just got an R

[BigBore24]

well first of all i just picked up an 86 250r with an 88 motor. i traded the quad for a 125 dirtbike, but the quad needs a lot of work. i have been living in the 400ex forum for a while now as i built up my ex, but now im gonna sell it for money to put into this quad. so i was just wondering if there is anything i need to look for as i go through rebuilding this thing. also i am in need of a left side case. apparently the previous owner broke a chain and it busted the case and then tried repairing with tig weld and silicone. i have my hands full with this project but i cant wait to get done i love the way 2 strokes run. thanks for any input and i am gonna get some pics up soon.

[BigBore24]

oh yeah i forgot one question. how do i know if my crank is stock stroke or not. it has a hot rods crank in it and the only # i see is a ck103. i googled that and found nthing.

[TheNewn]

Post up some pictures of the quad, tell us what you're looking for and what it needs.

I'm sure someone here can help you with the stroker crank question, i've not had a stroker before.

[86 Quad R]

unless i'm mistaken. i believe the ck103 is a log rod(87-89) i just took one from an engine i'm working on and it has the same number. i've searched around and the only way that i see to tell what stroke you have is to(with the cylinder on and piston in place)is to manually measure the pistons travel.

[BigBore24]

ok thanks, the guy sent a new piston kit with the motor because the other piston has a hole burnt in it. the piston he sent is a standard bore stock piston but the cylinder has been bored so it wont work. anyway i took the stock piston and matched it up against the one that came out of it and they line up perfectly from wristpin hole to the top of the piston. so this should mean it is a stock crank right? come to find out its been bored .080 over. is that too much? the cylinder is in great shape so i was gonna get another piston and just hone it. what does that make it in cc's? also what would cause it to burn a hole right in the center of the piston? the jetting is 160 main and 48 pilot with .080 over piston and fmf gold series exhaust. is this too lean? sorry for all the questions

[86 Quad R]

that puts you at about a 261.5cc's. to be honest a 160 main is a bit lean to me. the hole in the piston is likely from a lean condition. eighter from jetting or an alternate leak. to be on the safe side ya may want to have the bore checked for taper wear and egging. sounds like you have a long rod crank. there isnt a spacer plate between the engine and cylinder?

[BigBore24]

well i didnt see one. the motor was in a bag when i got it. the bottom end was intact but the jug and head was off. the gasket was on the bottom of the jug but i didnt see a spacer n e where. heres some pics. check out these meats on the back. needless to say i am in need of some rear wheels (i already have a set of tires)

[BigBore24]

im stripping the 2 coats of paint off the plastic

[BigBore24]

the busted case thats been welded and siliconed :(

[BigBore24]

last one

[trx310R#24]

you got some work to do!

[All250R]

Originally posted by trx310R#24
you got some work to do!
Yea big time. But it's fun if you love the R imo and it can be rebuilt to run like new if you're detail oriented. From eye balling that looks like an OEM bottom with a wiseco rod. I'd guess it's stock stroke (72mm). Cranks get fussy if they're mistreated. They're expensive too. There's a lot of ways a crank can be bad. It might be worth it to send your motor out where it can get spec'd and give you do-it-once advice, or even send it back to you complete, if that's what you're aiming for.

Left cases pop up on ebay often. My advice is find one that still has the bearings in it. Most are press fit so if they're tight in there, you know there's some life left in it. A new case starts to look cheaper after you bought a bad used one.

A 160 main should be ok if he was running the stock carb. OEM placed around a 155 in the various years. A 175 isn't a bad place to start for a 38mm PWK.

[All250R]

By the way, in my travels with these quads, I've discovered that the OEM paint is very good stuff. Aside from the well worn areas like at the boots, youcan often use a cleaner wax and polish the paint to like new shine, seriously. You'll be amazed. Also a trick I learned was to take mothers polish to the smooth variety bolt heads. They'll shine like new with a small amount of effort. Try it and see if you're not surprised. They'll look better than stainless allen bolts and overall this polishing process saves you money getting a bike to look good again. SOme guys may not agree wtih me, but I dno't like powder coating frames. I think the undercoating Honda put on was done well enough that it should stay put if it can especially if a 20 minute wax job (after degreasing of course) can make the original red shine like new.

