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Aftermarket BIG Valve Cylinder Head

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I have owned and modded up 2 Honda 100's in the past as my kids and nephews were growing up... Wish I still had them both... But... I recently acquired a 97 XR100R ... So it's game on, and I'm never letting this one go.. this one's for the old man...lol

The stock head has scorched and wiped cam bearing journals in it... Daughter wanted to use it to teach a newbie/ boyfriend...so I thought:

"Sure..why not?...I'm going to build it up in a bit anyways"

Well... Turns out all day wide open in 1st gear... Air cooled engine with max heat cycles at 10k RPM combined with first gear airflow speeds... Will ruin stuff...

Which is a bummer because I was going to use it and already bought performance springs and new valves for it...

So then I did a quick search and found some people mentioning the Shift Up/ Spartan head from Japan... No hardcore info anywhere that I found...but I thought.. all new and bigger valves for me to work with to build my 120cc mini thumper ... $230 + shipping.. why not?!... I'm still going to port it to match my desired output and bring all my parts together as a cohesive performance unit...

Wellllllllllllll........

I should have looked closer.... 

I bought a Wiseco 58mm 12:1 piston to go with the new HTB Big Bore nikasil cylinder... I was hoping to do some creative gasket ordering from Cometic and tighten squish clearance and maybe try to bump compression to 12.5:1 if possible...

Keep in mind the Wiseco piston is made to hit 12:1 with the chamber volume of the stock head....

The Spartan head has a true/ open "hemi" head... No flat squish area... No "trench or bathtub" shape to the combustion chamber... Which sucks for several reasons... The more compact chamber and chamber shape of the OEM head is better for suppression of detonation AND production of power...

The stock head has a 9.1cc combustion chamber....

The Big Valve Spartan head has a 12.6cc combustion chamber... 

HUGE difference on such a small engine....

You can kiss 12:1 compression goodbye with that much more volume!!☹️☹️

I measured the valves and port sizes also and wrote them down for reference... 

The Spartan head has an appropriately larger intake port diameter to go with the substantially larger intake valve... Still needs a lot of shape modding to make it effective ...

The exhaust port is has a touch less volume... Great for velocity and response..  still getting some grinder time though....

I know a couple guys from the thumper talk forums who could pull off some detailed chamber welding and then mill the head flat again... Wouldn't need shaping of inside of the chamber... I want to do that myself... 

I can't stand the thought of using the big valve head as delivered... No way... I want the midrange to pop hard on this mini thumper... If my friends don't say "Damn Dude!!" When they test ride it, I will consider it an epic fail... This little engine needs compression to make that happen...

I would be happy to compensate for their time and talent ... I'm not above begging either... 

Doogee... Tegrity... What would it take to interest you guys???

More later... But here's some pics..

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TT member , lifelong gearhead, and Uber Machinist Doogee57 has told me he would throw me a lifeline with the ridiculously cavernous head design of the Shift Up/ Spartan head...😎💪👍

Another part of why the chamber is so big is that it's cut deeper than OEM to "sink the bigger valves" by enough to not have them hit each other during overlap.... Makes perfect sense when you check the geometry... 

Anyways... Doogee said he would give the "filling in" of the head a shot... It will be quite a feat...

If material can be filled and milled flat, then I want to use my porting tools to blend it as close to this shape as I can get....

45160053_IMG_20200721_1904552.thumb.jpg.02a30e2d841b0de8c4e050d027434e22.jpg

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  Ooooo, I likes dat. Looks like an XR200 head judging by the gasket surface.

5 hours ago, greenhuman said:

4171AF1B-5A52-4839-875E-78BB113F6E5B.jpeg

 

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30 minutes ago, Doogee57 said:

  Ooooo, I likes dat. Looks like an XR200 head judging by the gasket surface.

 

Nope... It's some sort of diesel engine....

No spark plug....😎😁

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It's too bad Powroll wasn't still in business... Much easier dealing with them on the air cooled thumper stuff in years gone bye.... The first xr100 I built had a Powroll stroker and 58mm bore.... 130-someting CC's... Used to irritate an RM125 riding friend in our group by reminding him that since my 12yr old nephew was running 130cc , that his 125 was the smallest engine in the group....lol...

