pilot jet issues....

[jerryfaxman]

I bought a 2008 Hisun GY200 a few months back. It had no spark so a new CDI corrected the issue. Here's the issue that stumps Me. To make the bike idle at all I have to unscrew the air mixture screw out about 5-6 turns. Out of frustration I ordered a new PZ30 carb on e-bay and it looked identical. The original carb is marked K F pride of Japan and the new one is a Keinen PZ30. Other than that they are identical in every respect. The new carb also does the same thing...I must turn the idle/air mixture screw out about 5-6 turns. I've checked manifold mount and double verified there is no vacuum leaks. It is very responsive when You throttle on it and I'm certain it's not a main jet problem. It will not idle or run at all with the idle/air mixture screw out 1 1/2 or 2 turns. My son informs Me that by turning the idle/air mixture clockwise it makes the idle circuit run "richer" by restricting the air flow and allowing more fuel to the idle circuit. So therefore by unscrewing the air/idle screw it tells Me that the Pilot jet is to large, and by unscrewing the air/idle screw Your allowing more air into the idle circuit. His suggestion is to reduce the size of the pilot jet. It is not an issue with valve adjustment. When the bike idles it doesn't have that "thump..thump..thump idle. It will idle and "pop" occasionally through exhaust almost like a mis-fire. I'm baffled and any suggestions would be appreciated. So far the only advice is to reduce the pilot jet to a 25 size. I live in Minnesota and this bike only has 238 miles on it. Please Help Me cause I hate to order another carb! The question I have is should I go smaller or larger on the pilot jet? I want that smooth Thump..Thump..Thump idle. Also checked that choke was functioning and it does open all the way with choke off....

[Weldangrind]

With no disrespect intended towards your Son, he has it backwards. The more you back out the pilot mixture screw, the richer the tip-in mixture becomes. If you need to back it out more than two turns, your slow jet is too small.

Here's the kicker; you've replaced your carb with an equal carb, and they're tough to find replacement jets for. I install 30mm Mikuni carbs in every 200-250 Honda clone China machine, and they work really well. As a plus, jets are really easy to find. This is a good carb for you to work with: http://www.ebay.com/itm/30MM-MIKUNI-...bf060c&vxp=mtr Jets are as close as your local Yamaha dealer, but are also easily found online.

Finally, that popping sound definitely indicates a lean mixture.

[SpudRider]

X2 on everything Weld stated; he has given you excellent advice.

[jerryfaxman]

Thanks weldandgrind....I'm taking your advice and ordered a Mikuni on E-bay. I also agree it's an idle circuit issue and the problem with the Keihin carb I put on bike is it has no size markings on neither the main nor pilot jet. And the original carb which was a KF carb has no markings either. Just for fun and games I removed the pilot jet and got out my "Dremel" drill and My miniature jeweler's drill bits and drilled out the pilot jet. Unfortunately You can throw a small cat through the hole and as a result That bad-boy backfired and coughed and spit back. I wouldn't advise drilling out your own jets unless your a skilled machinist. I was also advised to raise the needle one notch and that would greatly improve the idle circuit. I strongly disagree. I also own a Lifan GY200 and it idles sweet. My son hinted that I should take the Lifan carburetor and try it on the Hisun and see what happens. I might just try that while I'm waiting for My Mikuni to arrive. Will keep in touch and thanks for Your advise. I'm led to believe that this bike never idled very well from the day the Guy that I bought it from owned it. I think He just put up with it and only drove it 234 total miles and threw in the towel. I've been told that a 26 pilot with a 110 main is ideal for My location in Minnesota. Thanks again!

[Weldangrind]

I've certainly drilled out main jets with numbered bits before, but slow jets are really small; I just buy new ones.

You're exactly right about raising the needle. Changes to needle height will affect the midrange, but not the idle.

I'm near sea level. With a free-flowing muffler and efficient (foam pod style) filter, I use a 110 main and a 25 slow jet. In cold weather, it likes a 30 slow jet.

[jerryfaxman]

I bought this Hisun GY200 and it had no spark. Put in a $5.95 CDI I ordered online and had spark afterwards. My Son now tells Me that not "all" 6 pin A/C CDI boxes are created equal. It still has a tendency to start hard and cough and spit till about 15 minutes of running. I ordered a "performance" CDI box for $12.95 and it's aluminum with cooling fins. It stated that at the time I ordered it that it works on engine code number HS163FML. (which is My engine code stamped on engine case) Is there any truth that not all CDI's are created equal. The $5.95 one in the bike at this point looks "identical to the old one. (waiting for the new one to arrive) As it's been explained to Me that the CDI not only helps provide spark but controls "timing" and "quality" of spark. My Son says that the one I have currently in bike may not be compatible with my engine. Any truth to this????? Thanks

[Weldangrind]

The only real difference in stock CDI's is whether they are AC or DC. If you plugged in an identical CDI and it started, it's correct. The remainder of your troubles are likely linked to the carb problems we spoke of earlier in this thread.

