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Workshop => Carburetor, Intake, and Exhaust => Topic started by: pantera1975 on July 14, 2013, 12:51:24 PM
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I have a ESR 330 ran it on pump gas last year ran great now I had a 50/50 dome made for it run vp blue 110 fuel when I start it with a 39 mm Keihin carb it runs higher rpm when I have on the choke it speeds up more yet. It sound lean plus I had to adjust up the throttle cable to hold the slide open to it would idle. Also I need to hold the throttle open 1/4 way too for it to start. once its warmed up is idles lower like I think it should. On straight 91 I ran trx 9 porting ESR exhaust in my ATC,full air box withno lid 32-1 kloz supertechinaplate oil 185 main 55 slow CEL needle on the center clip now with the 50/50 set up I went to the next slip richer, 58 slow and 192 main. It pings at 1/4-1/2 now to and cuts out in that throttle position. It did last year too but I only rode it idle or full throttle this year I've had it on some trails and need to use the 1/4 -1/2 position alot. Put in new reeds too. As of now I have to have the AS out like 3 turns when its warmed up other wise its slugish. I tried a DGH on the 3rd clip and it wasnt much differnt than the CEL on the 2nd from the richest.
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you didn't say,but Im hoping you have all ready ruled out air leaks,you need to get to idle with the adjustment screw and not the throttle cable when your throttle is that far open your getting away from were the slow jet and air mixture screw has much of an effect.the choke is its own circuit and if the slide is that far open ,using the choke could very well raise the rpms.maybe going down on the slow jet will let it idle without the slide being that far open and then work on the rest of the jetting.you really got rule out an airleak first
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I know I need to do a leak test i think. Do I need to do it on the cylinder and coolant system or just the cylinder? Like I said all I did was get a new dome from bdt and orings then put in new reeds which I three bonded the reeds in never had any issues last year. So for starter you suggest rest my throttle cable to let the slide all the way down but still open all the way. If I ran 55 slow and center CEL needle last year that should hypothetically be the same switching from pump to 50/50 fuel, I should really have to go richer and set my main 2-3 sizes richer.
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I would do leakdown test on the crankcase .an air leak could make it hard to start, explain the pinging and bog; since you changed the reeds, your leak may be there. after that work on the carb Im sure others will have opinions hopefully they jump in here soon .
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It was always 1-2 kicks cold and now its 3 with the throttle 1/4 open. Ill work on it. Is there a leak down procedure on here I have the stuff all made for it just not sure on the time and psi. Thanks
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I stand by my #1 rule when it comes to 2 stroke. NEVER SKIP THE LEAK DOWN TEST. That being said I agree it sounds like your jets are on the big side for the motor setup and it still appears to be lean. All points to a air leak. And a good size one at that.
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Do it for 6psi for at least 6mins.It should not noticeably drop at all in that time frame.First make sure your piston is at bottom of the stroke.If you see any dpop in pressure,take some windex and spray it at gasket areas.Especially your reeds,head,cylinder base,spark plug,case halves but spray first on the the plug you have in the exhaust port and at the connections on the leak down tester itself.You just need to spray enough windex to get the area wet.Then get a flash light and study the areas.A good leak will show up easier but the small leaks will foam up a little bit.Good luck
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Well I guess I got work to do. Prob end up pulling the motor out to do the test I gotta pull everything as it is. I put new orings in the head when I changed the dome. I have spares of both orings and reed gaskets. if its a leak I hope is the reeds. Other info is I replaced the intake boot too while I did the reeds and re-siliconed the pipe connection. I never pooped the dome from the head and messed with it but there is just 2 orings? inner and outer? Never noticed any coolant fluctuation and it runs between 165 and 190 depending on the speed. Thanks for the pointers
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One more question not that im trying to get out of a leak down test but with buying pump 91 octane non ethanol fuel mixed with vp blue which my fuel place says its the same as c-12 just non oxygenated. Could it be my 50-50 ratio needs more race fuel the dome from BDT was set for 50-50 using vp110 though which is slightly slower burning and 1 less octane I think the car shop says.
