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Discussion Starter #1
So I just picked up a TRX250r last night, a pretty good deal for what it is. I was with my brother and I told him to test it before we bought it, he kept saying no it’s fine he doesn’t want to get the cops called on us so we made sure it started and everything, turned on quick, I could feel the compression when kicking it, it kicked backed too. Anyways guy said he had it rebuilt and nothing was wrong, he said everything is new and everything does look new. He said he bought a new carb because the old one was dirty and he wanted to put a new carb instead of the old one, I asked him if he changed jets and all he said no, he just slapped the new one in, both old and new carbs are keihin he said the new one was a 38mm I believe ? But I have both carbs so today I tried riding it and when I wot, the power isn’t there, it doesn’t hit like it’s suppose to, it’ll catch up but slowly, In neutral it’ll rev out fine no problems. The throttle is kind of weird, I don’t think it’s adjusted properly.
the bike has fmf gold series exhaust and a keihin carb I don’t know about internally
 

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Update- i took apart the new carb, it has a 185 main jet and I think the other jet is stock ? The jets have definitely been swapped out I can see the little nicks on jets from the tools they used, he told me he didn’t mess with them and that the new carb is bigger then the old carb, The new carb is a 38mm, I confirmed with the guy I bought it from, isn’t a 185 huge for the carb? Especially upgrading to a 38mm
 

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Another updated, so I asked the guy what he did to the engine he said everything that’s done is on the radiator guards, the guards show stickers of wiseco, hot rods, hot cam, pivot works, & Hellbound racing, what’s actually internally i don’t know lol
 

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think really you need to ask him more questions and get some detailed answers as to what you got if he doesnt know himself then you will have to at least take the head off and have a look, is it a stock cylinder!
 

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185 is getting up there, but without knowing more about the setup it's hard to say. Do some plug readings. Make one change at a time. Make one step on the jet size at a time. Best to dial in the pilot jet first.
 

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Discussion Starter #6
185 is getting up there, but without knowing more about the setup it's hard to say. Do some plug readings. Make one change at a time. Make one step on the jet size at a time. Best to dial in the pilot jet first.
Yea that’s what i was saying about the 185
 

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Another update : I found out that it’s missing half the head gasket and it’s letting air out while it’s running, would that be my problem on why it won’t kick in?
 

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well thats the first i heard of that,yes that will cause a few problems not kickin in!will be the least of them if it was left like that not sure what you mean by half a gasket its hard to imagine.
 

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Discussion Starter #9
well thats the first i heard of that,yes that will cause a few problems not kickin in!will be the least of them if it was left like that not sure what you mean by half a gasket its hard to imagine.
So the bottom of the head, the base gasket, I would say half but a pretty good amount is gone. Towards the carb side I can see the gasket separating the head from the bottom end but towards the front there’s no gasket, it’s touching, when I turn it on and I can feel air coming out where it missing the gasket. The guy said he did a full rebuild and he took it back to his mechanic 2 times because he couldn’t find the problem on why it wasn’t staying on, that’s why I thought it was a jetting issue or carb tuning before, because I have the bike idling, it turns on first kick and kinda perfect but not fully because that gasket. Looks like they used a old one compared to the other ones I l can see on the case cover and whatnot. & I think 1 or 2 both on the top of the head were loose also. Like they were only hand tighten
 

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To much going on here that is not correct. Obviously the first step is to have an engine that does NOT leak; air, fuel or compression. Get the engine in good working order first, don't keep running it with known serious leaks and issues.

Carlos
 

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Discussion Starter #11
To much going on here that is not correct. Obviously the first step is to have an engine that does NOT leak; air, fuel or compression. Get the engine in good working order first, don't keep running it with known serious leaks and issues.

Carlos
Yea. I know. As I said before that’s why I thought it was a jetting issue till I saw the head gasket, because the guy said it ran fine before he rebuilt then after it wasn’t the same. His mechanic didn’t put a new gasket on and didn’t torque everything down correctly. I already ordered a complete head gasket kit, should be here by next Friday.
 

