Carb problem???

Hey All,

So I have a problem. I got my bike really cheap and have managed to get it running and rideable but I would like it to run a little better before I put it on the road. I have a set of carb sync gauges to use for the weekend, and have built my own YICS tool that seams to work fine. Worked a little last night but it got dark before i could get much done. So I went out tonight and my battery was dead and blew a fuse trying to get it started. But the battery and fuse are besides the point.

Start the bike, usually requires the enrichment circuit to be on a little bit, but even when it starts without it, the bike idles at 4000 and will not come down. I try adjusting the main idle screw and nothing seams to change. I did notice that without the bolt in where the YICS goes in(done by mistake) The bike runs much better, idles around 1200. I'm not sure what this means, I have no experience diagnosing motor problems.

Does the fact that the motor is idling at 4000 hurt me in trying to sync the carbs??

When I got it running tonight, I tried adjusting the mixture a little, but still nothing seamed to change. It started blowing a little white smoke out of the exhaust but was starting to get dark so I called it a night.

Am I doing something wrong, or am I just not experienced enough to sort the problem out. Nothing logical seams to help my situation. Can someone give me a semi step by step of what i should do to possibly remedy my problem.

 

You will probably find it will go down a bit as you sync the carbs.

Also make ure you have a bit of slack in the cable. Eg you should be able to turn the throttle a little bit before any revs change. Adjustment can be made using the cable adjustor near the throttle.

Also check the cables at the carby end to ensure the outer cable is seated in the bracket correctly and the swivel at the end of the cable moves freely.

Poke a long screwdriver in and check freeplay between the outer cable bracket and the end of the cable. If it's tight then adjust as required.

If (as often happens) your cable adjuster is rusted you can adjust freeplay by GENTLY bending the outer cable bracket down on the carbs. Doesn't take much force as it is soft metal.

Also check cable for free movement. Eg. wind the throttle wide open(engine off) and let it go. It should flick back into place quickly and with a clunk. If not then look at lubing the cable and throttle assembly.

Hope that helps get you started.

HG

 

White smoke and screaming idle would indicate a lean mixture at idle - check your carb bowls for water (especially if the bike spent a long time parked), fuel lines for obstructions, petcock for fuel flow, and if that doesn't sort it out, then give 'er a dose of seafoam to (maybe) clear out the carbs. Check your intake boots and vac caps for leaks. If this still doesn't help, you're gonna have to pull the carbs and ensure that the pilot circuit is clean (ports, passages, and jets). If the idle mixuture screws are accessible (no plugs) you may want to inspect/replace the o-rings. The fact that you're not getting any response from the mixture screws would indicate fuel starvation (blocked jet or poor supply) or air leakage into the intake (throttle shaft seals are notorious for leakage if you have the Hitachis). Refer to the dozens of other recent posts regarding idle/carb/jetting issues...

 

Well this stumped me for a while but after thinking till it hurt I would advise a careful check of the enrichment (choke) circuit. The YICS bolt removal is what throws me. I don't know if it means something or is just what would happen if something else is off. This would be air being sucked in past the venturi and in massive quantities. Just not sure how that would affect the engine. If mine were not apart I would experiment with it.
So if it does truely lean things out to the correct idle then it would indicate a rich mixture just rich enough to increase idle by pushing open the sliders. Introduce more air and this kills a lot of the venturi's draft and brings the fuel percentage down. Or!!! The mixture is lean and causing the high idle we have all dealt with before and removing the YICS bolt introduces so much air that combustion is compromised and the idle drops.
In this case do what Dave said. Other than that I wish I could get me hands on that bike. I really want to know what a colortune would tell me! So let's just see what you find after running through Dave's list.