Topic: 400F cam chain tensioner bolt sheared off

[Joel]

I loosened the lock nut and started to tighten the bolt into the case.  The cam chain noise didn't seem to change at all while I was adjusting.  I don't think the bolt went any farther into the case than it was before I started adjusting.  The bolt tipped to one side and then fell out along with a small o-ring.

Is it possible to extract the bolt and put a new one in without too much trouble?

[dave400]

The bolt is supposed to be backed off to adjust the chain! Ouch!   

[Joel]

Oops.

[bozo4onion]

Was your engine running? I thought this was done w/engine off and set to a specific timing mark. Then the lock nut is loosened and the bolt basically rotates and sets.. No?

[mattcb350f]

The PO of my bike did the same thing... exept he/she really buggered it up by trying to drill it out and made a real mess.

How much of the bolt broke off? Can you see any of it or is it flush with the threads?

I had a machinist friend repair mine (gave him the upper case; the engine was already apart).

He ended up putting a Helicoil in it since there weren't any threads left.

My advise: Have a professional repair it! Don't take a drill to it and try to tap it out.


 Matt.

[bryanj]

With great care, much patience and excessive amounts of luck it has been done with the engine in but exhausts and front mountings removed. Otherwise complete strip and rebuild

[Joel]

Was your engine running? I thought this was done w/engine off and set to a specific timing mark. Then the lock nut is loosened and the bolt basically rotates and sets.. No?

The manual I downloaded said to have the engine running at 1200 rpm.  It also said to loosen the bolt before re-tightening it so obviously I should have read it better. 

The PO of my bike did the same thing... exept he/she really buggered it up by trying to drill it out and made a real mess.

How much of the bolt broke off? Can you see any of it or is it flush with the threads?

I had a machinist friend repair mine (gave him the upper case; the engine was already apart).

He ended up putting a Helicoil in it since there weren't any threads left.

My advise: Have a professional repair it! Don't take a drill to it and try to tap it out.


 Matt.

It broke off flush with the bottom of the counter bored section of the hole.

[amemoryoncelost]

damn, i didn't even see this post as I'm dealing with the same issue. Here is a photo of mine, little bummed out and to be honest, not interested in a complete tear down, so it will end up sitting for quite a long time if that's what it comes down to. Any chance of pulling this out? There is a pretty nice tick in my motor, not sure if it's came chain noise or not, new to these motors.

 By the way, the break is about 1/4" or so, will see a professional for sure, just worried there is more damage than I'm aware of. I'll try and get an MP3 of the engine noise.

dustin

[Joel]

Does the tensioning bolt thread into anything inside the case or does it just push against something?  I took a look at a parts diagram for the 400 but the detail wasn't very good.  There did look to be a small hole near the bottom of the cam chain guide that might be for the tensioner bolt.

[Tim2005]

The tensioning bolt is just threaded into the case, it pushes against the side of the tensioning rod to clamp it in place.

With excessive drill work you can make the hole reach the camchain guide, I've a set of cases somewhere which somebody managed to do that to, oh dear...

[aptech77]

NO! The engine should NOT be running! It should be adjusted with the 2/3 timing mark post set to the line. loosen the jam nut. Back adjuster out. Tap down in adjuster hole. tighten adjuster bold. then jam nut.  This just happened to me last week and I'm going to fix it with a helicoil. No engine rebuild is necessary. Just tap, helicoil, and fix.

[Bodi]

There are two ways to adjust it according to Honda, running or with the crank set so the back of the chain is slack. Neither way works anyway - the spring that pushes the adjuster down is too weak, maybe because of the 35 years sitting in there compressed?
Nothing will get adjusted for you anyhow until you get that bolt out. It's a strange bolt really, the outer part has an 8mm thread for the locking nut and the inner thread is 6mm... but all that matters is that your is broken off and stuck. You could try an "EZ-out" but my luck with them has been poor and I usually end up with a hardened EZ-out tip broken off in the bolt stub... this makes it impossible to drill the bolt out completely and means a trip to some overpriced engine shop to have it EDM'd or lasered out.
The remaining bolt in there has a threaded portion (6x1mm) and a non-threaded tip smaller than the thread depth; this tip pushes against the side of the adjuster push rod. If you can manage to drill down the middle of the bolt remains with a 3/16 bit the tip should separate, leaving either a thin shell of bolt (if you went dead down the bolt centre) or more likely a partial cylinder with the drill having opened one side. You should be able to get that out easily as the threads will not be under any tension once the tip is loose. Then you have to get the tip out, it may fall out or use a magnet.
The trick is drilling down the middle of the bolt. Finding the centre and getting the angle exactly right are both difficult.This job is slightly easier with the engine out and apart but is still no walk in the park.
A simple longish 6mm bolt with a washer and locknut will work as a replacement, the fancy bolt uses an O-ring to stop oil leaks but there's really no oil in this spot. I've run the 6mm bolt for a lot of miles with no problem. Use anti-seize... maybe the O-ring is to keep water out that would rust the bolt in really solidly?

To actually adjust the cam chain tension by "helping" the ancient spring:
1)  Remove the upper bolt that covers the hole where the pushrod lives. This is just a hole fcap, the springs don't shoot out. Find a long thin screwdriver or nail that you can put in the hole touching the end of the pusher rod.
2)  Your timing and carbs should be good allowing a reasonably smooth idle. Start the engine and let it warm up until it idles OK.
3)  Now press down on the nail/screwdriver and loosen the lock bolt. Press down or even tap with a small hammer until the cam chain noise just quietens down. If the pivot is still free on the pressure shoe, letting up on the nail/driver should give more rattling and pushing down should make it quiet. If the pivot is damaged and stiff it won't come loose and get noisier - plus you can give too much tension maybe - so tap with the hammer as gently as is practical until the chain quietens down. Tighten the lock bolt.

