Topic: JMR billet block build with RSC 970 transmission

[MRieck]

No one has the 71.25 rings Per. Buzz would have had to order 100 sets or so for them to be made. I believe the Suzuki 71mm XA rings will work. While I have been a big proponent of XA rings I have begun to gravitate back to the XC rings secondary to the fact they are much easier to install. It is very easy to fold an XA oil rail.....it's happened to all of us that install those rings.
 The lateral gas ports with definitely improve seal though wear will increase a bit. The skirts to wall clearance is pretty tight on the Nikasil bores which reduces piston rock and wear.
Funny thing about the TMR's.....the needle you suggested were already installed in the TMR's I have. I was also able to find 2 sets on Weblike.

[PeWe]

I hope the 71.25mm rings will get a long life then
File the inner ends (rounded) of the oil rails helps the thin oil rails to not hook into the expander ring during assembly as I did.

-bigutah: Which bire size do you have?


I guess my billet block will run long enough with 71.25 mm pistons. Possible to bore for 72mm and new nikasil. A little bit complicated to find where except Millenium.

I did an oil change today thanks to bigutah's comment about TMR and 4-1 sound.
Warm-up afterwards. Video when warm and idling evenly.

Acc pump might need to be reduced. It smoke a little when giving heavy throttle. But might be as how it works.
I have seen the long squirts when carbs were off.  I can reduce the stroke by a small screw beside idle screw, was 6 turns out, turned in 2 turns after video.

https://youtube.com/shorts/IWY3EY26LnY?si=z4ON52fnKENu6MQ-

My TMR's had strange needles. The model for a bigger model. Maybe out of stock when built?

I have a pile of junk beside bike that I'll take to a recycling station. I stretched my back a month ago that reduced my abilities. Coming back into action.

Page below need to be scrolled down. Sometimes really slow

Carburetor Setting Method by YOSHIMURA

TMR-MJN/TMR/TDMR Carburetor Setting Parts

https://www.webike.ph/ph_news/webike-original/columns/20201229-carburetor-setting-method-by-yoshimura/

[Tracksnblades1]

I hope the 71.25mm rings will get a long life then
File the inner ends (rounded) of the oil rails helps the thin oil rails to not hook into the expander ring during assembly as I did.

-bigutah: Which bire size do you have?


I guess my billet block will run long enough with 71.25 mm pistons. Possible to bore for 72mm and new nikasil. A little bit complicated to find where except Millenium.

I did an oil change today thanks to bigutah's comment about TMR and 4-1 sound.
Warm-up afterwards. Video when warm and idling evenly.

Acc pump might need to be reduced. It smoke a little when giving heavy throttle. But might be as how it works.
I have seen the long squirts when carbs were off.  I can reduce the stroke by a screw.

https://youtube.com/shorts/IWY3EY26LnY?si=z4ON52fnKENu6MQ-

My TMR's had strange needles. The model for a bigger model. Maybe out of stock when built?

I have a pile of junk beside bike that I'll take to a recycling station. I stretched my back a month ago that reduced my abilities. Coming back into action.

Page below need to be scrolled down. Sometimes really slow

Carburetor Setting Method by YOSHIMURA

TMR-MJN/TMR/TDMR Carburetor Setting Parts

https://www.webike.ph/ph_news/webike-original/columns/20201229-carburetor-setting-method-by-yoshimura/

I have a complete set of (4) wiseco 71.25mm ring sets..
If you need the custom part number, I can break the seal on the box “under my bed” and get you a picture…


“Under my bed” quote was borrowed, shared,  or stolen from Meydo Bastos…

Last time I talked to wiseco, I was told they could rework the ring grooves of my new unused 71.25mm piston set for the easier to install oil ring type..and they could make a custom set of a two valve variant of the more desirable CR (CBR) 250R style pistons in the 71.25mm size.. originally I thought my itty bitty oil rings were low tension units and didn’t want an oil burner in lew of a few more ponies..

[bigutah]

I hope the 71.25mm rings will get a long life then
File the inner ends (rounded) of the oil rails helps the thin oil rails to not hook into the expander ring during assembly as I did.

-bigutah: Which bire size do you have?


I guess my billet block will run long enough with 71.25 mm pistons. Possible to bore for 72mm and new nikasil. A little bit complicated to find where except Millenium.

I did an oil change today thanks to bigutah's comment about TMR and 4-1 sound.
Warm-up afterwards. Video when warm and idling evenly.

Acc pump might need to be reduced. It smoke a little when giving heavy throttle. But might be as how it works.
I have seen the long squirts when carbs were off.  I can reduce the stroke by a screw.

https://youtube.com/shorts/IWY3EY26LnY?si=z4ON52fnKENu6MQ-

My TMR's had strange needles. The model for a bigger model. Maybe out of stock when built?

I have a pile of junk beside bike that I'll take to a recycling station. I stretched my back a month ago that reduced my abilities. Coming back into action.

