[Superchuck]

Nearing the end of my 50 mile commute today I was on a tiny stretch of highwaylike road just as it (route MD-40) dead-ends into the downtown of Baltimore.  Burning up in my leather and boots on the 100 degree roadway I decided to gas it and burn down the home stretch on ye olde thumper.

Got it up to, well pretty fast.. ok i was going seventy.  The bike loses pull, but not as gradually as when you're running out of fuel.  I coast over to the shoulder in the 'emergency stopping only' zone and start soiling my pants.  All the stories of seizing pistons on the forum and now my dumb@$$ has gone and done it.  I let her cool down with hopes that she'll start again but in ten minutes I can't get even one true thump out of her.  The kicker's moving alright though, and doesn't seem to be crunching anything inside, but I still expect the worst.

I start pushing her home (through the ghetto and into downtown baltimore's ritzy inner harbor) and still can't get it to turn over.  It's a long way to home, we'll say maybe 3 to 4 miles from where I broke down... long in city terms, but walkable, and I wasn't about to wait for the AAA guy during rush hour.

Nearing exhaustion I stopped on the sidewalk just outside little italy and decided to poke around inside a bit.  The only innards i'm the least bit familiar with are the pushrod adjusters, so i go and open the tappet cover.  The left one (intake) adjuster has come off it's bottom housing rod thing.  My apologies for lame-man's terms    I try and re-seat the pushrod thingie but can't quite get it on top.  Nothing appears to be broke from what I can see, but the pushrod is really loose up on top, and I wonder if the longer part of the pushrod has broken.  (is this called a rocker??)  again, i'm not a vocab wiz...

On the way home I run into my buddy and fellow forum brother ammburger putting along quite happily on his new used iron barrel.  Boy that thing looks nice, especially when you're pushing your machine up hill both ways to get home to the air conditioning!

The non-existence of my intake tappet explains why I had no compression to start the engine, but where I go from here I'm a little muffed.  (is that a term? )

What should I start checking to diagnose the problem and find what all's broken?

Please help!  Thanks much in advance!

Sincerely,

Chuck

[Ice]

Sorry to hear of your misfortune brother.

 The AVL engines have on occasion "thrown" a push rod when run at top RPM's

Pulling the fuel tank and the intake rocker cover are fairly simple and straight forward tasks.

 I believe CMW offers push rod adjusters with deeper than factory skirts to prevent just such a thing from happening. If CMW does not have them Hitchcock's does.

[Superchuck]

I believe I have heard of such things.  Is it possible for me to re-set my pushrod adjuster without taking off the rocker cover?

Also, should I be worried about having broken something else within the engine, and what should I look at?

Thanks!

Chuck

[Chasfield]

I would recommend lifting the rocker cover so that you can take out the push rod for a proper examination to make sure it isn't bent or had metal chipped off the end. On my classic, I would aslo be concerned that the valve stem cap might also be on the loose somewhere (do AVL valves have these fitted?).

If all is well, then re-assemble with caution and observe the engine carefully for the next few miles. I am not sure if it is possible to pop the push rod back in against valve spring pressure without releasing the nuts that retain the rocker shaft bearing blocks. I have only ever located a push rod as part of a top end build up, and in any case, I don't know my way around the AVL top end.

Excessive engine revs can bring about a situation where the valve spring just doesn't have enough muscle to push valve, rocker shaft, push rod and cam follower back fast enough to keep up with the retreating cam shaft lobe. Under these conditions, the valve clearance can  dynamically open up far enough for the push rod to be able to jump out side ways.

If a rocker shaft is binding, or a valve runs too tight in its guide, then the valve spring has to do even more work, and the conditions for a push rod jumping out would occur at much lower revs.

It is easy to check for free movement of the rocker shaft with the rocker cover removed and the push rod in your hand. Checking that the valve itself was free to move would necessitate a top end strip down and removal of the valve springs. However, it is unlikely that a valve stem is binding in its guide - these things usually flap around more than you want on British bikes (= top end clatter)

 



Keep the revs down in the comfort zone and all should be well.

[blueberry]

II happened to me while going 65 mph. Probably due to me now knowing the proper way to check them. I pulled the tank and rocker cover and with an extra pair of hands put it back and adjusted it properly. No problems since in over 3,500 miles. Scared the crap out of me too.

[Superchuck]

Chasfield, thanks for the great pointers...

Won't I need one of those special valve spring compression tools to get it apart and back together?  I'm trying to get this thing working tonight so I'm going to start by trying to get the pushrod adjuster back on the tappet without taking off the rocker cover, but I, too would like to look in there and be sure there's nothing broken or missing.  

I've got spare rocker gaskets, so that's no problem, but I don't have that tool that Reverend Snidal pictures in his book... the one that looks like a glorified woodworking clamp.

I'm off to look at more diagrams of my top-end and poke around inside for a bit.  Please keep the replies coming as I'll be on intermittently tonight until i get her back on the road (if and when  )

cheers

chuck

[Superchuck]

blueberry, good to know it's probably not a huge problem.  Knowing that they sell replacement upgraded tappets for the AVL to prevent this is comforting too (since that means it's quite a widespread problem)

Also, I noticed at higher RPM's that I would be getting a 'whum, whum, whum' sound as I let off the throttle.  I was going almost 70 mph earlier in the trip, but up a decent incline.  The additional load from going uphill prevented these 'whum whums' from happening then, but i noticed them real bad-like right before the tappet thingie blew.  It's a whum or woom sound that vibrates the crap out of the entire bike... feels like it's resonating through the fuel tank and stuff too.  Sounds to me like the engine trying to slow down in absense of throttle, but I don't know if it's typical or bad or other...

thanks!

chuck

[Superchuck]

...that said I won't be flogging it like this again for quite some time 

[Arizoni]

IMO the best thing to do is to remove the rocker covers and the tappet cover.