[amemoryoncelost]

 I'm gonna make some calls to try and get mine removed, not super siked on the situation at all, but I figure if I pay someone, should work out, hopefully. This is the only thing stopping me from being on the road, ugh...

[mark]

.....The trick is drilling down the middle of the bolt.........

Trick?  More like an art. With some science tossed in for good measure. It doesn't happen on your first broken bolt and is rare enough in your first hundred.

Easy-out? Leave the tapered kind alone - it will only expand the broken bolt, then snap off. unless you can put that 3/16 bit right up the center so it takes that nub off the end.

A good drill, left-hand bits, and the straight-splined Ridgid extractors are my friends.

From looking at the posted pic, it doesn't look like something I would want to try with the engine mounted. as in YIKES!

Good luck.

[mattcb350f]

  I must type slow.... I keep getting beat 

The trick is drilling down the middle of the bolt.

This is what the PO did to mine. Missed the mark.... a few times.

There were several attempts to drill it out and all it did was make several holes in the case around the broken bolt. The PO also broke a piece of drill bit off in there which really aggravated my machinist. Fortunately he found the broken drill bit before he starting milling  

If you're going to have a professional take it out, believe me they will really appreciate it if it's left the way it is for them to work on it.

 Matt.

[amemoryoncelost]

 No, never extracted a bolt and don't think this is something I'm going to learn on.

 Who exactly do I call to do something like this? I'd rather keep the engine in the bike if possible, guess it would really depend on the person taking it out, hell, I think I'd rather take the front wheel off than take the damn motor back out. Tempted to just sell this bike to be honest with ya. I'll give a couple people a call and if this doesn't work out, I might have two 400F's for sale.

[mattcb350f]

Well, the guy who does my work is an engine builder; high end automotive, engine rebuilds, cylinder heads, etc. He see's broken bolts all the time.

If you can find someone like him in your area I'm sure they could do the job - and I don't think inframe would be a problem.

Look for a machinist, engine builder, or a reputable motorcycle repair shop. They will (should) have the proper tools and know how to get it done right.

Don't give up on the old girl just yet 

 Matt.

[Joel]

Is there anywhere to get the tensioner bolt?  I've checked a couple parts websites and they list the part is unavailable.

[bryanj]

Modify a standard 6mm setscrew

[Joel]

Ok, I've decided to attempt this repair myself and have obtained a left-hand drill bit and bolt extractor.  I had to remove the oil filter housing to get the drill in the right location which wasn't a big deal since I'd planned to change the oil anyway.

So now for my little rabbit trail.  The PO, probably the same one who changed all the lights, decided to get rid of the warning lights on the bars.  I don't want to fill it with oil and fire it up with no way of knowing if the pressure comes up to normal.  I took my test light and was trying to use it as the warning light in the circuit but I keep getting nothing.  I used the neutral indicator light as a test light and was able to get it to turn on and off as I shifted.

How do I tell if the oil pressure switch is still good?  I tried running both power and ground to the switch and the test light stayed dark either way.  Does having the oil filter housing off affect the switch function?

Since I'm on the subject of oil filters anyway, is there a proper top or bottom to the filter?  It looks symmetrical to me so I just picked a direction and dropped it in the housing.

[bryanj]

The oil pressure switch grounds when there is none so you need a light with power to one terminal and the other terminal to the switch contact.
The filters are not "handed" but a spring and washer, often missing, goes in first

[Joel]

I did test the oil switch and I believe mine is either stuck or bad.

As for the sheared bolt, I haven't been able to get it loose so far.  Will it damage the head if I apply some heat to the bolt and hole?  Am I correct in thinking the cases on the 400F are aluminum?

[Joel]

Success!     For the most part anyway.

With a little bit of heat around the hole and the help of a tap wrench on my extractor, I was able to persuade the end of the broken tensioner bolt out of the hole.  Upon inspection of the extracted piece, I found that my drill bit had emerged from the tip of the bolt.  This probably means that I put a hole or dimple in whatever sits directly behind the bolt.  Is the part the end of the tensioner bolt sits against the cam chain guide?  It's difficult to tell from the parts diagram.

I'm gonna make some calls to try and get mine removed, not super siked on the situation at all, but I figure if I pay someone, should work out, hopefully. This is the only thing stopping me from being on the road, ugh...

It wasn't as tough as I thought it might be but it could've been easier if I'd done it differently.  I started with too large a bit and extractor.  I ended up getting it out but it probably would've been easier with a #1 extractor and the appropriate left-hand bit since it would've left more material around the outside for the extractor to bite into.  I also tried to use the extractor in an electric drill first and it wanted to either spin the extractor in the hole or spin the chuck around the extractor.  The tap t-handle was better suited for the job.  To apply heat, I bought a small pencil type butane torch and heated the hole and the area immediately around it for 30-45 seconds.  I ended up taking off both the oil filter housing and the exhaust system to get to the hole.  It might be possible with the exhaust still fitted but it would be more difficult.

[bryanj]

If you have drilled into it it is the rod on the spring loaded plunger that pushes the horseshoe to tension the chain. if its damaged you may find that the clamp bolt (the one you got out) will always tighten down on the damaged part so not leting the tensioner do its job.

You can use a 6mm setscrew with the threads removed at the tip---this is so that when tightened and it mushrooms slightly it dont damage the casing thread---- and use a standard nut with plain washer to lock it.

[Joel]

I've got a standard M6 hex bolt, washer and nut to lock the adjuster.  The bit that went through the original bolt and into the rod was a smaller diameter than the end of the bolt so the new bolt should sit over the hole rather than dropping in it.