So I get the bike that MrMoto35 posted a pic of that was rattling and making racket something fierce.

Here's what I found.

Cam tower loose.
Cam chain so kinked up that it wouldn't even fall down in the chain hole.
OEM tensioner flattened like a pancake

Further down..
The bearing collar on the crank had eroded something fierce. It almost looked like it was a bad casting beneath where the bearing rollers ran. There must have been .030-.050" of slop in the bearing.

The boot where the white chain guide rests in the case had the upper portion of the tab broken off. The oil pump pick up hold down had one of the fingers cracking off of it too.

But I think the root of the problem was the silicone that had plugged up the oil pick up screen.

The spark plug tube had come loose for whatever reason. The dealer that had their hands on it last tried to silicone the tube back into the head. A big flat piece of the silicone had come loose and worked its way down to the bottom end and plugged the pick up. Now, what further plugged the pick up is a guess because of the SAND, metal shavings and other random shit, its impossible to tell what caused which problem.

But, What I did find was a Hot Rods 3mm stroker crank, the rod was still good. The bore was edgy to say the least. The piston was worked over by the metal in the oil. Which was sad in and of its self because it was a JE with probably only a couple hours (Id say less than 20).
So we needed a cylinder and a piston, a main bearing kit for the crank (they come with a new collar) gaskets, chain, MCCT, new hold for the pick up, Oil pump etc..

Owner decided to go with the 100mm big bore to go along with his 3mm stroker which takes the engine out to 511cc. The compression worked out to 12.67:1. I ported the head to flow a bit more for all the Cubes...

Holy crap that thing is fast! It doesn't sign off the way I thought it might either. It just kept pulling and pulling. I had to shut it down since I was in the neighborhood, but the throttle response was instant and the front wheel just claws at the sky with ease.

It kicks easy, fires the first kick too.

Pretty proud of this one.

You created a monster. That things a fricken dragster now. Oh man he is one happy guy. We went to Milestone yesterday and he has been wearing a shit eating grin ever since. He has been going on and on about all the power that comes in instantly and with no end in sight.

I took him an oil filter and my stock engine covers (they might work with a little mod'ing) And he rode it down the street to warm it up. He got into third and was flying and he thought that it was topped out but when he turned it WOT it roared and the front wheel took off for the sky. I couldn't believe how fast he was going IN THIRD GEAR!!

Hard to believe it is the same bike. It sounds so much different. AND lets not forget it is running the stock pipe. Dave should have his new MRD exhaust ready for it soon.

We are probably going to Lake Elsinore MX tomorrow and I will ride it then. He kept bugging me to ride it yesterday but we had to leave early to go to family functions.

He is fricken stoked! He could see that very first time he met you that you are a top notch ace and he never had any worries. Never questioned anything. He knew all along that engine was in the best hands possible.

I really need to thank you too, you got my riding partner back out there with me. Thanks man!

Okay so I already have the 100mm bore.. are you saying that all I need is the stroker crank and ported head and my bike will be a 511??

How long is the motor expected to last with this setup or power

Rode it today and it is fast! The new front brake line really saves you because you are haulin ass in no time and need good brakes to get it slowed down. I think the MRD will make a big difference too. A lot more so then slapping an aftermarket exhaust on a stock engine. He is going to need his suspension done though. Both of us could feel a big difference between my bike and his suspension wise. Maybe a new rear tire as well...

That is a lot of power. But do you really need all of that power? Pros don't even use all of the 450 and you have 511. But if you are happy that is what matters. But you should have done your suspension first. But that is my 2 cents

It's a buddies bike, not mine. He started working out, changed his diet, and shed a lot of weight and now will need to set it up again.

GoBollzD33P, on 28 May 2012 - 05:48 AM, said:

For a vet, probably 150 hours.

If you've got the 100mm bore already, you need the stroker crank. Porting the head doesn't add displacement. It does allow it to breath and help the head handle the extra displacement.

The porting is why it doesn't run out of breath in the upper RPM ranges. You could do the crank without the porting for trail riding and be super happy I think.

