DR650 790 Big Bore Installation and Review

So sorry to hear this planemanx... there is nothing else to say really but that totally sucks - wish you all the best.

+1 on posting this and keep your chin up.

Desmodab

I'm pretty sure it was due to the ring gap. As I've posted here and in the big thread, I skipped the gaping process and ended up with these results... You live and learn I guess... Now to see what its going to cost to fix..

The piston is shot, no doubt about that. The cylinder is just scratched. If you run a finger over it, you feel it, but its not bad (compared to the piston) I have to see what procycle offers me to have it corrected.

Nearly shed a tear seeing that piston, I wish you the best.
Thanks for posting the build.

It seized momentarily. Did you run it low on oil? Maybe too lean. I think you said you jetted it lean to try and get better MPG. Not ideal for breakin or a bigbore.

I reset the jetting to a richer mixture prior to running it. I was good on oil. I assume the loud noise I heard was the first score (seize) from the rings expanding.

Do you guys think that there is another issue that was causing the noise in the video? I would have to assume that this was it. When I got home yesterday and drained the oil, It did eat some oil and was blowing blue smoke. This is expected though, if that is whats going on inside the engine. Nothing was sealed properly.

Take it to a shop and let them hone out the scoring. Put in a new top end. The tolerance was probably too tight. A couple thousandths more will prevent this from happening again. This is why Wiseco had the nickname Seizcoback in the day. Forged pistons need more tolerance and longer warmup time.

Sorry to see that. Can you measure the ring gaps now and post some photos of the rings? They are probably broken if they were too big. Lots of guys make the mistake of not checking the ring end gaps the first time they rebuild an engine, so don't be too hard on yourself.

I also am wondering about lubrication. You said that the oil temp was good. Is there lots if oil in the top end?

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Plenty of oil in the top end. Ill take some pics of the rings. they looks alright and if I fit them into the cylinder they still fit tight with no gap.

There seems to be your problem, no ring gap.
What did the instructions say about minimum gap?

When you first put the piston in with no rings, did it move freely in the bore? Just wondering what the piston clearance was.

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Sorry to see that.

wow thought i was having a bad day, sorry to see that , mabe ring broke when installing it.

Is the damage on the piston on both faces or only one? I can't tell from your photos. Assuming it is on both faces:

I didn't see this kind of damage occurring unless the ring broke and ended up between the piston and cylinder wall.

So, I did some research and here is what I found (this from www.ms-motor-service.com):

Initially, it looks like this:



But in these cases, damage above the skirt should be minimal. So, I did some more research and found this:







It definitely sounds like no end gap could cause this, although it is not identified specifically in the article. Your piston looks like image #4.

However, those who believe in the Motoman break-in strategy might want to take a good look at this....

If anyone wants a little light reading on this: http://www.boosttown.com/engine/piston_damage.pdf

The clearance was tight. Now without the rings, it fits very sloppy.

Thank you for the information. I think my problem was the rings were too tight, and didn't allow oil to pass, causing the issue. Running it hard on the highway created more heat, and ultimately chewed themselves up, and the metal chewed up the cylinder and piston.
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Procycle is really a great company and Jeff is an outstanding guy. He offered me a new piston and he will look at my cylinder to check if it can be honed out and used again. When I get it back, this time I'll check the ring end gaps…<o></o>

Later I will take more pictures of the damage, the rings, and how tight they actually are in the cylinder. I feel pretty friggin stupid, but thank you all for the support and advice with this issue. Hopefully the rest of this project goes smoothly.<o></o>

i don't know it off the top of my head, but there's a ratio to the ring gap/bore size that's pretty much universal ..... .xxx ring gap clearance times bore size in inches... here's the weisco one....

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

never hurts to measure twice, cut once.... grasshopper...(i love that shizzit!....)

one of my favorite sayings is... "we learn life thru suffering...."....

So they are offering to give you a new piston even though you caused the failure:huh

If that`s true......you got to give a big hand for that company..........that`s looking after a customer way beyond what they should...

But.......here`s a thought.....if you are selling a piston/ring/cylinder kit to the general public........maybe you should file the ring gap for them to ensure it`s done properly........does the company need to do this,no,but it would have prevented this..

I`ve seen this happen quite a few times......if the seller just sells the piston or cylinder separetely then fine,,you can`t gap the rings.....but if selling in a kit then they should just do it..since they have all the parts......this would take that part out of the hands of a person that`s not a pro builder........

Seems to me that if the seller gives you a new piston he kinda thinks it would have prevented this,,,,and is willing to take the hit to some point to keep the customer happy.......good for them,nice to see a company look after their customer..

B

Not giving it to me, I am paying for the piston. He could have said you broke it, so buy a whole new kit; but I thank Procycle for not going that direction.

I've offered planemanx15 a deep discount on a replacement piston to help him through this 'learning experience'. But first we'll take a good look at the cylinder and make sure it is salvageable. There's a pretty good chance it can be saved. The nodular iron sleeve material is incredibly durable. I know it looks like toast in the photos but a lot of what looks like damage will turn out to be aluminum from the piston that has transferred onto the cylinder.

Looks good on you offering a discount to help him out..that`s looking after the customer..

But.......i`ll say this..i`ve rebuilt a pile of engines,,i know ring gap has to be checked..a newbie isn`t necessarily going to though...

I still think if you are selling to backyard mechanics/do-it-yourselvers and are suppling the piston/rings and cylinder.........then the supllier should gap the rings...they have the means and knowledge to do so and can take this out of the hands of the first time builder.......yes the builder is responsible...but this would go a long way towards ensuring this wouldn`t happen ..

B