2-stroke engine problem

[Marls]

I need a vague idea of what this problem could be.
Yesterday after taking the bike on a long ride out west auckland to wellsford, and on the way back the bike just lost power :crybaby:, after riding it another 20mins in traffic on state highway1...i got the bike towed home, and then figured out that the one cyclinder wasnt firing, plus there is a knocking sound at idle.
When I disconnect the lead it ran fine on one cyclinder, wen i connect the lead it dies, i opend the plug and cleaned the one with the cyclinder that was not working, and the black fuel left on the plug had fine granules in it....

some one, please, let me knw the bad news, wat must i do to fix?
ths is my first bike and i need some experienced 2stroke advisors...

yamaha TZR250 3xv 92' (maybe sp model) its got dryclutch system
bike just clocked 40k, and i bought it with 39...

[WRT]

What do you mean by fine granules? Are we talking carbon or metal here?

[Ixion]

Well, you're a brave man. Or something. I guess one could find a less suitable bike for a mechanically illiterate novice. If one looked really hard.

At a pure guess, assuming you've done all the obvious stuff, like checking for sparks, bits fallen off, dead rat up the zorst, I'd say you've blown a piston. At least, maybe big end or power valve as well .

At any rate the top end's going to have to come down.

Do, as to what you do to fix it, answer is trailer it to your friendly local Yamaha dealer. Keep the trailer hitched up, you can use it to bring the money to pay the dealer back from the bank

That's two smokers for y'. We luvs them we does :love:

[Conquiztador]

A beer says there is a hole in the piston...

[FilthyLuka]

A beer says there is a hole in the piston...

ill take that bet

[Marls]

What do you mean by fine granules? Are we talking carbon or metal here?

Hard to say, everthng is black, and its fine so i couldnt be sure.

[Marls]

Well, you're a brave man. Or something. I guess one could find a less suitable bike for a mechanically illiterate novice. If one looked really hard.

At a pure guess, assuming you've done all the obvious stuff, like checking for sparks, bits fallen off, dead rat up the zorst, I'd say you've blown a piston. At least, maybe big end or power valve as well .

At any rate the top end's going to have to come down.

Do, as to what you do to fix it, answer is trailer it to your friendly local Yamaha dealer. Keep the trailer hitched up, you can use it to bring the money to pay the dealer back from the bank

That's two smokers for y'. We luvs them we does :love:

lol, crap
now all that fun is paid with frustration... :2thumbsup

[Marls]

A beer says there is a hole in the piston...

Remedy? the steps i can take to fix, i got tools, and the bike not goin nowhere. :cool:

[k14]

Remedy? the steps i can take to fix, i got tools, and the bike not goin nowhere. :cool:
Pull the head. First you will need to drain the coolant and then you can undo the head bolts (should be 5 or 6) of the cylinder that is not running and you should be able to see what is wrong.

First though, to determine if the cylinder has no compression. Take both plugs out and then put your hand over the plug hole on the cylinder you think is dodgy. Then turn the bike over by hand using the kick starter and you will soon know if there is any compression. If you can't feel anything pushing your hand then you will probably need a new piston or maybe more.

Check that out and report back.

[tri boy]

Head and Barrels off. Then you'll know. But any sign of dusty black deposits has me agreeing with Ixion.
You will enjoy the learning experience. (maybe not the $ depletion).
Fingers crossed for a simple Piston/Ring job.:msn-wink:

[Conquiztador]

ill take that bet

U'r on. Steinlager pleeze...:Punk:

[Conquiztador]

Remedy? the steps i can take to fix, i got tools, and the bike not goin nowhere. :cool:

Ten first steps in order:

1. Kids and missus away for the day.

2. Get 1/2 doz of favorite beer.

3. Phone off hook and battery out of mobile.

4. Clean up workshop so you have space and all tools are where you know they are.

5. Bike on central stand.

6. Plugs out.

7. Open first beer.

8. Finger in holes (one side at time) and turn motor over. You are looking for difference between the good one (air is pushed out past finger no matter how hard you push the finger in, a little like trying to stop a fart...) and the bad one (no such adrenalin pumping excitement)

9. Time to sit down and do some thinking. Here the beer you opened at #7 comes handy.

10. If there is a difference then head off. (Not yours or the beers but the bikes) Others have already told you what to do here. But if you are noob to this, then get a mate who also enjoys beer or buy a manual before starting. You will also need a torque wrench when re-assembling after all your beer money has gone on a new piston)


Good Luck!!

