues in 10+ years

 

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Found the 10.9 hardness Longer bolt, it now has strong grab and seems completely fixed

CASE CLOSED !

What a great solution that was, thanks a million

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On 8/18/2017 at 9:15 AM, Casey Pudwell said:

I read that when changing Cam chain / tensioner - you can really screw up timing if not done correctly, something about a flat head screwdriver with vice grips to hold tension

Just not sure on that whole process, and I am waiting for the Manual Tensioner to arrive before starting - hopefully it has instructions for how it replaces stock tensioner

Did not know I needed flywheel puller, I should probably order that now then + Stator gasket

 

Will look for 10.9 hardness bolt, measure and subtract 0.02" - and when cutting bolt for most perfect leading thread - any tips? (was planning to use Hacksaw...)

 

 

Thanks,

Casey

The auto tensioner is a spring actuated tension rod.  When it is removed from the bike the rod extends fully outward automatically.  If it is installed like this it will put to much tension on the chain and stretch it out so it is imperative to install it fully retracted. To retract the rod you remove the bolt in the center of the tensioner then take a small flathead screwdriver and turn the tensioner rod counter clockwise to retract it. The tricky part is that it will spring back to fully extended if you let go of the screwdriver. It's a lot easier to install with a second pair of hands but not impossible to do alone.  I hope this helps you understand how it works.  

I have never had some of the issues people have had with the automatic tensioners failing so I have never used a manual one.  I am curious as to how people keep the proper tension on the chain with them. 

Edited by Jdunn217

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