86 TRX250r

[tesser]

Hey guys...im new to these forums. I have a few questions...I have an 86 TRX 250r that needs a full top end rebuild...it needs a new cylinder, head, piston, rings, and a shorter rod(It has a stroker) I want to rebuild the motor myself this summer...I am pretty mechanical and I hear a top end job isnt too hard...do you guys have ne tips hints or tricks that could help me out...or info on what has to be done before I begin the work....boring etc...thx

[nacs400ex]

I would just pick up a clymer manual, or a honda manual. Thats all you need, most mechanically inclined people can work off those no problem. Best of luck with your R. You might want to check out www.rriders.com , its a website/forum dedicated to all 250rs.

[wilkin250r]

It needs a new cylinder and new head? Were they damaged? You should be able to just get a new piston, gaskets, and bore and hone the cylinder. Worst case scenario, you need to re-sleeve the cylinder if you can't bore it out any further.

You can't replace the rod without splitting the cases on the bottom end, which is quite a bit more difficult than a simple top-end rebuild. A top-end on a 2-stroke is pretty simple, I'd say most anybody can do it. Splitting the lower end is quite a bit more difficult, and I don't suggest it for a novice mechanic.

[tesser]

Dam...i had a feeling the rod was a bottom end job...well i suppose i can have the local shop split the cases....or i could keep the spacer plate thats below the cylinder...id rather convert it to a stock style rod so its more "reliable" i hear the spacer plate that allows for the stroker isnt so hot in terms of reliablilty...but my cylinder is bored out all the way....I can still re-sleave it? how much does that cost and is it hard etc?

[Aallron]

It should be able to be resleaved, as far as splitting the cases, dont be afraid, read a manual and make sure you understand what they are trying to get you to do before you do it, also make sure that you have the proper tool(s) or have them availible ( Mag Puller ) and get new seals/gaskets. If something dosn't "feel" right, stop and investigate. It is a rare thing that a motor goes together propblem free the first time.

[tesser]

opps..i forgot i def needa new cylinder..because that one is ported and polished and bored out all teh way.. im gonna sell it on ebay but i wanan get the top end back to stock...i think the bike has a kehein carb but i forgot what size..ill let u kno tommroow...if i conver it back to stock ...(new rod) piston, rings, and cylinder would i need to down size the carb ...im pretty sure its a large one now..ill double check..

[Bean]

spacer plate doesnt really change anything, just rev ability, spacer plates is for motors changing from 86 to 87 without changing rod, just really an extra gasket to blow out

[AndrewRRR]

Why does it need a shorter rod? What length is in it now?
Most people go to the 87-89 rod and use a spacer plate with the 86 style jug and piston. The longer rods are more reliable due to less side loading on it at BDC. Unless you are going to extremes the spacer plate shouldn't hurt reliablility. I haven't had any problems with the one on my 350r.
Make sure whoever ports it knows your stroke, rod length, and if you are using a spacer so they can get the port timing right.

[tesser]

well thanks for all the info guys yeah i suppose the spacer is ok..but i still need a new cylinder head cylinder , piston and rings....ill make sure that the person who orders all that for me knows the correct rod length..would there be a way for me to find out what size my rod is without splitting the cases...also i dont want to port and polish my cylinder this time becuase im not racing it for now...i just want to make it 250cc with a pipe no major engine mods for now :) thnx guys for all ur help

[wilkin250r]

Honestly, having a shop split the cases is rather expensive just to ease your mind about the reliability. This is purely my opinion, but I suggest you just keep the rod and crank as it is (as long as it's in good shape). If you have problems with it, THEN go through the expense of splitting the cases. Otherwise, I believe it falls under the old cliche "If it ain't broke..."

[tesser]

haha I definately agree with you there no need to spend extra cash, what has to be done by my local shop...once I purchace the parts...do they have to bore the cylinder right away...and also does any other maching have to take place before i replace the head cylinder piston and rings?

[AndrewRRR]

If you are getting a new cylinder (from honda) you shouldn't need to bore it. Yes you will have to get the right size pison and rings for the bore size you are using. There shouldn't be any machining necessary unless you have damage that needs to be repaired.

[tesser]

nice :) thx for all your help guys...I read this article which seems pretty good..for those of you who have done a rebuild before would you say this is a good site to go by...if not go you have any others..http://www.off-road.com/atv/2stroke.htm

[tesser]

also because I have that spacer plate do I need a diff cylinder? or a diff ne thing because i kno it was a stroker motor and the rod is long and there is a spacer plate...

[AndrewRRR]

It's impossible to tell without being there to see and measure the setup. Usually you need a spacer plate if you have an 86 style cylinder (which most engine builders use) with a 87-89 length rod (the long rod), to keep compression in check and port timing correct.

[wilkin250r]

Here's how it normally works with the spacer plate.

Honda changed their design a little in 1987. They made the rod a little longer, which gave a little smoother powerband and increased reliability. At the same time, they changed piston, specifically they moved the pin deeper into the piston. This basically made the piston "shorter". Not shorter on the total height, just shorter as it sat on the rod.

