440 cylinder

[TRX_450]

has anyone bought a 440 cylinder new from a company? if so, where did you get it and roughly how much was it? i bought one with a piston on ebay, but the damned sleeve is too think and wont fit into my motor

[AZ440ex]

My Wiesco was around $200 if I recall. The 440 sleeve needs to be pressed in the matched to the piston. I think that cost me about 80-100$

[speedfoxracing]

i am goin 2 get my kit off of ebay 4 like 400

[rideracelivemx7]

that happened to my buddys quad. he had me pujt in a 440 kit for him, and its was a new cylinder too. i ended up having to sand it down with a dremel. its time consuming but worth it. took me about hour and half. and 4 battery charges ont he dremel. have fun:)

[TRX_450]

dont buy the kit from atvunlimited on ebay. they sleeves are too thick and you have to sand them down. im sending mine back and getting one from c&d

[speedfoxracing]

the one i was goin 2 get was like numra or somthin or je

[speedfoxracing]

speakin of the 440 kits did any of u get head studs put in and if u guys dont wut have u done 2 have the gasket not blow out ?

[AZ440ex]

Originally posted by speedfoxracing
speakin of the 440 kits did any of u get head studs put in and if u guys dont wut have u done 2 have the gasket not blow out ?

This is Just My Opinion!


I don't run high compression and always use a TQ wrench for assembly.

This is kinda a short version of the explaination. You can search Micky Dunlap here and get some good articles that explain alot about the 400ex

Depending on the piston(most are this way) the ex pistons are .040 short, so even though you have an 11:1 piston if you truly measure the comp with oil the 11:1 440ex is really about 9.8 to 1 compression. Use a XR gasket or cometic 3 piece steel gasket(they are thinner) and you get between 10 and 10.3 or so. Replace the base gasket with silicone and now your at 11:1 and you have the Ideal "quench" area on the top of the piston which keeps detination from happening. Detination is over looked and will kill a motor fast.

You gan build a 5hr motor(a high compression motor that needs constant maintenace) or run a 11:1 with a thin head gasket giving you 10:1 and a mild cam, good fuel and it will run forever. I am going on 100hrs with no failures. Its getting ready for its second piston now.

Oh and I still run stock head studs.

I want to know how you figure your compression is that low without the xr gasket. the xr gasket only makes a .2 of compression difference. I think you are crossing and mixing dynamic compression and static compression or something.

[AZ440ex]

Originally posted by FoxHondaRider
I want to know how you figure your compression is that low without the xr gasket. the xr gasket only makes a .2 of compression difference. I think you are crossing and mixing dynamic compression and static compression or something.

I read his article, got the syringe, did the volume test and math and he was right.

"On most after-market pistons, the pin to deck height is the same as stock. You should have a minimum of .040 clearance between the piston and head with everything torqued down. Right now the piston is about .043 too low and you are not getting a true compression ratio as advertised by most piston companies. For instance, a 440 11:1 flat top piston advertised is really only about 9.75:1 if you measured the volume correctly. In order to get the deck heights better, I use Honda HT silicone seal on the cylinder base and an XR400 gasket if you are running an 80 over piston or smaller. This will get you close to what your deck height should be. Keeping the squish clearance down to .040 gives a better quench area around the outside of the piston keeping it cool and less chance for detonation. You will be able to run an 11:1 motor on pump gas in most cases and have a more efficient flame travel and quicker burn rate across the top of the piston."
Micky Dunlap Four stoke tech

[drew416ex]

Originally posted by TRX_450
has anyone bought a 440 cylinder new from a company? if so, where did you get it and roughly how much was it? i bought one with a piston on ebay, but the damned sleeve is too think and wont fit into my motor

This is actually a better sleeve. It requires a little more work and money by having to get the case bored, but it keeps temps down better.

[TRX_450]

i know its better to buy a new cylinder with a new sleeve, but you have to grind the sleeve down on this one to make it fit, so therefore its no better than any other, because it wont fit into the motor unless its sanded down

[jeepthing07]

Originally posted by AZ440ex
I read his article, got the syringe, did the volume test and math and he was right.

"I use Honda HT silicone seal on the cylinder base and an XR400 gasket if you are running an 80 over piston or smaller. This will get you close to what your deck height should be. Keeping the squish clearance down to .040 gives a better quench area around the outside of the piston keeping it cool and less chance for detonation. You will be able to run an 11:1 motor on pump gas in most cases and have a more efficient flame travel and quicker burn rate across the top of the piston."
Micky Dunlap Four stoke tech

Hmm im building a 426 .120 over 11:1 piston. should i use honda HT silicone on it and a thiner head gasket? im also going to instal a stage 2 hotcam. i want it to run on 93 octane pump gas and be reliable. (im not racing it just want more power)

[AZ440ex]

Originally posted by jeepthing07
Hmm im building a 426 .120 over 11:1 piston. should i use honda HT silicone on it and a thiner head gasket? im also going to instal a stage 2 hotcam. i want it to run on 93 octane pump gas and be reliable. (im not racing it just want more power)

I know four stroke teck makes a piston that compensates for the 0.040. Maybe others companies also do this now.

Also I think with a .120 over you would have to use a cometic gasket or some other one. I could be wrong but I don't think XR gaskets go that big.

I would read trough this link. It may help you decide.

http://www.atvriders.com/articles/askmickey1.html

I personally run the thin head gasket and use a base gasket but I am ok with a little lower compression and I always run race fuel so detination no a issue for me.