How to tune carbs.

DarkKnight · Posted: November 8, 2006, 11:40 pm Post subject: How to tune carbs.

I would, and I am sure others would, appreciate a step by step on how to tune the carbs on this bike. I have a 79 XS650 SF. I have baffled drag pipes, pod filters, carbs are freshly rebuilt, and I rejetted to match my set-up. It runs well. I want it to run perfectly. Now all I need is a little expertise on how to tune this bike to run like a champ. I am unfamiliar with bike carbs, so if anyone even has any sort of visuals with the controls labeled it would be a great help. (They don't resemble the good ol' Rochester I'm used to!) I know I need to get the carbs synched, but I'm not sure what exactly that entails. I do have a good vacuum gauge, and can modify it so it doesn't bounce. For tuning the carbs, my Haynes manual only lists the mixture screw and adjustment of the mixture screw. I'm betting there's more to getting this tuned in than the mixture screw, so I'm turning it over to you guys.
Thanks!

jayel · Posted: November 9, 2006, 12:28 pm Post subject: Re: How to tune carbs.

take a look at the posts from xsjohn, some good stuff there, drilling the air bleed hole in the slide really does give you more response on the diaphragm carbs, these carbs are rather simple tho' so getting them in balance will probably do the most good

xsjohn · Posted: November 9, 2006, 9:05 pm Post subject: Re: How to tune carbs.

I have 80 carbs which are 34'mm brass floats. Yours are 38's and my posts for early 34's won't work for 38's which I know very little about. Both of my friends hae 38's and they both leak if you leave the gas on. Rubber tipped needle valves may help this if you are having flooding problems if you leave the gas on unattended.
Ballancing twin carbs by ear is an ok way.

John Underwood xsjohn

shil · Posted: November 10, 2006, 12:24 am Post subject: Re: How to tune carbs.

Good advice here

grizld1 · Posted: November 11, 2006, 11:23 pm Post subject: Re: How to tune carbs.

DK, you don't want to damp all the fluctuation out of your gauges. The needles should bounce slightly; just damp down enough to get a coherent reading.

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