Pitster Pro XTR200 Idle problems

[motomaster]

Hello all,

As you may or may not know already, I have just purchased this bike, and it is my very first motorcycle. I am fairly mechanically inclined, but have never worked on motorcycles before so bear with me here

I have searched the forums, read all the related threads and have tried many of the possible fixes. First I will tell you whats happening...

I start the bike with the choke on, starts fine, everything seems fine. Idle starts to increase to 4k or so within a few minutes. I turn the choke off, and the bike idles around 2k or so.... but then will suddenly drop off and the bike will shut off. Okay so I think maybe it hasn't warmed up yet, but after 15-20 mins of the bike running with choke on, it will still do the same thing. So then I think, maybe the idle screw needs to be adjusted. I adjust it and okay, everything seems fine now, problem solved! But no... I take the bike for a rip, and after 15 mins of driving, I'm sitting at a red light, the bike is idling at 4k! I have to reach down and adjust the idle screw back down to where it was, and the idle is back down to 2k or so. I drive around some more, and everything seems fine again. Next day I go to start up bike and same thing... after warm up it won't stay idling. I just can't seem to get this thing dialed in!

I have a road test in a couple weeks and I don't want the instructor to think I'm stalling my bike, when it really is just cutting out on its own.... plus that doesn't look good either.

Things I've tried so far from reading the forums:
- Drained out old gas, replaced with new 91 octane plus a full can of seafoam
- Pulled carb apart, blasted out jets, sprayed and cleaned with seafoam
- Sprayed seafoam into the air intake with the engine running
- Sprayed WD40 around carb boots to check for leaks
- Changed oil (just because I wanted to anyway)
- Installed new spark plug

There is only 350 kms on the bike, maybe it just needs more riding?

[edtardo]

You could try changing out the CDI.

[david3921]

We'll need a picture to be sure but I think that your bike is really a Qingqi 200gy. Which means it's also a number of other names such as a Qlink XF/XP 200 and a Konker.

Anyway, I have a Qlink. I've had two problems relating to idle. One was a old (bad) battery and a torn intake manifold. The old battery would let it idle but not rev up beyond that. The torn manifold was harder to find because the carb is held tight between the head and air box. I think mine got torn taking the carb out to replace the jets. Mine was torn underneath. Try spraying the WD all around the manifolds while moving the carb a bit. That's how I found mine out.

Edit; If you do find that your manifold is torn I have a new one. I ordered one from the Qlink website but found a Mikuni while waiting for it to arrive. I installed the Mikuni with a little re-work. Let me know if you need it.

[FastDoc]

You have an air/vacuum leak.

[MICRider]

I agree with Doc, sounds like an an air leak. I had the exact same bike, and with a cold start full choke I don't even think the engine turned over a full revolution before it started. Idle was around 1200 or so I think, and dropped down when the choke was turned off. It was probably one of the best starting and smoothest idling bikes I've ever owned. Mine was the Konker variant, but exactly the same bike

[FastDoc]

Do you know how to test for this?

[motomaster]

Thanks guys!

FastDoc, MICRider,

Not sure how to test for this... is it with WD40 spraying it around the intake manifold? And just to be 100% sure, that's the rubber boot between the carb and the engine? I tried that but maybe I wasn't thorough enough... I'll try again. Once I spray with WD40 I should be hearing for changes in idle, correct?

david3921,

Thanks, I hadn't considered the battery before. The guy I bought it from had it sitting in his garage all winter. I'll try the WD on the intake manifold test again. And I have some pics of my bike in the new members section, if you want to check it out!

[SpudRider]

If the other solutions don't work, I suggest you adjust your pilot mixture screw (PMS).

[zingshoen]

that s a case of WCBS (weird carburettor behaviour syndrome).

does perhaps the slider get stuck? what kind of carb is it? do you have another carbie you could try?

[Weldangrind]

If it's not a vacuum leak or battery or PMS issue, I think the slow jet is clogged. The fact that it has been sitting makes that plausible.

[FastDoc]

I don't think WD-40 will work, and it will make a mess.

You need something flammable. Most guys use carb cleaner or starting fluid (ether). I prefer the latter.

I'm almost sure this is your problem, although a plugged jet can do it also as Weld suggests.

[motomaster]

I tried the test again last night with WD40 (before I read these replies), and still no luck. The idle was "surging" on its own before I even applied WD40, so it was hard to tell what was doing what. I'll try again today with something different.

Its a Mikuni Carb, and looks like the one in the Qlink XF200 manual. The only exception being - it doesn't have a pilot mixture screw! In its place is a round brass block, with either a hole or indent in the centre... I'll see if I can get a picture of it. I don't have another carb I could try unfortunately.

I've previously taken both jets out and soaked and blasted them out, and confirmed they are clean and free of obstructions. What is the slider?

On another note, I have this black plastic cylinder under the seat with all kinds of black hoses connected to it, some of which go to the carb. Is this some kind of carbon capture device? Should I be looking at this for a source of my problems? Can it be removed? With the bike running, if I pinch one of the hoses going to the carb, the idle increases drastically until I let go.

Sorry for all the questions, thanks again.

[SpudRider]

I sounds like you need to remove the brass plug to access the pilot mixture screw (PMS). I know Yamaha puts a plug over the PMS on the TW200 to thwart access for the owners. Partially thread a small screw into the center hole, and pull the plug out with some pliers; then you will have access to the PMS.

[motomaster]

Originally Posted by SpudRider

I sounds like you need to remove the brass plug to access the pilot mixture screw (PMS). I know Yamaha puts a plug over the PMS on the TW200 to thwart access for the owners. Partially thread a small screw into the center hole, and pull the plug out with some pliers; then you will have access to the PMS.

Thanks Spud! I will try this! Haha they were definitely successful in thwarting my access to the screw

Also, just tested the battery, and all is well. Had sitting voltage slightly above 13v and with engine running went above 14v. Never dipped below 12v.

[david3921]

Originally Posted by motomaster

I tried the test again last night with WD40 (before I read these replies), and still no luck. The idle was "surging" on its own before I even applied WD40, so it was hard to tell what was doing what. I'll try again today with something different.

Its a Mikuni Carb, and looks like the one in the Qlink XF200 manual. The only exception being - it doesn't have a pilot mixture screw! In its place is a round brass block, with either a hole or indent in the centre... I'll see if I can get a picture of it. I don't have another carb I could try unfortunately.

I've previously taken both jets out and soaked and blasted them out, and confirmed they are clean and free of obstructions. What is the slider?

On another note, I have this black plastic cylinder under the seat with all kinds of black hoses connected to it, some of which go to the carb. Is this some kind of carbon capture device? Should I be looking at this for a source of my problems? Can it be removed? With the bike running, if I pinch one of the hoses going to the carb, the idle increases drastically until I let go.

Sorry for all the questions, thanks again.

Your carb should be a Mikuni BS28. The idle screw is on top of the carb. It is hard to see and get at on the bike. I didn't have any plug at all on mine. The plastic cylinder is part of the emmission control stuff along with the air injector in the front of your cylinder head. You are effecting the air mixture when you pinch the hoses. There is also a check valve that allows air into the gas tank as fuel is consumed. The picture below should look familiar. The arrows are pointing at the check valve. I no longer have all of that stuff except the check valve, though.

On another note, Doc is right, you need something flamable. I used a propane cylinder...not lit, of course.

If it is surging all of the time, try lifting and/or pushing the carb up and down slowly and see if the idle changes. If so, you've got a leak of some kind at the intake.