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Aftermarket BIG Valve Cylinder Head

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14 hours ago, SteveThe Snakes said:

Time to whoop out the mighty XR80 and show those little XR100 boys what’s up.

   I think that's cheatin, Steveo

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2 hours ago, MetricMuscle said:

Have you ever welded a combustion chamber to "close" it a bit or do any of the aftermarket manufacturers do this?

This is the last project I worked on.

   Did you ever get that thing finished, and, if so, how did it work out?

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2 hours ago, MetricMuscle said:

Nothing at the moment.

Have you ever welded a combustion chamber to "close" it a bit or do any of the aftermarket manufacturers do this?

This is the last project I worked on.

I think you need a new challenge, a new engine to tinker with.  You need to get yourself a CRF230F and start working your magic.

I've welded combustion chambers in various engines with deep semi hemispherical designss and wide valve angles. BSA and Alfa Romeo are two. With those,  getting high compression without a big dome or any dome on the piston is helpful for various well understood reasons.

With the XR100 engines and without going into a lot of detail I can usually get the compression with a conservative piston crown. This is because their combustion chamber was designed around a long stroke,  small bore 50 cc configuration and is compact and shallow with the valves close together which ultimately limits their size and camshaft design. 

On the XR100 engine  I run 57, 58 and 62 mm bores and various strokes and up to 16:1 compression though a more usual number is 3 points lower. With a kidney trench chamber at those settings the piston will be too far down the bore to squish and the percentage of bore to open chamber is high. When I get my countershaft drive Dyno sorted I will do some testing. It may well be, like benchmark two valve engines in cars, that a shaped piston crown recess gives best specific torque under many conditions.

On the CRF230 I have a top end going on early SL100 cases for a MX bike that will run in a Pre1975 class. Judging by what can be done with the XR100's with fair reliabilty using top shelf bits - billet pistons with very thin rings, roller cam, bore coatings, proper valves, lightweight con rod etc 35 hp peak with a wide curve should be achievable despite the small ish valves these are limited to.

Edited by Momus
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14 minutes ago, Doogee57 said:

   Did you ever get that thing finished, and, if so, how did it work out?

Excuse me?

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21 hours ago, Momus said:

Excuse me?

I believe Doogee is referring to my project.  

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22 hours ago, Momus said:

I've welded combustion chambers in various engines with deep semi hemispherical designss and wide valve angles. BSA and Alfa Romeo are two. With those,  getting high compression without a big dome or any dome on the piston is helpful for various well understood reasons.

With the XR100 engines and without going into a lot of detail I can usually get the compression with a conservative piston crown. This is because their combustion chamber was designed around a long stroke,  small bore 50 cc configuration and is compact and shallow with the valves close together which ultimately limits their size and camshaft design. 

On the XR100 engine  I run 57, 58 and 62 mm bores and various strokes and up to 16:1 compression though a more usual number is 3 points lower. With a kidney trench chamber at those settings the piston will be too far down the bore to squish and the percentage of bore to open chamber is high. When I get my countershaft drive Dyno sorted I will do some testing. It may well be, like benchmark two valve engines in cars, that a shaped piston crown recess gives best specific torque under many conditions.

On the CRF230 I have a top end going on early SL100 cases for a MX bike that will run in a Pre1975 class. Judging by what can be done with the XR100's with fair reliabilty using top shelf bits - billet pistons with very thin rings, roller cam, bore coatings, proper valves, lightweight con rod etc 35 hp peak with a wide curve should be achievable despite the small ish valves these are limited to.

I believe at one point Mixxer was going to have Doogee weld his Shift Up/ Spartan head but went another way about it.  Doogee has been one of the only other members interested in this kinda mod and has been a great help.

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1 hour ago, MetricMuscle said:

I believe at one point Mixxer was going to have Doogee weld his Shift Up/ Spartan head but went another way about it.  Doogee has been one of the only other members interested in this kinda mod and has been a great help.

It's an appealing sort of out there mod but would need to be back to back proven as  torque increasing to justify the work and risk. You can get good compression without the risk of distortion, seats falling out or leaking and other issues.