With a longer rod, but a shorter piston, the overall length doesn't change. So you can use ANY cylinder, 86, 87, 88, 89, and the port timing is all basically the same.

Now, here's where the spacer plate comes in. Many people liked to use the longer rod from the 87, but also use the taller piston from the 86. Now, this DID increase overall length, so you need a spacer plate to move the cylinder up. This give you a larger crankcase volume.

Now, keep in mind, all this is with the stock crank. You have a stroker crank, which may change things. However, usually when somebody does a stroker crank, they also adjust the rod length to keep all the timing the same. It's hard to say. I think you'll have to take it to a good shop that can map out the cylinder, with your stroker crank, and make sure all your timing is set up properly.

[tesser]

cool...thx for all your help guys..i think rite now its jetted for a huge bore size would i have to re-jet after the rebuild...and if so how do u jet b4 u break it in?

[tesser]

also im not sure i get the whole re-sleeving thing..could some1 plz explain everything you could want to know about cylinder sleeves there purpose, and when they are used...

[AndrewRRR]

If you are going with a stock cylinder and a stroker i'd probably start with a 170-175 main (if you are using a keihin). Breaking the motor in you won't be on the main jet much so it's not super critical right away, but just go bigger than you'll need. It's better to start rich and lean it out.
Sleeves are usually done if you are out of bores or really destroyed the bore. Some people install larger sleeves to get more CC's out of the motor in banshees but I don't know if anybody does that with 250r's (it's more common on banshees). Again if you are going with a new cylinder don't worry about sleeving.

[tesser]

cool thx man..well im not sure about the sleeving thing ill have to pop off my cylinder and bring it to my local shop to see if it can infact be sleeved...but i kno it is bored out all the way...hopefully theres no damage...would you say re-sleeving makes the motor more likely to blow?

[skidaddyjr]

If you have a spacer plate motor and want to run it without one why there is no reason other than too much oomph but just use an 1988,89 style piston without the spacer.

[tesser]

im cool with the spacer now i just have to find out of my motor is a stroker...

[AndrewRRR]

Originally posted by tesser
cool thx man..well im not sure about the sleeving thing ill have to pop off my cylinder and bring it to my local shop to see if it can infact be sleeved...but i kno it is bored out all the way...hopefully theres no damage...would you say re-sleeving makes the motor more likely to blow?

Resleeving the motor won't hurt the reliability. Basically it's starting over from scratch. So if you get a stock size sleeve you start at stock bore like when the bike was new, and if you hurt the motor again you can start boring it out. I think there are a few companies that make 300cc sleeve kits for the R. I personally don't like putting big cylinder bores in small jugs because you can reduce the transfer port size.

[skidaddyjr]

IK heres the deal 86 motors had a shorter rod 87,88,and 89 had the long rod length.the crank is the same, the 86 style piston works on 86 short rod motors without a spacer and 87-89 with a spacer OK!Now long rod motors can use either 88,89 style pistons without a spacer (stock setup)or 86 style piston with a spacer. the wrist pin location in the pistons are different is how this works.you can use either cylinder. the 86 or even the ATC cylinder are more popular because they can be bored larger, but any of the above can be used.also you say your cylinder and head is bad they can bored 86 which I assume is what you have,can be bored up to .120 over. also proXpistons come .10 overbore sizes while wisecos have less sizes available.If you going to plit the cases it would cost at least a gaskets set and torch to get the crank.tip replace the crank with a new or rebuilt one while you have it apart.

[skidaddyjr]

dont waste money on have you cylinder sleeved it is expensive and threre are to many variables. If you cant find a good used one by a new 88($200)make in looking for used one try to look for one that is has no kind of porting and overbored no more than .40 to give you a good base for later mods if desired.

[wilkin250r]

The "sleeve" concept is pretty simple to explain.

Picture the entire top end of your engine, the cylinder, the head, and the piston. The cylinder isn't just one solid chunk of metal. Inside the cylinder is a "sleeve". It fits really tight, and that's what the piston is actually inside. When you bore your motor and put a bigger piston in, you are actually boring the sleeve. When you run out of bores, it means that the sleeve is getting too thin to bore any further. So, what they do is they press out the old sleeve, and put in a new one, so you are starting all over again.

However, you said your cylinder was ported, and I'm not entirely sure how that works with a re-sleeve. I'm pretty sure they would have to port your new sleeve all over again to match the porting of the cylinder, and that would be expensive. You'd probably be looking at $500 for a re-sleeve and porting. You're much better off just buying a new cylinder.

[tesser]

hahah i finally see...makes sense now thanks a million guys uve been a great help...hopefully ill see if i can find a cheap good cylinder to use ...i would like to use an 86 cylinder any suggestions on sites that sell em new for cheap...or used for cheap...id rather new...but if you guys know anywhere i can get one for like 200 or less plz let me kno :) thx

[AndrewRRR]

If you want one for that cheap you should try ebay and see if you can find one that's got several bores left with virgin ports. You can get a new one from Service Honda but they are about $500.
I had an 86 that was .020 over with a very mild port but I sold it on ebay a couple months ago. I think it went for like $120.