I'm running a similar setup on my 2006 crf 450r. I have a 3mm stroker crank and a 3mm overbore (99mm). I installed a JE 12.5:1 piston and my ratio (with the stroker crank obviously) puts me at 13.1:1. This also comes out to 500cc. I absolutely love my motor. I also have a hot cam stage 2 installed and the loger duration of the cam really helped "smooth" it out and pull farther in the revs as well. I run a light mixture of race gas and pump gas and mix it to 98 octane. I know it isnt required for that compression ratio but I really think it helps it start easier and run smoother. I am running faction mx valves and their high rev valve springs just in case you're curious. I weigh 135 pounds and ride 90% on michigan singletrack and the enduro series. haha power is definitly not needed by any means! I'm just a power thirsty teenager.

At first I installed just the stroker crank and a 13.5:1 piston and this put me at 14.2:1 compression and 470cc. I then added the hot cam and shortly after (10 hrs) I blew a head gasket. At this point I had just over 50 hours on that rebuild. Anyhow whenever I went to replace my gasket I just got greedy and ordered a 99mm piston and sent my jug out to millenium to be overbored/plated. I also opted for the 12.5:1 piston because this ends up at a tolerable 13.1:1 with the stroker. 14.2:1 was just... too much. Pain in the rear to start and too much money spent on $8 gallon gas.

I now have 25 hours on my stroked/bored rebuild and am extremely happy. After getting jetting dialed in I have no issues and it runs like a CHAMP!! power is head and shoulders above stock. I crushed my stock header and slip on this weekend in the same wreck.. so now I'm shopping for an exhaust system for this bike.. and I dont wanna hijack this thread but any suggestions? thanks. Also, i need the option of a spark arrestor/quiet insert for tech @ enduros. And I also plan on having Ron do work some magic on my head @ next valve job (probably this winter).  Sorry for the novel, thanks!

The MRD is the hot ticket. Thats whats going on this 511cc. Hand made quality exhaust. Awesome performance. Has the arrestor/quiet insert. Got everything you need. If you contact Dave the owner he will build you an exhaust to go great with your setup. I have one and I love it. I ditched my FMF for the MRD and I am very happy that I did.

http://www.mrd-racing.com/page05.html

Hey Shawn, would you mind tellin me what you did with the porting?  I understand if you'd rather not, but it would be much appreciated!  I've been thinking about doing some port work on my big bore / stroker.

On a side note...  what have you guys been calling these beasts?  I find myself still calling mine a 450 because when I say 510 nobody knows what on earth I'm talking about!

I love when people ask "is that a 450?"

"Well, it USED to be....."  

Edited by pur3evil, 30 May 2012 - 07:37 AM.

shawn how did you fix the broken cam chain tensioner holder? new case? when i got my bike the previuos owner did something and i only have about half of it still there , found the other half sitting in the bottom of the case behind the oil pickup along w/ a old valve shim some people just shouldnt work on there own bikes , mine has held now asis for over 4hrs but makes me cringe nowing the half still there could let go,

that thing must be a monster on big outdoor mx tracks, how does it effect the heat does it piss out the over flow much?

I didn't notice much of an increase in heat, however that could be partially due to running less compression. When I was running at 14.2:1 and 470cc it was really bad and puked a lot. I struggled to keep it below 200 (vapor in line temp sensor) With 500cc and 13.1:1 it runs very happily and I haven't puked coolant at all yet (runs around 170-180) even after a 4 day ride in michigan single track this past weekend, with the high around 75-85 degrees throughout the weekend.

Also, thanks for the reply, I'll give MRD a shot!

Didn't piss out at all. Not a drop.  We were mostly riding the vet track which is much smaller and tighter so that was a good indicator that it is not overheating. It was super easy to start too. Just as easy as my bike and my bike is dialed in and a little old lady could start it.

fgrote, on 30 May 2012 - 08:16 AM, said:

I fitted the guide and there's enough of it left to hold the guide in place. From what you described I found exactly the same thing.

I also found a big flat super thin piece of black silicone in the oil pump pick up. Somebody at one time tried to glue the spark plug tube back into the head using black silicone. Its not tough enough for that...I cleaned it all up and put the tube back using Permatex HighTack. I got it spotless first with Acetone and skuffed the tube a little bit. Its perfect now. But a sheet of that black silicone worked its way down to the pick up and blocked the oil pump from pulling all it could.
I think that was the root of the main problem which was the main bearings being totally used up.

As far as the porting goes...I opened the bowls, broadened the cross section, sharpened the divider, cut out a couple random bumps and blended the seats. I didnt go nuts.