[atleastitsnotaford]

I barely know how to type so there is defiantly no photo shop going on with me :lmao: Can you do me a favor and take my quote out of your post :thanks: Again sorry for making this a who’s a better build in Eric’s thread. You seem to know a lot about the 824 kit that I didn’t think was even going to be around for months. Can you tell us more about it?

How's that? (If I took it all out, my post wouldn't make much sense.)

That is a nifty nos bottle mount then.

Hmm, more about it, ok:
stock 102mm x 84mm.........(5.1cm x 5.1cm x 3.14159 x 8.4cm = 686.387cc
824 kit 108mm x 90mm.......(5.4cm x 5.4cm x 3.14159 x 9.0cm = 824.479cc
(824.479cc - 686.387cc)/686.387cc = 20.119% increase in displacement
(90mm - 84mm)/84mm = 7.14% increase in stroke

Using as an example, Alba stage 2 kit (11:1 piston, mild cam, mild port)nets 54.75 hp. As a general rule a % increase in displacement will result in an equal % increase in hp so 54.75hp + (54.75hp x 0.20119) = 65.765 hp

The 7.14% increase in stroke is important to note because it will result in more low end torque (around 55ft-lbs) wich means a broader, smoother power curve.

That's all I really got, anything more will be finalized by Eric over the next few months until the kit actually becomes available to the rest of us.

 

[08700xx]

...

 

[VelociRaptor]

I remember back a few years ago 65hp was the golden # to hit on a race build 686 Raptor, now if your not hitting 80 you need to go back to the drawing board. I feel the XX will follow the same suite.

 

[xxTheDarkLumpxx]

I'm pretty much all about the trails, but I would buy a set up for 824 if it had a solid bottom thru mid range with a good top end. Something a bit like stock +20 HP but targeted over total range. Really don't want or need a top end screamer. Or a hard starter, or sh*t breakin all the time, you get my meaning...

11:1 CR
stage 1 cam

Since we need more flow per stroke with the bigger cc, then try to size everything to match...

New air box?
+3 TB
mild port +1 valves
PCIII
Of course full exhaust

Basically a, "What if the XX came with a 824 cc motor stock" Perfect! I believe the Renegade is 799cc and 71 HP...it can be done and still have a very trail worthy machine. Not just it can be ridden on the trail, I mean it rules the trail.

Top end is OK, but I would love to have that bottom thru mid range to power run the trails like a mad man...this is the element where the xx already kicks butt...now it would truly dominate...untouchable... Just makes sense...sign me up..

 

[DL700]

How's that? (If I took it all out, my post wouldn't make much sense.)

That is a nifty nos bottle mount then.

Hmm, more about it, ok:
stock 102mm x 84mm.........(5.1cm x 5.1cm x 3.14159 x 8.4cm = 686.387cc
824 kit 108mm x 90mm.......(5.4cm x 5.4cm x 3.14159 x 9.0cm = 824.479cc
(824.479cc - 686.387cc)/686.387cc = 20.119% increase in displacement
(90mm - 84mm)/84mm = 7.14% increase in stroke

Using as an example, Alba stage 2 kit (11:1 piston, mild cam, mild port)nets 54.75 hp. As a general rule a % increase in displacement will result in an equal % increase in hp so 54.75hp + (54.75hp x 0.20119) = 65.765 hp

The 7.14% increase in stroke is important to note because it will result in more low end torque (around 55ft-lbs) wich means a broader, smoother power curve.

That's all I really got, anything more will be finalized by Eric over the next few months until the kit actually becomes available to the rest of us.

your general RULE is wrong.... if the VE stays the same the hp will increase on a percentage with the cc size....


basically if the head only flows xx amount, and is pushed to its potential with the current cc size(more then likely) then the increase in cc size will have greatly reduced Hp returns... i seen it all the time with other bikes....yes, you will see a faster ramp on the hp/torque curve but its highly likely a very small hp increase..

id be willing to wager on the 100+ cc increase only making an additional 5 hp over the 686 if that, same head and all......

 

[atleastitsnotaford]

your general RULE is wrong.... if the VE stays the same the hp will increase on a percentage with the cc size....


basically if the head only flows xx amount, and is pushed to its potential with the current cc size(more then likely) then the increase in cc size will have greatly reduced Hp returns... i seen it all the time with other bikes....yes, you will see a faster ramp on the hp/torque curve but its highly likely a very small hp increase..

id be willing to wager on the 100+ cc increase only making an additional 5 hp over the 686 if that, same head and all......

Yes the VE must stay the same for the hp increase to match the cc increase. All the engines I've messed with in this manner have flowed well enough that the ve did not significantly change. Are we really that close to the max flow of the xx head? If so, maybe all the r&d would be better spent on a new head.............

 

[EHSRACING]

flow in the head is def not maxed there is a lot of room for improvent +1 valves aint gonna get the job done for big HP it will for most people but not big#'s i think a 40mm/34mm setup with a 6.0mm stem would do nicely the valves these come with are beastly

i know 39mm will work i will have a head soon with those to be testing hopefully soon

you make more power with more cc's to an extent there is really no math that is correct all the time the biggest thing with more cc is supporting parts if that cant handle it your not going to see the gains your motor is only as strong as the weakest link in it.

the power band you can create with more cc is hard to match with smaller motors just becasue it dyno's close to the same dont put it the same in action a 2500-3500 rpm range will beat a peak # all day these guys aint going to be at 8000rpm all the time

 

[VelociRaptor]

40mm will fit the stock seat so dont worry about 39s fitting.
Like Daniel said-cylinder head being the same; if its the limiting factor, will make the engine find the limit quicker in the rpm band.
I havent yet but someone will find hidden airflow in these XX/XR intake ports that will bring it up to a simular level as the Raptor cylinder head but then your limited by valvetrain design. Not saying the Raptor has a perfect valvetrain design(its limited too compared to the DS engine) but not as bad as the Honda in its current state.

 

[DL700]

flow in the head is def not maxed there is a lot of room for improvent +1 valves aint gonna get the job done for big HP it will for most people but not big#'s i think a 40mm/34mm setup with a 6.0mm stem would do nicely the valves these come with are beastly

i know 39mm will work i will have a head soon with those to be testing hopefully soon

you make more power with more cc's to an extent there is really no math that is correct all the time the biggest thing with more cc is supporting parts if that cant handle it your not going to see the gains your motor is only as strong as the weakest link in it.

the power band you can create with more cc is hard to match with smaller motors just becasue it dyno's close to the same dont put it the same in action a 2500-3500 rpm range will beat a peak # all day these guys aint going to be at 8000rpm all the time

just depends on the rpm being used.... so for any type of racing the 2-6k rpm is a waste....

so big Tq yes.. but big hp.. no, thats in the head

my theory has alway been to push the smallest cc size motor to its max potential, then use what was learned and go up in cc size from there and attempt to make the same hp per cc as the small bore.,..
much is lost in going to a big cc from the start..