 

And...same as it ever was... More guys into more building / fabbing/ hot rodding/hardcore wrench spinning in this 230 forum than in all other forums combined....

Most of the other forums are just a zillion questions about how to band-aid a machine that has been abused back together .... So it can continue a life of torture and neglect... No tech... No hot rodding....

Surprising to me is that it's a lot more difficult to find parts and info for the Honda 100's than I thought it would be...  The market has really went full bias for the 110 pit bikes...

Too bad (for me) that adnohguy and some of the rest of you aren't into the little XR's...lol... serious info as well as stateside info and parts are close to non existent beyond the BBR stuff....

Next up will be blab about several stroker cranks I have found and have been considering as a way to bump compression ... And oddly enough , both strokers say they recommend lightened flywheels for the reliability of the crankshaft...?!?  One said the full weight flywheel would cause "crankshaft blurring" whatever that means... 

 

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Brief description of both stroker cranks....

Stock stroke is 45mm / Bore 53mm

Bore kit I have is 58mm 12:1 with stock head... 120cc with stock crank..

 

The 48.8mm Stroker seems like something I can't use because it needs different clutch case with an oil filter in it .. would be 128.8cc if I could use it...

 

The 52mm stroker would be 137.3cc if I could use it....BUT it says it's overall compression/ deck height is 0.8mm LOWER than stock... specifically to LOWER compression... And add to excessive squish clearance ...

gross...

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Edited by mixxer

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2 hours ago, mixxer said:

No spark plug....😎😁

  Maybe he ain't just drilled it in there yet   :thinking:

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Mr. VortecCPI....

If you read this thread, I may want to have some custom pistons made with help via your Wiseco connection... 

While I have everything apart I can get accurate dimensions on everything....

 

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3 hours ago, mixxer said:

Mr. VortecCPI....

If you read this thread, I may want to have some custom pistons made with help via your Wiseco connection... 

While I have everything apart I can get accurate dimensions on everything....

I can contact David at Wiseco and see what he thinks.  So far he has been very helpful and receptive...

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Just now, VortecCPI said:

I can contact David at Wiseco and see what he thinks.  So far he has been very helpful and receptive...

A few mods to their 12:1 shelf piston that's made for the 58mm /120cc XR/CRF100 would be great....

I will measure assembled squish at some point... I have both heads for modeling....

It might be worth it to make a Spartan Head edition...?!?

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I'm sure you guys know this stuff that I just found out by trying to search for stuff for the xr100 engine...

Honda makes quite a few really cool and different 100 sized bikes, all with this same engine.... I want them...lol

A cafe racer one ....

One that looks something like a street legal xr75...

And a super motard version...

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On 7/22/2020 at 7:49 AM, mixxer said:

TT member , lifelong gearhead, and Uber Machinist Doogee57 has told me he would throw me a lifeline with the ridiculously cavernous head design of the Shift Up/ Spartan head...😎💪👍

Another part of why the chamber is so big is that it's cut deeper than OEM to "sink the bigger valves" by enough to not have them hit each other during overlap.... Makes perfect sense when you check the geometry... 

Anyways... Doogee said he would give the "filling in" of the head a shot... It will be quite a feat...

If material can be filled and milled flat, then I want to use my porting tools to blend it as close to this shape as I can get....

45160053_IMG_20200721_1904552.thumb.jpg.02a30e2d841b0de8c4e050d027434e22.jpg

Has anyone done this to a crf230 head. I thought I remember seeing a thread about this type of mod but I don’t recall any results or whether it was completed. 

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Yes... Dougee made the copper plugs for that project... He did it to protect the valve seats and heat sink them during the welding... I don't know how it all ended , but I know it was done.

Screenshot_20200722-202503.thumb.png.9ac509e6e1e0c72b592e9c16800f2772.pngScreenshot_20200722-202528.thumb.png.9c462317d973dc42c9503b5d2d71bb1d.png.

Edited by mixxer
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8 hours ago, mixxer said:

Yes... Dougee made the copper plugs for that project... He did it to protect the valve seats and heat sink them during the welding... I don't know how it all ended , but I know it was done.

