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Discussion Starter · #1 ·
The carbs have arrived . I installed them tonight . They are a bolt in no problem . Well maybe a couple.
First there is no vacuum port. So You can not operate the fuel valve. I got around this by using a manual shut off for the fuel. Just like the old days.
Also also there is no choke just an air bleed . So toss the cable ..It is a thumb lever on the side of the carb.

I have not run them more than start up and adjust the idle. But they look great and the bike feels strong.

I got them from carb parts warehouse. Ask for Jeff. He had the best price under 450 shipped . And they have all the tuning parts. He asked a couple questions and they set them up for you . He has mine already tuned with the jets I will start to tune with.

They come with stacks that are nice but all the air filters that fit stock carbs fit these including the stock air box.
http://www.carbparts.com/
 

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Discussion Starter · #5 ·
I plan a full half day on the dyno to test jetting, air filters and fuel .I will need to wright a new ignition map as well. I will do that near the end of February . Then 1/4 mile testing through out March.I will post up results as I go.

It is 20 deg F hear now . So I don't even want to run the bike . much less tune anything.
 

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Discussion Starter · #6 ·
so far the carbs on the dyno are great. I did not get a chance to tune before I had a trans problem .But the ease of tuning is fantastic. Four screws to adjust the needle .And just one nut to remove for jet changes.

So far the engine is making good power but has a bit of a flat spot around 8000 rpm. I am running the #118 jets and that is just a little rich.But it is 50 deg F So I will go to a # 116 or #114 jet. The CR carbs are race carbs So Wacking the throttle is something you should not do at low rpm anyway .
I raised the needle to the second position and it helped a lot But more tuning is needed.
 

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Discussion Starter · #8 ·
I had it on the Dyno Saturday . It makes over 30 hp from 8000 to 13500 RPM with a high of 32.9 at 12700. That is running rich across the board with #118 jets.
I will be back on the dyno with a new ignition map #115 jets and a new transmission . Next week
 

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Discussion Starter · #14 ·
Now having lived with the CR special carbs . I do think they can be tuned for the street. That said I have not ridden with them on the street.
Riding them on the track I love them . And the little bit of riding that has not been Full throttle has been great.Like around the pit and return roads.
I did have to raise the needle up to the next to last slot but they feel good .

The problem with bottom end people talk about is from opening the throttle to fast .It is easy to get used to Vacuum slide carbs .You just wack the throttle open and wait for the engine to catch up. With these you just open the throttle smoothly and the bike goes well,I am tuned for top end only and could easily ride this on the street. With back pressure and an air box I think it would be great.That is, on a modified motor. There is a lot to be said about the stock carbs.
 

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Discussion Starter · #15 ·
On the dyno last week . I went tried to fix the flat spot that comes when you open the throttle to rapidly.Above 7500 rpm they are great. and the Idle is fine. Just a bit of a flat spot in the midrange. The bottom end is rich the idle is OK .Then in the midrange it goes lean then it is perfect on the main .

at this stage I have the neddle one clip from the bottom.If I pull it out further it will make the bottom end richer.
I have a 55 slow jet
and I am using 118 mains

I think the next step is to try 65 slow jet and maybe a thinner needle. Lower down .That will lean out the bottom end and richen the midrange some .I think. I will update this as I learn more. I love these carbs . It is just a matter of tuning to get them streetable. As for now . The stock carbs are hard to beat.
 

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Discussion Starter · #17 ·
I cant recommend them for the street. I did not get THAT much HP increase. They are RACE carbs Because they don't have an accelerator pump. So they have a wicked flat spot if you open the throttle to fast at low speed . If you learn to ride with them it is OK . Once you get past 7000 RPM they rock . Changing any jets or needle s takes seconds and you don't have to remove the carbs to do it.

The main reason I got then is the CV carb will not work as well with nitrous .I think the slide may drop during spray.
They also are VERY thursty.

they have a choke but you have to reach into the frame to get to it .
 

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Yea X, accelerator pump? Is that a circuit in the carb? I've been looking at these simply for the ease of changing jets. Next time you do, could you take some pics for me? Unless you already have some up on your other CR carb thread.... I'll check that one pronto.

Audacia, not sure if you know, thought I'd throw it out there: On slide carbs the throttle is directly linked to the slide, and therefor the amount of air one allows into the carb. Thus, if you slam the slide open, there won't be enough vacuum built up in the system to draw enough gas for all of it to work properly, and you'll just kill the bike, or it will hesitate, as X describes. unless it's a seriously fast-revving (not necessarily high revving) engine.

Is this correct X?

On CV (constant velocity) carbs, the throttle isn't connected to the slides at all, but rather a set of butterflies which opens and closes the exit side of the carbs, allowing more or less air to flow through. The air flowing through is what raises the slide and needle, mixing the air/fuel appropriately.... You said in a different post whoever invented the transmission was a genius. I agree, and I say the person who invented the carburetor made the transmission genius look like an idiot.... Fluid dynamics are baffling!
 

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right, my yamaha blaster '2 stroke' was slide operated.

hit the gas, pulled up the slide and needle assembly, is this close to the type of carbs he is using? i could slam the gas from a dead stop and it would take off like a mad ape...

thanks for the wight up spooph
 
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