Rejetting question

[blowerbike]

blowerbike, have you heard of anyone needing to rejet CV carbs for elevation changes?

honestly all my work has been local but in my opinion i would think the CV's would need the same adjustments as mechanical carbs with large altitude changes.
maybe the changes won't need to be as large compared to RS seriers miks but still i think adjustments/jetting would need a little help.

[koolaid_kid]

Perhaps this is the scenario:
Pipe installed at 4000 ft. Since the air is thinner up there, the fact that the jets were not changed did not show as much, perhaps even compensated for the fact that they were too large for that elevation.
At sea level now, so the fact that the jets are too small is more evident.
Sound plausible?

[blowerbike]

plausible yes IMO..

[bill761mac]

Sorry guys for the late response, I work a lot of hours.

I have read all the responses. thank you to all. I decided to rent a garage and get this done. I am going to start with checking to tappet clearance, why not just get it out of my way for now. This weekend I will take the carbs off and see what size the jets are. I have a set of 115 that I can put back in and go from there. Yes, I rejetted them after the mac 4 into 1 I installed. Im not that far out of the lope lol. I am not new to maintenance and can interpret a manual very well which I have. I'm a turbine guy. Just not great at older recip bikes. Thanks for all the info.

I'm still open ears to all the knowledge on here. I appreciate all of it.
After all that has been said you think going back to 115 mains are a waste of time? You think I can, with them installed just play with the mixture and get it right?

Will post more info as I go, as I work around my schedule. Would like to post a pic of the bike but the quality is to high for the site to take. I have done a lot of work to her. A lot of you might not like it because it is deff no longer stock. Nice flat black paint job too.

[koolaid_kid]

Thanks for the info, bill. We were just speculating because we did not have thei information.
How many sizes did you go up on the mains when you installed the pipe?
I would certainly not go back to stock, you need to be 2-3 larger than stock to start.
What color are your plugs? That will tell you if it is indeed a lean condition causing the knock.
After that, it will be time to do some plug chops.

AFA the resolution of your pictures, an app such as paint.net will allow you to reduce it to any resolution you want and still look excellent.

[bill761mac]

My 1983GS1100L

[bill761mac]

picture of #1plug

[bill761mac]

picture of #2 plug

[bill761mac]

picture of #3 plug

[bill761mac]

picture of #4 plug

[bill761mac]

I have to say the camera really makes the plugs look way worse. Its like when you get a hd picture of your face. picks everything up lol.
What are your thoughts?

I don't recall the size of the jets, will find out this weekend.

[bill761mac]

Go figure turns out my main jets are 115. Hmm. I Am not to sure about the credibility of the guy that rejetting for me. Want someting done right just do it yourself. I am going to throw in a set of 125 main jets and go from there.

Now thinking about it. Maybe when I installed the new headers it required the jet size to go back up to 115 which just happened to be factory.

[bill761mac]

matter of fact. I have a set of pods I never installed. You think that would require 3 size increaseof stock 115 with the mac 4 into 1 exhaust?

[tkent02]

Your CV carbs should not need rejetting, that is one of their benefits.

The elevation compensation of these CV carbs is very good, but when different intakes and exhausts are used, all of that goes out the window. They are still better than VM carbs. You can usually ride them through quite a range of elevations without changing jets, but not like the stock system where you can ride from sea level to 14,000' or more without changing anything, and have them run more or less correctly the whole time. I'm sure they could be tuned nearly as well for a 4-1 and pods up high as the stock jetting with air box and exhaust, but it would take a a lot of testing at different elevations and a lot more knowledge than I have. I'm too lazy, I'll stick with an airbox for something to ride up in the hills around here, especially if I want it to work fine down low too. For zipping around a smaller range of elevations, say S.L to 4,000' - 6,000' or so, pods are fine.

Some with altered intakes are a lot better than others. It also depends on tuning and how picky the rider is. Some are content to have it run at different elevations without misfiring, others expect perfection, with great throttle response, at all elevations.

If his bike was tuned for pods and such at 4,000 it could very well be lean at sea level.

[GSX1000E]

Depending on which pods and how well that Mac system flows the 125 main jets should be real close. Typically, at/near sea level, they tend to end up in the 122.5-127.5 range.