Cv carb tuning tutorial.

[chuck hahn]

Maybe those with CV carbs will find this very informative. Save it somewhere. And maybe someone can have Frank save it as a sticky.

http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

[Steve]

There is probably a bit of truth in the process, but I have a definite problem with setting the float height in the THIRD step, not the FIRST.

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[mrbill5491]

Omg just read that and now my head hurts. Not sure I would want to use it. That's alot of installing and pulling the carbs. Think the way we typically do it is just fine.

[Joe H]

There is probably a bit of truth in the process, but I have a definite problem with setting the float height in the THIRD step, not the FIRST.

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Remeber here you are not actually "setting" the float height you are "adjusting" the float height. You defiantly want the float height at recommended level BEFORE you start playing with the jetting.
I have a factory kit and followed the instructions and it really worked well, I had to adjust the floats to lower the fuel level by about .5mm and it did make a difference! I was surprised.

[chuck hahn]

You are correct Joe. You DO need the initial setup..OBVIOUSLY....DUH. And as you change jets you are also changing FUEL CONSUMPTION RATES in the bowls. Hence, youll need to readjust floats to meet requirements.

[Joe H]

Omg just read that and now my head hurts. Not sure I would want to use it. That's alot of installing and pulling the carbs. Think the way we typically do it is just fine.

It is/was a pain. I took it real slow, weekend rides and while riding doing the testing, then make one change and drive it again latter, sometimes weeks later. Took me most of this summer. Just didn't do it all at once to much. But I will say it is running better than ever, it may take a bit but it works.
Just have fun doing it! The kits, dyna or factory pro work pretty darn good.
Jetting is a HUGE pain, thats why there are so many questions about it!
Stock may be crock but it sure is easier! And many times better.

[mrbill5491]

I would like to see a dyno sheet showing any gains or losses myself. IMO taking most of a summer to "dial it in" would interfere to much with riding time (plus I don't like pulling my carbs if i don't have too of which I just had to do this weekend for a hung float or fuel needle). I figure a good cleaning and a carb sync and some plug chops to check the overall mixture is good enough, then have more fun and go ride. I ride a lot at different altitudes here, from 3,800 to 9,700 ft, getting it perfect (of which there is no such thing, just damn near close) is going to be impossible. My plugs show a nice med tan color so all is good. Though if that is your thing go for it.

[Joe H]

Ya Dyno sheets would be nice. I think most guys I know would have thought it was good enough the way it was, but I have always loved wrenching on bikes (AS A HOBBIE I don't think it would be as much fun as a job!) Most of the people that know me think I like working on them as much as riding and they might be right… And as I was doing all the tests that are mentioned here I was getting noticeable improvement which was cool.
I also don't think a dyno can tell you if your transitions from pilots to needles to mains are the best they can be, and I don't think it can be an accurate measure of throttle response (maybe a really good dyno operator and dyno set up can) A dyno can tell you the bulk jetting and get it REAL close but the devil is in the details and I have been rewarded with better carberation; better (crisper) acceleration through out the rpm range, and better milage for it.

And at those altitudes getting it spot on..not likely, I can notice a difference when the temps change! I cannot imagine altitude.

[mrbill5491]

Ya Dyno sheets would be nice. I think most guys I know would have thought it was good enough the way it was, but I have always loved wrenching on bikes (AS A HOBBIE I don't think it would be as much fun as a job!) Most of the people that know me think I like working on them as much as riding and they might be right… And as I was doing all the tests that are mentioned here I was getting noticeable improvement which was cool.
I also don't think a dyno can tell you if your transitions from pilots to needles to mains are the best they can be, and I don't think it can be an accurate measure of throttle response (maybe a really good dyno operator and dyno set up can) A dyno can tell you the bulk jetting and get it REAL close but the devil is in the details and I have been rewarded with better carberation; better (crisper) acceleration through out the rpm range, and better milage for it.

And at those altitudes getting it spot on..not likely, I can notice a difference when the temps change! I cannot imagine altitude.

Yup going from desert heat to the cool mountains is nice. With the altitude, first thing you notice is the idle, thinner air means it will struggle at idle some. Me I run my idle a bit higher then most so i don't have to adjust it any in the mountains. Power is the second thing, thinner air means less power, takes a bit longer to get things moving some lol. Though the CV carbs do a good job.

[Joe H]

One more thing that helps me with jetting is ear plugs. Being able to NOT hear the exhaust note has allowed me to have better feel for stumbles and power during acceleration runs.
I do testing with earplugs (under my helmet of course) and then without, listening to the exhaust note.
Could be my imagination the only evidence I have is my experience with the very few bikes I had jetted.

Just thought Id throw that out there.