TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: evaneyeball on July 22, 2020, 02:20:56 AM
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So my cdi went bad today and I talked with arlen already and he gave me some things to try and they didnt help so I'm going to call him tomorrow and see what he thinks but I also kinda just want to know what you guys think of the hpi like is it worth it or do I just get a old oem cdi and have something else blow out in a week and fix that and have the new cdi go out idk. Just for shits and giggles. And it was detonating when I was going up banshee hill and I stopped as soo. As I heard it. And I knew it was detonation so I went back to check things out and there was grey sludge in the cylinder.
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"Trying" another stock CDI (assuming someone has a good one for you to borrow/buy "cheap") would be the easiest thing to test first. HPI is reasonably priced but I don't know more than a couple people that have ran them. @coops86250r posted a nice install thread here (https://www.forums.trx250r.org/index.php?topic=8701.0).
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Yeah I cant find one to buy but I'm sure if I look hard enough I can. But i do have one from a 85 atc
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Yeah I cant find one to buy but I'm sure if I look hard enough I can. But i do have one from a 85 atc
85 atc250r is the only oddball CDI. It’s a round plug
Joe
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Ok I didnt notice that I haven't torn into it yet and I just got home.
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i got a ricks you can have. people complain that these have kick back. yes, they do if you dont kick it right but other then that its fine when it is running. The only reason i removed it was because i bought a 2001 CR ignition.
PM me your address and i ll have it in the mail tomorrow morning.
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kinda off topic but i did notice that when it was detonating and it was only up a hill with a lot of load it did lose power and it couldn't go any further if i did try (and i didn't, as soon as i heard it i stopped) it did start to lose power before detonation occurred so do you think i fried it or not, i did notice it was easier to kick over after it happened once. and i haven't taken a compression test before and i didn't want to take the plug out because i was worried about the threads and it coming out again because if threads so bad on me for that but i can take one tomorrow because i probably should change plugs now just for maintenance and i might have to take the topend off it you think i hurt it
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Sounds like you are going to be doing another top end..
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Sounds like you have problems, not enough octane, too much ignition advance, or plug heat range, lean condition. The grey sludge mentioned is not good. Loss of power is probably a partial seizure of the piston, it needs to come apart. Detonation heard over the pipe, is bad, can melt a piston before you can even hear it.
desertR
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Damn it. I guess that that means I'm getting either a new cylinder or sleeve if I have to bore it because I'm already bored at 69mm or 68.5 I cant remember.
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What is your current carb size and jetting? My boys R's both have 38mm airstriker carbs and 48 pilot/175-178 main/DGH needle at the 3rd groove. 13.5:1 compression running 92 octane non ethanol gas mixed 40:1 klotz R50.
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You may also be able to hone it and install another piston and rings. Depends on what the cylinder looks like.
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better that you caught it now. may be able to save the cylinder.
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I talked to arlen and he said to take the head off and so I did and its blown even the cylinder and head are gone
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People don't understand just how important octane is. On my daily, I run premium, and 50/50 water/meth and that works out to 115 octane. Lots of safeguards on the meth setup (Aquamist) but with 23 lbs of boost, you need it. I run 50/50 as more isn't needed and it gives me another 1/2 second run time, before melting a piston, If the meth fails, and yes, I drive it hard.
desertR
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Your lucky it's not worse. I expected to see a partially melted piston, but you won't know for sure until you pull the cylinder
desertR
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I am running straight vp110 with klotz r50 mixed in at 40:1 it does have a gouge in the cylinder. I talked to arlen and told him I'd like to run a cylinder size in the 300's some where and he said all his are on back order from 300 to 310 ceo cylinders and mine is on its last bore so I'm in kind of a dilemma
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So we know what octane fuel you are using and your mix ratio, but we do not know your jetting! Going up banshee hill is going to be on your main jet mostly. If you have any kind of porting and are running an after market pipe you better have at least a 175 main!