[BigBore24]

thanks for the input guys. yeah i agree with all250r about the frame. it actually looks pretty good, im just gonna clean it and buff it a bit. for now im more focused on making the plastics look halfway decent and getting the mechanical part going.

[BigBore24]

ok another question. how do i find the exact year of my motor. the guy said it was an 88 but i wanna make sure

[BigBore24]

anybody know? i wanna order some parts and need to know if its an 86 or 88

[LONG-ROD]

Don't buy a case with bearings in it. Buy a case and new crank bearings with seals, like $50.00 put the case in the oven for 10 min on the lowest setting and the bearing in the freezer for 20 min, it will fall right in. then but both halfs in the oven after the bearings are in when it is time to assemble this will make the crank go in easy. You need to measure the rod to determine what piston you wil need, cal Duncan Raceing, talk to Lauren. You will be better off sending it to him so he can mic it out and properly fit a piston to it, and he can also send you the right jetts and needle for it. you will need to know what pipe carb, reeds pipe and silencer, head, or dome, weather, and rider weight. This with cost about 250.00 so for less than 400.00 you will be good bottom to top. I recomend this because the bike has really been neglected and you have no idea what you have, if not you will end up chaseing your tail untill you hate 2 strokes.

[All250R]

Originally posted by LONG-ROD
Don't buy a case with bearings in it. Buy a case and new crank bearings with seals, like $50.00 put the case in the oven for 10 min on the lowest setting and the bearing in the freezer for 20 min, it will fall right in. then but both halfs in the oven after the bearings are in when it is time to assemble this will make the crank go in easy. You need to measure the rod to determine what piston you wil need, cal Duncan Raceing, talk to Lauren. You will be better off sending it to him so he can mic it out and properly fit a piston to it, and he can also send you the right jetts and needle for it. you will need to know what pipe carb, reeds pipe and silencer, head, or dome, weather, and rider weight. This with cost about 250.00 so for less than 400.00 you will be good bottom to top. I recomend this because the bike has really been neglected and you have no idea what you have, if not you will end up chaseing your tail untill you hate 2 strokes.
Thought I'd chime back on a couple items. Not hating 2strokes is setting the bar low. A well running 2stroke will make him love them. The reason you may want to consider buying a case with bearings has to do with the case being good, not an inability to change the bearings. Changing the bearings is easy compared to wasting money on bad case halves. The service manual doesn't say outright that the cases are bad if the tolerance fit has been ruined. From what I've seen left halves that look good go for more than $50. I've been looking for one and they're going for well over $100 - at least the ones recently that I would have bought. The cheapest new one you can get is $224 with a retail value of $340. Long rod OEM crank is $265. Basically, you really don't want sloppy bearings... it's not good in the long run. It's not correct. Additionally a full OEM bearing and seal set (which is probably required), not including the clutch arm bearings is about $170 from service honda.

Just to clarify, you really don't need pay someone to measure a crank to know what piston to fit to it. The difference between the long and short is 5mm. If you know the value a simple ruler should be sufficient. You may need to pay someone to spec it though if you don't have the tools to see if it's good or not.

Lauren Duncan (if it's Lauren) is going to set you up with safe jetting. He's not going enter all those values into a DRI blender and tell you exactly what your best jetting is. He's a conservative guy. He knows from experience that he needs to keep people's engines running more than he needs them to run on the cutting edge. There are less problems that way when a customer wants to blame him when his piston seizes and he doesn't understand why. He doesn't keep his business profitable by setting up the masses with the same setup the racers get who he sponsors and you see in dirt wheels advertisements. In critical cases especially like jetting, you're going to get largely generic service at big name companies unless you pay for their dyno time. Not to say those up front values aren't useful, but they are probably more important to have when considering porting. Jetting is truely tuned from a running motor.

I think all of the maintenance problems you need to overcome to make that motor run like it should and be reliable for many years is to take your time and do it right, or send it wholly to someone to spec it and make suggestions. The closest you'll get to a $400 dollar invoice for a top to bottom makeover is if you do everything yourself and you don't have any unexpected surprises, like the crank being bad, water pump, clutch, trans, c-balancer, reeds...

