Author Topic: Interesting CR carbs  (Read 401 times)

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Offline MRieck

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Offline slikwilli420

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Re: Interesting CR carbs
« Reply #1 on: November 07, 2018, 07:56:26 am »
Those are some real next level stuff right there. Being able to 3D map ignition as Brent Hyde discusses would add a massive level of capability to the tuner. Too bad stuff like this is no bueno in AHRMA vintage classes. You popping on a set for the million dollar CB Mike?
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline MRieck

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Re: Interesting CR carbs
« Reply #2 on: November 07, 2018, 08:54:17 am »
Those are some real next level stuff right there. Being able to 3D map ignition as Brent Hyde discusses would add a massive level of capability to the tuner. Too bad stuff like this is no bueno in AHRMA vintage classes. You popping on a set for the million dollar CB Mike?
No...I'll stick with the RS's for now though I do have a set of 36 TMR's sitting on a shelf. ;D
Owner of the "Million Dollar CB"

Offline PeWe

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Re: Interesting CR carbs
« Reply #3 on: November 07, 2018, 01:15:17 pm »
I noticed the description for those CR carbs!
For Driverability and stability, it is Level equal to or more than OEM negative pressure Carburetor, FCR Carburetor Body, TMR etc.
Also, like FCR Carburetor Body, especially TMR, we do not do excessive Response which is beyond Rider's consciousness, such as being hurried.
This will be another Carburetor with the appearance of CR Carburetor.


I got some déjà vu when reading that... if they say that TMR are a little bit too responsive ;)
Too lean pilots made my TMR's extra sensitive on low throttle lift, sneezing on 1:st-2:nd gears=risk for a wheelie.
Stock pilots were 27.5, 30 was minimum to avoid pinging at take offs despite rich needles, 32.5 made better at low speed after needles were corrected. (needles too rich 4:6, my have 2:6 after some dyno runs.)

Last  detail to get a stable pre 3000 rpms (on 5:th gear) was to make sure that ignition is not too advanced. I retarded ignition and that helped. It ran like too lean pilots/fuel screws (occassional sneezing carbs at low speeds.
Still really quick response, but not as hysterical before. I look forward to next summer, I found  the last adjustment for only a month ago.

My TMR's have pods. Stock jetting must be for stacks which will make pilots even leaner, but needles more understandable.

31mm for <1000cc, right? 1000cc need more like 32-36mm? Ported head and 34mm in valves....
« Last Edit: November 08, 2018, 11:49:13 am by PeWe »
CB750 K6-76 1005cc JMR Billet block.
CB750 K2-75 stock looking project started 2017

Offline turboguzzi

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Re: Interesting CR carbs
« Reply #4 on: November 08, 2018, 06:39:37 am »
cant trust too much this japanese-english auto-translation for meaning accuracy IMHO :)

wouldnt mind trying MJN's in my CR29 for the 500R resurrection.

best (read cheapest :) ) source?

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Interesting CR carbs
« Reply #5 on: November 08, 2018, 10:45:42 am »
Agree about the translation especially "It has the setting data based on a large number of wearing cases in factory serum mackerel". Sounds kinda fishy  ;)
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline MessnerMoto

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Re: Interesting CR carbs
« Reply #6 on: November 09, 2018, 05:28:22 am »
Do they have just throttle position sensor or some additional control like variable jets?

Offline slikwilli420

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Re: Interesting CR carbs
« Reply #7 on: November 09, 2018, 06:28:10 am »
Do they have just throttle position sensor or some additional control like variable jets?

The description (bad as it is) makes it sound like there is lots more going on there. If it was just a TPS it would be nominally more expensive than a regular set. A TPS isnt that expensive but you need something to plug it into which makes all the difference.
All you gotta do is do what you gotta do.

Vintage Speed Parts Mashup: http://forums.sohc4.net/index.php?topic=133638.0
Rickman CR Parts Kit Refresh: http://forums.sohc4.net/index.php/topic,154837.0.html
AHRMA CB750 Racer: http://forums.sohc4.net/index.php/topic,158461.0.html
AHRMA Superbike Heavyweight Racer: http://forums.sohc4.net/index.php/topic,173120.0.html
'76F CB750 Patina Redemption: http://forums.sohc4.net/index.php/topic,174871.0.html

Offline turboguzzi

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Re: Interesting CR carbs
« Reply #8 on: November 11, 2018, 03:16:59 pm »
Mirko it has mjn so thats already nice jetting help....
Besides something to plug the tps into, youd need also free access to a dyno to develop the mapping, not a small undertaking....

Offline MessnerMoto

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Re: Interesting CR carbs
« Reply #9 on: November 12, 2018, 04:57:37 am »
yoss I understand the mjn thing and tps..... but I was just not clear if there is something else because of bad translation....

... I heard or read on somewhere that there is in existence some carburetors that have electronically controlled variable jets... or something like that

not sure cant remember were I seen this
« Last Edit: November 12, 2018, 05:15:45 am by MessnerMoto »

Offline PeWe

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Re: Interesting CR carbs
« Reply #10 on: November 12, 2018, 06:52:30 am »
A mix of fuel injection and carbs....
CB750 K6-76 1005cc JMR Billet block.
CB750 K2-75 stock looking project started 2017

Offline simon#42

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Re: Interesting CR carbs
« Reply #11 on: November 12, 2018, 10:48:51 am »
there are in existence carbs that have electronically controlled jets ,  dellorto have made them for years as have mikuni and keihin .
the mikuni and kehin turn off a small extra main jet when the engine revs get past peak torque . at this point the engine needs less fuel and this gives the engine more over rev . the dellorto carbs can vary the size of the jet but only to make it smaller . all history now with fuel injection . here are two on marco simoncelli's gilera which was really a rebadged aprilia

Offline turboguzzi

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Re: Interesting CR carbs
« Reply #12 on: November 12, 2018, 11:22:32 am »
mirko, before you get exited it's a two stroke :)
even towards the end of carburetors in WSBK, cant remember anyone doing electronic variable jets, maybe power jets in front of the carb were electronically controlled as on-off

Offline simon#42

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Re: Interesting CR carbs
« Reply #13 on: November 13, 2018, 10:12:58 am »
you would not have seen them in wsb as that is a road based series and the carbs would have to have been fitted to a road bike to be homologated . the 8 hour bikes are a different story though if you want to see the trick stuff this is where to look .

Offline turboguzzi

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Re: Interesting CR carbs
« Reply #14 on: November 13, 2018, 02:11:35 pm »
true about the "road based" carbs, that's was the reason for the various SP, RR and other homologation specials of the 90s.
But still cant recall electronic carbs in endurance, have any pics in your secret stash?
Plenty of other exotic stuff sure, am still a sucker for those suzuki france special framed GSXRs that only vaguely resembled stock....
 

Offline simon#42

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Re: Interesting CR carbs
« Reply #15 on: November 13, 2018, 03:06:23 pm »
i might have !   it was not so much the european endurance racers but the suzuka 8 hour bikes . back in the 80`s and 90`s they were pretty much all factory one off prototypes . they used that race to try out all kinds of strange stuff , even the marshals rode oval piston hondas .

 

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