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I don't see octane/fuel causing the issues you are having.
Don't forget to check your case vent hose for leaks also. If you have a leak you can't find pull the side covers and check the crank seals.
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What would the vent hose show a oily film? I have it routed with a small fuel filter on it.
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What would the vent hose show a oily film? I have it routed with a small fuel filter on it.
When you do you leak down if you have a leak this hard to find drop the end of the vent house in some water. If it bubbles your getting air into the gearbox. Usually means the center case gasket is leaking around the crank area.
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Got it now thanks!! But man you keep answering my questions with bad news!! But I do have well over 50 gallons of fuel run thru this motor since spring of 2012 It was all new then
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I am not a carb tuning specialist, but I can try and go over the charts with you and follow the changes so you can better understand the changes you have so you can make a educated guess for your next move.
But before we go there, a leak down test is really should be done and yes a pain to do the first time because you do not have all the pieces but once you spend the time making up what is needed than after that it really takes no time at all.
If it checks out OK then lets look at your jetting pieces, going by the needle chart supplied by Keihin the change from a CEL to a DGH should have made the following changes
1st letter is the Taper
2nd letter is L-1
3rd letter is Diameter
C to a D You richened the 3/4 throttle position but also the 1/4 to WOT
E to a G You Leaned the 1/4 throttle position but also the 1/8 to 3/4 throttle
L to a H You richened the 1/8 throttle position but also the idle to 1/4 throttle
You ran the CEL clip at richer clip position so it could be said that you leaned the 1/4 throttle even more than the amount predicted by the chart when you changed to the DGH
seams like a DEG may have been a better change
(http://www.maultechatv.com/techguides/carbneedle.jpg)
(http://i143.photobucket.com/albums/r155/WilliamLynne1/NeedleEffect.jpg) (http://s143.photobucket.com/user/WilliamLynne1/media/NeedleEffect.jpg.html)
(http://www.sudco.com/CatalogJPG/058.jpg)
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I red up the post you did in this section already Seems like alot of info on here I have red about but never seen to this extend on trx.net,3ww or 3w.org. Very informational. I just browse at all 4 boards never really look at everything 2 stroke. When doing the leak down can I leave the coolant in and have the cap off? or drain as much as I can? Does it matter with a warm or cold motor. 8 psi for 8 min 6 for 6 I read all different. In general with a 38 or 39 Keihin carb when you start with a COLD motor should the choke make it run at a higer RPM or bog it down like snowmobiles do? Thanks for the help
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I think they should be kind of boggish because there is nothing to up the idle mechanically like on many street bikes,cars ect...
IMO its OK to check with the coolant in it with the cap off but if it leaks then pressure check the coolant system to make sure its not the leak.
I dont like allot of pressure, 6 lbs is enough IMO and as long as it holds for a couple minutes I do not worry about.
I have always done them cold not sure if a warm engine would seal better or not.
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Motor does not need to be warm for leak down. Radiator cap really shouldn't matter unless you are leaking into the coolant passages. To be safe I would take it off. Time really doesn't matter much as long as it holds pressure for a good 5 minutes. Last time I did mine it held 6 psi overnight. Be careful not to put to much pressure in or you can blow seal out.
As far as the choke goes if the motor is cold the motor should rev higher when choked and then begin to,bog down once it starts to warmup. Once warm and you choke it it should bog.
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So a air leak can or will make it idle hi with he choke on then?
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Yes it can.
the advice about the choke I just gave was how it should operate normally with no air leak. Your best bet and safest is to do a leak down and then once we know you have no leaks we can point you in the right direction on jetting. Trying to jet if you have a air leak is a lost cause.
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This is a good read on Keihin jetting. It's also listed in the Technical Section of this board for future reference.
http://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdf