[MonkeyWood]

I will tell the story later, but here is a 1985 Kawasaki KX80 with a Honda XR100 engine. Built by John Cartwright of Cartwright’s Conversions back in 1992. I’m going to fix her up…

 

[mrrcx]

Langtown bike?

 

[MonkeyWood]

Langtown bike?

Not sure if this bike ever ran a Langtown, but it was a regular at the XR Nationals in Dallas, TX.

 

[Hetrickson]

Yesssss I love weird swaps. Also that swinger looks CHONKY in the pics. Keep us posted.

 

[MonkeyWood]

Bike has been sitting for probably 15 years, maybe more. I don’t think the shock or forks have a drop of oil left in them. So those are getting a rebuild. Here are a few shots of the bike with less plastic…

 

[MonkeyWood]

Shocks off to get re-built, re-valved and sprung. I’m going to pull the forks apart and get them re-built. Might go with some race tech emulators and springs for my weight. Got all new bushings and bearings for the chassis. Tires, tubes, rim strips. Chain and sprockets. Front brake is getting a full overhaul as well.

On to the fun surprise! Pulling the valve cover and finding this is one of the early roller cam mods John Cartwright did before Al Gore had the internet and e-commerce really going😜 Back in ‘91/‘92 Takegawa did not offer roller cams. This is a small custom product run done by John for a few of the early conversions. I really love this custom stuff! Speaking with John he can’t remember all the details, but assumes this is a high compression 120 with his custom roller head (rockers are not roller in this one).

Heck, this thing might be pushing double digits 😆

 

[Hetrickson]

LOVE stuff like that. Makes the days of hot rodded flatheads seem like not-so ancient history. We're gonna need some sound bytes when you're done. You're gonna make up an alternate "KXR100" lettered seat for this based on that box too, right?

Edit: The more I look the more I dig the atmosphere of these pics. That's one trick stand you've got the bike resting on!

 

[MonkeyWood]

LOVE stuff like that. Makes the days of hot rodded flatheads seem like not-so ancient history. We're gonna need some sound bytes when you're done. You're gonna make up an alternate "KXR100" lettered seat for this based on that box too, right?

Edit: The more I look the more I dig the atmosphere of these pics. That's one trick stand you've got the bike resting on!

🤔 That’s a great idea …KXR! I have the 1984 SR125 Ward rode in my mind too.

Amen, love hot rodding! I got an old flathead mill that hopefully will make it into a rod someday soon.

🔈🔈✊✊

 

[MonkeyWood]

Pulled the head today - here are a few more pictures of the one-off roller cam setup. Also, I confirmed that the stroke is stock at 45mm and bore is 57.9mm so my math says it 118cc. I assume this an old Takegawa big bore, maybe Powroll?

 

[Hetrickson]

Damn. I need to get some line boring tools. Is that plug there stock or is that an artifact of machining out the bearing journal? And does that little bump on the closest journal feed oil Into the ball bearing on that side?!

 

[MonkeyWood]

Damn. I need to get some line boring tools. Is that plug there stock or is that an artifact of machining out the bearing journal? And does that little bump on the closest journal feed oil Into the ball bearing on that side?!

The plug is not stock, it was required after the stock cam journals were hogged out. The roll pin you see may serve dual purposes, but is absolutely there to stop lateral movement of the cam. Might serve up some oil will look closer. It’s a trick setup. I was hanging around John’s shop at the time he was building these bike, he was always doing cool stuff!

 

[JAZ-SFT]

Great bike looks like a fun project 😃

 

[MonkeyWood]

So, it’s a Powroll 58mm (ART) piston. Damn sleeve was very snug in the cases!! Cases were fly cut to fit, but like pulling a stuck bearing. Lots of heat and some dead blow persuasion…

assuming I can still source rings since ART is a standard industry piston. Maybe a 500/4 Honda? Shout if ya can help. Talking with google now.

