Rick sent me his Pilot Engine that has the CR500 cylinder mod, the crank is twisted, pulled the Engine apart and confirmed it really twisted bad not sure what happen to cause it to break the welds and twist the crank but its twisted.

Pulled the top end looks like it was rebuilt never run or only run a few short minutes.

Will let Rick fill us in on the details of this Engine.

Recoil pulley removed and recoil discarded?

Little JB weld on the cases must have had a leak or weep some place?

Dowel pin on one side damaged it will be replaced.

Crank so twisted you can see the seal is not even sealing on one side because the bent crank is pushing it out of round so much.

Head removed looks all new like its never been run.

Crank cases apart looks like clutch side seal was sucking dirt?

Crank removed you can see it has been rebuilt looks to be the CR500 rod, crank was blasted then assembled then welded.

Clutch side bearing stuck with the crank had to take to my buddies and use his clam shell puller to pull the bearing.

Bearing removed you can see the welds are broke.

I don't have any experience with cranks twisting like this then being repaired, if it was mine I would send it to Speedchaser and have him remove the current rod and replace it with a new one, align the crank and weld again maybe do a full 360 weld this time?

Parts list...

Full gasket set
All 3 seals for the crank (I have the clutch side seal)
Both crank bearings
CR500 top end gasket set
One circlip for the piston ( I have these)
One dowel pin for the Engine mount ( I have these)
Rod kit for the crank.

If this one was welded then does that mean that when the rod was pressed into the lobes it was too loose? Seems like it would take a lot of force to break loose the weld if the rod was pressed tight.

To me ,it doesnt look like there is enough weld there?It should be chamfered much more than that,then filled with the bead all the way around like hoser mentioned.The ends are stress riser.

I cant imagine any weld holding there due to the stresses and flexing but I don't really know anything about it.

On pic#24 where the JB weld has been used,that is the same area that my ol Pilot LT500 was damaged.
Had to rebuild the Engine and crank case damage,sucked in air and leaned out the Engine.
Must be a problem area with the 500 mods.
It was ex Niel's ATV Racing personal Pilot.
Here's a pic of it at Northam Speedway.

I would hate to say this but if you look at that end it looks like this is the second time this as been done
plus it looks like they used the wrong welding rod and no preheat before welding .
bear in mind that the two pieces of steel are different. One is hard and one is not.
The best welding rod to do this type of welding would be a 880 stainless
now for that crank just think for a moment on how we would press this a part.
First we would go after that weld and grind it all out and hope we get it all.
Because the pin will open up the crank inside diameter and score the snot out of it if we do not get it all.
With that being said that crank may be junk all ready because it looks like this is the second time its been welded and pressed apart
How bad is the rod and rod bearing if there are still usable we might be able two grind out the weld and recenter the crank half's then re weld
but this may not work if the crank to rod bore is to lose all ready. your just taking a chance and looking for luck .

If it were Me I would be looking for a new crank because your all ready have the cr500 top end . a good stock crank is all ready stressed by the stock 400 top end and now you went bigger .


SpeedChaser

Good points

From what I understand whats usually done is you grind down the welded area on both the pin and the crank then press it apart if you grind past the weld affected area then it should not scar up the hole as its pressed apart? Who knows what care was used when this one was worked on last

Once apart you could bevel the opening so a good weld could be applied using the preheat and proper filler.

Rod looks new or really low hour but I would replace it anyways unless someone had a new and correct pin and bearing to replace the current.

I would want a full weld myself.

Usually when pins on cranks are a problem like this its because they came to a sudden stop, Engine running WOT (Wide Open Throttle) then locked up or a bad belt caught in the clutches, crank stops the flywheel and Engine balancer tries to keep spinning, something has to give.

I just dropped ricks new crank off to nick p. Hes going to press it out of the case he bought from me and send the crank to hoser.

Does it have the 400 rod or the CR500 rod?

400 tts the crank from the "can you feel my pain" motor (( Internal Combustion Engine ? ))

Thought your suppose to use the CR500 rod on the engines using the CR500 cylinder and piston?

Thanks again hoser for taking on this CSI.
I acquired this Engine from todd i believe the bottom end was assembled by atvracing and the port work was completed by jimmy yokum. I used this Engine in the Briggs when I participated in my first race. I ended up blowing the clutch in half after the pucks came apart. I literally blew the Clutch into two halves. The Engine was then removed in order to be installed into my wifes pilot. I made the mistake of having atv racing reassemble my wife's pilot(never use atvracing for anything unless they pay you)Neil put a fresh topend in and slapped some jb weld on the cases and didn't even offer to take me to KFC for some chicken because I like to eat after I get ((Bad Word))!!!
Anyways Im having Chris send a crank with the 400 rod in order for the pro's hoser/speed to assess which crank should be utilized for the rebuild. I will start buying all the parts you have listed including the new 500 rod.
Hoser- now that youve purchased your new welder will you be able to properly repair the cases?
And I know the hoserized 400 will compete with a atv racing 500, but for those of us who still want a 500. Can you provide the case modifications to board members?

I would love to experiment with a 500 Engine and I have a spare set of cases here Hoser if you like to try this?

nope the one i had was a 400 with a 500 piston,base plate and 400 rod with a 500 Bearing.when you use the cr500 jug you need to use the 500 rod. The cr500 mod will beat any modded 400. This Engine when hoser is done with it will have about 75 hp maby more. atvr will get you 75. Hoser may get you 80 hp My 400/500 piston when it was running was getting about 55 hp

I was going to say the same thing, I bet that weld cracked as it cooled down!

It looks as if the other started to follow suit. Even if it was welded all the way around it would have failed. The other side would have failed inspection had anyone taken the time to look

Hoser now that you have the received the crank from nick p What are you recommendations