100 used left half
170 bearings and seals
75 ebay piston
50 bore and hone
11 wrist pin bearing
45 complete gasket kit
E=451

Hope that helps.

[BigBore24]

thank you. thats kinda what i thought as well. i am a diesel mechanic by day and a atv tinkerer by night so i feel like i can do most of the general inspections myself. not that im nearly as good as anyone at duncan racing but i feel i can make fairly intelligent decisions on my own. i deffinately want to do this right when it comes to the internals of the engine because i dont want to be taking it back apart in a month. i think its also important to mention that im not gonna be racing this machine just trail riding and maybe some sand. the good news is the bearing in the right case is still in there extremely tight and will have to be heated to get it out, so it looks like i still just need a left case. i did determine that my crank was a short rod by the number that was on the piston. so ive got most of my parts coming that i will need. i saw a bottom end bearing kit on ebay for 100 bucks. you think that they are any good? my major concern now is getting the jetting close enough to be able to break the motor in when it comes time without damaging the piston and sleeve. right now its at 160 main 48 pilot with the needle clip in middle notch. it will b .080 over piston with fmf gold series pipe and what looks to be aftermarket reeds. i will post some pics of them and see if anyone knows what they are but there is just one reed petal on each side. any kinda ideas on jetting would b appreciated, this is my first R

[All250R]

Hey. If you're running the stock 34mm PJ carb those jetting numbers are absolutely fine. You're only going to notice small if any improvements in jetting by going leaner. That main jet is actually more rich than what Honda put in the bike so you're not too lean. You may or may not know this but lean conditions and detonation (holes in pistons) can be caused by more than one thing, jetting being one of them. Another common cause is an air leak. THere are procedures you can find out there when you assemble the motor for making sure there's no air leak. The basics are clean and FLAT gasket surfaces, quality gaskets, evenly, and correctly torqued bolts and a leak down tester. Getting the gasket surfaces flat can be done with a lapping stone. I bought mine at rutger tool. THe leak tester can be made from lowe's junk including a low pressure gas gauge. I have two fittings, one for a 34mm carb boot and another for 36-39 (keihin).

I've always run OEM bearings and seals (particularly the main bearings) because I know the ebay vendor is not going to pay for motor repairs if a main goes early or a seal was made poorly or any of the above are defects. I know Honda is going to sell me what they use in manufacturing, so I gamble my motor with Honda. That's just me! I've never run the others, so I don't want to discourage you either. EIther way, do replace them all. Make sure you check that counter balancer big bearing too. I can be replaced if you take to the right guy.

p.s. The ironic thing about big name companies is their quality is usually less than a reputable owner operated company that can't afford the big advertising. It's kind of not fair, but that's capitalism. It's up to us to figure it out. I would send it to Neil at C-Leigh before sending it to Duncan. I've started my own shop as a business last year and I've gathered a reasonable amount as to what it takes to make these engines stay together correctly. On the other hand, an employee at Duncan may or may not have the same drive and care for the customer and the motor, or maye they were hired knowing a lot about 2strokes, but not a lot about the R. You don't know when you send it to "name brand" though who actaully works on it. Owners tend to care more. I've met Loren and sat side by side wtih him at my R to have him build me a head once. Loren's a passionate guy and for that day I got be treated by the owner, but in this case even he was wrong. I had a squish clearance of . 080" after he told me he would only set it to .045" after I requested it to be a .040" talking him down from .050". He sold me the head gasket by the way AND had the motor in front of him to measure. All builders make mistakes and even owner operated isn't fool proof. In fact it may be easier to get your money back from ESR (I've had to friggin do that too), but a reputable owner operated I feel will get you the most repeatable results over the short and long run. That's just my opinion and 2cents worth for you.

I love the 250R and 2strokes and I wrote all this crap and do what I do because I want other people to remember and have the positive experience that can be had on a well running 250R. I think it's the best, (on top of it cheapest) racing ATV ever made. Good luck man!

p.s.s, did you have to use a bearing puller to pull the left case half off? THat main on the left side of the crank is a tolerance fit. If it slid right off, that's a bad sign for the crankshaft. Typically actually the right side of the case is supposed to be removed, leaving the trans and crank in the left half. I have to recommend you buy or get a copy of the honda service manual too.