 

[JAZ-SFT]

Had a quick google for ya
It seems you might be in luck finding a piston
Can’t be 100% sure if this is the right one

Powroll Performance Piston Kit Set Of 2 Big Bore 58mm Bore Honda CB500 | eBay

High Performance Top End. Qty: 1 Set Of 2. May Fit Others. CB500K2A MOTORCYCLE, JPN, VIN# CB500-2100001. CB500K1A MOTORCYCLE, JPN, VIN# CB500-2000001. CB500A MOTORCYCLE, JPN, VIN# CB500-1000001.

www.ebay.com.au

also found this

HONDA TRX90 TRX 90 HIGH COMPRESSION 114cc BIG BORE KIT CYLINDER PISTON RINGS DHL | eBay

NEW complete 114cc BIG BORE KIT FOR ALL HONDA TRX90's. Aluminum cylinder with 56mm big bore. 53mm piston kit. PART STARTING 54MM ABOVE WILL NEED TO BORE THE CRANKCASE FOR FITTING IT. This kit is comparable quality to "Genuine Honda" parts.

www.ebay.com.au

 

[MonkeyWood]

Had a quick google for ya
It seems you might be in luck finding a piston
Can’t be 100% sure if this is the right one

Powroll Performance Piston Kit Set Of 2 Big Bore 58mm Bore Honda CB500 | eBay

High Performance Top End. Qty: 1 Set Of 2. May Fit Others. CB500K2A MOTORCYCLE, JPN, VIN# CB500-2100001. CB500K1A MOTORCYCLE, JPN, VIN# CB500-2000001. CB500A MOTORCYCLE, JPN, VIN# CB500-1000001.

www.ebay.com.au

also found this

HONDA TRX90 TRX 90 HIGH COMPRESSION 114cc BIG BORE KIT CYLINDER PISTON RINGS DHL | eBay

NEW complete 114cc BIG BORE KIT FOR ALL HONDA TRX90's. Aluminum cylinder with 56mm big bore. 53mm piston kit. PART STARTING 54MM ABOVE WILL NEED TO BORE THE CRANKCASE FOR FITTING IT. This kit is comparable quality to "Genuine Honda" parts.

www.ebay.com.au

Thank you.
The piston is in good shape and was also carefully “clayed” and releaved for valve clearance, so I’m going to keep it. Digging around for rings. I saw a Honda CBR125r piston and rings. Maybe I can just get rings somewhere and hopefully they fit🤞
Like this

Honda CBR 125 R GENUINE Piston & Rings Set 2004 - 2011 ** GENUINE & UK STOCK ** | eBay

PISTON & RINGS SET. 1 X PISTON & RINGS SET. GENUINE & NEW HONDA PARTS. GENUINE HONDA PARTS, NOT FAKE INFERIOR CHINESE. GENUINE HONDA . HONDA CBR125R -. FEEL FREE TO TAKE THEM TO HONDA FOR AUTHENTICATION!

www.ebay.com

 

[Hetrickson]

if you’re comfortable adjusting end gap you could totally just get blanks for ~the right size bore.

 

[MonkeyWood]

if you’re comfortable adjusting end gap you could totally just get blanks for ~the right size bore.

Got no issues with that. Any recommendations for where to source?

Again, this is an ART piston. My best digging found that the Honda CBR125 has a 58mm bore and there are rings available. Found these…

58MM (STD) PISTON ASSY - 13MM PIN (CBR125R (ALL ) / SONIC125)

58MM (STD) PISTON ASSY / 13MM PIN (CBR125R ('04- ) / SONIC125R / SONIC125RS) (K-KGH-STD) (13101-KGH-901 / 13101-KGH-902)

www.yuminashi.eu

 

[dirtbkr188]

I saw a Honda CBR125r piston and rings. Maybe I can just get rings somewhere and hopefully they fit

From HERE possibly? The Netherlands is a lot closer than Thailand.

 

[MonkeyWood]

From HERE possibly? The Netherlands is a lot closer than Thailand.

Good Shout! On order👍

 

[dirtbkr188]

Just an FYI for you, HERE'S a possible Plan B, from New Oxford, PA, in case Plan A from the Netherlands doesn't work.