293cc kit by Lukesracing.com?

How does this kit by Lukes Racing (http://www.lukesracing.com/luksr/yz300.htm) compare to the Eric Gorr 293cc kit?

The pic on the website shows that it has o-rings for the head gasket (like stock), Eric Gorr uses a full head gasket. I prefer the o-rings but I did not think it was possible to use them on these big bores?

Here are the specs from the link above (the link has a pic too):

YZ250 1999-2011 300 Big Bore kit.

The kit includes: 72mm 293cc big bore cylinder. Wossner 72mm piston, rings, pin and clips, top-end bearing and a top-end gasket set..This is a bolt on kit, no case mods needed. Send your top-end(cylinder, head ,and powervalves)

This kit is fully ported and polished Fits: 1999-2011 YZ250 (2 -stroke)

Total for the kit: $750.00 on your cylinder, head and powervalve

does not look like he offers the power band options like eric. doubt his support is up there with eric. the EG kit is cheaper why would you not go with it ?

also removing the o-rings is not a requirement for the BB. however, eric said 75+% of the failures he saw on the yz was because of the o-ring failing. he decided to change it to a standard gasket which i like much better. the o-rings can be a pia.

I'm just attempting to get smart on all my big bore options before I choose one. I'm glad to see another company offering big bores...

I recall reading the Yamamha GYTR is making a big bore cylinder, is that still true? ECD? And I think Harris Performance also bores out a stock jug? And is Harris making big bore cylinder too?

How does the Wossner piston compare to the double ring Wiseco EG uses?

Eric designed MANY of the big bore pistons on the market. Going with something he disigined recently is probably a great idea. No idea on Lukes as I've never dealt with them.

I talked with a lot do places before I had mine done and was offered a huge discount by one of the biggest out there. But afew things made me go in the direction of Eric's place.

I learned that 285 is as far as the yz cylinder can go to with the stock o rings AND still be thick enough to support the cylinder and o ring. Eric's way around this is to weld in the o rig groove and use a full-on metal head gasket. The danger in doing this is warping the top of the cylinder. From the reports back, Eric has found a way to deal with this. It also takes a lot more labor doing it his way. He would have left the o rings in place if it would have been a viable and reliable option at 295cc's.

I wish you guys could see my pm folder. I get to hear about a lot of bad stuff about people we think we can trust. I had a message from someone who had a big-bore done by a reputable place. They did a great job other than forgetting to match his/her powervalve to the large bore size. The end result was not good. It was NOT Lukes Racing (or anyone mentioned in this thread). If something goes wrong, you want people who will stand behind the work. I KNOW Eric will, but make sure the place you deal with will as well.

Really, if you search a little, it woudl be easy to do these yourself. Its not hard to find a plater, a big piston, and someone who can port. If you went into this all-out, Wiseco can make proprietary pistons for you if you order in sufficient quantity.

I woudl also want some details on the piston being used. One advantage of using Erics design is the piston weight is almost identical to a stock, cast yz 250 oem piston. This helps with vibration.

Again, please donttn look at anything said as a comment on Lukes. They might be great. Until I hear otherwise, I presume they probably are. Look it this more as questions to ask before goign ahead.

Wiseco can make proprietary pistons for you if you order in sufficient quantity.

.

10 being the number they quoted me.:smirk:

Thanks for the education - it did not understand the reason for the full metal head gasket! Great points regarding Eric's service too. He built my RM250 motor and it exceeded my performance expectations and the customer service was just as good.

How real is the rumor regarding Yamaha GYTR making a new 293cc cylinder (like the SX300 kit)?

Unfortunately you won't hear much about other big bore kits involving 2-stroke yz's in this forum.

Just throwing this out there; I am on my 5th metal head gasket and the "support" from EG hasn't been that great.

Unfortunately you won't hear much about other big bore kits involving 2-stroke yz's in this forum.

Just throwing this out there; I am on my 5th metal head gasket and the "support" from EG hasn't been that great.

You can give details on what went wrong...keep the personal attacks out and its not a problem. Really, it sucks that you had issues, but posting what went wrong might help the next guy. Looking back on your posts shows head gasket issues due to the bike overheating.

If the bike is overheating, solve the issue or you might as well get 20 gaskets and change them daily.

I have that kit and I now check the gasket every six hours. I ride mine pretty hard in the AZ heat and lost a head gasket at 22 hours. When I pulled it apart I noticed my head bolts were no where near the 180 inch lbs Eric recommended Torquing this thing in proper sequence and then checking them every few rides seems to be pretty important. The o rings seem to cut you a little more slack as far as keeping them torqued. I can't speak to the kit you mentioned but I cannot get off my bike with the EG kit on it. Its honestly the most fun i've had on a bike.

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