TRX250R.ORG
Workshop => Carburetor, Intake, and Exhaust => Topic started by: FloridaRiderSG on October 07, 2018, 04:44:39 PM
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Hello guys, Im Shawn and I just got an 86" a few months ago for the track for when I moved to Florida. Someone else built it, it was never ridden just broken in and he thought the tuning was "close", so I wanted to try to get it best as possible before hitting the track. Been here for 5 weeks and got my R on a dyno finally. Been a long time since I had a 2 stroke and I was never very good at tuning. Its a 330 esr, trx-5b pipe, ?carb?. I ended up getting it real close but there was so many people around and I was getting rushed because others wanted the dyno (was at a bike shop special event) I wasnt thinking clearly so I didnt get it perfect. I have 170 main, needle 4th clip down, 50 pilot. It was lean at idle (which I believe turning the air screw in should solve?) but he was bringing it to 4000 rpm then hit it full and it would lean out from there until 6000 then level off. Do you think its just getting to much air and the air screw again will solve this? Also it would just be a little rich all the way up 9500, but I was kinda happy about that, if I take air away will that lean it out up top also?
Thanks guys, sorry if you need me to explain it better, just say.
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I'm assuming you are at sea level? 170 main on a 330 with a 39pwk seems lean. I have a esr 310 cylinder and a 38mm airstriker carb with 52/185 jetting and 3rd groove on a dgh needle. I like to keep my air screw at 1.5 turns when getting the pilot set so as conditions change I still have adjustment room. Maybe Gene will chip in a little insight. He has a 330. Good luck, Loren
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I'm assuming you are at sea level? 170 main on a 330 with a 39pwk seems lean. I have a esr 310 cylinder and a 38mm airstriker carb with 52/185 jetting and 3rd groove on a dgh needle. I like to keep my air screw at 1.5 turns when getting the pilot set so as conditions change I still have adjustment room. Maybe Gene will chip in a little insight. He has a 330. Good luck, Loren
Thanks for the reply.
Is there anyway to see if mine in fact is a 330? Im going to see if the cyclider is marked, I did not build it. It put out only 45 horse, but it was with holeshots, the guy said with street tires he figured around 50. Seems all the 330's are around where you are main jet wise. Not sure why my main is so much lower. It was just a little rich up top with a 170.......maybe the needle on 4th clip made a difference?
Again thanks, hopefully more people will chime in.
Shawn
Btw I cant believe I got my R on a dyno and I bungled it so bad.
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I'm assuming you are at sea level? 170 main on a 330 with a 39pwk seems lean. I have a esr 310 cylinder and a 38mm airstriker carb with 52/185 jetting and 3rd groove on a dgh needle. I like to keep my air screw at 1.5 turns when getting the pilot set so as conditions change I still have adjustment room. Maybe Gene will chip in a little insight. He has a 330. Good luck, Loren
Thanks for the reply.
Is there anyway to see if mine in fact is a 330? Im going to see if the cyclider is marked, I did not build it. It put out only 45 horse, but it was with holeshots, the guy said with street tires he figured around 50. Seems all the 330's are around where you are main jet wise. Not sure why my main is so much lower. It was just a little rich up top with a 170.......maybe the needle on 4th clip made a difference?
Again thanks, hopefully more people will chime in.
Shawn
Btw I cant believe I got my R on a dyno and I bungled it so bad.
When referring to the needle are you 4th grove from top or bottom of the needle
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Yes 4th down. Now that I think of it Im wrong on the carb, I have to take it off, I never checked Im not sure why I thought 39.
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I assume that you have an "O"ring head. Take that off and clean the top of the piston. There is a part number on top which has the size. 76mm is a 330 I think?
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I assume that you have an "O"ring head. Take that off and clean the top of the piston. There is a part number on top which has the size. 76mm is a 330 I think?
OK appreciate the info.
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My 330 +5 stroke I have a 38 as carb, dgh needle middle clip, 52 pilot and I think am 195 on the main. I'm a little rich all over. But left it that way after having issues my last time out.
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OK so here's the max power and air to fuel. He was rolling it from 4200 to 4400. The blip at the end was him.
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My 330 +5 stroke I have a 38 as carb, dgh needle middle clip, 52 pilot and I think am 195 on the main. I'm a little rich all over. But left it that way after having issues my last time out.
Im right there with you but far off with the main jet. Sorry for sounding stupid but with more stroke do you need more gas? More stroke =more displacement=more gas ?
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You're right Shawn. I believe his setup is a 330 cylinder with a +5 stroker, which is around a 350cc of displacement.
I can't say for sure if yours is lean or not based off the jet number, but on a 185 main, mine is very rich. So you may not be too far off.
Does it seem to be running solid now? Did the person tuning/running the dyno mention the lean spot on the AFR graph?
