New bike, engine advise needed

[Bbriles10]

I just joined your forums and Im brand new to the r world. I've had blasters in the past but nothing to exciting. Here's the deal, I picked up a 1986 trx250r with a 87-89 long rod motor. I was told by the po it is a 5mm stroker with a trx9 port from Esr ( which is verified by the engravings on the bottom of the reed casting) along with it bored .120 over. has a keihn 39mm carb with a ct pipe and a cool head. The problem is the piston exploded and the guy didn't wanna mess with it. Long story short I pull the cylinder and the bottom ear that recesses into the case is busted off and I assume the peice is in the bottom end. I plan to split the cases as soon as my tools arrive to investigate. The cases don't look damaged nor does the crank or rod. Few small dings on the sides of the crank that are visible. The question is with the specs listed above what would the best option be pending no major damage to the crank or bottom end that I can't see yet? I can send the cylinder that's been ported and bored to advanced sleeve and have them resleeve it and port match the work that's been done or I have a stock unmolested cylinder as well. Do I just have it ported and slap a piston in it and go or do I need to bore it to a certain spec since its a stroker? I do plan to pull it apart and post some pictures. I'm hoping the crank has some identification markings you guys can help decipher. I am gonna install new main bearings and seal/ gasket kit as well.  Sorry for the long winded post. Thanks in advance for all your help.

[Bbriles10]

The cool head done number is
720t6755R20

[JesseA420]

its really up to you what you do. dont try putting your stock unmolested cylinder on that 5mm stroked crank tho. it would require a spacer plate that would then throw ur port timings way off. depending on how old the cylinder is, i kno the esr stock stroke cylinders that are spacer plated up and ported to the crank are way down on power compared to what they should be. you can just get that cylinder resleeved but you will still be with the same setup, or you can get ahold of eddie and have him cut you a cylinder to your stroke length that will have the correct port timings for your crank, in whatever bore you want to go with. since you are going to be splitting the cases, u might as well do it right and get a big one . eddie is kind of hard to get ahold of, so you could call arlan and he will get you the cylinder very quick from eddie and have arlan port it how u want it also.

[Bbriles10]

I posted pictures provided I did it right and a mod approves em. I appreciate your response. I talked to Eddie yesterday but he asked if I could measure the stroke and send him pictures. It might be a dumb response but I'm not exactly sure how to measure the stroke without a piston to go off of. That's why I figured I could verify it mabe by the crank identification or something. this did have a cylinder spacer but I didn't measure it yet.

[Tbone07]

Let's verify what crank you have before making any other assumptions, you never know if the previous owner knew what he was talking about. If he couldn't fix it himself there's a good chance of that.

I think re-sleeving a cylinder would be a more lengthy, and costly option. The ESR kits are so cheap you might as well buy a brand new one.

If part of the piston skirt, or part of the sleeve cracked and fell off, I wouldn't assume the crank is good just because there's no visual damage

[Bbriles10]

Ok I'll verify it when the tools arrive and I get the chance to split em. I get caught up like a hunting dog on a trail. I've been looking at his cylinder kits and what not. I mean that's crossed my mind to just slap a new crank in it with a cylinder kit. I'll post pictures of the carnage but I welcome any advise from you seasoned 250r guys. Thanks a lot for the responses!

[Bbriles10]

Hey guys I got my tools yesterday and had the chance this am to rip it apart. I'm will attatch pictures but I think the po was full of shit. It looks to me as if the piston exploded/ broke what ever and the rod slapped the cylinder breaking the ear off. Thr crank bearings are fine, although I will still replace them. The rod bearing is definitely bad and I'm not sure if I can salvage the crank or not. I will probably take it to my local machine shop and have them look at it. All advise is welcome. Opinions of the case scarring? Let me know what you guys think.

[Bbriles10]

Cmon mods I posted pics 12 hours ago!! Ha ha I talked with Eddie at Esr and I'm pretty positive im just gonna get his 330 cylinder kit with a new +4mm crank. I got the cases at my local machine shop getting cleaned up. Gasket/ seal kit main bearings and I'll be in buisness

[Skeans1]

Try using Tinypic or Photobucket to post your pictures.

[Bbriles10]

I did post with photo bucket. I believe it's because I'm a newbie it has to be approved by a moderator

[havinnoj]

I believe it's because I'm a newbie it has to be approved by a moderator

Yup - we have some automated spam prevention settings that works great 95% of the time.. but you just happened to get flagged .  In your case, new users posting a lot of pics and/or web links in their first few posts back to back typically get flagged.

[Bbriles10]

Wow well let me try to post this for a second time! Damn it. Figured I'd update you guys. I went with a 330 npv cylinder kit with a 4mm striker from ESR. By the way Eddie will always have my business, what an awesome guy to deal with. I sent him my cases to be bored for the big bore cylinder and received them back within two weeks - coast to coast!! Epic deal. I reassembled the bottom end and the top as well to complete the motor build. Hit it in the bike and have been breaking it in following ct ravings procedure as it was the most suggested after much researching. I'm running 110 race fuel redline oil mixed 32:1. Eddie sent me 3 main jets 190,188,and 185 with a new needle clip on the 3rd notch and a 46 pilot. Running that was extremely rich. I tried both smaller jets but ended up putting a 176 main and having crazy top end lower but extremely sluggish low end lower rpm power. I out the 42 pilot I had and it screams it's balls off. Pulled so hard the whole range. I couldn't be happier. The build was extremely fun almost as fun as building fire arms!! What a blast. I have a question for you gurus though. I haven't had a chance to do plug chops yet to read the plug, but tonight was about 10 degrees cooler after I got the chance to ride her. It seemed pretty laggy in the bottom end but still crazy power up top. Would the temp change be that much to really make that much difference or do I need to do some more adjusting with the air fuel screw? Currently 1-1/4 out. I know my pet cock needs cleaned cause when it's in run she starves for fuel but reserve runs like a champ. Also I ordered a rebuild for the carb (pwk 39mm) and float assembly cause she over fills and dumps out the vent only when it's off. This thing also will about rip my foot off if I kick it at the wrong spot I guess. Is there a trick to safely start it with out blowing my knee out or is that just the nature of the beast? I'll post pictures here in a second. Thanks for all tour guys help!

[Bbriles10]

This one is my daughter. She loves this thing. She's 2-1/2 yrs old and can't get enough. I ripped it through 6th for her and she was loving every second.

[JesseA420]

glad eddie got you setup! looks like a great motor build.

[etccb]

Sweet deal. Love the naty lite on the work bench.