TRX250R.ORG
Workshop => Carburetor, Intake, and Exhaust => Topic started by: benoladdict on April 19, 2015, 05:15:59 PM
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86trx250r 2nd ive ever owned. Stock carb ported engine. Looking for a few more ponies I have 35mm a.s. carb as well as 35mm pwk at my disposal was wandering if it would be worth the swap my bike currently has the stock airbox with lid and im not against deleting it all together. So is it worth the extra 1mm plus newer style carb?
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I think you would definitely have a noticeable difference with either carb and lid off ,its just an air pump ,the more you can get in and out the better its going to run.the pwk and a/s are basically the same carb ,the a/s supposedly being the better of the two
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86trx250r 2nd ive ever owned. Stock carb ported engine. Looking for a few more ponies I have 35mm a.s. carb as well as 35mm pwk at my disposal was wandering if it would be worth the swap my bike currently has the stock airbox with lid and im not against deleting it all together. So is it worth the extra 1mm plus newer style carb?
If the 35mm carbs are free I would use one of them. If you are going to buy a carb, I would increase it to a 39 or larger. One mm larger on a ported motor is not going to do much.
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I put a Mikuni TMX 38 from a cr250 on my bike with a ported stock cylinder and I like it a lot better than the keihins I had on it.
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38 a/s, cr ignition, uni filter, rad valve and a good pipe to match what you have in your engine and you will notice a huge improvement everywhere.
john
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Thanks for the input and yes the carbs are left over from my twin cylinder. So they are just sitting around. Ill try and find a used 38mm to buy or trade thanks to all
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I have a 38mm a/s bought new a couple months ago, still perfect condition 175.00 shipped
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Thanks I ha e a buddy who has a 38mm mikuni carb hes going to check and see if he can find it and ill try that out has to be better than the 34pj
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You will find more info on jetting the kehin pwk. More common than any other after market carb. What type of riding are you doing?
Best regards
-Jason
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We do mostly open trails but it always ends in drag races hahaha I have jets already for the kehin but dnt wanna spend anymore money if I can get the 38mikuni for free. Ill keep a look out for a good used kehin
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Most people use the keihins because there is a ton of info on jetting on the Rs. I was never really happy with the jetting and and performance of the keihins I had. I didn't use a new one. I decided to do some research on mikunis on my own since there not much out there for the r. I set it with specs for the cr250 and won't go go back to keihin on this motor. I don't know what style of mikuni he has but just research jetting on a 250 for that carb and that should get you close. If it is one like I have, I can give you the jetting I used.
Don't be afraid to try the mikuni espcially if its free.
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We do mostly open trails but it always ends in drag races hahaha I have jets already for the kehin but dnt wanna spend anymore money if I can get the 38mikuni for free. Ill keep a look out for a good used kehin
Most people use the keihins because there is a ton of info on jetting on the Rs. I was never really happy with the jetting and and performance of the keihins I had. I didn't use a new one. I decided to do some research on mikunis on my own since there not much out there for the r. I set it with specs for the cr250 and won't go go back to keihin on this motor. I don't know what style of mikuni he has but just research jetting on a 250 for that carb and that should get you close. If it is one like I have, I can give you the jetting I used.
Don't be afraid to try the mikuni espcially if its free.
I wouldn't mind trying a Mikuni too. I know from previous posts that Jerry Hall likes using them more than the Keihins
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Yea cant beat free actually the motor has hpr on the side of it im happy with the stock carb but im trying to beat a bigbore z400 its supposed to be quick im nt sure. I have kehins on my banshee but am completely new to the mikunis I hear they are super easy to tune. Im pretty sure anything is easier than the air strikersstrikersn I dont know of any good tuners in north florida and most here dnt even know what a 250r is.
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(http://images.tapatalk-cdn.com/15/04/21/091399ae86c2faceb013971321c508b4.jpg)
This is the style I used. It is off of a 02 cr250. 01-03 are the same but the needle and needle jet are different between years. I used the jetting specs on the Pro Circuit website for the 02 and only just raised the needle. It runs amazing on my bike. If you post on any R site about a mikuni, all you will here is "throw it away and put a keihin on it".
I'm not saying it is the end all be all but there are other options that work.
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i use keihins because i am familiar with them, but my brother is running a 38mm tmx on his 310 mx port and it has amazing throttle response for still using a stock trx ignition. he picked it up along time ago when eddie used to sell them, great carbs.
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That was first thing I noticed was the throttle response. It is smooth power right off the bottom.
I'm glad I didn't listen to the masses. But then again I did put a go kart axle in my 3 wheeler so I'm a little different anyway.
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The tmx seems to be thw norm I just spoke with him and he said it was off a 500cc snowmobile engine he put on a atv frame (deathtrap) so hes nt sure of the model but its free so its worth checking out. And I dnt want to loose throttle response Iove how my 250 is snappy and very predictable unlike the banshee which has a lightswitch p.band.
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I recently lined up with a stockish yfz450 and I was beside him till about mid 3rd gear then he pulled away pretty bad he was about 50lbs lighter than me but does that sound about right? By end of 300ft. he put about 4 to 5 bikes on me
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The tmx seems to be thw norm I just spoke with him and he said it was off a 500cc snowmobile engine he put on a atv frame (deathtrap) so hes nt sure of the model but its free so its worth checking out. And I dnt want to loose throttle response Iove how my 250 is snappy and very predictable unlike the banshee which has a lightswitch p.band.
Snowmobile carbs usually have small float valve seats. Small float valve seats (2.0 mm or smaller) are necessary to control the fuel flow when the fuel pressure is above 1 psi.
The fuel pressure at the carb on most gravity feel fuel systems are less than 1/2 psi. Using a float valve seat that was made for using with a fuel pump on a gravity feed fuel system will starve your engine for fuel and burn your piston.
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Alrighty then so much for that idea.
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Thanks for the heads up jerry a burnt piston would have made the wifes head spin
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nah that is a good thing in terms of mikunis, it is another circuit with adjustability, on keihins it is pressed in and when it gets worn the carb is shot. pick it up and get correct seat.
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Im getting 3 of em a 36mm and 2 38s he thinks so ill wait and see what I have and report back with actual model numbers
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So it looks like im the new owner of 38mm vm carbs research shows they arent that great. Is it worth the trouble?
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I ran a vm 44 on my zilla and it worked well
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Cool ill check it out this weekend if the weather holds