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I believe it would be a good time for you to do some plug chops. The tool to chop the spark plug is about $15. You can do a few of those proper and post some good pics here and get some help reading the plugs. That will tell you what is going on inside the cylinder.
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You're right Shawn. I believe his setup is a 330 cylinder with a +5 stroker, which is around a 350cc of displacement.
I can't say for sure if yours is lean or not based off the jet number, but on a 185 main, mine is very rich. So you may not be too far off.
Does it seem to be running solid now? Did the person tuning/running the dyno mention the lean spot on the AFR graph?
Yes he did but didnt really have an answer and kinda had enough and had people waiting. Im thinking maybe the air screw needs to go in a half turn, it was very lean at idle also.
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I believe it would be a good time for you to do some plug chops. The tool to chop the spark plug is about $15. You can do a few of those proper and post some good pics here and get some help reading the plugs. That will tell you what is going on inside the cylinder.
Ok I have plugs and was thinking about taking some where for a ride to see how it feels. I haven't even rode it yet....at all, just around a dirt parking lot in NY and up my road here quickly.
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There is a method to tuning the air screw. I believe it may be in the Duncan Racing link I sent at one time. If the air screw is below 1.5 turns or over 2 turns when idling the highest you need bigger/smaller pilot jet, respectively.
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Also want to say, don't be afraid to put a fat main jet in it and go test ride it. If it's all fat and smokey you can come down a jet size or two and test again. Nice and safe.
As for the lean at idle, while it may need some fine tuning to correct, it's not going to hurt anything.
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Also want to say, don't be afraid to put a fat main jet in it and go test ride it. If it's all fat and smokey you can come down a jet size or two and test again. Nice and safe.
As for the lean at idle, while it may need some fine tuning to correct, it's not going to hurt anything.
Thanks buddy. Im going to grab my tools, jets, plugs and head down to Croom tomorrow to take it for a few runs, see how it feels a what the plug looks like.
From the dyno graph I dont think it looks to bad.....what do you think. Maybe one of the motor guys on here will pop in hopefully.
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Be careful with a lean condition down low. That's when a cold sieze can happen.
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I stand corrected. I did not think a lean idle could hurt the engine. Apologize for the wrong info.
That is a perfect example of why I try to read things 2 or 3 times before applying them to my quad lol. Patience pays off.
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Be careful with a lean condition down low. That's when a cold sieze can happen.
Thanks.....you think turning the air screw in a half turn would help? Im 1 3/4 out I believe, I have to check and make sure the dyno guy didnt touch it.
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Ya it can happen when running hard and then just chop the throttle.
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Be careful with a lean condition down low. That's when a cold sieze can happen.
Thanks.....you think turning the air screw in a half turn would help? Im 1 3/4 out I believe, I have to check and make sure the dyno guy didnt touch it.
I do not think that will hurt. That should richen up the pilot circuit some.
I'm just curious if that lean condition on the graph is under full throttle or not. I'm not questioning the dyno operators abilities at all, just curious. I know that part throttle will read lean.
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Be careful with a lean condition down low. That's when a cold sieze can happen.
Thanks.....you think turning the air screw in a half turn would help? Im 1 3/4 out I believe, I have to check and make sure the dyno guy didnt touch it.
I do not think that will hurt. That should richen up the pilot circuit some.
I'm just curious if that lean condition on the graph is under full throttle or not. I'm not questioning the dyno operators abilities at all, just curious. I know that part throttle will read lean.
He would hold it at 4000 then hit it, it would lean out then catch up with fuel. The guy jammed me up bad, ruined my train of though with the way he was doing things.
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Do you have some main jets on hand?
If it ran decent on the dyno, I would turn the A/S in a bit as you said. Then I would throw a much larger main jet (say 180) in and do some testing. At worst, it's so rich that it wont run real well. If it does run well and cleans out I think that would tell you that the 170 was in fact lean.
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I did the air screw, now it 1 turn out and yes I have some mains. I dont think its lean up top, just in the middle. I think Im good, going to ride it and check plugs. It is what it is.
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I did the air screw, now it 1 turn out and yes I have some mains. I dont think its lean up top, just in the middle. I think Im good, going to ride it and check plugs. It is what it is.
You got it man. Just get some seat time and see what the plugs say. Have fun!
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Thank you for all your help!! Very glad I met you.
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No prob at all man. I'm right there with you. Got a ton of help from these guys when getting mine right.
I'm still messing with jetting actually. Just fine tuning now.
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This was after riding for 15 min, I could not do a wide open test, no room.
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Don't want to trust a plug too much that has been ran at all RPM's, but I'd still say it's rich based just off the base ring of the threads being jet black.
Once you can open it up to full throttle, warm it up well and then throw a fresh plug in it and do the pull, shutting it off with the throttle wide open. That will be the most accurate spark plug to read.
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Ya didnt have the room.