Questions on 480 kit

[mymastifftucker]

Couple questions on the Athena 480 kit. I think the compression ratio is only 10.7:1 or something like that. If I have the head shaved, how far can I go to get to 12.5:1 so I can still run pump gas. Second, how does the power compare to using a 13:1 Wiseco piston in the stock cylinder?

[quadgod440ex]

I have the Athena kit with the hot cam stage 3 and a mild port job to the head . My buddy has a stage 3 cam with the wiesco 13.1 compression piston and a full exhaust with some jetting done . My bike beats him the straights by about a quad and half . We even switched bikes and my bike still beat his by about a quad an a half. Both bikes make very nice power . I love the 480 set up i have right now. Im very impressed by the power range that the piston and the cam make. No complaints on the 480 kit. As for the question about shaving the head to get about 12.5 comp. Im honestly not sure.

[ricks450]

thats a good ?. but there is no substitute for cubic inch. a bigger bore is better. no matter how tight you compress the air. dont take this wrong but wantin it be cheaper to get a differant bore kit with higher compression. like a 500 or 520 kit. then to get the 480 kit and then shave the head. i dont know.

[racernorris]

you can have your cylinder bored and replated for about $200 plus the cost of a piston and gaskets, you can get a 13.5 to 1 in a 480 from wiseco, j e, and cp. i do not recommend larger than a 480 on the stock cylinder, and i do not recommend shaving the head!


racernorris

[sandmanblue]

I can't comment on the Athena kit. Mine was done by KBR. My numbers speak for themselves....

I certainly wouldn't waste my time with a 480 at anything less than 14:1. Compression is good. Shaving heads is pointless when you can buy a great piston and get the right compression with it and the right gaskets.

My compression is about 14.5:1.

[mymastifftucker]

Originally posted by racernorris
you can have your cylinder bored and replated for about $200 plus the cost of a piston and gaskets, you can get a 13.5 to 1 in a 480 from wiseco, j e, and cp. i do not recommend larger than a 480 on the stock cylinder, and i do not recommend shaving the head!


racernorris
isnt it better to buy the Athena kit and have a cylinder designed to be a 480, not the stock one bored out? To go that big has got to make the walls of the stock sleeve pretty thin. The cost comes out to the same thing eith way. You can buy the Athena kit for $600 with the jug, the gaskets and the piston. Is the 10.7 the only ratio they sell or can you get a higher compression?

[quadgod440ex]

I think the 10.7 is the only compression piston that Athena sells with the kit. Wiesco , Je and other companys do make a higher compression for that same bore. Bro you wont be disappointed in the athena kit i promise u.

[400exrider707]

Originally posted by racernorris
you can have your cylinder bored and replated for about $200 plus the cost of a piston and gaskets, you can get a 13.5 to 1 in a 480 from wiseco, j e, and cp. i do not recommend larger than a 480 on the stock cylinder, and i do not recommend shaving the head!


racernorris

why wouldn't you recommend shaving the head?

[400exrider707]

Originally posted by sandmanblue
I can't comment on the Athena kit. Mine was done by KBR. My numbers speak for themselves....

I certainly wouldn't waste my time with a 480 at anything less than 14:1. Compression is good. Shaving heads is pointless when you can buy a great piston and get the right compression with it and the right gaskets.

My compression is about 14.5:1.

You could still shave the head to gain more compression than that as well.

[mymastifftucker]

Thats my question......how much to shave it to get the compression up to 12.5:1. Is shaving it going to put the valves to close to the piston?

[Colby@C&DRacing]

You would have to shave a lot off of the head to get those gains. Shaving to head on a 4 stroke is just asking for clearance issues.

[racernorris]

you have answered you question, how much do i shave it!
not only do you have clearance issues, now your timing chain is to long!

cylinder wall: the 04-05 cylinder is plenty thick, (4.71mm) but i still do not recommend going larger than a 480.

pistons: wiseco 13.5-1 $165, j e $155, and cp $250
gasket kit: $35

there are over heating issues with very high compression engine,not to mention you have to run a motor octane of 112-115 when you go above 13.5-1, you might have a hard time finding fuel close by.

racernorris

[sandmanblue]

Originally posted by mymastifftucker
Thats my question......how much to shave it to get the compression up to 12.5:1. Is shaving it going to put the valves to close to the piston?

You don't have to shave the 06/07 motor to add 1/2 point in compression. Just use the 2 layer head gasket for the 05 CRF-X motor. It's 0.009 thinner and will add that 1/2 point. BUT...

With the 480 bore, you can just go buy a 12.25:1 piston from KBR so you can run pump gas - if that's what you want to do.

I'm sure C&D can hook you up too.

[400exrider707]

Originally posted by Colby@C&DRacing
You would have to shave a lot off of the head to get those gains. Shaving to head on a 4 stroke is just asking for clearance issues.

Have you checked out chad502ex's 15:1 piston... he is shaving his head another .040 I believe to get something rediculous like 16:1 with plenty of Piston to valve clearance.

[sandmanblue]

Originally posted by 400exrider707
Have you checked out chad502ex's 15:1 piston... he is shaving his head another .040 I believe to get something rediculous like 16:1 with plenty of Piston to valve clearance.

1 - those are not 480 bore.

2 - there are 6 in existence.

3 - they haven't been tested and finalized.


Wait until some dyno runs are posted with a comparisons to other pistons before coming to any conclusions about new stuff like that.



.

[DirtDevilBT]

It is not worth shaving the head to get the extra compression when all you really need is another piston. Shaving heads will gain compression when you can't get anymore using another piston or head gasket. A motor with a 12:1 piston and shaved head, that brings the compression to 13:1....will beat a 13:1 piston equiped motor. The scavagging and overlap between the exhaust/ intake charge will be better with a flatter top piston, IE: lower compression piston.

However, you are talking about a minimal amount. Once you shave you can't go back, and for you I think the answer of going with another 480 kit would be best. You can get a 12.25 480 kit that will run pump gas. Or a 12.1 480 kit. Etc etc. Don't get hooked on that Athena big bore. You wont save anything if you have to shave the head anyway. Find a 12.1 480 kit. Golden, IMO