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Aftermarket BIG Valve Cylinder Head

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6 hours ago, Momus said:

I have 3 or 4  XR100 based bikes that will run rings around yours. 

Oooooo, is that a gauntlet I hear hitting the floor?:thinking:

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Posted (edited)
6 hours ago, Momus said:

I have 3 or 4  XR100 based bikes that will run rings around yours. 

The first photo below is of the slowest but most rideable- 100Kg on board.

Those Shift Up heads you were playing with are designed for an engine with 47 more cc ie  57bore- 56.5 stroke- and a domed piston- dome volume is 3.5 cc...

When assembled thus they give around 12:1 and with a real camshaft- high lift and  short duration and a decent carby they go well.

Second picture shows another build with a good head- Takegawa- that comfortably out powers 85 cc two strokes.

The two fastest, not shown, are out to 171cc,  running 31 and 32 Ti intake valves, properly big carburettors and revving to 16000 reliably.

Cheers.

 

 

XR75 Betty.jpg

Harry Clarky.jpg

That's like saying I have a 200 2stroke that will outrun a 125 2 stroke.... Big effing deal if you are running a huge displacement advantage....

You don't have any idea of how I setup a head to run so you really are unqualified to speak about anything of a head I have made for a particular use.... I have built engines that pro riders have topped pro podiums on in many off road sports for many years... Flattrack / sand drag/ arena cross/ hare scrambles... You name it... But these classes are all displacement limited,  So volumetric efficiency is king... Not unlimited displacement ....

 

I'm flat out saying I'm better at setting up heads that feed well enough to offer true advantage to all the other band aides to produce power within a displacement class...

16k rpm reliably and making power... Well now you are a true God of engineering in the XR100 world....

You should probably wear your chest protector on backwards to keep you back safe from that level of self congratulatory back patting....

If I start a teaching thread and show/ help people how to make something quite special and on a budget... What is your point of just jumping in and saying you spent enough money to buy your own trophy factory on machines with huge displacement advantages that will beat it?!?

I invite you to go practice self love... And host your own teaching threads...

Also on the 16k power production...

Dyno Graphs to support....or all lies...

Cheers👍

Edited by mixxer
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6 hours ago, Momus said:

I have 3 or 4  XR100 based bikes that will run rings around yours. 

The first photo below is of the slowest but most rideable- 100Kg on board.

Those Shift Up heads you were playing with are designed for an engine with 47 more cc ie  57bore- 56.5 stroke- and a domed piston- dome volume is 3.5 cc...

When assembled thus they give around 12:1 and with a real camshaft- high lift and  short duration and a decent carby they go well.

Second picture shows another build with a good head- Takegawa- that comfortably out powers 85 cc two strokes.

The two fastest, not shown, are out to 171cc,  running 31 and 32 Ti intake valves, properly big carburettors and revving to 16000 reliably.

Cheers.

 

 

XR75 Betty.jpg

Harry Clarky.jpg

That's like saying I have a 200 that will outrun a 125.... Big &%$#@!ing deal if you are running a huge displacement advantage....

I'm flat out saying I'm better at setting up heads that feed well enough to offer true advantage to all the other band aides to produce power within a displacement class...

16k rpm reliably and making power... Well now you are a true God of engineering in the XR100 world....

You should probably wear your chest protector on backwards to keep you back safe from that level of self congratulatory back patting....

If I start a teaching thread and show/ help people how to make something quite special and on a budget... What is your point of just jumping in and saying you spent enough money to buy your own trophy factory on machines with huge displacement advantages that will beat it?!?

I invite you to go practice self love... And host your own teaching threads...

I have owned and operated 2 dyno driven R&D performance shops over a 40 year span of pro engine building... My favorite game is feeding people with mega dollar builds a dose of humble pie by the use of proper application of physics... Not just BIGGER everything because plenty of classes ... And especially pro...are displacement limited...  I have known true power and true speed my entire life... And am completely comfortable in my evaluation of what is and isn't fast...

My little trail running budget XR is fast... Been serving up hot humble pie for 40 years now... Still making it fresh every day...come get some...😎♥️

Cheers👍

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You Mixxer.... are the God of engineering in the XR100 world....  👍

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Posted (edited)
3 hours ago, mixxer said:

That's like saying I have a 200 that will outrun a 125.... Big &%$#@!ing deal if you are running a huge displacement advantage....

I'm flat out saying I'm better at setting up heads that feed well enough to offer true advantage to all the other band aides to produce power within a displacement class...

16k rpm reliably and making power... Well now you are a true God of engineering in the XR100 world....