As mixxer's failed experiment showed with no reference you can still get big improvements with the XR100 (because they are in a stationary engine tune standard) and impress yourself. His kidney trench engine needed massive extra ignition advance to work. Normally the standard setting or a bit retarded is the sign of goodness.

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10 minutes ago, Momus said:

It's an appealing sort of out there mod but would need to be back to back proven as  torque increasing to justify the work and risk. You can get good compression without the risk of distortion, seats falling out or leaking and other issues.

As mixxer's failed experiment showed with no reference you can still get big improvements with the XR100 (because they are in a stationary engine tune standard) and impress yourself. His kidney trench engine needed massive extra ignition advance to work. Normally the standard setting or a bit retarded is the sign of goodness.

I’ve been doing research on your points ignition choice. 
so you are trolling yes or yes? 
19k doesn’t happen with points my good sir. 

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51 minutes ago, Bigfatredpig said:


19k doesn’t happen with points my good sir. 

Research what I actually said?

I've never said anything about 19K- one of the dickheads threw that shit onto the wall to disparage me.

Edited by Momus

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16 minutes ago, SteveThe Snakes said:

Um in 1966 I think they only had points for the high revving five cylinder 125. 😳

 

Nope electronic ignition.  They switched to battery powered coils, which I have to imagine is the early form of electrical ignition systems. 
 

Edited by Bigfatredpig

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3 hours ago, Bigfatredpig said:

I’ve been doing research on your points ignition choice. 
so you are trolling yes or yes? 
19k doesn’t happen with points my good sir. 

Half speed is all that is required on an XR100 engine- they don't need to be fired every RPM and a 12 volt battery can provide plenty of juice compared to a magneto. 😉

 

 

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Edited by Momus

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3 hours ago, Momus said:

It's an appealing sort of out there mod but would need to be back to back proven as  torque increasing to justify the work and risk. You can get good compression without the risk of distortion, seats falling out or leaking and other issues.

As mixxer's failed experiment showed with no reference you can still get big improvements with the XR100 (because they are in a stationary engine tune standard) and impress yourself. His kidney trench engine needed massive extra ignition advance to work. Normally the standard setting or a bit retarded is the sign of goodness.

Listen you half baked half read  retarded jackass....

No welding or changing of the "as delivered" Spartan combustion chamber was done... None of any sort ... I was looking at that as a possible option to increase compression...  Discussion only...

You are going to hurt your new groupie Metrics feelings if you have much more negative to say about the combustion chamber altering I clay molded to cc measure the "potential change to compression"...as that idea was his baby for working on the CRF230 combustion chamber...

That's funny as hell... You are busy going on about my "failed experiment" that never happened because you failed to fully read or comprehend the context ... And metric started falling in 💕 with you  because he is always lurking for another hero to argue with me... ROFLMAO🤣🤣... and now you are calling HIS idea stupid and proof of failure... when all I did was clay it up and measure compression change...

Get a room and work this all out you 2.... Hahahahahahahaaaaaaa 🤣🤣

Momus... Start your own thread you blowhard assjack...

See how much interest you can generate without being so desperate for attention that you can't stop posing and posturing all over the thread I hosted... Sadly , now you are addicted to thinking you have an audience for your half baked BS, simply because you piggyback on my work and thread... Lame as hell my man... Lame as hell... Grow up... Get a life... Host your own thread like a big boy...

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4 hours ago, mixxer said:

Listen you half baked half read  retarded jackass....

No welding or changing of the "as delivered" Spartan combustion chamber was done... None of any sort ... I was looking at that as a possible option to increase compression...  Discussion only...

You are going to hurt your new groupie Metrics feelings if you have much more negative to say about the combustion chamber altering I clay molded to cc measure the "potential change to compression"...as that idea was his baby for working on the CRF230 combustion chamber...

That's funny as hell... You are busy going on about my "failed experiment" that never happened because you failed to fully read or comprehend the context ... And metric started falling in 💕 with you  because he is always lurking for another hero to argue with me... ROFLMAO🤣🤣... and now you are calling HIS idea stupid and proof of failure... when all I did was clay it up and measure compression change...

