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odd engine question
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Posted by: mineralgrey01gt

Today quite a few of us went riding again and towards the end of the day my 250r spit and sputtered, then died and when I took the plug out there was 2 small chunks of aluminum lodged inside the spark plug, so I figured maybe I just blew the thing up, I put another plug in it, and it cranked up but now it will only crank on choke. Now when I ride it, it will hesitate until I hit the powerband in any gear, first gear spits and sputters and 1/2 way through each gear after that its the same thing, and sometimes it will spit and sputter while in the powerband.

Could the 2 chunks of aluminum be pieces of the intake and exhaust port chipped off?

Posted by: my88r

quote:
Originally posted by mineralgrey01gt
Today quite a few of us went riding again and towards the end of the day my 250r spit and sputtered, then died and when I took the plug out there was 2 small chunks of aluminum lodged inside the spark plug, so I figured maybe I just blew the thing up, I put another plug in it, and it cranked up but now it will only crank on choke. Now when I ride it, it will hesitate until I hit the powerband in any gear, first gear spits and sputters and 1/2 way through each gear after that its the same thing, and sometimes it will spit and sputter while in the powerband.

Could the 2 chunks of aluminum be pieces of the intake and exhaust port chipped off?

man you seem to have alot of engnie trouble.lol

for the spit and sputter that sounds like a jetting issue. but then again im not sure.

Posted by: mineralgrey01gt

lol i know i do, but oh well.

It never spit and sputtered until that happened to it. Ive been riding it like this for the past 3 weeks.

Posted by: my88r

quote:
Originally posted by mineralgrey01gt
lol i know i do, but oh well.

It never spit and sputtered until that happened to it. Ive been riding it like this for the past 3 weeks.

then i would do a compression test on it. then go from there.

Posted by: mineralgrey01gt

i didnt have time to fool with it while I was at my parents house today but ill get it running again. A part of me kinda hopes that it let loose so I can step it up to a 310 or 330

Posted by: my88r

310 or 330

Posted by: mineralgrey01gt

yea man, the stock 250r engine is a fun little engine but I want more....

Posted by: C-LEIGH RACING

You sure it was a piece of aluminum you found on the plug.
If it was, then it had to have come from somewhere, off of something.
How much time on the engine sence a rebuild.
If its been a long time, could be a piece of broken off piston. Pistons will crack after a lot of hours on them.
You at least need to do inspection of the engine to see if it is a cracked piston.
If it is cracked & you keep running, you could bust the piston up, it fall into the crankcase & ruin the crank & could even bust the cases.
Neil

Posted by: mineralgrey01gt

it looked like aluminum to me, i wouldnt know what else it could be. I didnt ride it much at all after that, in fact, i may have put 10 minutes of running time on it after it did that.

I have no clue how much time since the last rebuild. I bought the engine off of ebay from a salvage yard.

Ill pull the head off of it when I go back to my parents house to see what is going on. I thought it may be a piece of the piston but I didnt think it would still run with the piston messed up like that

Posted by: Rich250RRacer

Sounds more like a big end rod bearing coming apart.

Posted by: mineralgrey01gt

quote:
Originally posted by Rich250RRacer
Sounds more like a big end rod bearing coming apart.

if that would be the case, then where could I get a good stroker crank for it? I dont want a HOT ROD stroker crank, is there any others? Ill go ahead and go all brand new for that type of stuff.

Posted by: 86 Quad R

dade gum!!!! between you en you brother, yall are gonna depleat the rest of the world of R engine parts lmao j/k man.......

but seriously! even if the engine was a good one when ya purchased it. you owe it to yourself to atleast visually check things out. it's good insurance. these things cant be taken for granted.

i bought my last R for my sons 13th birthday last year that had a "fresh build" but, i took it down to naked cases and good thing i did. the tranny had questionable signs of fatigue, the "new hinsen basket was grooved, the counter balancer bearings were half worn and the head gasket had a tee-tiny leak. had i "took it for granted" that it was A #1 i'd been buying a COMPLETE engine b4 long. see i'm im headed with this. my motto is do it right the first time and never take anothers word for anything regarding a high performance engine.

as i step down from my soap box, it sounds as tho the piston may be coming apart on ya and/or it leaned out(for what ever reason) and the only way to know is to "pull ur down" regarless of what the problem is. take your time and cover all the bases it getting it back going. dont cut any corners.

good luck with it.

Posted by: mineralgrey01gt

its definitely coming apart before it moves again. If it shows any signs of chipping ill refreshen the engine and replace what needs to be replaced. While its down I may go ahead and send off the cylinder to Neil to get ported for some extra power

Posted by: All250R

Aluminum doesn't stick to a magnet, so if you still have the spark plug, you can see if the pieces are attracted to the magnet or not.

Either way, you have a problem that really should require a tear down. It sounds like you're been through your motor several times so you probably know that top ends are easy to change. Take your time. Make sure gasket surfaces are clean and do a leakdown test whenever you split surfaces that were mated with a gasket. You may want to take your cases and cylinder to someone to make sure they are flat and can lap them if they've become warped. If you're having problems it's nice to know surfaces have the best chance to stay sealed before you look at other potential causes.

If you have a lean condition caused by a leak and you start detonating you'll eventually lose metal off the piston.

You shouldn't really have repeated problems with the motor unless it's been modified irresponsibly. I've recently opened stock R motors and discovered the original piston was still installed and/or the crank still good. So maybe check your assembly procedures and make sure you're doing what you can to make things right.

Good luck!

