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Buell Forum » Knowledge Vault (tech, parts, apparel, & accessories topics) » Engine » Fuel System: EFI/DDFI, Carb., Filter, Pump, Tank, Filler-Cap, Fuel » Archive through September 11, 2006 » Keihin CV 44 vs Mikuni 42 Flatslide « Previous Next »

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Rick_a
Posted on Friday, June 10, 2005 - 08:58 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Anyone compare these two on a dyno? Anyone try both?...or either? I'm trying to decide between the two and keep going back and forth!
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Captainkirk
Posted on Saturday, June 11, 2005 - 01:11 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick;
If you check the KV you'll find a comparison/dyno chart for the CV40 V. HSR42. While the 44 flows more air than the HSR, I think you'll find the throttle response and tuneability much better with the HSR. I had the same questions regarding my 40 and am really pleased with the performance of the HSR. While the actual HP/torque curves are not that different, "seat-of-the-pants" (butt-dyno)performance is quite noticeable. Hope this helps.
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Rick_a
Posted on Thursday, June 16, 2005 - 02:06 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks. I'll check it out. Edelbrock has claims of outperforming most competing carbs but no one seems to have experience with them.
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Captainkirk
Posted on Friday, June 17, 2005 - 12:28 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick;
I've seen Edelbrock's info on the KwikSilver-looks to be a pretty decent carb. You're right about the support tho- nobody out there sells parts and virtually ALL the Harley/Buell parts/techs I talked to were clueless....which is one of the reasons I went with the Mikuni. You'd be on your own, probably dealing with Edelbrock direct...that being said, they are, from my automotive experience, an EXCELLENT company with very knowledgeable people.
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Jmartz
Posted on Friday, June 17, 2005 - 08:12 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick,

The 42 is not 42 but 40. It is 40 at the junction with the nanifold and 42 at the mouth. the CV44 is 44 all they way through. 44 is too big for a 1200cc motor and will cause starting and drivability problems. It does have stellar top end though. No doubt the Mikuni 42 is the better working carb but it is big and ugly.

I have run a CV44 for 5 years or longer and after much headache was finally able to tune it. The mid range is a bear to set. Look a my profile for details.
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Rick_a
Posted on Friday, June 17, 2005 - 01:53 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I set up a bike similar to mine (XL with SE heads, bolt in cams, SE 6800 RPM ignition) with a 44. It gained power through the entire range but you do need a good collection of needles to find one that works.

I know the 42 Mikuni is capable of supporting well over 100hp.

My biggest concern with the Edelbrock is that the slide is not roller bearing supported. Generally that means a heavy return spring and high effort under high vacuum conditions.

The Keihin 41mm FCR flatslide looks perfect, but at twice the price isn't worth it.
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Rick_a
Posted on Saturday, June 18, 2005 - 08:32 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks for all the input. I decided to go big and ugly. I've got the Mikuni on order. Due to the resounding positive comments and logistical reasons it seems to be the wiser choice. Any comments I got about the Edelbrock were mixed at best. The only applications they seem to have any marked success in seems to be dyno shootouts, drag racing, and show bikes with the dual carbs.
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Captainkirk
Posted on Sunday, June 19, 2005 - 12:57 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick, a word of advice;
I know you'll be tempted to hang the HSR and run it. But check 2 things first. The stock pilot jet will probably be a 20 which is way too small. Also check the position of the needle clip. I think this is the issue I'm dealing with at present, which means (sigh) pulling it off once again. Start with at least a 27.5 on the pilot.
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Rick_a
Posted on Monday, June 20, 2005 - 09:38 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks. I'm planning on starting off on the rich side for safety and dialing it in from there. Better to foul a few plugs than to harm a new (I.E. rebuilt) engine.
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Joe58
Posted on Monday, June 20, 2005 - 12:02 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I HAD A 42MM. AND SWITCHED TO A 45MM. MIKUNI ON MY 95C.I. FXD AND IT WAS STILL SLIGHTLY LEAN. I TOOK IT TO SIMMONS PERFORMANCE FOR A DYNOTUNE. THEY ARE A HARLEY PERFORMANCE SHOP IN PA. OUTSIDE OF TRENTON,N.J. THEIR DYNO IS A DYNOJET 250 WHICH CAN READ YOUR FUEL MIXTURE. ANDY SIMMON SR. DID THE WORK AND ALLOWWED ME IN THE SHOP TO WATCH THE ENTIRE PROCESS.THE BIKE NEEDED THE NEXT SIZE LARGER JET AND THE MIXTURE WAS JUST ABOUT SPOT ON.BECAUSE THAT THIS WAS ALL THAT IT NEEDED; HE GAVE ME A BREAK ON THE PRICE OF THE DYNOTUNE. HE DID A TOTAL OF 9 PULLS. ANDY SR. SET MANY DRAG RACE RECORDS ON A VARIETY OF XR AND XLH MACHINES. IT WAS INTERESTING TO SEE A H.D. DEALERS DRAGRACE X-1 IN THEIR SHOP AT THE TIME. AND THIS DEALER HAS THEIR OWN DYNOS TOO. ANYWAY; WHICHEVER CARB YOU CHOOSE BRING YOUR BIKE TO A SHOP THAT HAS A DYNOJET 200 OR 250. THEY HAVE THE AIR/FUEL MIXTURE SENSOR. GOOD LUCK.
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Rick_a
Posted on Monday, June 20, 2005 - 12:14 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Yeah, we have a dyno here that I'm free to use on the weekend. I can usually get very close to optimum by just riding the thing around.
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Bluzm2
Posted on Monday, June 20, 2005 - 02:27 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick,
My HSR42 was very dissapointing with the stock jetting.
I'm at a 27.5 pilot right now and that may still be a bit lean.
I think the main is close (sorry don't remember which one is in it now) but I still have a pinging problem.