[Richard Mc F]

Ooooh Ooooh can I join in ?

You may have got real lucky and run a big end.......try somthing magnetic on the granules and see if they stick to it.............if they do you have:doh:.........may god have mercy on your wallet

ps if you want a true :doctor: cynic to look at it pm me

[Marls]

Pull the head. First you will need to drain the coolant and then you can undo the head bolts (should be 5 or 6) of the cylinder that is not running and you should be able to see what is wrong.

First though, to determine if the cylinder has no compression. Take both plugs out and then put your hand over the plug hole on the cylinder you think is dodgy. Then turn the bike over by hand using the kick starter and you will soon know if there is any compression. If you can't feel anything pushing your hand then you will probably need a new piston or maybe more.

Check that out and report back.

Ok, lower cyclinder has no compression, acording to the finger test, ther is noticable difference between the two wen turning the engine over,
ill attempt at opening the head later today, and take a look at the piston, where can I go buy new pistons and parts from?
and what else would u recomend i change while its in peices..? :laugh:

[Pancakes]

Pictures would be good for us following your adventure.

[F5 Dave]

Best take the cylinder off for a proper inspection. Check the powervalves & the exhaust ports, they can crack between the sub & mains, erm or the side & transfer?. . .Memory accessing picture in head & I can't remember, but if there is a crack you will see it under close inspection.

If this has happened of the plating has been damaged it can be repaired by someone like US Chrome fairly economically.

Dry clutch is SP model. I'd love one, but they are high maintenance & lets face it ageing a little for a performance engine.

[Number 5]

Ok, lower cyclinder has no compression, acording to the finger test, ther is noticable difference between the two wen turning the engine over,
ill attempt at opening the head later today, and take a look at the piston, where can I go buy new pistons and parts from?
and what else would u recomend i change while its in peices..? :laugh:

Sure does sound like you have holed a piston.
I had frequent holed pistons when I raced 2 stroke Yams, the cure, after replacing piston and other damage, was to use 2 spark plug washers under each plug.
This moved the flame path of the ignition a little further away from the piston crown, no loss of performance but certainly cured the holed piston syndrome.

[Marls]

Sure does sound like you have holed a piston.
I had frequent holed pistons when I raced 2 stroke Yams, the cure, after replacing piston and other damage, was to use 2 spark plug washers under each plug.
This moved the flame path of the ignition a little further away from the piston crown, no loss of performance but certainly cured the holed piston syndrome.

True cause i replaced the spark plugs, not long ago well, roughly 300k ago, because the last time i had a problem, it was the plug on that cyclinder, and they are NGK BR9EIX iridium....$23 a plug....
I think its a hole in the piston aswell, from wat i can sence, but ill put some pics up when i start takin it apart... i will have to take the whole engine out of the bike anyways, ya?
any particular order to do it in?
usualy i work on cars, so hopefully bikes are simpler

[k14]

True cause i replaced the spark plugs, not long ago well, roughly 300k ago, because the last time i had a problem, it was the plug on that cyclinder, and they are NGK BR9EIX iridium....$23 a plug....
I think its a hole in the piston aswell, from wat i can sence, but ill put some pics up when i start takin it apart... i will have to take the whole engine out of the bike anyways, ya?
any particular order to do it in?
usualy i work on cars, so hopefully bikes are simpler
I hope you got the correct plugs. If you got ones that are too hot then you can burn a hole through the piston. If you got ones that are too cold you can sieze it too.

Let us know what the deal is when you get the head off. It could be so bad that it may not be worth even rebuilding it. Hard to say. Not sure about parts, yamaha shop will be able to source them I think but may be cheaper to buy from overseas.

[Conquiztador]

Pictures would be good for us following your adventure.