You should probably wear your chest protector on backwards to keep you back safe from that level of self congratulatory back patting....

If I start a teaching thread and show/ help people how to make something quite special and on a budget... What is your point of just jumping in and saying you spent enough money to buy your own trophy factory on machines with huge displacement advantages that will beat it?!?

I invite you to go practice self love... And host your own teaching threads...

I have owned and operated 2 dyno driven R&D performance shops over a 40 year span of pro engine building... My favorite game is feeding people with mega dollar builds a dose of humble pie by the use of proper application of physics... Not just BIGGER everything because plenty of classes ... And especially pro...are displacement limited...  I have known true power and true speed my entire life... And am completely comfortable in my evaluation of what is and isn't fast...

My little trail running budget XR is fast... Been serving up hot humble pie for 40 years now... Still making it fresh every day...come get some...😎♥️

Cheers👍

Quote

 

 On 10/5/2020 at 2:12 AM, mixxer said:

If there's a faster XR100 based bike out there... I'd love to see it... I would line it up against ANY xr100 based engine with no hesitation whatsoever... This thing is more fun than a barrel of monkeys....🤘😎😁

 

LOLS. The above is your bragging, swaggering quote that prompted my reply.  Yo said ANY XR100 engine: no mention of capacity, money spent or back patting irony or humble pie.😁

I've just shown you two race winning  145 cc bikes that I reliably estimate will be a lot faster than what you are touting.

 

This is what a 16000 rpm XR100 inlet port looks like: ignore the valve it is just a stand.

 

 

SAM_0123.JPG

SAM_0119.JPG

Edited by Momus
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Posted (edited)
On 8/18/2020 at 9:30 PM, Doogee57 said:

  I'm thinking shims in the bottom of the main bearing pockets is how he's done it. We've got a bunch of stainless shim stock in various thicknesses here at the shop. Wouldn't be too tough to make some shims the proper thickness. My questions: Center the crank?(shim both sides) Shim to the right? Shim to the left??? Sounds like a dance step.  :D

You shim the crank to align the cam sprockets- and shim the cam to maintain it's end float to within 002"

I make shims from thin shim stock -002" that cuts easily with scissors and when I have the thickness I need cut the install shim from hard stainless or 4130 steel.

 

 

Edited by Momus

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1 hour ago, Momus said:

LOLS. The above is your bragging, swaggering quote that prompted my reply.  Yo said ANY XR100 engine: no mention of capacity, money spent or back patting irony or humble pie.😁

I've just shown you two race winning  145 cc bikes that I reliably estimate will be a lot faster than what you are touting.

 

This is what a 16000 rpm XR100 inlet port looks like: ignore the valve it is just a stand.

 

 

SAM_0123.JPG

SAM_0119.JPG

Poachers sell those to Asians as Aphrodisiacs for huge amounts of $$$$. 
The ones in the photos appear to be synthetic? 

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On 10/11/2020 at 6:58 AM, mixxer said:

27mm pumper currently on the bike... No choke assembly... Tuned in better than I hoped for... Sharp response... Lots of power...perfect...

Starting from cold is a bit of a several pump shot and throttle dance to get some heat in it..  lights right up... But needs some throttle voodoo to keep it running ... Engine warm is perfect all around...

But...

I wanted to try a pz30 pumper carb and see if I could leave the choke assembly intact... Still have throttle response and good WOT flow/ power...

We will see....

The accelerator pump assembly on the 30mm carb shoots good and straight right out of the gate...

I just couldn't leave the choke assembly alone... It's like a downed tree smack in the middle of the flow path....

Lots of cutting needed on the 2nd intake manifold I'm setting up just for it... 

Waiting on some strange style pilot jets before I try it out...

PXL_20201010_152703627.thumb.jpg.8dd2896c1fe92021dd80cc82a56d97d4.jpg

PXL_20201010_155754059.thumb.jpg.a11e2bedf4df2a4bcecc26677eed8dc5.jpg

PXL_20201010_191630707.thumb.jpg.f81fa26524c1cb164f15fe03eb507727.jpg

Wow, that's a hell of a lots less sail in the wind. Makes what's left of the screws look gross and fat and ugly.

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1 hour ago, SteveThe Snakes said:

Anyone who needs serious lightened racing valves let me know. 🤙

5E09F057-FC1E-4F75-9274-9A7164AD08BF.png
😂😂😂

You could remove the auto decomp for sure. 

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15 hours ago, Old Plonker said:

Wow, that's a hell of a lots less sail in the wind. Makes what's left of the screws look gross and fat and ugly.

Agreed!