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I'm using a James lucky intake a cr500 carb a ct racing port and a aaen pipe. When I got my motor back from arlen a while ago he told me to start out at a 170 main and a 58 pilot and when i put that in and at the dunes it was running rich in the bottom end so i changed out the pilot to a 55 and it ran great and that was the first ride on it so if it was a jetting issue wouldn't it have seized already or does it take that long for it to sieze with lean jetting? I have about 8 to 10 hours on the motor
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Because of the 55 pilot you were probably getting enough fuel through that circuit bleeding through to keep it from seizing until you started doing long uphill pulls.
I would have started at 50 pilot/180 main and worked from there.
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Better to start FAT!
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Yup she's f*cked up. I pulled the cylinder and the piston isnt great so I'll replace it once I get a 310 because my sleeve is coming off the cylinder and also just the cherry on Top is my head is all pitted from before and also my reeds are completely see through
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doesnt look like the sleeve moved. is this stock jug? if so the sleeve does not just come off. sure looks salvageable to me. the head and piston is a different story
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Theres a big crack in between the sleeve and cylinder you can't really see it in the picture and it is a 85 cylinder and there are big burn/scratch Mark's above the where the reeds go in
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Most definitely lean
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I wouldn't worry about that! Hone it and see what it looks like. Honing at home can for sure ruin your cylinder so you better be careful
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To add, You might have run the float bowl dry which would cause it to lean out. When doing hill climbs, the gas will be towards the back of the bowl, which makes the Venturi effect less effective on pulling gas through the main jet
Any one else running klotz at 40:1? I honestly don't know much about the product. Probably over 20 years ago since I ran it
If you can't catch your finger nail on the scratches on sleeve, have Arlan check it. You might be able to hone it and be on your way.
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I can barely feel it with my finger nail and so you do think that my detonation is coming from lean fuel and not from a bad cdi. And it only detonates when going up hill
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I run klotz R50 at 40:1 and have for 6 years. A bad cdi in my experience won't allow the engine to rev. I have never experienced detonation due to a bad cdi. The only time I had detonation was when I had a bdt 17.5:1 dome in a pump gas cylinder lol. Evan your engine ran lean! You have to figure out why! Could be your petcock, but I feel it's your main jet!
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could my reeds that are shot have something to do with it, there are big gaps in between the pedals and the cage. but in my mind the gap is letting more gas in but i could be wrong and i will take a look at my main jet and i next time i will start out super fat and go lean.
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Could also be the vent for the fuel tank. I hear that the shorty vent with the valve on top can fail. Pretty cheap thing to take out a motor with, I'm going to get rid of mine and go back to a hose.
desertR
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Could also be the vent for the fuel tank. I hear that the shorty vent with the valve on top can fail. Pretty cheap thing to take out a motor with, I'm going to get rid of mine and go back to a hose.
desertR
Yes! A hose without anything on it or in it, is best tank vent.
I have probably thrown away 50 of the billet piston shaped vent line bling things on customer motors that torched pistons. Many of the springs in the check valve on these bling items are too strong. This causes a vacuum to occur in the fuel tank and reduces the fuel supply to the carburetor. It seems like most of the fuel tanks were full of fuel when these bling things failed to vent properly.
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i actually got arid of mine while back and went to a regular hose. and i talked to arlen and he said it needed a hone job and put it back together, he was impressed i didn't burn the piston to the ground lol
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Ya most can't hear detonation, or know what it is. You got lucky it wasn't much worse.
desertR
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Now Evan once you get it back together please start your jetting off at 48/180! The pilot circuit is only really going to change starting/idle. If you can start your R without the choke your pilot is too rich! I'm not trying to be a jerk here buddy, but I believe that you were lean! Not lean enough to burn it up right away, but lean enough to burn it up on a long hill at wfo throttle! My son's have similar engines and are both 48/178 and dgh needle at the 3rd groove. Please give that a try and prove me wrong if you can.