Yes, we are delighted to part-take in others suffering.. ;)

[Pancakes]

I know your kiding but He seems to be taking the prospect of a full build or gone motor way better than I would! Just helps me and others learn too, way better than words.

[Conquiztador]

True cause i replaced the spark plugs, not long ago well, roughly 300k ago, because the last time i had a problem, it was the plug on that cyclinder, and they are NGK BR9EIX iridium....$23 a plug....
I think its a hole in the piston aswell, from wat i can sence, but ill put some pics up when i start takin it apart... i will have to take the whole engine out of the bike anyways, ya?
any particular order to do it in?
usualy i work on cars, so hopefully bikes are simpler

If you can get head off without engine out then you be OK to chek her w/o taking engine out. Depends on frame and space. But if there is a hole then yes, out she comes and apart as you will have bits inside.


I know your kiding but He seems to be taking the prospect of a full build or gone motor way better than I would! Just helps me and others learn too, way better than words.

True. Just have learnt that what has happened has happened, so no use to get too depressed re it. And yes, he is doing well!!


Sure does sound like you have holed a piston.
I had frequent holed pistons when I raced 2 stroke Yams, the cure, after replacing piston and other damage, was to use 2 spark plug washers under each plug.
This moved the flame path of the ignition a little further away from the piston crown, no loss of performance but certainly cured the holed piston syndrome.

Good advice!! And remember, that plugs come in different thread lenghts too...

[Marls]

I hope you got the correct plugs. If you got ones that are too hot then you can burn a hole through the piston. If you got ones that are too cold you can sieze it too.

Let us know what the deal is when you get the head off. It could be so bad that it may not be worth even rebuilding it. Hard to say. Not sure about parts, yamaha shop will be able to source them I think but may be cheaper to buy from overseas.

ok, the plugs quoted from the JAPANEzy manual, says BR9ECM and mine are BR9EIX (as i just replaced wat was in there) and i cant realy judge the distance between the gap (dont have that tool, but the manual says .7mm - .8mm)

[Conquiztador]

Bike........................Year...........NGK.... ...Alternative.......Iridium
TZR 250 " V2".........1991-1995..BR9ECM....BR9ECMVX
TZR 250 (2MA)........1987-1989..BR9ES......BR9EVX..........BR9EIX
TZR 250R/RS/RSP....1993-.........BR9ECM....BR9ECMVX

You have a Iridium plug that is for the TZR 250 (2MA) 1987-1989. Apperently not recommended for any of the other TZR's. From the NGK website.

[Marls]

#$@#$
well.... cant do anyting now... ill just have to live n learn.... start the dismantling friday...me day off... expect some pics

[Marls]

ok, couldnt wait, so i took some pics, they ok, for my fone so....comon lets get some theories.... the top of the piston looks like it had somthing smashing it... i am just wondering if the other piston is in similiar condition now.

[Conquiztador]

Bummer...if there is no hole in the other one I owe Luka a beer...

A wild guess: Stretched conrod/damaged big end and piston hitting the head??

[Richard Mc F]

I should have put money on my original prediction..............looks bad........xt660 conversion any one ?

[imdying]

Just rebuild that motor.

[Ixion]

Bummer...if there is no hole in the other one I owe Luka a beer...

A wild guess: Stretched conrod/damaged big end and piston hitting the head??

Not entirely. The piston skirt may have collapsed, can't tell until the barrel is off. Somethings taken out the compression. Either a piston's gone or a big end is badly run.

EDIT: If the big end is gone, the conrod doesn't need to be stretched, just the play in the big end will allow the piston to rise too high in the cylinder, thrown upward by the other cylinder and inertia.

[gijoe1313]

:( yowsa, at least you are getting onto it and sorting the donk out!

[Motu]

Looks like detonation in the squish band.

[Richard Mc F]

my money is on it being a big end

[k14]

Looks like detonation in the squish band.
Yeah possibly. We need some clearer photos to tell.

What fuel and oil were you running? The sparkplug is still in tact? That could have fallen out and hit the head.