[BigBore24]

ok so i mic'd the inside diameter of the side of the carb that goes into the intake and it is 36mm. so is this bigger than stock? also would this change my jetting? i didnt have to use a puller to get the cases apart:grr: . i just pryed and did some light tapping and finally it split. i know its not a great idea but im gonna put the new bearings in it and ride it. i hate to have it torn down in the garage when its nice out. i plan on doing a little more to it this winter when i tear it all down so then ill look into replacing the crank. hopefully it wont come apart, but the bearing isnt sloppy on the crank by any means it just isnt so tight youd have to press it on and off. im deffinately gonna follow the break in sticky at the top of the 250r page, and i got some klotz oil. anything els i should know? i plan on running castrol motorcyce oil, is this ok and what weight do you recommend? thanks again for all the help

[BigBore24]

oh yeah the carb is a keihn

[TheNewn]

The stock carb is a 34MM PJ by Keihn.

Try and find out if that carb is a PWK (airstriker would be ideal) or a PJ. If its a PWK you'll be golden, if its a PJ you can make do.

[All250R]

Originally posted by BigBore24
ok so i mic'd the inside diameter of the side of the carb that goes into the intake and it is 36mm. so is this bigger than stock? also would this change my jetting? i didnt have to use a puller to get the cases apart:grr: . i just pryed and did some light tapping and finally it split. i know its not a great idea but im gonna put the new bearings in it and ride it. i hate to have it torn down in the garage when its nice out. i plan on doing a little more to it this winter when i tear it all down so then ill look into replacing the crank. hopefully it wont come apart, but the bearing isnt sloppy on the crank by any means it just isnt so tight youd have to press it on and off. im deffinately gonna follow the break in sticky at the top of the 250r page, and i got some klotz oil. anything els i should know? i plan on running castrol motorcyce oil, is this ok and what weight do you recommend? thanks again for all the help
These are your PWK's: PWK (http://www.keihin-us.com/am/products/pwk.php)

PJ (Stock): PJ (stock 34mm): (http://www.keihin-us.com/am/products/pj.php)
You should be able to tell looking at the pictures if its stock or not.

You need to measure next to the slide. You can't measure on the outside and get an accurate reading, however, the 34 reads close to 35mm on toward the end of the reed side.

Running a loose crank is not great for your motor or the new bearings. You're basically just putting off a problem at the expense of the lifespan of the other new parts you buy. The crank will hammer on the inside of that bearing, ever so slightly, many, many, many times. The rod is not meant to move laterally either. It's just bad for everything. Put a good crank in it and do it right would be my sincere advice. Also if any of those bearings come out of the case easily too, time for shims machined into the cases, or new cases. I actually had this problem recently and double checked with some very experienced builders and it doesn't sound like there are many options, especially with the main bearings.

[atvmxr]

good luck getting that back together as in the pics on page 1.... :huh

you are going to have hell getting both the transmission shafts, clutch fork pins, shifter drum, and counter balancer to all line up. maybe you'll get lucky, but if it was me I'd take it all apart and install it on the left side case per the service manual.

[BigBore24]

ok thanks i will do that

[ameier5051]

Hey, I am actually wrapping up an 88 TRX project and I just wanted to throw some info out there. My bore was only 66.5 and I was told not to go higher than .80 over. I just ordered a 66.75mm so 72mm is pretty spent. I am not an expert on these things but that is what I have been told...

[BigBore24]

thanks for the suggestions. im at .080 over now and next time i need to rebuild i will replace the cylinder. thought id post some updated pics. after drooling over the r's in the show off thread i realize mine is no prize winner but its a work in progress. im currently waiting on some rear wheels from ebay then i can complete my motor break in. i have started it and let it run for 10-15 min. at a time and it sounds pretty good, just need some fine tuning once i ride it.

[BigBore24]

another

[BigBore24]

last

[hondarider101]

any new ones?

[BigBore24]

actually yes, thanks for the interest. i took it out to haspin last weekend and had a blast. i dont care what anyone says this thing is even more fun on trails than my 400ex. still have to mess with the jetting a bit but she really rips through the woods. any other good ways to get it into the powerband a lttle qucker? ill post some new pics tonight

[BigBore24]

pic