Loren
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I 2nd what Loren said. A 55 is a big pilot. Joe's R had a 55 pilot & after dropping it down to a 48 it's still on the rich side down low.
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Evan if you want help jetting, I'm happy to help you get setup either before the meetup or at the meetup.
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Yeah I might start at 180/48 and jet it down a little just so it isnt quite so fat. And then I'll jet it the rest of the way while I'm down there because I'm jetting for close to sea level and were at about 300 ft.
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Jetting from sea level to 300 ft, will be the same, Very little difference in air density, and unless you have the proper instrumentation, it's not worth the time to do it. Engines will make more power when leaned out, right up until they melt a piston, so most stay 1 or 2 steps to the rich side
desertR
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Evan I have a feeling that you won't need to go lower than a 178 as you had piston failure with a 170..... You will be surprised to find that your R will run just fine at 48/180 until you try hitting 3/4-full throttle. If in fact 180 is too rich your engine will start breaking up. When jetting I don't shoot for perfection, I shoot for reliable jetting that I can live with all year. So I try to set my main jet in February when I go to florence.
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I cant get to 3/4 full throttle here because 1 room and 2 I only have paddles right now and I dont go for perfect jetting either and I thought I was rich but obviously wasn't and I also like the extra piece of mind that i jetted at sea level, even though it does nothing
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Sorry if this was mentioned previously but what needle are you running Evan?
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So I got my hpi on and set I will put up the electrical on tomorrow I also put on my top end and new reed cage, they're v force 3's.
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Be very sure that you jet correctly! 48/180!
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Will do sir
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I took my carb apart and I have a 168 main and a 55 pilot. I will change the pilot to a 48 pilot and I dont have a 180 main and the biggest I have is a 195 main and then down to a 172 main and 170 main. I had the 195 main in and a 50 pilot in before the complete motor rebuild then arlen told me to put a 170 in and a 55 I did that and was bogging in the top end so I threw the 168in and left the pilot. In short should j put the 195 main back in and the 48 pilot or should I put a 172 in because I cant get a jet kit in time for the winchester ride.
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Buy a 180, 178, 175, main and whatever else you need, there cheap, when compared to what the cost of doing it again is.
desertR
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That bog was from a lean condition most likely. You can order a 180 main and definitely have it to you before the meet. If not I am sure I can give you the correct jet when I see you down there.
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I'll see if I can get some jets from arlen and if not then I'll see if one stop has them. Because the jet kits for a cr500 carb aren't that cheap.
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It doesn't matter which bike the carb came from. Keihin pj/pwk jets are the same. You need a hexagon shaped keihin jet in 180, 178, 175, 172. They are 3-4 bucks each. A CR500 carb is usually a keihin 38pj which is the same carburetor that came on some CR250's. I personally prefer keihin pwk quad vent carbs to pj's. I hate adjusting idle with the choke knob!
Loren
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I hate this carb too but it's working now and I will get a better one soon but I have a 172 and am getting some on friday from arlen a 180 a 178 and a 175
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Just did a quick search & found a place that works on bikes called TNT motorsports in McMinnville. They might have main jets in stock. You guys have an awesome Napa there too, maybe they have something.
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The napa in newberg you practically have to go get it from the back yourself lol. And TNT is sketchy but can give them a try but if all else fails LED has the jets I need
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I finally got time to work on it and It started first kick and i am extremely surprised and throttle response with the new reeds is awesome. I did get it to idle with my crappy carb and i rerouted my throttle cable so it dosent change the idle when I turn left and right.
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Hopefully you did several heat cycles before revving it up! Glad it running again. As far as your carb goes, keep an eye out for a 99-00 CR250 38mm airstriker used on Ebay. I picked one up for $95 shipped. It's the same pwk airstriker that everyone is using for a fraction of the cost. Swap out the dirtbike needle with a dgh, dgj, or whatever you want. Then jet it for your engine.
