Cv or Mikuni? / Plus a strange issue...

[fin_676]

I paid £200 for the one on the softail just over 3 yeas ago and £100 for a used one + £50 for a rebuild kit for the one on the dyna which i thought was a fairly good price for a quality bit of engineering that has greatly enhanced the use of the 2 bikes
although the sportster works very well on an up jetted stock cv

Brian

 

[Jack Klarich]

IMO I would start over with a stock C V carb and forget about the Thunderslide and dynojet kits, more trouble IMO C V carbs are cheap and available parts are cheap hard to beat a properly tuned C V carb:s

 

[Doug S]

Bubbie,

I've tried a 46 & 48, running a 45 right now, the 48 was too fat and I didn't notice anty difference with the 46 so I went with the smaller one. Definately something wrong with this carb and the slow speed circuit in geneneral but I've had it apart a number of time trying different jets and needle settings, and I don't think it can get any cleaner...LOL

D

 

[ckhismine]

Starting over may be you best bet. Having a unmolested carb and modding it your self would be the way to go. That way you will know what you have and know where you going with it. I have tryed reworking a CV that someone else had modded but ended up trashing it and started fresh. Do you know the spec of the cam ??

 

[Doug S]

Do you know what cam is in the engine? could be an overlap problem at low speeds

The PO said it was a Crane and gave a number that I can't seem to match up to anything crane made, CV-3 is what he said. I have to say that although I know the carb is an issue, my gut tells me that replacing/fixing it will not cure the rear cylinder issue. I'm leaning towards the cam area myself, maybe they pressed on the gear one spline off or maybe it's just too radical. I have heard cars back in the day sound almost the same way after a cam change, sound real bad driving in town but a real screamer on Friday night. By this winter I should have nearly 40k on the clock and it will be time for lifters and I want to check out what kind of cam bearing is in there so I'll probably be replacing the cam at that time. It will me real nice if the carb does the trick, maybe it is firing on the waste stroke it's too rich....

D

Brian,

My main concern with the Mikuni is fitment, I don't want to replace my aircleaner and it is not stock. Is the Mikuni the same depth as the CV?

D

ckhismine,

Negative on the cam specs. And that's where I'm at with this carb, by the time I buy a new slide, gaskets, emulsion tube and whatever, Istill won't know what other stupid stuff has been done to it. My neighbors bike was running badly and he was working on the carb, everything looked like the bike should atleast run ok but it didn't. I started asking questions and it turns out that he wanted a bigger jet and didn't have one so he ran a small drill bit through it to "open it up"...Who knows what's been done to my present carb...LOL

D

 

[ckhismine]

I am thing you have a Andrews EV-3 cam. Check the Andrews cam web site to get the specs. Now we are getting to the bottom of the problem. See it only takes a word or number to get things rolling.

 

[fin_676]

Mikuni hsr is a direct replacement for the cv carb however it needs a wee adaptor plate to allow fitting of air cleaners for the cv just did a quick search and found this
Mikuni HSR Air Box Adapter

However if you get one of the easy kits then it comes with the adaptor in it
You can use stock choke cable stock throttle and idle cables has a vacuum take off for the voes and works with any stock air cleaner or air cleaner setup for the stock cv with the adaptor

Brian

 

[nmaineron]

The only problem I have found with the Mikuni is the noise of the slide bouncing when idling.For some reason I found that wicked annoying.Ron

 

[karlsbike]

Ron: I haven't noticed any idle noises from my Mikuni - could you have worn slide guides?

Doug S: if it is an Andrews EV-3 you have the specs look ok for a mildly trimmed bike. IMO, if all cylinder parameters & tests, intake & ignition parts are checked out ok this is an odd problem. I don't really see how it could be a cam gear timing issue either - if so, both cyl should be equally off, plus you're saying it runs great at higher rpm's...
I assume you've checked your pushrods, although again it should then get worse at higher rpm's...

My money is on the carb, and here's a theory to chew on:
The rear cylinder cycle is 315 degrees after the front, while the front is 405 degrees after the rear. The carb therefore has more time to supply its A/F charge to the front than the rear, and if the carb is a bit worn somewhere it could show up as a disturbance at idle...

 

[fin_676]

Both my my mikuni carbs are quiet i have no noise at idle

managed to dig up an installation manual for the easy kit shows a few different options on fitting stock and SE air cleaners

Brian