Longer intake runners vs stock bolted carb to head Q's

der_nanno

Faster!
Regarding the Dell'ortos: The old (German) TR1 racing crowd is split 2/3 to 1/3. The bigger group thinks they are the best thing since sliced bread and quite frankly there's some pretty good recipes out there from Sepp and the others , which will get you to a bike that runs a lot better than stock quickly and the much smaller group uses TM38s and TM40ies plus there's a few outcasts, who run... "other stuff".

Interesting you mentioning the float level, I had the same thing on mine, but thought it was due to buying them from a rather shady reseller, assuming that mine were more of the 3rd choice quality level and not that this is sort of the norm, even from reputable resellers. Also agree on the half turn on the air-screw. Once you're close a quarter turn is the difference between high 11s and low 13s and with them also affecting the airpassage to the needle, you have to deal with that sort of fun all the way up to about 1/3 of the throttle, which makes the whole lot a bit challenging to set up. That being said, once they are set up... oh boy.
 

HollywoodMX

Coast to Coast
Ya the deltoros are in the class of fcr and hsr as they are flatslides with another fuel circuit, the accelerator pump. But if u compare any mikuni to any keihin carb the quality of keihin always comes on top and its not even close.

I would not be surprised the deltoros are better than mikuni but the Japanese just have a way with bikes and bike tech. The fcr is race proven pre fuel injection like no other carb. Even the float actuation from tm to fcr is leaps and bounds better tech. The tm's floats can stick with that stupid rods in float tech. I bet they were trying to stop angle elevation issues with that design for snow mobiles maybe, it's dumb as the rods cause friction with float actuation and it's bad engineering.
 

doc_rot

Oh the usual... I bowl, I drive around...
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Eh, thats a bit like comparing apples to oranges. FCRs are a completely different beast to TM38. TM series carbs would never be my first choice on a 4 stroke street bike. They are fairly rudimentary carbs originally designed for two strokes.

Maybe you could compare the FCR to the Mikuni RS series carbs, as they are both flat slide and have accel pumps, but the RS carb is an "economoy carb" compared to FCR

I think the only realy comparision between Kehin FCR would be the Mikuni TMR-MJN.

 
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HollywoodMX

Coast to Coast
They are fcrs copies in the end. Also you can get fcr parts and jets everywhere because they put them in lots of dirt bikes! Yay! I have boysen thumb adjustable accelerator pups on my xv too.

I bet I quote that mikuni carb to my top dealer in the city and they will scratch their heads. Rip. Even the tm jets where hard to find.
 

doc_rot

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Yoshimura sells them. Realistically performance carbs are a boutique industry these days. If you went into my local dealer asking for performance carbs they'd probably come back out with a bag of raw oats and some muscle milk!

The TMR-MJN have some rather unique features available - copies they are not. Its true they never caught on like the FCR probably because they are more expensive than the FCR, and when they became readily available the high end performance market had already moved on to EFI, either way they are the only real comparison to FCRs

Id love to get a set of these on the right project.

Screen Shot 2022-08-17 at 12.19.16 AM.png
 
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HollywoodMX

Coast to Coast
Yoshimura sells them. Realistically performance carbs are a boutique industry these days. If you went into my local dealer asking for performance carbs they'd probably come back out with a bag of raw oats and some muscle milk!

The TMR-MJN have some rather unique features available - copies they are not. Its true they never caught on like the FCR probably because they are more expensive than the FCR, and when they became readily available the high end performance market had already moved on to EFI, either way they are the only real comparison to FCRs

Id love to get a set of these on the right project.

View attachment 236566
It's a cool pick but that's for true race bikes not very practical for day to day use. How many needle options 1-6? vs 20+ for fcr? You can get a venturi style injection kit for fcrs too but it's not popular as it messes with the leak jet and adjustable accelerator pump. Also is more prone to clogging just like that needle Pic.

You can also modify the accelerator timing with your hand with ease. Also you can get remote idle screws for ezpz thumb adjustment. I can modify all 3 functions with my hand at a stop light.

I would not want those carbs, chacing parts is an annoyance and that's super obscure stuff. Some bikes may not respond to that needle atomization style either. Not enough vaccum? Looks like a pooling disaster. Probly meant for inline 4s.

Fcr every dealer that carries Japanese bikes has parts pretty much, at least in North America and Japan.
 

doc_rot

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25+ needles last i checked. They are huge in asia on tons of small stuff. They actually might be good for your application, but "practical" for you - maybe not. But hey slapping snowmobile carbs on a vintage twin with limited support doesnt seem practical to me. lol.
 

HollywoodMX

Coast to Coast
25+ needles last i checked. They are huge in asia on tons of small stuff. They actually might be good for your application, but "practical" for you - maybe not. But hey slapping snowmobile carbs on a vintage twin with limited support doesnt seem practical to me. lol.
OK must be a Japan thing. Those guys that drop 40k all day long on kz1000s. Not for me.

I agree with your snow mobile comment. I felt bamboozled. I mean I made it work but took 14hrs which is rediculous for a "bolt on kit". I gave them all my specs and then some and shipped with Australia jet specs and I told I'm 3400ft. I also don't like the hair sensative fuel screw. Nanno saying 1/4 turn is 13s vs 11s is redonkulous. You have to take one carb off to adjust both fuel screws. Then after that your idle is messed up.
 

irk miller

You've been mostly-dead all day.
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I resemble the snowmobile comment, LOL. I put Mikuni VMs from a sled on my XS chopper. No chokes, so I ran a primer bulb like a sled would. It was fun for a few months. HAHA
 

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