Jetting advice needed before I push this thing in the pond.

[hoosierlogger]

Ok hate to have to ask for help, but I am at my witts end here. I have a 85 200x that I did an auto x conversion on. The S motor is an 85 as well. I have a bad hesitation on the bottom end. It have a 108 main jet, and the needle on the middle slot. Top end and mid range is running great. When you stab the throttle with RPM set at 1300 on the dot, it falls on its face and dies. I have had the same results with slow jets #35, 38, 40, and 42. All passages and jets were sprayed out with carb cleaner and blown out with an air compressor. With the #35 idle jet and the air screw turned out 1 turn it runs fast for about 10 seconds after the throttle returns to idle. It doesnt run on with the #42 jet, but the hesitation is still there.

If you flip the choke to half choke the hesitation goes away and revs without hesitation when you stab the throttle.

How big of a slow jet is it common to have to go up to? The motor has a fresh top end rebuild with good compression and no smoke. It is using the stock 200X header and silencer. The plug looks good until you do it with half choke, then is obviously black and sooty.

I have been using the links to the service manual Oscarmayer posted. Ill bet I have blown 15 hours working on this and $50 on jets, carb cleaner, and gas driving to the ATV shop. These are brand new Kehin jets by the way.

Any suggestions before I use this motor as a boat anchor?

looked in the search function and read 9 pages of posts
looked in world class help section = no help on this problem
Air cleaner clean and unobstructed with entire filter intact.
new spark plug
timing is dead nuts via manual
carb is spotless
tried 4 different advance weight assemblies, several jets and all needle positions

[Yamaha_Rules69]

That screw on the bottom of the carb is a fuel mixture screw, not an air screw. It may be the culprit in this case. To tune it is kinda a pita because of the location, but out is for more fuel (richer) and in is for less leaner. The correct way to do this is to turn it out until you hear a hesitation in th RPMs count the number of turns in 1/4's, and in until you hear a hesitation, counting again, then go exactly between the two adjustments you just made. Hope this helps, and give it a try and report back. Make sure to have the engine fully warmed up before adjustments are made.

[hoosierlogger]

You said screw in = leaner. I think I was confused and was turning the screw the wrong way. I read in the manual at altitudes over 5000 feet to turn the screw in 1/4 turn. Well as I sit here thinking of what you said now I think that I interpreted that bassackwards. Ill try it in the morning. The bike is too loud to play with in the drive way at this time of night.

Do you know how big of a dumb ass I am going to feel like if that is what fixes it? It usually is something simple.

[hoosierlogger]

Tried every combination of jets on hand with every position of the air screw and still no improvement. The run on is still there unless I go to the bigger jets where it is not as bad. At a loss here.

[200XMichigan]

I think you might have an air leak. It runs good with the choke on, either its just not up to temp, or its too lean. Since you have played with every combination of jets around I would look for an air leak. Its been a while since I had my 200X apart. Inspect carb boot, remove it, there is an O-ring behind it. Check both surfaces to make sure they are flush.

[hoosierlogger]

Yep I think I found it. I took the boot off and made a plate to fit on both ends, hooked it to vacuum and found there was my problem. The part that really gets me is I looked it over and didnt see anything....twice. The rubber evidently is stiff enough that you cant see it when trying to flex it by hand. I put the carb on it and bolted the engine side to the plate I made for vacuum testing and clamped it in the vice. pushed on the carb and that magically made cracks reveal themselves. So I smeared the outside of the boot with silicone let it set and wrapped electrical tape around it until a suitable replacement is found. Time to re start the jetting procedure.

[hoosierlogger]

New intake boot on order from Honda. I didnt want to spend $60 on one, but didnt want to risk getting one in crappier shape than the one I have.

Edit:

Damn, Honda just called back and said they are discontinued and none are available.

[HONDA_ATC_FREAK]

Hit ebay up and get the part number and just google honda then # and you'll be supprised what you'll find. I find a lot of NOS in the wrapper stuff that way.

[hoosierlogger]

Yeah I was looking on there all I found was 2 of them. Ill try finding it with the honda part number. Hopefully Ill get lucky. Is there any one who makes these? I cant see why it has to have the rubber in it unless it is there for heat dissipation.

[HONDA_ATC_FREAK]

they say they have em http://www.cheapcycleparts.com/model...ssemblies/4911 it's part number nine right they say they have it for just under 30 bucks thats almost the same price for crappy used ones on ebay can't beat that.

[hoosierlogger]

That is for the S the X is the one they didnt have. The s intake wont work with the 200 autox conversion. The angle is wrong on them. Thanks for trying.

[HONDA_ATC_FREAK]

oh I can find one for a x too

[HONDA_ATC_FREAK]

ya they say they're discontinued dangit

[HONDA_ATC_FREAK]

found one one this site I guess you have to contact them and tell them you want it. go to the bottom of the list then up 24 spots and there it is.http://www.atcheaven.com/Nos.php

they've got one too http://www.speedsupplies.com/cartdisplay.asp

[hoosierlogger]

sweet, Ill have to bookmark those sites. Thanks for the leg work you are doing. You coming to trikefest? If so Ill have a couple of beers for you. If not Ill drink them for you. LOL