So I'm starting to build a CR500 conversion Engine I've been wanting to do for while but little to no time to do it. I'm using a spare Engine to use for parts needed to build the CR500. Have to give a big thanks to Nick P. and Peter K. for getting me what I needed to start this project..

May I ask who did the work to modify the cases? Also what year cylinder is that you are using? Looks like the older cylinder from 85-89.

A local guy here in Southern California you used to race in Superlites back in the day I believe. I didn't buy the Engine directly from him but from a close friend of the builder.

I think this cylinder is 90' or newer. This cylinder has the water jacket that comes from the side of the cylinder instead of the front from the 85'-89' cylinders.

I took some pics of the spare Engine being partially torn down to allocate parts needed to complete the 500 Engine. I have to say two tools have proven themselves aiding me in this project. The first tool is the Engine stand. It's really been a lot easier removing parts from the right side crankcase. There were a few times I need to put the Engine on the ground with the stand to apply more torque in certain situations. The second tool that seemed to work well was the gear jammer I got from Motion Pro. The tool did the trick in removing the big nut that holds the sprocket to the crankshaft.

The discoloration of the flywheel normal?

Also, after looking at the mechanical seal, is it safe to reuse again? How can you tell if the seal is worn and should be replaced?

Image 1654...is that a crack? lower right?

Sure looks like one. I'll check it when I get home later today. If it turns out it is a crack and I missed it, I'm retiring my tool belt!!

Hard to tell from the pics....I hope its just in the dirt.

When I first opened your pics I saw that piston and crank on the wall and my brain started blinking trying to scale everything in the picture! LOL! It took a second, but I figured it out!

Haha. That's funny. The crank belongs to a Go-Ped that used a weed wacker Engine. It was the first Engine I ever took apart so it has some nostalgic worthiness..

That gear jammer is a cool "toy"! The mechanical seal can still be purchased from Honda for about $30. Do some searching here and you will find the part number (Note: not the FL400 mech seal part number). When the mech seal was readily available, Randy used to replace it when doing a bottom end. I just had a top and bottom done and then oops,after a few hours it began to leak so I say get that new seal installed, also get the mechanical seal's oil seal as well. Its still available too.

Thought their was a reason why the older cylinders was used on the Pilot engines other than price and availability?

After rebuilding more than 40 Pilot engines I have never once used a Engine stand or the gear holding tool YES I know I have mention NOT NEEDING the Engine stand thing before and how it would just waste my time whilst your bolting the Engine to the case I already have my top end off and am splitting the case's after you remove your top end and start to remove the Engine from the stand I am cleaning and inspecting my entire Engine that is completely disassembled, I am pointing this out again because you word it as if its a MUST to have a Engine stand when people read this in the future I want to ensure they understand its not a must and just a personal preference thing. If ANYBODY has any questions on how to to ANY Pilot Odyssey or ATV Engine without a stand just start another thread and ask Engine stands are NOT REQUIRED in the ATV world.

To remove and install the big nut on the end of the crankshaft I just use my impact and the socket, I keep the crankshaft from spinning by holding the clutch end of the crankshaft with my bare hand, I install the nut the same way, impact and holding the clutch end of the shaft with my hand you watch the nut tighten as you rattle it on with the impact when you see it slow remove the socket you can see where it was torqued too from the factory, line up the mark where it was at the factory, naturally the threads are cleaned and loctite was applied to the threads on both parts before assembly.

The teeth on the flywheel are case harden after they are cut looks like a flame harden process is used.

Red stuff on the end of the flywheel is a thread locker you should see it on the nut also, see the "red" like in your picture on engines rebuilt by ATV Racing also usually see that white silicone sealer looking crap all over the Engine where ever their is a gasket used.

The seal in your red stuff picture is located behind the recoil starter OIL SEAL (35X52X7) 91201-402-015
that seal ALWAYS leaks its a poor design if you study it it takes a few hours of Engine run time to get oil to the seal, if you grease the lips of the seal before installing it lubricates the seal until the oil shows up this helps a little, I go one step further and grease the seal, install the seal then before installing the recoil basket use my Zoomspout oiler https://www.google.com/search?q=zoomspo ... 8&oe=utf-8 filled with balancer oil I fill the void between the back of the seal and the Engine case. Look close while apart at the design you will see what I mean, pre lubed then the seal will last, not pre lubed and the seal will weep most its entire life. Replace that seal use my steps to install you will be fine.