Get a room and work this all out you 2.... Hahahahahahahaaaaaaa 🤣🤣

Momus... Start your own thread you blowhard assjack...

See how much interest you can generate without being so desperate for attention that you can't stop posing and posturing all over the thread I hosted... Sadly , now you are addicted to thinking you have an audience for your half baked BS, simply because you piggyback on my work and thread... Lame as hell my man... Lame as hell... Grow up... Get a life... Host your own thread like a big boy...

😉So it was an XR200 head with the weld- a lot more understandable.

So we'll have to assume it was the 'porting' and that god awful PZ pumpa carburettor that caused the requirement for all the extra advance. 

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....🤘😎😁

 

Still not getting it are you mixxer?  

The Japanese engineers that develop the various kit parts you bought, and butchered, have sold hundreds, even thousands of kits a lot faster than your self-impressing homebrew.😁

Edited by Momus

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On 1/15/2021 at 8:50 AM, SteveThe Snakes said:

I think it’s full flow. It’s tapped off of the factory pressed in plugs. 

Bypass.

 

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8 hours ago, Momus said:

😉So it was an XR200 head with the weld- a lot more understandable.

So we'll have to assume it was the 'porting' and that god awful PZ pumpa carburettor that caused the requirement for all the extra advance. 

Still not getting it are you mixxer?  

The Japanese engineers that develop the various kit parts you bought, and butchered, have sold hundreds, even thousands of kits a lot faster than your self-impressing homebrew.😁

4d advance flywheel key and a stock factory OEM CDI box is “ all the extra advance” 😳🤔🤪

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1 hour ago, adnohguy said:

4d advance flywheel key and a stock factory OEM CDI box is “ all the extra advance” 😳🤔🤪

What would you rather on a medium speed engine you put together?  Four degrees more ignition advance or standard to retarded from standard?

Edited by Momus

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4 minutes ago, Momus said:

What would you rather on a medium speed engine you put together?  Four degrees more ignition advance or standard to retarded from standard.

Your point ignition, you use a centrifugal advance or a vacuum setup?

how do you get around spring bounce at high rpm? Your dyno went past 16k 

Why does every single engine builder using the older xr100s update to a Cdi ignition?

 

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19 minutes ago, Momus said:

What would you rather on a medium speed engine you put together?  Four degrees more ignition advance or standard to retarded from standard.

For a 35 RWHP 230f: With major torque from just off idle until approx 8500 rpm. Short shift and feel it pull in every gear (6), 15-45 overall gearing, flat, wide torque curve with no steps or surges in power band. Able to be just as reliable as stock in tight gnarly single track 30 miles and 3 canyons away from your transport truck that there is no possible way to get it out if it broke other than a helicopter. 
 Willing to learn your methods in your own new training thread that are explained in detail. 
After that Maybe a training thread about a 300cc, 2020, 4 valve FI 250f how to for information and a how to, using your methods would be very helpful as well. 
Sl 100’s and sl125’s, xr 75 stuff, while interesting, all goes in a different thread. 

Edited by adnohguy

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1 hour ago, adnohguy said:

For a 35 RWHP 230f: With major torque from just off idle until approx 8500 rpm. Short shift and feel it pull in every gear (6), 15-45 overall gearing, flat, wide torque curve with no steps or surges in power band. Able to be just as reliable as stock in tight gnarly single track 30 miles and 3 canyons away from your transport truck that there is no possible way to get it out if it broke other than a helicopter. 
 Willing to learn your methods in your own new training thread that are explained in detail. 
After that Maybe a training thread about a 300cc, 2020, 4 valve FI 250f how to for information and a how to, using your methods would be very helpful as well. 
Sl 100’s and sl125’s, xr 75 stuff, while interesting, all goes in a different thread. 

I'm not sure what you mean by my training thread.

To build a 230F - say 250 cc actual capacity to make 35 hp at 8500, let alone less, would not be easy at all.  It requires 22 lb/ft of torque which works out to a BMEP of 221 psi which is a fully developed Nascar 2 valve engine bench mark figure. 

It would require a lot of specialised components and development. 

Unless someone wanted to fund it as a project I would not be trying for that figure.

Edited by Momus

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