Like Captain, I think it's the needle.
Bike runs great off idle, pulls hard when cool.
When it warms up or when I've been doing freeway speeds at about 70Mph an hard roll on will produce pings after the revs start to build.
Throttle is not full open, maybe 3/4 or slightly less.
Probably a combination of main and needle setting.
The Mikuni is much more responsive to throttle changes than the CV40.
Only other complaint is the return spring is a bit stiff compared to the Keihn.
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Captainkirk
Posted on Tuesday, June 21, 2005 - 12:44 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Bluz
Stock is a 160 main
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Kahuna
Posted on Tuesday, June 21, 2005 - 06:14 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I could take my mik off in my sleep from the times i did that. i'm finally at 30 pilot and 165 main, the bike is runnng great. I'm 300ft above sea level. I can't believe it came with a 20 pilot!!??
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Captainkirk
Posted on Tuesday, June 21, 2005 - 10:30 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick & Brad;
After reading my HSR tuning guide a wee bit more carefully, I'd like to revise my statement regarding the needle clip...needle POSITION (Taper) controls 1/4 to 3/4 throttle and needle DIAMETER (straight part)controls off-idle to mid range. So rather than raising the needle (by lowering the e-clip) I should be installing a smaller diameter needle. Stock is a 97, I'll probably try a 96. Hope this didn't confuse anyone
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Rick_a
Posted on Wednesday, June 22, 2005 - 08:12 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

No problem. I've got an assortment of jets and a couple needles on order...now if I could just get the rest of my motor here...
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Ceejay
Posted on Wednesday, June 22, 2005 - 09:15 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick a - not sure what your set up is but I have 536's with stiffer springs and ported heads. I started with a 35 pilot which sent it rich and backed down to a 30 with a 167.5 main seems to be pretty close, I still have the stock ignition so I get some strange feedback at times. has a slight stutter off idle to WOT which could be more of a cam profile thing. Still trying to quiete that force down a bit which will make it more rich but am waiting on an ignition before I start monkeying with the jets again. With the stock ignition my plugs seem pretty close to right on but have a bit of heat glazing, too far advance is what I am thinking. Hope this helps a bit.
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Rick_a
Posted on Wednesday, June 22, 2005 - 12:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

My set up is going to be an S&S 555 cam (same specs as Andrews N9 but $100 less), ovate beehive springs, light port work, and 10.5:1 pistons. I'm keeping the stock ignition, too, unless the dyno says I need a higher rev limit. I'm hearin' that single fire works better with long duration cams. My plan is to work on the jetting first, then the ignition, then tune the SuperTrapp and repeat if necessary.
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Ceejay
Posted on Wednesday, June 22, 2005 - 12:35 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

you might know this, I was screwing around one day doing "testing" and missed a shift, watched my tach go up to 7700!! I didn't think it was possible with a stock ignition. Did I disconnect something, or didn't it kick in becuase I got off the gas quick.
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Craigster
Posted on Wednesday, June 22, 2005 - 12:44 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Even with a limiter the inertia in an engine can spin it beyond the ignition and fuel cut set point during a missed shift.