I suggest pulling the barrel (you have to do it regardless to change the piston) and see what lies there. Are there any scores on the barrel?

Looks like something has got in there and pounded the head to pieces. Possibly something in the bottom end fallen out and then gotten into the combustion chamber.

[speedpro]

My money is on a collapsed big end bearing cage and a whole pile of those bits have made it into the chamber and got friendly with the piston and the squish area.

[kevfromcoro]

Wrong plugs.....done that once......put a hole straight through the piston
Dont think your bottom end has anything to do with it...

[Marls]

Bummer...if there is no hole in the other one I owe Luka a beer...

A wild guess: Stretched conrod/damaged big end and piston hitting the head??

well, i'd be getn prepared to give him that beer, lol cause i am pritty sure this piston is the one that is causin the problem.
I guess ill start takin the engine out the bike tomoro, and start documenting the internal damage.
this is a cool hobby :mellow:

[Marls]

Yeah possibly. We need some clearer photos to tell.

What fuel and oil were you running? The sparkplug is still in tact? That could have fallen out and hit the head.

I suggest pulling the barrel (you have to do it regardless to change the piston) and see what lies there. Are there any scores on the barrel?

Looks like something has got in there and pounded the head to pieces. Possibly something in the bottom end fallen out and then gotten into the combustion chamber.

Ok, running 95ron Caltex fuel from wellsford.... Hmmmm dodgy, although i did run out of gas comin into wellsford, maybe there was some dirt at the bottom of th tank that could have goten into the combustion chamber.
I run Motul motor oil.... some off road brand.... :bleh: picture .... is this stuff good, cause after the previous owner and the plugs, i am not to sure if i should use any of the stuff he has givn me.

I ran my finger on the inside of the barrel and it feels as tho there is a slight crease or score on the wall... :( but realy small and 2 of em...
the plugs are fine, but i gues thats from the recessed postion in the chamber, it must have definately hit the top of the cyclinder, cause if u look at the damage to piston face its around the outter area, matching the cyclinder ceiling shape.

Tomorw i start the large task of taking the engine out, hopefully i do it well.
anyone Know a rough order of things to disconnect before i take the engine off its mounts and lowwer it out...
experience is key.... how do i stop the fuel from runnin out etc

any special tools i need? best i get it now... or some1 could borrow me those, that would b awesome, otherwise i got connections

[Number 5]

Sorry to hear the sad news that its more than a holed piston, does sound as though the big end bearing failed and allowed the piston to hit the cylinder head.
This could have been caused by using differing types of two stoke oil, note it is type not make, it may have been running on a mineral oil, and sometimes the two don't mix the type you changed to may have been synthetic.
It is not really a problem on 4 strokes as they bathed in neat oil, but in 2 strokes as the big ends are lubricated by the fuel, and the oil mixed in that fuel (be it by injection or pre-mix) the oil film is washed off the bearing allowing overheating and failure.
It used to be recommended that when changing types of oil in 2 strokes that the crankcase is swilled with neat petrol, then swilled with the oil you are to use.
Sorry but this info is useless to you now.
But to replace the bigend bearing is not a job you can do at home, as the crank webs will have to split, new bearing fitted, and then then crank assembled, trued and balanced.

[tri boy]

If you havn't split crancases/crankshafts before, or been trained in this work, may I suggest simply removing the engine as is, and allowing someone more skilled to tackle it.
One thing mechanics hate, is a box of bits passed onto them.:nono:
The strip down and inspection process allows them to ascertain the reason of the failure which will help you understand the cause.
In the long run it will be cheaper, and less stress. Too many people have thrown $$$$ into parts etc, only to make mistakes on assy that trash those parts in quick time/kms.MHO:yes:

[Richard Mc F]

Where is the bike..........I may be able to help

[Marls]

Where is the bike..........I may be able to help

Help would be appreciated, followed by a case of beers

The bike is sitting at home, on the North Shore, i have been pricing all the parts to rebuild the engine, looking at 1500, thats 1 new crank and 2*top end rebuild kits, plus one cyclinder... (this is off ebay), any other places to price up parts would be helpful...