The screws are staked/splayed to 100% guarantee they can't back out for the engine to ingest....

It is perhaps possible to trust red loctite and shorten the screws to grind off/ eliminated the staked section

I was looking for a jewelers silver solder rig to do the ultimate trick setup.... Remove one screw first and silver solder though that screw hole... Then pull the other screw and silver solder that hole also.... Perfect setup with choke blade silver soldered to  thin shaft ...and zero screw protrusions....😎

It's on the to do list still...

 

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On 1/8/2021 at 8:01 AM, millwoodva said:

You Mixxer.... are the God of engineering in the XR100 world....  👍

I would argue if I could, but when you're right you're right....

However...

I prefer the title :

"Lord of Combustion"

😁

 

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Posted (edited)

These Keihin PWK copy 'OKO' carburettors with the crescent shaped slide are probably the best all round economical performance carb for the XR80/100's- from mild to wild. They are spigot mount, so very easy to fit and come in 24, 26, 28, 30, 32 mm diameter small body sizes and come with a needle and needle jet combo that works well on engines from mild to wild. US $ prices from about $25 to $40. I use the non power valve units though don't see them advertised as often. OKO branded units have size marked jets and take  Keihin brass

These things have good direct internal circuits and when size matched give tremendous response- far better than antique round slide carbs, even those with accelerator pumps to bandaid their airflow issues because of the huge expansion just past the slide.

 

image.png.efd62130373450bb6aec9c27854a5f91.pngimage.png.2abc774f3b15868a7e89f8b496cc4a62.png

Edited by Momus
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Not as cool on a retro thumper as a Keihin PD pumper....

Everybody knows about the smoothbore 2 stroke carbs adapted to 4 stroke use....

The 26mm pumper I have on mine now has throttle response , even off idle on single track roots....sharp and almost preemptive in its pull...grin inducing for sure...

I will finish modding the 30mm pumper for testing sometime....

Momus... I'm going to invite you to read a thread like the one I hosted in the DRZ400 section here on TT... "porting, the final limiter to all components"

I have taught on many forums for many years and always enjoyed breaking down all sorts of topics and explaining nuances of power production to anyone that it would be of help or interest to.... 

Carbs... Compression... Combustion chamber design... Port flow theory... Critical clearance...Piston design.. Etc...etc...

My "secret weapon" has always been me... Or rather the researching and understanding all I could from so many engine gurus authoring so many books over the decades... Read..  Grasp... Understand (that's a big one)... Apply... Flow bench... Dyno test... Document... Learn...and do it all over and over because you love it to the core of your soul...

So... My favorite performance advantage is me... If I had to bet on someone getting all they can out of anything within whatever budget or displacement limit... I simply would never bet against myself... Not saying that as chest beating... Just as a fact, and I can be proud to say I have learned and experienced all that I have... because it has been my quest...

Not a competition to see who can spend the most money... Or build the biggest... But to optimize every detail to add up to whatever power/ efficiency goal that you have.... 

I know what I know... And at the end of the day it feels pretty good... Confidence inspiring...but I do share all that I can...

It just is what it is....

 

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3 hours ago, mixxer said:

I do share all that I can...

  And we are all the better for it. Thanks, Mix.  :cheers:

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Posted (edited)
On 1/10/2021 at 2:48 AM, mixxer said:

Not as cool on a retro thumper as a Keihin PD pumper....

Everybody knows about the smoothbore 2 stroke carbs adapted to 4 stroke use....

I've got a two-cable accelerator pump carby from a CB125 on the GF's XR100/120.  It certainly increases the fuel use.

I'm not sure what the smoothbore 2 stroke carbies adapted for 4 stroke use are?

The OKO are not smoothbore.

The main jet needle carbs  Yoshimura have patented- I think-they have- are phenomenally good though pricey.

 

image.png.2d2d5dfd50d591ce30cf99627411d3cc.png

 

T56.jpg

Edited by Momus
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TM series carbs and clones...

PJ & PWK carbs and clones...

Were both originated for 2 stroke use..... Unless you know of oem factories putting them on 4 strokes as original equipment...

Smoothbore term was originated for carbs that do not use a throttle plate or choke plate.... WOT leaves no bore obstruction except for needle.... No plates or plate axles...

Literally everything available for these is available from WeB!ke japanese website.... Just depends on how much you feel like spending...

But the big holdup to power... Same as it ever was... Is in port flow dynamics and also valve / valve seat geometry.... Glad I don't have to pay for or rely on anyone else for expertise in that arena... 

Like the Spartan head in this thread... Pure junk as delivered... Big valves and horrendous port design... Better as a door stop than a power producer.... Volumetric Efficiency beats Cubic Dollars every time....

