|
|
Post by dexameth on Oct 17, 2017 15:51:45 GMT -5
So yesterday I got my 22mm Mikuni round slide carb installed and running. I had to use an old exhaust header cut down to bolt to the carb. That cut tube then fits inside the intake manifold and viola! Well, I did have to make a rubber spacer to couple them together. It does form a seal.
I mocked everything up, cranked it and it fired right up. Luckily I had it on the center stand because it was hanging around 3k rmps. I played around with the idle screw and mixture screw until I had a 1900 sustained idle. Perfect.
Blip the throttle and it would hang at high rpms for a bit before settling down. I was looking at the slide when I pulled on the throttle cable and it wasn't sticking, it would settle back down to normal and the idle would still slowly creep down. The throttle response is amazing, I started cracking the throttle over and over and it was great, except the settling down.
I put a home-made cardboard gasket between the carb and intake runner, and a new gasket under the intake manifold. I had to make both, the intake manifold gasket may have a leak? I'll check that next.
Does anyone know if I'm missing something? I've taken the entire carb apart, inspected and it looks fine. It's a stock pull from some 125cc something, and seemed to never have had gas in it... a friend bought a lot of 5 off eBay and hooked me up with one to test.
|
|
|
|
Post by pinkscoot on Oct 17, 2017 19:10:36 GMT -5
Sounds like an air leak.
|
|
|
|
Post by cagiva4ever on Oct 18, 2017 2:16:16 GMT -5
before anything else, is it 2t or 4t version ?
i assume its pitbike carb being 4t. if its 2t, that is a problem....
in any case you need to specify its jetting, emulsifier model etc....
as long as if you dint create fittment parts that dont airleak, then its down to jetting/carb model 2t vs 4t.
as would be silly if your throttle cable is under lenght etc silly...
|
|
|
|
Post by uglo on Oct 21, 2017 16:05:26 GMT -5
Needle setting might be too rich? Going to check the same thing on mine but I think I'm lean!
|
|
|
|
Post by dexameth on Oct 22, 2017 7:20:19 GMT -5
before anything else, is it 2t or 4t version ? i assume its pitbike carb being 4t. if its 2t, that is a problem.... in any case you need to specify its jetting, emulsifier model etc.... as long as if you dint create fittment parts that dont airleak, then its down to jetting/carb model 2t vs 4t. as would be silly if your throttle cable is under lenght etc silly... It is a 4t pitbike pull, you're correct. 100 main, 30 idle jets. I run a 24mm CVK carb with no issues and I believe the jets are bigger in it than the slide carb. I tried again yesterday with new gaskets and it fired right up and I got it to barely idle. It would still hang on throttle response. I played with a/f screw and idle screw with no results. Put CVK carb back on and did 100 miles with most on highways. Scootie did good on 275! Haha. |
|
|
|
Post by RollingThunder on Oct 22, 2017 8:49:46 GMT -5
Usually when the idle hangs like that, it's because the idle is set too high yet or you have an air leak. Do you have enough slack in your throttle cable so the idle screw is actually allowing the slide to drop further when you adjust it?
|
|
|
|
Post by dexameth on Oct 22, 2017 9:40:41 GMT -5
Usually when the idle hangs like that, it's because the idle is set too high yet or you have an air leak. Do you have enough slack in your throttle cable so the idle screw is actually allowing the slide to drop further when you adjust it? Yes, the throttle cable was just hooked up in the carb but not the handle. This way I can manually "tug" on the cable by hand. Honestly didn't wanna hook it up til I knew it ran right. The slide does in fact rest all the way down. When I tug on it by hand it moves freely and the spring has great tension. |
|
|
|
Post by pinkscoot on Oct 22, 2017 9:48:48 GMT -5
Do you have the boot on the cable going into the carb? Always a source of air leaks.
|
|
|
|
Post by RollingThunder on Oct 22, 2017 10:39:06 GMT -5
What happens if you drop the idle down to around 1500 RPM? Does it still hang?
|
|
|
|
Post by dexameth on Oct 22, 2017 10:52:17 GMT -5
Do you have the boot on the cable going into the carb? Always a source of air leaks. For real? No way... I didn't have the boot sealed, you think?! Thanks for the hint!! |
|
|
|
Post by dexameth on Oct 22, 2017 10:52:35 GMT -5
What happens if you drop the idle down to around 1500 RPM? Does it still hang? Yes, hangs no matter the idle rpm |
|
|
|
Post by RollingThunder on Oct 22, 2017 10:54:07 GMT -5
What happens if you drop the idle down to around 1500 RPM? Does it still hang? Yes, hangs no matter the idle rpm Time to spray it for air leaks.  |
|
|
|
Post by dexameth on Oct 22, 2017 11:17:18 GMT -5
I think pinkscoot solved it. Gonna try after work tonight. |
|
|
|
Post by dexameth on Oct 23, 2017 8:43:11 GMT -5
Confirmation of success! That rubber seal was definitely the issue. I hooked up the cable and it fired right up. Idled high, so I turned the mixture screw out until I had it around 2k. Then I blipped the throttle and it was perfect! Drove to work today, feels like I may need a bigger jet. Needle @ middle notch, cracks when accelerating, needle @ bottom notch and it has more throttle response but hesitates just a little at WOT.
BOTTOM LINE IT WORKS.
|
|
|
|
Post by pinkscoot on Oct 23, 2017 9:35:21 GMT -5
I'm glad that worked for you. The boots on the throttle cable aren't there to look pretty, they do a job of keeping air out of the carb. I have had this problem and that was the cause.
|
|