Posted by: mineralgrey01gt

I personally never did a teardown of a 250r motor before. My brother has and we have another short rod engine at my parents house so if I need parts, I know that those are good. I think while its down im going to build it up a good bit and get some prety good power out of it.

Posted by: C-LEIGH RACING

Had this happen to us, one of my engines.
265 ESR engine bought from somebody, installed new piston kit for start of season, went to practice day, she rode about 30 minutes & stopped.
I was doing other things when she came off the track so didnt know why she stopped untill I went & asked.
Engine ran away she said, so I started checking things. kicked the kick start with my hand, just didnt sound right, looking the engine over, both case studs on the clutch side broke, nuts gone & gasket blowed out.
I guess it did run away.
Come to find out, something small & made out of brass got into the engine, chewed up that brand new special flat top 265 piston & head dome along with busting off those two case studs.
I checked everywhere I could think of that something brass could come from, nothing so I just sat that engine to the side & bolted in another one.

A few years past & my son decided he was ready to race again & that engine was all I had left he could use, so here we go again, new studs, piston kit, gaskets, bolted it in & run.
Got just about through the 07 season & it let go again, wouldnt you know it, something got on top of the piston again.
Looked like it had happened very early on because the damage places had carbon build up. Anyways, when pulling the engine apart I disected every part I could think of trying to find where that stuff came from & couldnt find anything. Pulled the crank apart thinking it could be the big end bearing, a piece of thrust washer or even a piece of the tins, nothing.
Hey, I guess when its time for a R engine to be sit to the side or completely rebuilt, dont make no difference who it belongs to thats for sure.

wonder where that stuff came from.
Neil

Posted by: mineralgrey01gt

from what everyone is saying, ill check out the obvious stuff first, piston, cylinder, etc. but ill probably end up tearing the whole motor down and inspecting everything. Thanks for all the replies and I will update this thread when I find out what it is

Posted by: mineralgrey01gt

well i ordered a new piston a little while ago. I won a Pro Lite Wiseco piston off of ebay NIB for $61 shipped. Its a 67.5mm bore piston so at least it will have some more power now after the bore.

Posted by: C-LEIGH RACING

But, what did you find.
Neil

Posted by: mineralgrey01gt

I didnt even get into the engine yet Neil. Im not at my parents house to tear it down and see what it is. I just picked up the piston since im just going to replace it anyways while I have it that far down. Ill update when I find out what it is

Posted by: Aceman

You bought a piston before you measured the bore? Do you even know what style crank you're running?

Posted by: mineralgrey01gt

i wanted more power so I got a 67.5mm piston which makes it a 258cc according to an online piston place. Thats the reason I bought it, just to get more power, plus ill have it ported if its possible to do that also. Im 99% sure the crank is an OEM 85 short rod crank.

Posted by: Aceman

quote:
Originally posted by mineralgrey01gt
i wanted more power so I got a 67.5mm piston which makes it a 258cc according to an online piston place. Thats the reason I bought it, just to get more power, plus ill have it ported if its possible to do that also. Im 99% sure the crank is an OEM 85 short rod crank.

But how do you know you're not already at 67.5?

Posted by: mineralgrey01gt

i honestly dont. If it is then im set up with the piston, but i sure hope its not. I was told it was bone stock, but then again ive never been into the motor before. Ill have to do that asap.

Posted by: Aceman

I'm only saying this because you really never know what you're getting off Ebay, especially when the seller is a salvage yard. It'd be really easy to end up with parts you can't use...

Since you bought that piston off Ebay you wouldn't even be able to return it. Alright, I'll stop busting your chops.

Posted by: mineralgrey01gt

ill use it, between me and my brother, we have 2 tranny's we arent using. A good short rod crank, 2 good cylinders, a good stock head, etc. Ill put together another engine and have a spare

Posted by: my88r

quote:
Originally posted by Aceman
busting your chops.

you do a good job at that.lol

Posted by: mineralgrey01gt

alright guys, here is a little update of the situation so far...

My brother took the head off the bike a little while ago and he said there isnt any scarring, cracks, chips, etc anywhere to be found on the top end. The head looks good, the cylinder walls are smooth as can be, the piston has a hairline crack in it he said but no chipping at all. Only thing I could think of is a piece of the reed block chipped off and got sucked up into the plug. Is that possible? Im seriously puzzled right now with this thing. Im going down there tomorrow to take the reeds off and open up the carb to see if anything in the carb might have broke or anything.

Posted by: 86 Quad R

i'm curious to know aswell.

Posted by: C-LEIGH RACING

Go ahead & pull the piston off the rod & inspect it closely on the underside, see if you find where the piece came from.
You didnt say where the hair line crack was located on the piston,

bet its from the wrist pin hole across the top on one side or either completely across.
Neil

Posted by: mineralgrey01gt

well Neil, I figured out what it was. The bottom of the piston broke off and the other pieces were in the exhaust pipe. Im going to go ahead and tear down the whole motor down and inspect everything to make sure no other pieces went down in there

Posted by: C-LEIGH RACING

Busted piston normally means complete rebuild, at least at my shop it does.
Once you get the botton end pulled apart & press out the main bearings, look & see how much aluminum is in the hole where the bearing came from. Should be little pieces of piston behind the bearings & could even be pieces big enough to lodge themself in the oil feed hole above the bearings.

Oh, something else, check the crank tins, if any damage on them probably need to get a new crank.
Neil

Posted by: mineralgrey01gt

neil, how much would you charge for a full rebuild? Also I would get you to go ahead and port the cylinder but from the way it looks it already had port work done to it.