 

 

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On 1/11/2021 at 6:42 AM, mixxer said:

TM series carbs and clones...

PJ & PWK carbs and clones...

Were both originated for 2 stroke use..... Unless you know of oem factories putting them on 4 strokes as original equipment...

Smoothbore term was originated for carbs that do not use a throttle plate or choke plate.... WOT leaves no bore obstruction except for needle.... No plates or plate axles...

Literally everything available for these is available from WeB!ke japanese website.... Just depends on how much you feel like spending...

But the big holdup to power... Same as it ever was... Is in port flow dynamics and also valve / valve seat geometry.... Glad I don't have to pay for or rely on anyone else for expertise in that arena... 

Like the Spartan head in this thread... Pure junk as delivered... Big valves and horrendous port design... Better as a door stop than a power producer.... Volumetric Efficiency beats Cubic Dollars every time....

 

 

Congratulations, you are keeping Rumsfeld's expression "then, there are things we don't know we don't know" alive.

You just make stuff up as you go along.

I'm not talking about the design origins of PWK carbies.  I'm saying they're not smooth bores.

Smooth bores usea tubular slide section and the carb body is trepanned so that fully open the bore is circular with no slide bottom disrupting flow.

The PWK's, TM's, TMR's, YD's, VM's  PC's, PD's etc all have the slide bottom a visible disruption. NONE are smooth and the worst flowing and poorest fuel air mixers are probably the accelerator pump fitted Keihin PD's and Mikunis with the huge pressure recovery expansion.

For those  interested in what a smooth bore really is - R to L. Two Keihin smooth bores, a 22 mm and a linkage operated 26mm,  probably originally for a CB400 or 500 four set but sold separately. Middle photo shows the view down the bore; you can clearly see the roof of the venturi is formed by the carb body- very precise and difficult machining work required- to the left is the slide which is a tube and with draws completly from the bore. None of the slide underside is visible or an obstruction at full throttle. The LH photo shows a view down the slide bore; again the top side of the venturi is visible. These carbs were designed by Honda subsidiary Keihin for their 60's road race program.

 

 

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Edited by Momus
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On 1/11/2021 at 6:42 AM, mixxer said:

 But the big holdup to power... Same as it ever was... Is in port flow dynamics and also valve / valve seat geometry.... Glad I don't have to pay for or rely on anyone else for expertise in that arena... 

Like the Spartan head in this thread... Pure junk as delivered... Big valves and horrendous port design... Better as a door stop than a power producer.... Volumetric Efficiency beats Cubic Dollars every time....

More of your made up guff that flies in the face of actual experience Mixxer.

 

Here is a Shift Up/Spartan head that I'm about to put on a  120 cc- 58 mm bore XR100.

These are very good, better than the Honda OE in terms of build quality and light years ahead for performance.

28 mm intake valve with a 4 mm stem, nickel bronze valve guide and an accurate 5 angle valve job with a properly positioned venturi

and a throat about 86% of valve diameter.  The valve train weight is significantly reduced 24 grams for the Spartan versus 33 gram for the std Honda parts

These ports flow well but more importantly, with displacement, the right cam, high compression and a decent carb work extremely well in actual riding and racing conditions with a very wide power spread They need no further work and IMHO are a performance bargain.

The head on the bike in the photo is the Kitaco version of the Shift Up/ Spartan- same valves, same porting and combustion chamber the only difference is the valve seat material. We estimate 18 to 20 hp from 145 cc. It has been raced successfully and reliably for years.

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XR75 Betty 1.jpg

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Well i will readily admit that the older cr smooth bores are truly smooth and cylindrical.... they must not have been the ultimate in carb design because they did not endure to the modern age... I have heard of them but never had use for such, so no experience with them... My nomenclature was wrong with my reference to carb venturis compared to those CR's... but I still have no use for a true smoothbore after being corrected... 

Nice pictures of the bowls of the Spartan head ...lol... Why don't you post up some pics through the ports like I did... BTW, why aren't your pics as clear and we'll lit and in focus as mine?? I'm just using a cell phone to take mine...

As long as your game is to keep posting up unsupported power numbers with zero dyno graphs from a known dyno brand, on big displacement builds at supposedly 16k reliable RPM.... This will never end... Big money spent... Zero info on head work because you spend big money and bolt it together and then make up whatever power level you decide sounds great and then post it as fact....

That's an easy game to play... Check this out...

Mine makes power peak at 17.5k....

28 reliable hp and an amazing early torque peak with 18.3 tq... 

Top that with 130cc...🤘

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