Won't stay running w/o holding throttle

Message

TechTMW · #11 Unread post by **TechTMW** » Wed May 17, 2006 5:59 pm

Ok, your bike should be idling around 1100 rpm or thereabouts.

You might have a screwed up idle circuit on the carbies after all. Just make sure you've checked all the obvious things before you crack open the carbs.

once you've cleaned the carbs, you might as well also make sure the valves are in adjustment and the synchronise the carbs.

rapidblue · Wed Jun 14, 2006 4:48 pm

So after being kicked over and such, i took the bike to the dealer and had them check it over to see if anything was wrong. They replaced the plugs becasue they were fouled from being on it's side. Said the only thing it could use was a carb clean and sync but that it wasn't necessary quite yet.

It ran great for the past two days and now I went to go for a spin tonight and it's doing the same thing, won't stay running and the throttle feels real sluggish. It was running fine 4 hrs ago.

I sounds like it's missing when I hold the throttle at 1500rpm but any more than that and it sounds fine?

argh!! i'm so frustrated.

TechTMW · #13 Unread post by **TechTMW** » Wed Jun 14, 2006 9:19 pm

Your idle circuit in the carbs is screwed.

Above 1500rpm, and the bike is running on the mid-range circuit. Clean and synch the carbs, and pay special attention to the air passages in the idle circuit. (Air passages get crud and they often get overlooked in a cleanin - even putting carb cleaner thru the tank doesn't help - because no fuel runs thru there.

rapidblue · Thu Jun 15, 2006 1:59 am

TechTMW wrote:Your idle circuit in the carbs is screwed.

Above 1500rpm, and the bike is running on the mid-range circuit. Clean and synch the carbs, and pay special attention to the air passages in the idle circuit. (Air passages get crud and they often get overlooked in a cleanin - even putting carb cleaner thru the tank doesn't help - because no fuel runs thru there.

will do thanks

rapidblue · Thu Jun 15, 2006 3:19 am

So my next question since I don't understand carbs too much,

is how is it that the bike ran great for a few days and then all of a sudden back to this?

The carbs hadn't been cleaned since I was having the trouble last time.

Thu Jun 15, 2006 6:15 am

Is there rust or trash in the tank?
Even after you clean the carbs there may be junk still getting in the idle circuits. they are so tiny almost anything will clog them up.

rapidblue · Thu Jun 15, 2006 6:23 am

fireguzzi wrote:Is there rust or trash in the tank?
Even after you clean the carbs there may be junk still getting in the idle circuits. they are so tiny almost anything will clog them up.

I thought there was no fuel flowing through the circuits, just air?

TechTMW · #18 Unread post by **TechTMW** » Thu Jun 15, 2006 10:15 am

Depends on which path in the circuit we are talking about. I pointed out the idle air path because that's the most often overlooked place when carbs are cleaned. One thing that's overlooked in 80's era inline carbs are the pilot screws - the ones that are "Tamper proof" sealed from the factory. you may need to take them out and look in there for crud and nastiness. However, It is also possible that it's a fuel path in the circuit.

Does using the choke still not affect the idle at all?

rapidblue · Thu Jun 15, 2006 11:29 am

The tricky thing with my bike is that in the mornings, even with the choke pulled I have to hold the throttle to keep it running.

When I started it in the mornings I used the choke, when I would let off the choke it would try to die even more.

I can set the idle screw so that I don't have to but when it warms up it's idling at 3000 and that not good.

No of this sounds normal so maybe after I get the carbs cleaned, it'll be different, or maybe it's something else.

TechTMW · #20 Unread post by **TechTMW** » Thu Jun 15, 2006 12:03 pm

OK, i'm almost positive it's your idle circuit then. Clean EVERYTHING. Including the pilot mix screws, but be carful with them they are very delicate they are so small that when you put them back in if you bottom them out, they will strip. be gentle.

What's happening is that you bike can't run on the idle circuit, it's blocked. When you crank open the idle speed screw, you are just openin up the throttle plates, allowing more air in. Eventually, they open so much that the carb switches from the Idle circuit to the slow/midrange circuit - this is why you get the sudden jump in rpm, and why the bike will only run like this.