mystery diagnosis part two

[toadstool]

I am beyond discouraged and frustrated but am going to spare the unpalatable bitching and get to the facts. While driving today I was accelerating quickly, not redlining, when I immediately noticed a loss of power, exhaust note change, and excess vibration. Upon inspection the front cylinder has two cracks in the top of the valve cover. What I the hell could have caused this. I have limited funds to dump into this bike because I already spend over $10K in massive mistakes last year, plus untimely primary repairs this season.

 

[KaptinAmerika]

You've apparently had some form of valve train failure. The cost of repair can't be determined until the top end is opened up. Or if you have a scope pull the plug and take a look from inside the cylinder. Any way you slice it it probably isn't going to be a good thing. The problem with tinkering with something like these engines is once you start tinkering you will generally end up with a "Tinker Toy".

 

[ksmike]

Cant tell much from the picture, but it looks like something in the valve train came loose or broke hitting the underside of the cover? Maybe broken rocker, valve, spring, etc? Let us know, im curious.

 

[Brew]

I'm in agreement with both inputs, some type of valve train failure... :zzdisappointed:

 

[Bobby Schulz]

Same as above ^^^^ best to pull the tank/ rocker cover to take a look. Dont run it again until you have taken a look.

 

[erldawg]

Ditto open that baby up......

 

[BadBrad]

What's odd is that you have cracks on both sides of the rocker box cover. The larger crack appears to be directly on top of the front exhaust valve. This could have been from a broken spring and/or collar or perhaps just a bolt stripping out from the stand to the head. The opposite side just about has to be from the stand being pushed up against the rocker box cover. No need to keep guessing. You've got to open that baby up and have a look see. Take a pic when you do. Just curious how that could have happened. You're upgrades may have been more than it could handle. If the bolts stripped out of the head, you can go back with inserts or helicoils and a new rocker box cover, assuming there's no other internal damage. Definitely pull the roller rocker rod out and check it for straightness. Good luck.

 

[toadstool]

What's odd is that you have cracks on both sides of the rocker box cover. The larger crack appears to be directly on top of the front exhaust valve. This could have been from a broken spring and/or collar or perhaps just a bolt stripping out from the stand to the head. The opposite side just about has to be from the stand being pushed up against the rocker box cover. No need to keep guessing. You've got to open that baby up and have a look see. Take a pic when you do. Just curious how that could have happened. You're upgrades may have been more than it could handle. If the bolts stripped out of the head, you can go back with inserts or helicoils and a new rocker box cover, assuming there's no other internal damage. Definitely pull the roller rocker rod out and check it for straightness. Good luck.

I will dive into this on Saturday and post my findings. I am currently in anesthesia school and have about all of five seconds to spare during the week. Thanks for the replies. I contacted my builder and he seems to think the roller rocker bolts ( x 4) are to blame - meaning one gave, allowing the others to chatter and snap. I am about to give up. This poor bike has been in the shop more then on the road lately.

 

[Little-Boo]

You seem to have the same build up I have, except for the Nitrous set up which I don't have and would not consider using on a street bike. I even have ARP cylinder studs and still wouldn't consider using NOS on these engines. I have use NOS on my 99 LS1 and I know what one Nitrous back fire can do. It will pull threads, break rings, melt spark plug electrodes and even lift heads just enough to kill you head gaskets. The heat it puts out is way to much in my opnion. It only take one Nitrous backfire to put it back in the shop. Lets hope that is not the case with your dog. Just a thought :loony:


Carlos

 

[toadstool]

Nitrous Oxide has the potential to be dangerous, I agree. This threat increases with ignorance and lack of understanding surrounding its use. A negative stigma tends to be attached to nitrous oxides use in automotive applications. I usually find this is due to peoples misunderstanding and stories of hearsay. With the correct knowledge and skill, nitrous oxide is a very affordable and safe means to add power to a correctly built engine.

Ponder this: An engine manufacturer produces parts that are able to handle much more stress then the stock motor delivers, otherwise the high failure rate would be catastrophic to business. My nitrous application adds about 30% above the stock HP. This is within the engines tolerance, BY FAR. Many applications can safely add 50% increase on the stock motor, (important part here) as long as the air fuel mixture is compensated. With the nitrous, my A:F was confirmed on a dyno.

Bolt on supercharger applications increase HP by 50% and run without issues. Safety and understanding are paramount.

NOS was not in use during my failure.

 

[BadBrad]

I'm sure that 650 cam creates a lot of lift and takes a very stiff spring to handle it. The 4 stand bolts (roller rocker stand) are tapped/screwed into an aluminium head, not steel. I've had a bolt strip out running my 600 cam. While you have the rocker box cover off, look to make sure you have all your lock washers. When mine stripped, it vibrated the lock washer until it broke it in half. Half of that lock washer made it into my oil pump and caused the key to shear on my scavenger gear, thereby not pumping oil back to my tank.

 

[Sven]

I too am in agreement with posts #2 thru #6. My guess is your sig line with the increased valve diameter. Since it just a guess, your engine note or you saying that the sound changed, are we looking at a seat movement? Were any seats replaced so you do not grind too deep past that valve moving up in the head?

Then, what about a valve not hitting and dropping into the piston? Why didn't this occur? Strange that the keepers did not pop out and there goes the valve deep 6'ing into parts. There goes that engine note. Because you are still riding it, correct?

You would be on the side of the road with one cylinder running, or trying to. How could that crank sweep around to move the other piston's strokes? At idle, it would spin dead, right?

Can't be a pushrod growing. Can't be a lifter turning solid. Can't be a lifter galling or it would have more clearance and make noise, right? I know I'm probably missing something. Hindsight is going to kick me anyway, so I'm going to guess a seat sunk someway, somehow is to move that rocker way up there?

 

[john sachs]

Who did the mods ?
John

 

[liferider]

Nitrous Oxide has the potential to be dangerous, I agree. This threat increases with ignorance and lack of understanding surrounding its use. A negative stigma tends to be attached to nitrous oxides use in automotive applications. I usually find this is due to peoples misunderstanding and stories of hearsay. With the correct knowledge and skill, nitrous oxide is a very affordable and safe means to add power to a correctly built engine.

Ponder this: An engine manufacturer produces parts that are able to handle much more stress then the stock motor delivers, otherwise the high failure rate would be catastrophic to business. My nitrous application adds about 30% above the stock HP. This is within the engines tolerance, BY FAR. Many applications can safely add 50% increase on the stock motor, (important part here) as long as the air fuel mixture is compensated. With the nitrous, my A:F was confirmed on a dyno.

Bolt on supercharger applications increase HP by 50% and run without issues. Safety and understanding are paramount.

NOS was not in use during my failure.

But superchargers don't backfire destroying engines. They come apart and send shit down the engine. NOS does it in reverse. Makes carbs puke parts. I watched a idiot on a West Coast Chopper at the burn out bridge at Buffalo Chip push the button on a baby bottle and the topend went EVERYWHERE! Couple of people got taken away in a ambulance from flying metal hitting them in the face.
The other question is. Is the engine still under warranty?