[tesser]

cool..do you think i could get ne thing for mine? its ported and polished by smith racing but has no bores left over...also i took apart the top end yesterday and i saw my .100 piston and its f'ed up rings...no real scratches on the cylinder...but the quad doesnt kick over and the rod wont move up and down any ideas what that could be..the last guy who fixed it gave it back like that...it wont kick over at all and the rod seems to be "fixed" in place...what could be causing that? I almost forgot...how do you get those dam circlips off the piston..i got one off other is givng me some trouble is there a special tool used?

[AndrewRRR]

If it's a .100 piston than it should be an 86 cylinder which can be bored to .120, so you have 1 bore left over (the 87-89 cyls can only go to .080 over). If your bike won't kick over and the piston isn't siezed than it's a bottom end problem :(
Pull off the cylinder and see if it'll move. If not you either have a crank issue or your tranny is locked. Either way you will have to split your cases.

[tesser]

hmm sounds like im in a ****ty position...well Ill try and diagnose the problem further...but in the worst case senario that i need bottom end work done..am i better off just buying a brand new engine from service honda...because i need a top end rebuild also...so it seems like it would be pricey :(

[tesser]

is there anything else it could be besides something that I would have to split the cases for?

[wilkin250r]

You can try taking off the flywheel cover and turning the engine manually, but if you can't move it with the kickshift then is sounds like it's locked up.

A new engine from Service Honda will run into the thousands of dollars. A complete tear-down and rebuild will run you about $400 + parts. Of couse, those parts can get expensive. A crank alone will run about $250.

You might be able to find a used engine for a decent price, going rate is about $700 or so. Of course, this can be a gamble. You can rest assured it will run, but you don't know if it's on it's last leg or not.

[tesser]

sounds ok...i think id rather have it rebuilt so i kno that it will work...but splitting the cases and having a complete bottom end rebuild of anything that needs to be replaced will cost be like 400? where!??!?! where would you recommend taking it also...must it be a honda shop...i had a shop close by but they got shut down by the IRS dont ask...but theres a few other shops around not just honda tho..i dont think they are honda dealers is that ok? please get back to me about the prices if you have anymore info...

[AndrewRRR]

I personally wouldn't take it to a Honda dealership. That's probably the most expensive place possible, plus they'll want to use all OEM parts on it when you can get better aftermarket parts for less money.
I don't know your area so I don't know what shops are around. I guess check your yellow pages. You can also send off your motor to get done by someone (if you do that choose a well known shop). Shipping isn't as bad as you'd think.

[wilkin250r]

Now, keep this in mind, the $400 is for the basic rebuild ONLY. This usually includes all the labor to split the cases, inspect everything, replace bearings, gaskets, and put it all back together. Basically, a complete teardown, inspection, and reassembly. It doesn't include actual repair work, like truing the crank, or cost of parts like replacing broken gears or stuff like that.

I've seen a local shop charge as little as $250 for the basic rebuild, but that was labor only. You have to add the cost of gaskets, seals, ect.

If you're going to have a shop do the work, get your cylinder before you send it in, so they can install the cylinder and you get back a complete running engine.

As for shops, I don't really recommend the dealer. They are expensive. I'd take it to a local motorcycle racing shop, or ship it to a reputable shop. There are several that advertise on this site, I'd imagine you won't be dissapointed with any of them.

[tesser]

cool thanks...you know of any in local NY?

[tesser]

hmm I found a few local shops..one of them claimed splitting the cases and diagnosing the problem would take 1 hour! and it would cost me 78 bucks to tell me the problem with the bottom end...is that possible or do you think he was mistaken or confused...

[AndrewRRR]

Splitting the cases isn't like pulling the cylinder off the motor. It's a big project. An hour sounds reasonable. The price sounds a little high (I don't know any ATV builders that charge $78 an hour) but it's not unreasonable.

[tesser]

hmm an hour seems ok but then i just called back they said its gonna be more than that cause the hour only covers splitting em not putting em back...i heard from a friend they are slow with repairs...i think im gonna send the motor out to LRD performance, they have done well for me in the past and they seem reliable any1 ever use them b4?

[AndrewRRR]

LRD does good work. They are just down the street from me. They get busy sometimes so you might wanna call and find out the turnaround time.

[tesser]

yeah i called them up there really nice and they arent too busy right now thanks for all your help guys :) i think im gonna mail it to them or give it to a local motorcycle place to have my bottom end fixed..then ill do the top end myself...just one more question....how do u put on the circlips is there a special tool or u just use a needle nose pliers or somin...im pretty sure i can do it...just checking to make sure i do it right ...if you have anymore tips on a top end rebuild please let me know thanks guys :)

[AndrewRRR]

Put one end in the groove in the piston then use needlenose pliers or a screwdriver to compress the circlip and work the rest in there. It's kinda tricky but once you get the hang of it it's not too bad. You might want to put a towel over the area in case you loose your grip so it doesn't shoot off and get lost.

[wilkin250r]

Spend $6 at the local auto-parts store for a set of spring-clip pliers...

[tesser]

spring clip pliers..can u post a pic