Loren
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I did jet it but I couldn't get my hands on a 175 so I went down to a 172 and I think a 175 would be better. And i put a 50 pilot in and it started without choke but there is no bog so I'm not worried I do want to go a little fatter on my main because there is barely a deep noise when I revv it up, I'm confusing myself typing this and cant find anyway to make it better. I did do 2 heat cycles before revving it up because I only put in new gaskets and a wrist pin bearing in
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Keep in mind a bog is usually from a lean condition. When you have a rich condition your engine will usually stutter or break up when trying to rev. If it is grossly rich it will spit and sputter like it has a miss. If you hear your engine being real zingy like a cr85 or something you are still lean.
Loren
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I did jet it but I couldn't get my hands on a 175 so I went down to a 172 and I think a 175 would be better.
Gotta be honest here, I don't understand why you'd only go up one jet size after burning up your top end with a 170 main. As suggested start with a 180, if you can't source the jets locally order them from somewhere so you have them on hand. Not having an assortment of main's, pilot's & needles makes it impossible to properly tune a carb.
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I went up 2 jets and I am only missing a 175. And I am ordering a 175. And i never got an answer on if jetting can cause detonation because to me it looks like I put the most strain on the electrical and then it couldn't even go up the simplest of hills and dont see how jetting was a part of that. But yes my jetting was lean but it did not detonate once before that hill. And now that I think of it one of my friends has a video of that hill you cant really hear it but right at the top it does it. When he sends it to me the audio is jacked up so he posted it on instagram he is 515ryguy on Instagram. Sorry I didnt think of it earlier
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Yes jetting will cause detonation! Electrical will not! A bad cdi will cause it to cut out or not run at all. In the end Evan this is your engine and you can run whatever jetting you want. People who have many years of experience have been trying to kindly tell you that your going to burn your piston again if you choose to run a lean condition. I don't want to scold you like a child, but dude LISTEN! Start out at 180/48 and work from there. You already tried a 50 pilot and you stated that it started without the choke. That means you should drop to a 48! If you go out and ride your R with a 172 main you are rolling the dice unless you prove that it only needs a 172. That is why you start rich and work your way down. I have 2 stock cylinder R's with porting running 48/178 and my boys can run banshee hill over and over until they are bored and they have not burned up their engines.
But like I said this is your R do with it what you will. Keep in mind that a ton of experience is telling you that you are destined for piston failure at your current jetting.
Loren
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Have you performed a leak down on the engine?
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Yes arlen did one when I got it from him but I haven't made one yet so this time I put it together no I haven't
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Evan good to hear you're making progress. The Duncan jetting guide is very useful, but this flowchart is also a great way to check on your jetting (especially the idle/air/pilot circuits).
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To make the tester go to your local Lowe's & pick up a Shark Bite test pressure gauge p/n 25489Z(aisle17/bay 23), steel 3/4" -1/2" threaded reducer, steel 1 /2" close nipple & a pvc 1 1 /4" slip to 1/2" npt reducer. Then get a 1 1/2" rubber pipe plug for the exhaust flange. Also grab some Teflon tape & Teflon paste if you don't have both already. Clean all the fittings than make 2 wraps with the tape than do a coating of paste & according to my good friend who's a plumber you'll have a leak free seal. Make sure that engine is sealed before attempting to tune it.
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I did get it to idle and I did ride it just in the yard and it had full power, almost no low end bog and filled the place with smoke and almost instant power wich in my mind it is jetted and tuned almost perfect for not trying to make it perfect. I will do a leak down test but with how it's running I'm sure that it has no leaks but I will double check
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https://www.google.com/url?sa=t&source=web&rct=j&url=https://thumpertalk.com/forums/topic/1226441-2-stroke-detonation-fix/&ved=2ahUKEwji-P3Eof3qAhVTOH0KHaXpAhoQFjARegQICxAB&usg=AOvVaw1nFsFKqZYQzq99-fHrloap