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Discussion Starter #12
Alright so I got the head gasket yesterday and put it on, both head gasket we’re completely screwed, they tried using Gasket sesler on al the cracks the gasket had, too and bottom, replaced them now she starts and runs, but now I’m sure it’s my jetting, the 34mm carb had a 185 main jet and 48 pilot, 38mm the main jet 148 and a 40 pilot, but I switched it out and out the big jets on the big carb to see if that would make a difference, and i got it to where it doesn’t bog 1/4 throttle but it bogs high end, yesterday when I had the 148 main in the 38mm it was bogging but not as much, it would at least give me some of the power, what jets do you think I should try ? I don’t wanna buy a whole bunch and waste time
 

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I have 2 stock cylinder R's with 38mm airstriker pwk carbs. One has a 48 pilot, 175 main, and DGH needle with the clip in the 3rd groove.
The other R has a 48 pilot, 172 main, DGH needle with the clip in 3rd groove. Both carbs have the air screw at 1.5 turns. I jet my R's at sea level at 60°F.
Depending on your elevation running a 148 main jet is going to burn a hole in your piston! Jets are way cheaper than a top end rebuild!
Good luck
Loren
 

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if your cylinder is sock and not been messed around with i would stick the stock 34mm on and stock size jets and set your needle and air screw to recommended specs and it should run ok cos thats what they were made to run with and they run good as well on a 34mm carb bigger isnt always better cheers paul
 

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Discussion Starter #15
if your cylinder is sock and not been messed around with i would stick the stock 34mm on and stock size jets and set your needle and air screw to recommended specs and it should run ok cos thats what they were made to run with and they run good as well on a 34mm carb bigger isnt always better cheers paul
Idk if it’s stock or not, the guy said it has wiseco piston, hot rods, & hot cam with fmf gold series exhaust
 

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Discussion Starter #16
I have 2 stock cylinder R's with 38mm airstriker pwk carbs. One has a 48 pilot, 175 main, and DGH needle with the clip in the 3rd groove.
The other R has a 48 pilot, 172 main, DGH needle with the clip in 3rd groove. Both carbs have the air screw at 1.5 turns. I jet my R's at sea level at 60°F.
Depending on your elevation running a 148 main jet is going to burn a hole in your piston! Jets are way cheaper than a top end rebuild!
Good luck
Loren
I’m going to try that, ima just put all the big jets in the 38 and I’ll go from there, to see what range I’m in also I’m like 30ft ab sea level, im located in California, should I delete my air box lid ?
 

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assuming you got a stock cylinder and not a big bore i would say that 185 main jet is on the big side but you can always work your way down on the jetting and keep doing plug chops to check colour of your plug, is like burbling/ spluttering at full throttle if so thats also a sign of being too if big on the main jet but just keep checking your plug colour,if its oily and black too rich come down in size there should be a post on here somewhere telling you the correct method of jetting/ plug chops you will need a selection of jet sizes
 

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Hot cams? 2stroke engines do not have cams!
I would caution you against changing anything (air box lid) until you get the engine running correctly. I will also suggest doing a compression test. I don't do plug chops. I tune my 2 stroke based on sound and the way it feels. I always jet up until it runs better or worse. If it runs worse I jet back down. If it starts running better I make a note of the jets in the carb for a baseline and then continue jetting up until it starts to run worse. I now have a jetting range for that engine.
A stockish cylinder should probably won't need a 185 main. I would try a 175 main and a 48 pilot with your needle clip in the 3rd groove and the air screw at 1.5 turns out. Bring the main up or down one size at a time until it runs crisp all the way through the throttle. Then jet back up one size! That way you will have less of a chance of burning a hole in your piston when you go out and do a long wfo run.
Loren
 

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as i said there will be posts on here on the correct way to get your carb jetted right for what ever engine it is you have !i would really want to know what i was dealing with if it were me,especially with what issues you have allready found with it gaskets etc
 
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