Turn the engine over until it is at the top of its compression stroke.  That will assure both valves are closed and there will be no load on the rocker arms when the push rod is reinstalled.

Remove the retaining cap for the rocker that has lost its push rod, remove the loose push rod and examine it for damage.  Remember which end was up so it can be reinstalled the same way.

If it is not bent and the ends are not marred you should be able to install it back into the tappet, locate the upper end back into the rocker arm, replace the rocker arm retention cap and then the valve covers.

Check the clearance of both push rods at the tappets and adjust them if needed.

Replace the tappet cover, gas tank, fuel lines and you should be back in business.

Happy riding and next time try to keep the revs down a bit.

[Superchuck]

Playing craps with mother nature as we speak... deciding if these storm clouds look menacing enough to scare me inside off of my sidewalk 'streetlamp garage.'  I've been reading up in Reverend Snidal's manual and my Super Factory Manual along with looking at the diagrams on the parts cat and it seems do-able.  Not sure I'm going to get into it all tonight because of the impending rain but I may at least try and get the tank off, so next time I can do it quicker and I can worry about more important things...

thanks again everyone for the info, it's really a huge help!

chuck

[Superchuck]

Got it all apart and got it all back together.  Nothing's broke except for the gasket I mangled prying off the rocker lid.  Luckily I payed attention in class (ahem enfield forum) and bought a set of spares a few months ago.  Unfortunately I cheaped out and went for a fleabay seller as opposed to the trusted and esteemed nfieldgear and somehow I ended up with the wrong gaskets.  They're rocker gaskets alright, but not the sleek rhomboid shaped ones of the ever-so-sexy AVL.  Nope, so now I've got to order a new set of gaskets before this thing is complete.  Took everything apart... nothing was bend or anything.  It was really easy as everyone on here has said, and the thing that took the most time was me sitting there with two tiny wrenches trying and trying and trying my hardest to get the PERFECT pushrod adjuster settings.  I might add as well that it would have been impossible to re-set the pushrod without getting into the rocker cover because the top of the pushrod sits neatly in this tiny ball-and-socket joint in the rocker just as it does in the top of the tappets on the bottom, and no one other than a jedi master could have finessed it into there blindly.

Good news: it's gonna be just fine.  Bad news:  I'm waiting for parts again.  Let's try and make it more than one 100 mile commute next time the thumper's running.  Scratch that... 96 mile commute, 4 mile hike with a bike.  Someone better coin that.

Chuck

[Ice]

96 mile commute, 4 mile hike with a bike.  Someone better coin that.

 You just did brother ! 

Congrats on the successful repair.

 The AVL's  shaft mounted rockers are superior to the saddle block mounted rockers of the Iron Barrel but they do have a fair bit of mass to them and they do not reverse direction as easily as the Iron Barrel rockers.
 That the AVL's rocker system is more accurate, consistent and far more durable than the I.B.'s is a good trade off IMHO as top rpm is seldom required anyway.

 What happened at top rpm was the cam rotated and the tappet followed the cam down a hair faster than the valve spring could push the rocker arm and push rod temporarily creating gap enough for the push rod to jump or throw off of the tip of the tappet.

 Bullet Whisperer had made up some sets of cams to address this in his high rpm race Bullets.

 

[Chasfield]

Chasfield, thanks for the great pointers...

Won't I need one of those special valve spring compression tools to get it apart and back together?  I'm trying to get this thing working tonight so I'm going to start by trying to get the pushrod adjuster back on the tappet without taking off the rocker cover, but I, too would like to look in there and be sure there's nothing broken or missing.  


cheers

chuck

Well done on the repair.

A valve spring compressor would have been required if a thorough examination of of valve train components had been deemed necessary A tight valve guide is most unlikely and certainly never seen on any British bikes I have owned. These in general had top ends that sounded like a bag of hammers being shaken around because of large valve guide clearances.

If the push rod problem reoccurred at cruising revolutions then that would be the time to go out and buy the valve spring compressor.

[cyrusb]

O.K so if it happens again you can do it right there in the breakdown lane right? Do you carry enough tools to accomplish this? This is the very nub of (old)enfield operation. "You look a lot smarter fixing it than pushing it."

[Superchuck]

Lol, and thanks for all the input.  I think i could do it again on the spot as long as the rocker covers aren't as hard to get off as the first time (grease will do you good).  So I can't wait for the correct gaskets to come in the mail next week from nfieldgear, and more importantly I can't wait for my new snazzy royal enfield logo coffee mug that's comin with it!

cheers ya'll

chuck

[Bullet Whisperer]

 Bullet Whisperer had made up some sets of cams to address this in his high rpm race Bullets.

 
[/quote]
 Just a small correction, Ice, the cams I had made were for street Electra X machines, I had 6 sets made and they sold very quickly, with no horror stories I am aware of.. They help get the engine rpm past the 5,800 mark, where they usually hit a brick wall. There is a good bit of power left in there if the extra engine speed is unleashed !
 B.W.

[Ice]

Oops ! my mistake, I apologize,thank you for clearing that up B.W. 

 If you ever decide to have another batch of cams made, I know of one fellow who would jump at the chance to have a set.

[Chasfield]

Lol, and thanks for all the input.  I think i could do it again on the spot as long as the rocker covers aren't as hard to get off as the first time (grease will do you good).  So I can't wait for the correct gaskets to come in the mail next week from nfieldgear, and more importantly I can't wait for my new snazzy royal enfield logo coffee mug that's comin with it!

cheers ya'll

chuck

You will feel like a real pro strolling around your bike shed with that RE mug in your hand. No technical problem will be too great.