Limiters can be pretty accurate during extended rpm pulls (like wheelies) where you fail to shift, but often allow some over-rev during WOT with zero load. They also cannot protect mistaken down shifts for upshifts!!! Ouch!
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Rick_a
Posted on Wednesday, June 22, 2005 - 06:29 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Yeah, I've had that happen, too.
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Ryker77
Posted on Tuesday, June 28, 2005 - 01:42 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

what about street driveability which is better the cv40 or hsr42?

I never had a problem with my 92 883 sportster. But now that I've got a bike that has the ability to make double the power... not sure what carb to replace the fuel injection with.
2002 x1 with nallin XB stage 3 heads and Andrews N80 cams, force intake and force exhaust.
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Captainkirk
Posted on Tuesday, June 28, 2005 - 06:46 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The HSR is a much better carb, overall. With the N8's you've got a lot of overlap at low RPM that causes a stumble/hesitation below 3K when you get aggressive with the throttle(believe me, I know!) This can be compensated for on the HSR by adjusting the accellerator pump stroke to suit your particular engine. Oh, yeah, and jetting changes are a lot easier too!
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Ryker77
Posted on Tuesday, June 28, 2005 - 08:50 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I'm actually using n80's cam much higher lift and longer duration.
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Orion1
Posted on Wednesday, June 29, 2005 - 08:05 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick,

One thing to be aware of if you go with the HRS42 is that when it comes time to switch gas to "reserve", you get NO warning!

The stock CV carb on my 2000 M2 gave me plenty of warning; it started to miss & I had plenty of time to reach down and switch to reserve. It's not much of an issue until you're suddenly w/o power in the middle lane of a crowded interstate!

I try to remember to go ahead & switch to reserve at around 170 miles if I find myself in the dreaded "crowded interstate" situation.

I gained ~2 hp all the way across the rpm range when I put on the HRS42. The runs were on the same dyno, but about a year apart, with a different guy doing the pulls.
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Rick_a
Posted on Wednesday, June 29, 2005 - 08:51 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Well, I've got a Pingel petcock on it, so I already get no warning. I usually fill up as soon as I can't see fuel in the center of the tank.

Ryker, have you had that bike running? That was one of the combinations I was considering but I felt it'd be a little too radical for something I'd still be riding on the street.
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Ryker77
Posted on Wednesday, June 29, 2005 - 10:47 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I actually purchased the bike with all the engine mods. The previous owner had used the race ECM then he went back to the stock ECM and PC. I guess he got tired of screwing with it.

I've got the PC dialed in some. But its not 100%. Either needs TPS or AFV replaced or adjusted. Plus the timing had been retarded.. So I need to adjust that as well. Plan on using octane boosters all the time.

It's wicked fast. Kinda too fast to enjoy. Those rpm's just fly and its time to shift.. then your going double the speed limit and time to slow down.

I guess for the money a brand new HSR42 from ebay for 250.00 is what I'll buy. I've got an A/F ratio gauge on the bike so tunning should be simple.
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Rick_a
Posted on Wednesday, June 29, 2005 - 12:44 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

If you go with a carb you can get an adjustable ignition module that'll help get detonation under control and still allow a decent total advance.
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Ryker77
Posted on Wednesday, June 29, 2005 - 01:21 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I know the the best setup would be the a nice Dyna ignition. But not quite sure how to convert from ECM to aftermarket igntion-- and idiot lights, tach, speedo, and other things working properly. see this topic- http://www.badweatherbikers.com/cgibin/discus/show.cgi?47623/124108
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Rick_a
Posted on Thursday, June 30, 2005 - 01:11 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I got a Crane HI-4E. It has more adjustability and doesn't require a laptop to access all its features.
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Ceejay
Posted on Friday, July 08, 2005 - 11:43 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Rick, that thing together yet?
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Rick_a
Posted on Monday, July 11, 2005 - 08:25 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

No...not yet. I finally got all the motor parts on Friday. I still need to gap the rings so I can get the jugs and heads on...then I need to check some clearances. If that goes well I can buy the rest of the stuff I ordered (ignition, coil, rearsets, carburetor, etc) and she'll be running next weekend. If I need more machine work it'll be the following weekend!
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