You can shorten the spring length on most any seal by removing the spring from the seal look close you can see where the spring is joined together you simply unscrew the spring too take it apart then you can shorten its length by cutting off the non tapered end of the spring then screw it back together this will put more tension on the seal and make it tighter on the shaft, how much to shorten is just a wild ass guess you can see the engineered length to get the proper tension when you take it apart

https://www.google.com/url?sa=t&rct=j&q ... wqaKdrAoDg

Can be had for Price: $7.83

Bullnerd: Checked to see if there was a crack on right side crankcase and thankfully it was just dirt. So the tool belt goes back on..

Hoser: Appreciate the input. I figured Honda used a red loctite for the nut. I've always had problems with the recoil seal leaking. Applying grease inside the lip of seal usually seemed to fix the problem. Didn't know about taking the spring out. In regards to the stand, never mentioned it was "must" to rebuild an Engine. I will agree it is definitely a personal preference to use. As I said before, it's worked well for me in working to remove the right side case and I know it will work well for me working on top end. I would obviously have to remove the Engine from the stand to rebuild the low end of the Engine.

If I am not mistaken, both the older and newer cylinders have the water jackets on the side of the cylinders. I could be wrong though! I think the older cylinders have bigger transfer ports which intrude further into the clutch. This is why the cylinder needs to be ground down next to the clutch so the clutch will not rub the cylinder. The new cylinders do not require as much of the cylinder to be ground down. Transfer ports are smaller on the newer cylinders.

Cruz, I noticed that the right case had welds in it. I don't believe the right case should require any modifying. The left case should be the only side that requires modifying so that the larger 500 cylinder has a full flat surface to sit on. I am just speaking based off of my 500 engines. One of the engines has the newer cylinder and the other Engine has an older 85-89 cylinder. Maybe the case was damaged at some point and the piston or rod damaged the case? Might be a good idea to make sure the welds on the right case are In good shape and are not porous.

I know the cylinder is definitely a newer style cylinder. How did the older cylinder work with two water jackets on it? I hope I won't have an issue with the ports being smaller.

When you say the right case, your referring to the magneto side case, right?

Ok, let me clear up some of the items with you. When you said water jacket I thought you were referring to the coolant inlet on the side of the cylinder. Mine are welded up and the inlet is off the back of the cylinder. Transfer ports shouldn't be an issue.

Yes the magneto side.

Here are some pics:)

So the water inlet on your cylinder comes above the intake on cylinder therefore the side inlet was welded shut, right? Whereas the cylinder I'm using only has the water inlet that comes on the side of the cylinder. Wonder why Honda made the change on the cylinder..

I'm starting to get a grasp on the CR500 conversions but still have a lot to learn. My case has quite of bit of welding on the magneto side crank case. Take a look at the links below PilotBird. The first link was a CSI hoser did on afastcar's 500 conversion. His right side case has a little bit of welding inside of it. The second link is another CSI hoser did on Mrclean's 500 conversion. His right side crank case also has quite of bit of welding in it.

I'm intrigued that your 500 doesn't have any welding in the right case.

viewtopic.php?f=25&t=3948&start=25

viewtopic.php?f=25&t=5511&hilit=CSI

Cruz, my apologies I stand corrected! There is some welding to the right case, but very little.

I think the 500 cylinders come with the inlet on the side, but on the back of the cylinder should be another inlet that can be drilled and threaded to have the inlet on the back of the cylinder.

I also think the side inlet for the coolant on the cylinder might be a problem as it may run into the gas tank. Maybe you can put a 90 degree elbow or have it welded up like mine.

Back side of the clutch also needs machined down for clearance of the transfer ports as shown in your picture where the cylinder has not been ground. On a side note I have never seen a Comet 102C run on the CR500 conversion perhaps its because of the clearance issues?

The plan is to use the current powerbloc clutch I'm running right now in the pilot. Once a shave off some material on the cylinder for clearance, I am still going to have to trim some fat off the clutch face plate too for everything to clear?

Where has the "gear jammer tool" been all my life???? Ordered. Awesome. And THANK YOU!

Worked pretty well loosening the big nut to the sprocket. Although, there is a youtube of a guy using the same tool on a CR500 bike and snapped the tool. Who's to say the guy was doing something wrong but he did break it.

on the 500 cylinders, the 89 and newer has the water inlet on the front right side of the cylinder, the older ones have the inlet on the back of the cylinder, also the older 500s use a shorter rod, without a little research I could not tell you when that change occurred.