[Number 5]

Shouldn't need a new crank, strip it and take it to an engine reconditioner to fit the new big end bearings (need a press to re-assemble the crank), as to the barrel there are anumber of options, 1) rebore to oversize pistons, wiseco do bigbore kits for most bikes, 2) if the barrell is beyond rebore have it resleeved if it has a cast iron liner, if it is a chromed bore this can be repaired also, look in the services section of kiwirider.
other than repairing your engine you could get a used one from a wreck, Bucket n Bits down here in Wellington may have one, google the name as he has a website showing what he has in stock.

[Marls]

i didnt mean new crank, a new crank rebuild kit, it has all the bearings and seals...

[FilthyLuka]

macs black please :-)

[F5 Dave]

That Motul 800 is some of the best oil you can buy & is the biz for road racing or dirtbikes.

But it is not suitable for oil injection. Think that is Motul 600 (was 300 then changed, haven't kept up). The 800 is too thick & will clog in the injector.

[Max Preload]

Looks like detonation in the squish band.

That would be my position too.

[pritch]

I guess ill start takin the engine out the bike tomoro, and start documenting the internal damage. this is a cool hobby :mellow:

Go far you will Luke. The force is strong in this one. :scooter:

[Marls]

sweet... so me and richard discovered that detonation was the cause, crank and bottom end is fine amazingly enough, YAY,... cause by lean out, and the crap from the bottom of the fuel tank... i ran out of gas that day.
next ahead is sourcing the right parts...

According to the stamping, and some Japanese translating, i have the SP model HAHAHHAHA mean!!!! :woohoo:

but unfortunately the parts are hard to come by, or atleast the ones i found on ebay are for the year above mine. meaning that the YPVS is electroniclly controlled and mine is machanical. sigh (can forsee a long head ache of searching for the right part ahead)
I need a Cylinder head - 3xv11 y-2, Cylinder 3xv10 y-2, piston, and the gaskets, o-rings, and piston rings for a top end rebuild.

HAD a look at the other piston, and shess sweet. hahahaha. so, if i am lucky i can hav it running as soon as get my hand on these parts :D

[Kickaha]

I need a Cylinder head - 3xv11 y-2, Cylinder 3xv10 y-2, piston, and the gaskets, o-rings, and piston rings for a top end rebuild.


Interesting thing with the 3XV is that all the TZ race parts bolt straight on, you could have a 80hp road bike :yes: of course it means a rings every 250km and pistons every 500km

[Sketchy_Racer]

That Motul 800 is some of the best oil you can buy & is the biz for road racing or dirtbikes.

But it is not suitable for oil injection. Think that is Motul 600 (was 300 then changed, haven't kept up). The 800 is too thick & will clog in the injector.

What he said. Get some spectro gold injector two stroke oil.

Now, remeber to pull your carbs apart and clean them, because i'd say that the crap from the bottom of your tank has blocked the jet. a simple running out of gas would not cause that damage, it is prolonged lack of fuel, causing detonation that has done that. Hence i would pick that the jets in the carb are blocked.

Only a 5 min job (well, maybe a bit more, but you get my point) and it could save you from doing the same damage to all your new parts when you get them.

Cheers,

-Glen

[k14]

I know the head is pretty stuffed but it may be machinable. Go find a good 2 stroke tuner and they may be able to restore the head to its former glory. Hard to say though. A piston kit should be relatively easy to come across. Go to the local yamaha shop.

[Marls]

Interesting thing with the 3XV is that all the TZ race parts bolt straight on, you could have a 80hp road bike :yes: of course it means a rings every 250km and pistons every 500km

lol, that is interesting, but i am not lookin for a race bike being a learner and all... its quite fast as is... I rode my friends gsx250r the other day, and well.... i am not liking the gutless four-strokes at top end aye...
where can you find TZ parts in anycase, just for future knowledge :drool:

[bimotabob]

Hi

Does yours have o-rings for head gaskets?
Are the power valves gullitone type or rotating?

Yamaha do all the parts you just have to identify the model specs.

The CDI is restricted and you can't easily change it to give it the full power as it's digital.

Cheers