Mikuni 42 or Stock CV

With your build you will have more torque at lower rpm with the smaller 40cv
(38 mm throat). you may see a few more horsepower from 4500 up with the 42 mik. But nothing you will feel..on paper only. for the money..stay with the CV.
I'm of the opinion that the increased throttle response reported with the mikuni is due to the fact that the travel at the throttle grip is about 25 percent less from closed to full open than with a CV.

Is there a way to decrease that throttle travel on the 40 CV? Its strange how everyone keeps telling me to get the 42 Mikuni. All the shops especially. Guess its a ploy to make money. But they all swear the CV is a boat anchor. Maybe for more aggressive builds but not mine.

cdirk said:

Is there a way to decrease that throttle travel on the 40 CV? Its strange how everyone keeps telling me to get the 42 Mikuni. All the shops especially. Guess its a ploy to make money. But they all swear the CV is a boat anchor. Maybe for more aggressive builds but not mine.

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the 40Cv will support 100/100. Its a ploy to make money for a build like YOURS.
funny ..but all the Jap bikes going 180 mph before EFI came onboard use CVs.

Makes sense. If I ever get more aggressive head work done I will buy it. Until then I guess I should put that extra cash into tuning what I have.

Thanks,

I have personally been down this road on my first motor build except I did have head work done and was running SE 251 cams. The CV40 was on it first and bike ran 95hp/99Tand then bought a 42 Mik and it rocked 104hp/105T. Then Bought a 45Mik 101hp/103T. I personally think the 42 is a great carb and the throttle reponse was like night and day over the CV40.

Just my results on my bike with the 42 mik.

Dave, was yours a 95" mild build like mine? whos heads did you have on yours.

One pro and one con. Any other opinions?

Sir,

I had my heads done.

I know there are some really great guys on here that do really outstanding heads and custom parts but I have all my heads and parts done by Big Al's Performance......if you would like his web link PM me and I will send it you.

I really like the guy as he has been very helpful, colorful to talk to, and truly has a passion for this type of stuff, plus he has a heavy professional racing background. I had a problem with one of the sets he did related to core shift and he made it right asap, no quibbling or bs, just fixed it and then some. To me that speaks volumes.

As for the Mik42.....for me its a sweet part.

Mikuni HRS 42

The stock CV carb. is an excellent and versatile unit. However out of all the different exhaust, filters, ignitions that I've tried thru out the years. Some products would make no difference and some would be better than others. I would have to say that the Mikuni HRS42 was best performing bolt on product and also the bang for the buck, that I have experienced.

I've also found HSRs to be an excellent (but admittedly expensive) cure for carb farts. A lot of guys are able to get rid of them by rejetting the CV and adjusting the idle mixture screw, but that didn't work for me. The bikes ran much better with the HSR.

John

I think a Mik 42 easy kit will be my next purchase. Seems like a good part for my setup. Thanks for all the input.

Go for it, the 42 will live long and run hard

I've had the stock , and rejetted CV and a Mik 42 , the CV is an OK carb never any problems, the Mikuni was to me hands down better . Much better throttle response , and noticeable gain seat of the pants performance. I've got a re jetted CV, it works fine , but isn't nearly as quick, I have a new HSR 42 to be installed with my 95 build .

JRS said:

I've also found HSRs to be an excellent (but admittedly expensive) cure for carb farts. A lot of guys are able to get rid of them by rejetting the CV and adjusting the idle mixture screw, but that didn't work for me. The bikes ran much better with the HSR.

John

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Same here, I tried many things too get rid of the carb fart. The HSR did it for me.

MW

my first mod was the mik 42 on a stock 05 deuce with a force winder breather with [email protected] big radius pipes. I get a lot of back fireing when when I let of the gas and just rolling in gear, like approacing a red light. It really goes crazy when I am trying to use the gears to slow going down some of the north G. mtns. I found if I turned the idle way up it helps alot. Could it be the pipes? Does it need re jetted? Has anyone experianced this.

I'm also debating the 42mik in place of my 40CV. A guy at a local shop speaks very highly of them. Thanks for the additional input guys!

I like the HSR42's so much that I got two !!!