The performance CDI might have a more aggressive ignition advance curve, and the by-product might be that it will be a little hard to start. I recommend that you move forward with the Mikuni, jet it properly and then try the bike with the factory style CDI. If it runs well, you've established a baseline, and from there you can experiment with the performance CDI.

[bogieboy]

i have both the stock and the performace cdis, it is really hard to start with the estart on the performance cdi...the baseline timing is almost too advanced for pump gas... i would like to try some race fuel with it this summer for giggles... almost bought 2 gallons of race fuel yesterday...but ended up with 93 instead...hard to justify 7.50 a gallon right now...LOL

[jerryfaxman]

Hate to continue being a pest but I received the new Mikuni 30MM VM26 that You strongly recommended in place of My stock P.O.S. thats currently on bike. Gonna be almost 60 degree's out this weekend so I am anxious to install it. The Mikuni shipped to Me with a 100 main and a 20 pilot. Should I install "as is" and keep My mitts off it and assume it's jetted O.K......I have no intent of ever riding this bike in cold weather. Rejetting this bike is a real pain! I can't rotate the carb and remove the bowl....I'm forced to remove the carb because of the extremely limited room. The carb requires a lot of patience and a "shoe horn" to remove it. I'm gonna guess Your advice is to install it and try it as it is. It gives me the impression that when they built this bike the built the frame around the carburetor. Thanks again and I'm crossing My fingers that this carb will work just fine with its existing jets.

[bogieboy]

in stock knick, that should be pretty close... if you have a pod style filter and or aftermarket exhaust, it will be pretty lean... i myself am in need of the mikuni conversion...LOL my bike has both a UNI pod filter and an almost straight thru FMF powercore silencer (silencer is a term used quite loosely....LOL)

[jerryfaxman]

Thanks for the feedback...bike has stock exhaust and stock air filter box. If the bike wasn't so "cherry" I'd give up but only has 238 miles on it. I will try it without any modifications to jetting and hope for the best. The needle is also in the "highest" position and I think I'll just leave it that way. (it has 4-5 positions to adjust it to) As I said I'm not looking for "performance" but would love a good starting bike that idles good and will move my sorry 63 year old butt around at 30-35 mph. I'm not a speed demon and as long as it starts good and idles I'll be in 7th Heaven.....thanks again for all the valuable feedback...will keep Ya all posted .....

[bogieboy]

i will say my engine in my shineray dislikes idling until its good and warmed up... it takes probably 5-10 min of riding before my engine will want to idle decently, especially when its cold...

[Weldangrind]

I doubt that the stock jetting will bring joy; it's more likely to want a 110 main and a 25 slow jet. I hope the slider isn't too difficult to remove once the carb is in place, because you might need to move the clip.

When you say "The needle is also in the "highest" position," do you mean that the clip is in the highest groove, or the needle will achieve maximum lift because the clip is in the bottom groove?

Bring on the questions. That's why we're here.

[jerryfaxman]

Put the new Mikuni on this Sunday (60 degrees out) and still starts hard and coughs and spits when you finally get it to idle. I have another Lifan GY200 that runs cherry. It starts first kick and idles like a "swiss watch". So out of frustration I "borrowed" the carb off the Lifan and put it on the Hisun GY200. No improvement! The fuel is fresh and every connection has been checked. Replaced coil but no improvement. I'm beginning to lean towards ignition issues at this point because 4 carburetors can't all be incorrect. So here is the weird thing! On the left side of engine (shift side of bike) there is an oblong chrome cover with 4 screws that attach it to the case cover. Out of curiosity I removed that oblong chrome plate and low and behold.....oil poured out of it! Lots of oil! On the top of the side case I'm talking about, is a chrome flat blade screw that I believe is for checking timing. I do not believe oil should be inside that side case cover cause My guess is thats the stator and flywheel. I think the idiot I bought it from thought that is where you added oil. Am i correct in assuming that no oil is supposed to be in there? The previous owner had "zero" knowledge of anything mechanical and even admitted it. I removed the side plate on the Lifan and "No Oil" came out of its case cover. If thats the case and no oil should be there then I'll pop off the case cover...new gasket...and some brake cleaner and clean up stator and flywheel. I do have a "flywheel" tool. PLEASE tell Me that no oil should be in that side case! Thanks Again...

[stretch8668]

Here's a link the stator is suppose to be in oil to help it keep cool this is a lifan 200cc. http://www.justanswer.com/motorcycle...otorcycle.html