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Not trying yo move away from original post but dougee what was the final results? Worth the effort?

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2 hours ago, mg600 said:

Not trying yo move away from original post but dougee what was the final results? Worth the effort?

   The CRF230 head I used was a donor from Ricky Racer that he had broken thru the intake port into the cam box. It was an experiment to see if the chamber could be welded up without ruining the valve seats. It worked. I/we have not yet tried to fix the break thru in the port to make the head usable (been busy with other projects: building a Hawk GT, etc.). Therefore I have no results to see how it actually works on a bike. Metric Muscle modded a head using my copper plugs and was also successful in altering the chamber. I think he's actually finished and been running his bike but no report as of now. 

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59 minutes ago, Doogee57 said:

   The CRF230 head I used was a donor from Ricky Racer that he had broken thru the intake port into the cam box. It was an experiment to see if the chamber could be welded up without ruining the valve seats. It worked. I/we have not yet tried to fix the break thru in the port to make the head usable (been busy with other projects: building a Hawk GT, etc.). Therefore I have no results to see how it actually works on a bike. Metric Muscle modded a head using my copper plugs and was also successful in altering the chamber. I think he's actually finished and been running his bike but no report as of now. 

It would be interesting to know what compression ratio / combustion chamber cc was the result....

I really wouldn't want to add compression while limiting flow via valve shrouding...

It's always a dang trade off... Nothing for free...☹️

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I actually don't know WTF to do with this whole mess I'm building here...

I'm learning more every day about the versions of the Honda 100 that area sold in different versions in Japan... But also transfer parts to the XR/CRF models sold in USA...

I think Mr Balls to the Wall Adnohguy may have to re think his Honda 100 ownership status once he sees what he can get for one of them...

Big Strokers....

Custom Transmission gearsets...

Small diameter flywheel rotors...

Roller rockers and Roller Cams....

Even a complete Dual Overhead Cam 4 valve from billet conversion...

The sky is the limit...

Here you go Guy:

Screenshot_20200723-085559.thumb.png.6e90dc290c49459b125b65bd9ead8f72.png

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I wish I knew a couple months ago what I know now....

Crash course in all things Honda 100... Holy Moly...😳😳

I would NOT have made the choices I made....!!

Just want a special/ fun/ torquey 100....  

I think I have my current dilemma solved in the simplest / most cost effective way...not going to have to pester Dougee or anyone...

Wish I knew more in depth details about the stroker cranks... Maybe another time...

But for now my search has come up with a piston that should be a match with reliefs for the bigger valves in this head ... 58mm... Takegawa...

Note to self :

* better buy some more modeling clay*

I guess we will see...🤞

Screenshot_20200723-100537.thumb.jpg.f075fb5506185d4a47e573bf15faaaf5.jpg

Edited by mixxer

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21 minutes ago, mixxer said:

I wish I knew a couple months ago what I know now....

Crash course in all things Honda 100... Holy Moly...😳😳

I would NOT have made the choices I made....!!

Just want a special/ fun/ torquey 100....  

I think I have my current dilemma solved in the simplest / most cost effective way...not going to have to pester Dougee or anyone...

Wish I knew more in depth details about the stroker cranks... Maybe another time...

But for now my search has come up with a piston that should be a match with reliefs for the bigger valves in this head ... 58mm... Takegawa...

Note to self :

* better buy some more modeling clay*

I guess we will see...🤞

Screenshot_20200723-100537.thumb.jpg.f075fb5506185d4a47e573bf15faaaf5.jpg

How thick is your wallet John? 
You need all of it ASAP. 
 

I have so many 150f and 230f engines that I would just try to shoehorn one of them into the 100 frame. 


let’s see here: 

Got a perfect condition 2005 150f kick start 247cc 12.5-1 with all the good stuff (mega cycle stage 3 cam, porting, 32mm flat slide, billet kick start gears, strong clutch,  extremely lightweight 150f flywheel, 8d advance key, just setting on the work bench starring back at me..... reves/sounds just like a 150r.  Very fun indeed.  Roll on, Wheelie producing power. 
 
It would tax the suspension completely. So maybe  just a plain old 120 kit would be better for your wallet? 

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