Page below need to be scrolled down. Sometimes really slow

Carburetor Setting Method by YOSHIMURA

TMR-MJN/TMR/TDMR Carburetor Setting Parts

https://www.webike.ph/ph_news/webike-original/columns/20201229-carburetor-setting-method-by-yoshimura/

72 10.5 to one JE I believe


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[PeWe]

I have a complete set of (4) wiseco 71.25mm ring sets..
If you need the custom part number, I can break the seal on the box “under my bed” and get you a picture…

“Under my bed” quote was borrowed, shared,  or stolen from Meydo Bastos…

Last time I talked to wiseco, I was told they could rework the ring grooves of my new unused 71.25mm piston set for the easier to install oil ring type..and they could make a custom set of a two valve variant of the more desirable CR (CBR) 250R style pistons in the 71.25mm size.. originally I thought my itty bitty oil rings were low tension units and didn’t want an oil burner in lew of a few more ponies..

I have a new complete set of 71.25mm XA rings. Minus one oil rail I can reuse from the used set.

-bigutah, you have 72mm with the thin XA oil rings?
Photo of your pistons?

72 mm pistons will probably be available in the future when you need after looong use.

The Billet block with nikasil might need new pistons after long use. Nikasil hopefully as new. Hone pattern in need of cleanup maybe.

Rework oil ring groove will end up in thin land over and under. The arc above wrist pin is higher on the 71.25mm pistons.
70mm XC vs 71.25mm XA.

[bigutah]

The only picture I could find on my phone.


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[PeWe]

That piston look like what Dynoman sell today, DP1026  CR 10.5:1

Keihin "tickler carbs"!
Old style that cost some. For a time correct build.
https://www.ebay.com/itm/266659299581?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=n-yz_JTHQ1q&sssrc=4429486&ssuid=XgCEg0CPSya&var=&widget_ver=artemis&media=COPY

[bigutah]

That piston look like what Dynoman sell today, DP1026  CR 10.5:1

Keihin "tickler carbs"!
Old style that cost some. For a time correct build.
https://www.ebay.com/itm/266659299581?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=n-yz_JTHQ1q&sssrc=4429486&ssuid=XgCEg0CPSya&var=&widget_ver=artemis&media=COPY

I forgot I hadn’t pulled that ad down. Haha


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[bigutah]

Update picture, Going in frame tonight. Sure is pretty lookin.


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[Medyo Bastos]

I have a complete set of (4) wiseco 71.25mm ring sets..
If you need the custom part number, I can break the seal on the box “under my bed” and get you a picture…


“Under my bed” quote was borrowed, shared,  or stolen from Meydo Bastos…

[/quote]




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[PeWe]

I have a complete set of (4) wiseco 71.25mm ring sets..
If you need the custom part number, I can break the seal on the box “under my bed” and get you a picture…


“Under my bed” quote was borrowed, shared,  or stolen from Meydo Bastos…

I have a set of new rings. The photo I attached is the 4 packages of rings.

[PeWe]

Update picture, Going in frame tonight. Sure is pretty lookin.


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I'm sure those MJN carbs will make a difference. Is it 32mm?
https://www.bikebros.co.jp/vb/...sfeat/yoshimura-carburetor-en/

"Let’s image, you are entering corner with throttle fully closed, with needle jet type carb which draws fuel into combustion chamber to the point where spark plugs could get almost flooded vs.
MJN such effect is very minimum due to again using straight hollowed tubes. This effect would make your transient accelerating throttle work much smoother."

[bigutah]

And that’s it for tonight’s progress.


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[RAFster122s]

Very nice

[Finnigan]

Amazing! Plan to use the jetting that came with the carbs or changing with the increased cc?  Those carbs use stock push/pull cable?

[Tracksnblades1]

Very nice

👍 +1…

Tell us about the alternator and covers..?

[johno]

 Very nice nice nice 
Great to see those barrels on a race bike.
And tell us about the standard coils and leads  the leads are a pain if your a plug colour chopper 

But nice nice nice 

[bigutah]

Amazing! Plan to use the jetting that came with the carbs or changing with the increased cc?  Those carbs use stock push/pull cable?

I’ve switched mains up to 125, but that’s my baseline starting point. I have a Dynojet 250 i and will tune in that way.


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[bigutah]

Very nice

+1…

Tell us about the alternator and covers..?

They are RSC “Racing Service Center” honda OEM parts before HRC became a thing. This kit was offered in the early 70’s to turn a std cb750 into a race bike. With all part numbers ending in “970” to signify race use.

[bigutah]

Very nice nice nice 
Great to see those barrels on a race bike.
And tell us about the standard coils and leads  the leads are a pain if your a plug colour chopper 

But nice nice nice 

They work very nice. I like the TEC coils way more than the hitachi ones. I run iridium plugs so they work very well at high RPM


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[Tim2005]

Is this the motor build that was on facebook the other week? It is good to see it in detail on here

[bigutah]

Is this the motor build that was on facebook the other week? It is good to see it in detail on here

Yes.


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[bigutah]

RSC rear magnesium hub will get laced up soon to Wm5 boranni rear rim. Nice detail for the bike


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[seanbarney41]

Wow!  You are really splashing out for the unobtainium authentic goodness!  That bike was already killer to start.  Gonna be soooo good.

[PeWe]

Those hubs looks fantastic!
I saw an italian site where they made new hubs, a limited numbers of magnesium hubs for CR750 builds.
They had Borrani or replica rims too. Must have been 12 years ago.