ET 967 Tuning Thread

Has anybody done the bottom end epoxy/porting themselves? Just buy the top end from ET and good oem bottom end and some epoxy and a die grinder? I'm wondering if this is a thing that can be successfully done by a more adventurous DIY'er or if you really need to buy a complete motor from a builder.
 
Has anybody done the bottom end epoxy/porting themselves? Just buy the top end from ET and good oem bottom end and some epoxy and a die grinder? I'm wondering if this is a thing that can be successfully done by a more adventurous DIY'er or if you really need to buy a complete motor from a builder.
Cases have to be fly cut pretty big on a mill to accept the big sleeves on these. Might be able to do some notchy work with a die grinder but cases get pretty thin and its probably better to spend the $350 to have it done right.
 
Has anybody done the bottom end epoxy/porting themselves? Just buy the top end from ET and good oem bottom end and some epoxy and a die grinder? I'm wondering if this is a thing that can be successfully done by a more adventurous DIY'er or if you really need to buy a complete motor from a builder.
You need porting on them too
 

Big Kahuna

Administrator
I'm not sure what you mean. The case needs to be opened up like all of the big motors doesn't it? Or are you talking about porting on the top end?
Cases have to be modified to fit the big bore sleeves, flycut for clearance of the crank. In doing this, you have to epoxy the voids and even install a plate on the bottom of the cases because sometime the builder has to machine so much they penetrate through the cases (Or gets very thin). Then there is the porting aspect. Why are you going to spend $4000.00 on a cylinder, plus the stroker crank and then skimp on the cases. When you build one of these motors you are building a package, not setting up a bottom end to accept the cylinder. Sames goes with your carbs. You pick the carbs to go with the package to get the optimum results. Yes, you can slap some 44's and get it to run, but you have just spent a crapload for a motor that is gonna have the power of a 85mm Big Bore.............
 
Cases have to be modified to fit the big bore sleeves, flycut for clearance of the crank. In doing this, you have to epoxy the voids and even install a plate on the bottom of the cases because sometime the builder has to machine so much they penetrate through the cases (Or gets very thin). Then there is the porting aspect. Why are you going to spend $4000.00 on a cylinder, plus the stroker crank and then skimp on the cases. When you build one of these motors you are building a package, not setting up a bottom end to accept the cylinder. Sames goes with your carbs. You pick the carbs to go with the package to get the optimum results. Yes, you can slap some 44's and get it to run, but you have just spent a crapload for a motor that is gonna have the power of a 85mm Big Bore.............

I think you might be mistaken, 967 doesn't use a stroker crank.
 

Jcary85

Site Supporter
I think Erickson machining has a nice YouTube video on a 967 build. He might cover the case work and what’s involved. Eh I guess he doesn’t but good video anyway
 
If you see the amount of material removed from cases for a large CC engine, you might change your mind. I think it’s worth the money for someone experienced to do it correctly to get the most out of it. Not saying you can’t do it, just might not be as good as it can be. Get a base gasket for a 967 and stick it on top of some stock cases and you’ll get an idea of how much material has to go for the transfer and bore size. Obviously the tunnel porting is a whole different area.
 
I think it would look something like this.

To me it looks like deal breaker here for an average guy is that there are areas where the aluminum is completely gone and the epoxy is actually forming the sealing surface for the base gasket, so you need a mill to surface the top of the case.

Anyway, it sounds like the answer is no, nobody has done this. Would be cool to see/hear about if somebody has, but at this point I'm just derailing the thread so sorry guys.

1600802473179.png
 

McDog

Other Administrator
I think it would look something like this.

To me it looks like deal breaker here for an average guy is that there are areas where the aluminum is completely gone and the epoxy is actually forming the sealing surface for the base gasket, so you need a mill to surface the top of the case.

Anyway, it sounds like the answer is no, nobody has done this. Would be cool to see/hear about if somebody has, but at this point I'm just derailing the thread so sorry guys.

View attachment 401760
I think Gilligan did it with a DASA cylinder. Highly unrecommended.
 

Blue

Port for the Sport
I have built several of these 967 kits for customers and you are correct the top of the case needs to be epoxied higher and milled to ensure a good seal.

Sent from my SM-N950U using Tapatalk
 

Christian_83

Xscream
Has anybody done the bottom end epoxy/porting themselves? Just buy the top end from ET and good oem bottom end and some epoxy and a die grinder? I'm wondering if this is a thing that can be successfully done by a more adventurous DIY'er or if you really need to buy a complete motor from a builder.

My buddy did it himself on a ET 967. Just bought a ET 967 topend kit. He is mechanically good (butnot a mechanic).
He hed a stock 64x bottom he expoied and ported.
Basically pour devcon in viods around sleeves on top case, and also stator area where "front intake port" is. Let it hardn. Put cylinder on top part of crankcase. Start porting until you got a port match.

Will a ported cases set from the engine builder perform better? i donno.
Does my buddies setup rip and work nice - yes :)
 
My buddy did it himself on a ET 967. Just bought a ET 967 topend kit. He is mechanically good (butnot a mechanic).
He hed a stock 64x bottom he expoied and ported.
Basically pour devcon in viods around sleeves on top case, and also stator area where "front intake port" is. Let it hardn. Put cylinder on top part of crankcase. Start porting until you got a port match.

Will a ported cases set from the engine builder perform better? i donno.
Does my buddies setup rip and work nice - yes :)

Any chance he used 44mm carbs? *JOKING*

More seriously, do you know how he handled the surfacing of the top of the case? Did he do any porting of the cylinder? My understanding is that ET "CNC ports" the cylinder so the top end wouldn't have to be touched, but not sure how real that is.
 

Jcary85

Site Supporter
Any chance he used 44mm carbs? *JOKING*

More seriously, do you know how he handled the surfacing of the top of the case? Did he do any porting of the cylinder? My understanding is that ET "CNC ports" the cylinder so the top end wouldn't have to be touched, but not sure how real that is.

FWIW he definitely CNC ports them. Every cylinder is exactly the same - one of the reasons I love these motors. There aren’t some that rip and some that suck because of porting inconsistency. The only hand porting he will do is if you ask for raised exhaust ports for some reason.
 
Any chance he used 44mm carbs? *JOKING*
haha for the record I've been running my 967 on AM 44s and it rips too. FW Flips came around perfect at sea level and i only have 4 hours of ride time on the ski. That being said 46s or 48s are now at the top of my list since i now have a good ignition set up and i know I'm leaving power on the table with the smaller carbs.
 
Top Bottom