Pilot 465 kit info

[ludedude]

OK this keeps coming up....well not here yet..but it will So I'm adding what I know/have found out. And some questions of my own.

I've heard the 465 is not reliable as there is not much cylinder wall left...resulting in less cooling mass....heats up very quickly....

It was developed for the pilots when they were raced in a series, reliability was not as strong an issue.

They were pistons that are no longer made.

piston diameter was 86.6mm

Wiseco will make just about any past production piston for a minimum order. Did they make the 465 piston?

Did it run a spacer plate?

It would be a lot cheaper than a 500 conversion......which is more reliable? Guess it depends who does the conversion and how well it is done.

How large do the Wiseco's go for the stock pilot jug?

I have one at 82mm, at least 1 more at 81 or 81.5mm....

What else does a person do with the jugs when they go past max available piston bore size.....re-sleeve....heard that's a hit and miss too, again need someone who knows what they're doing....maybe we should resurrect the 465kit?

[ludedude]

Was originally done/developed by ATV Racing
Developed it just for the MTGP - they allowed larger displacement near the end of the Series' life.
Used a .180" spacer under the jug to make up for the difference in height between the wrist pin and top of the piston (it's .180" taller than a Pilot).
Used Suzuki 500 quad piston.
Needed to move ring locating pin move from intake port to make reliable, but they never did it - only ran this setup for three races and then the Mickey Thompson series was toast, so they never really pursued it from there.

Heating was not an issue as you've stated above - if anything, a thinner cyl wall helps transfer the heat to the coolant.

The big issue was ring reliability. Worked fairly well on a jug bored to stock Suzi Quad piston, but first over was an instant ring snagger.

It was never reliable and pretty much a stadium setup.

I thought that ATVR sold a 465 kit for a while that used a CR4?? cc piston.

CR500 is VERY reliable if done correctly (read done by ATVR and nobody else - they have all the jigs for doing the really precise stuff)
Bore Tech can do resleeving. He understands how to do them and how to keep them from popping out of the jug as they cool.

Oh - one other thing - Pro-X sells a shitload of oversized CR500 pistons (up to something like 6th) - you CAN NOT USE PRO X if you've touched the exhaust port with a grinder - even slightly. The recess around the wrist pin is exposed to the port on the exhaust side. Wiseco doesn't recess that area as much, so there's not a problem, but the Pro-X will blow by the return exhaust pulse and fry the sides of the piston.

[ludedude]

I looked for Wiseco CR pistons and couldn't find anything in the 86/87 mm bore area......so not sure what one that would be  :?:

So if we had 500 Suzuki quad pistons with relocated ring pins...it should be reliable?

Or what about oversized pilot pistons....how large of a bore can you actually go (if the pistons were available) on the pilot cylinder?

[atvnut]

I think it used a CR450 piston (2 stroke)

http://100megsfree4.com/honda/h0400/cr450.htm

[PilotHawK]

Just to add more speculation. I am pretty sure the 460 kit was a mid to late 70's tm 400 piston which is no longer available.

As for the pilot, the max bore for a wiseco is 82mm. Unfortunately there are only 4 aftermarket piston sizes for  a pilot cylinder. 6 total if you count a 1st, and 2nd over honda pistons. Stock 80 mm honda and wiseco, 80.25 mm honda only. 80.5mm honda and wiseco, 81.0 mm wiseco, 81.5 mm wiseco, and the last is an 82 mm wiseco.

Be careful when using the larger wiseco pistons and a stock head gasket, make sure the piston you are using will pass through the head gasket before using it or you may run into problems with detonation; especially if you are running a ported/decked cylinder.

[atvnut]

the cr450 had an 85mm bore and I am pretty sure it was the donor piston for the 465 kits. the early suzuki tm400 pistons were used in 440 kits

[ludedude]

85 will only give 448cc...you need 86.6 to get a full 465.....hmmmm

[ludedude]

465 kit did use the 81 cr450 piston  The CR450 was only made one year and nobody's making pistons anymore - if you do a quantity of 500, Wiseco will make them for you.

Ring pin location - right at edge of transfer port - good casting or non touched port and it didn't have issues, but on 1st bore or bad casting it would snag.
ATVR did edm some pins out and relocate the pin, but still not reliable.

head gasket too thin on bore - high comp blew gaskets - even with custom made copper gaskets - back to the head flex thing

It was a torquier engine  - good for woods and short twisty MX setups.

Can build 400 that makes more power and is more reliable

Spacer plate - ATVR has about 50 of them will sell 7.00 each.

Others (companies) used TM400 piston - very heavy, very heavy wrist pin - made 430cc but woudn't rev out.  Too much mass.

[Vrroom]

More (somewhat usless) info on Pilot "big bore" mods.

I have a Pilot cylinder that has a bore measurement of 3.354" (85.192mm). I've found the following pistons but have no idea if they will work. I also don't know any of the pin height measurements of these pistons.

Polaris 400 (x2 over stock) measures 85mm
Suzuki LT500r = 86mm
Kawasaki KX500 = 86mm

A 3.346" diameter (85mm) piston would give a piston to wall clearance of .004". and create a 450 cc displacement with my jug. Is that too much?

I don't have the time or ambition to mess with it at the moment because my pilot is almost brand spankin new (I just changed the rear break pads that were put on at the factory). The jug and head I have are for sale if anyone is interested. (jwhims@charter.net)

Vrroom

[bleederboy]

Many things to think about:

You have to take into account the ring pin locations of these pistons.

If the pin(s) are not located correctly (they need to be lined up with the cylinder wall, not a port) the ring ends will snag the port and then bad things will happen.

Ring pins can be relocated, but it's a major pain in the butt and not very reliable.  Most of the time the pins are EDM'd or machined out and then a new one is put in the correct location.

The problem is keeping the new pin in it's new location.  The heat cycles, different coefficents of expansion of the metals and such make it more than just drilling a hole and sticking a pin into the piston.

How about piston crown to wrist pin height?  The spacer on the 465 kit (using the CR450 piston) was to take up the difference.

If the wrist pin to dome height is more than a Pilot's, then you can make a spacer.  If it's less, then you would have to do one of the three:
A) Deck the top of the jug
B) Cut the bottom of the jug
C) Deck top & cut bottom.

Remember, you're changing port timing with the difference in height.

Ideally, the lip of the piston will be even with the bottom of the intake port at BDC.

Also, what about skirt length?   If the piston has a longer skirt then you'll need to make sure that the skirt and the crank don't meet each other at BDC - that would be bad....

The skirt also has to be long enough to close off the ports at TDC.

Sounds more and more like someone needs to go to Wiseco and just pony up the bucks to have a couple hundred 3rd, 4th, 5th over replacements for OEM.

Last but not least, how about the recessed area of the pistons where the wrist pin pins go in.  - do they cover the exhaust port or do they let the exhaust port open up to the recess (as the CR500 Pro-X pistons do).  

Blow by will result in an instant boom.