Smartcarb SC2 users?

[gasgasman]

That idle is way too high.
I have mine set where it barely idles.

May be a vacuum leak. While the bike is running, spray carb cleaner around the carb boot and see if the idle changes.

[Wbdisco]

That was my suspicion but I?ve double checked the boot, it looks fine. I?ve got one on the way from CPD. I am tempted to take it out and put the old carb back on and start over. Truly the only place that it can be is that boot between the carb and reeds. I never had any issues before so I?m guessing I must have done something on install.

[gasgasman]

I wouldn't be afraid to turn the idle screw down even more.
I've never got that 2mm throttle slide gap number to work, always lower.

Also, open the throttle slightly ( engine off) when adjusting the idle. Keeps the adjustment screw from digging into the throttle slide.

[Wbdisco]

I?ll give it a try, I did adjust the idle screw way lower but it ran like hell. I realize it?s a a give and take between the metering rod and idle adjustment. I?m just going to take a real close look again this evening, but dang it?s not like I was rebuilding the top end, it?s just a carb swap.

[coopernicus]

I know what you mean. The exact same thing happened this past spring when I swapped out my Lectron for the SC2 as the only thing I did on the bike. I figured (wrongly) that the existing cable and throttle tube would work. I installed the SC2, it started fine, rode it up and down the street, and all seemed okay with just a little play in the throttle. I checked for the sound of the slide bottoming and it was a distinct "thunk" sound and I thought it was good for a riding trip the next weekend. Right before I left, I started the bike and it revved really high...I shut it off and traced it to the throttle tube (which apparently was not stock). The cable was binding in the throttle housing as the slack was causing an issue. I rigged it for the ride and I had intermittent revving while I was riding. When I got home, I ordered that new Motion Pro cable and pulled the throttle tube off of my 2014 that I bought from new and knew the throttle tube was stock. When I went to install the new cable, I found the old cable somehow was not secured in the slide properly (the only explanation is that I failed to install it properly or the excess slack allowed it to get sloppy in there). Once I had the new cable installed and a stock throttle tube, it has been perfect ever since.

[Wbdisco]

Well I have a cable that should be here today, the rubber hopefully tomorrow or Thursday. I?m trying to rule everything out. The throttle cable I?m not sure of, I took it completely off the throttle housing and cam and it didn?t effect anything. Only thing I can do it start from scratch and be more careful, although I feel I was careful from the start.

[Wbdisco]

Cable came in today, no change. I went ahead and pulled it. I?m gonna start from scratch. My new clamps and rubber boot are on the way so it will give me some time to study a little.
I did notice that the rubber boot does obstruct air/fuel flow, see picture. I will probably port match the new rubber. After porting chainsaws as a hobby I realized that even little things can have big effects. Also, I checked float level and it is a little high with the carb mounted like it is for clearance of the chain and case. I will keep updating as things go, maybe I?ll figure it out and be able to help the next guy.

[Wbdisco]

Keihin is back on, same air boot, same clamps, same fuel line with filter. Heck even had the cable choke. Runs like a sewing machine, smooth and no hanging idle. Here is a vid I filmed.
https://youtube.com/shorts/aIxzkcVN0C8?feature=shared

I will put the SC2 back on when I get my new boot and clamps, although I pretty sure it ain?t the problem.