Question about 2002 Yamaha TT-R 250

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Correct timing chain marks. is a diagram available?

I have a 1991 tt250 .i have replaced piston and rings and new gasket kit, after finding the bike had a seized piston. i got the bike free!.i have the bike running but seems to lack torque at the bottom end. i am unable to find a workshop manual anywhere. looking to see if anyone has better idea for timing marks on the cam shafts. im quite certain i havnt got the timing spot on, can anyone advise me?

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If the timing chain is off i dont think it would run, id suggest getting you're cams checked and reseat your valves, i have the same bike and an electronic copy of a repair manual, not for the exact same bike however. i have not been able to find the correct copy.

Posted on Dec 10, 2008

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Hello,go to repair to get a shop manual. If timming is off, don't run the bike.

Posted on Nov 28, 2008


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My question is if the piston seized up into the cylinder head do I need to replace the whole head or just buy a top end kit

The piston wont seize into the cylinder head it will seize into the cylinder and you will have to replace the piston the rings the cylinder. crankshaft bearings and seals and gaskets. maybe the cylinder head if it got hot enough to warp

Oct 18, 2015 | Motorcycles

1 Answer

My bike is smoking a lot changed piston valves seals guides but no good result can ya giveany tips

New valves, valve guides, valve guide seals; all fine but probably not needed. When the piston was changed, did you run a cylinder hone in the bore to check for distorted cylinder walls? Was the old piston seized up at any time? Were there scratches or grooves cut into the cylinder wall from being seized? Did the new piston get new rings? Chances are you will need to have the cylinder bored then install a new 1st oversize piston and rings. Please rate my answer.

Aug 10, 2011 | 2005 Honda CRF 230 F

1 Answer

My son 06 250 sxf motor seized up won't start

If the bike has been seized up it's important to check out the piston and cylinder head. It's a good learning experience and not that hard a project. Remove the seat, tank, pipe and maybe the carburetor and you should be able to get at the head bolts. Pull the head and inspect the top of the piston and ring area. Rings usually get stuck to the piston so there is not any compression. Pull the jug and more than likely there will be alloy from the piston transfered to the cylinder heard.
Take it to a bike shop or automotive machine shop that can hone it to first over. Purchase new 1st over-sized piston and matching rings. Re-assembly and replace all gaskets.
Thanks for contacting FixYa,

May 11, 2011 | 2006 KTM 250 SX-F

2 Answers

What should the engine compresion be when i pull the cord it doesnt feel like any coompression new piston rings and cyclinder slevve jus installedt

It realy depends on how much oil is around the piston, and in the bore, however you should be getting over 100 psi

Mar 27, 2011 | Garden

1 Answer

I need instructions and parts list for a seized stihl MS170 as the shop says it is not worth repairing

if it's seized, first off, take out the spark plug and pour a little diesel in it. You can get away with wd-40 too, but diesel works best. You'll want to let it sit this way for a couple of days. Next, you can try to tap the piston lightly with a plastic punch and a dead blow hammer. If it won't go, don't hit it too hard; you'll put a hole in it. If you haven't broken it loose by now, you may have to use the grease gun method. This is where you modify an old spark plug to attach to a grease fitting, screw it in, and pump it full of grease to use the hydraulic pressure to push the piston out. You'll want to unbolt the cylinder for this part. Once you get the piston out, look at the cylinder bore. If it's scored deeply, you'll want to get a new cylinder. If not, you can usually just hone it to get light scratches out, and put in a piston kit. As for cost effectiveness, your shop is right though. You can usually find a decent running used ms 170 for less than the parts you'll need to rebuild this one, especially if you're dealing with a seizure. If it seized due to oil mixture issues, you have no idea what kind of shape the rest of the bearings in the engine are in, and you're piston kit may be great, but you toast a bearing a week down the road. Piston kit runs about 30 dollars includes a piston, rings, wristpin, and clips, and you'll need a gasket kit as well. Another Option, is to find a shortblock, even used, and put rings in it just to play it safe. Hope this helps you out.

Apr 24, 2010 | Garden

1 Answer

1991 yamaha TT250 wiring diagram

Hi, Shane for this scenario you will need your service/owners manual if you can't find the best tool you ever bought for your Yamaha, despair not, for a mere zero $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the blue links below. Good luck and have a wonderful day.
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Nov 22, 2009 | Yamaha TT-R 250 Motorcycles

1 Answer

My bike stopped running and was leaking coolant.

A coolant leak from the bottom of the cylinder indicates a blown base gasket. easy fix if you have a manual and some mechanical knowledge.
If you lost all you coolant, you may have also seized the piston.

you will require a top end gasket set, and most-likely a piston kit (Now is probably a good time to freshen that up anyway.)

If the engine was running good you probably did not get any coolant in your engine which is good.
-here is an idea of what is involved

(label everything and keep it nice and clean)

1) clean your bike good. You do not want dirt in the engine.
2) remove seat, fuel tank, rear subframe, and the pipe. This should give you easy access to everything.
3)drain whats left of your coolant into a bucket, the drain is usually one of the lower bolt holes on your impeller cover . A copper washer might give it away.
4) remove the carb from the boot going into your engine. the carb can stay connected hanging out of the way on its cables.
5) remove the cylinder head
6) remove any exhaust linkage covers if so equipped, and the screw holding the linkage. there may be a hole that will line up with a slot in the arm/clip. Use an appropriately sized drillbit to stop the thing from turning on you. Be careful, these are fragile (on Yamaha's anyway)
7)remove the 4 nuts holding the cylinder on. you should now be able to slide the cylinder off of the piston.

& cleaning

Inspect the piston for any rough metal, scrapes or gouges. same with the cylinder. if damaged it will need to be replaced. Iron sleeved cylinders can be bored out 1 size and honed, nikasil can be cleaned of minor aluminum deposits with muriatic acid (don't get this on your skin) or will need to be replaced as a unit. Make sure there is no coolant inside the engine case. Crank should turn over smoothly with the bike in neutral.

Clean the old gasket off of the cases where the new base gasket will go. A plastic putty knife does wonders. make sure you get it all off, DO NOT use metal on the sealing surfaces. gasket remover can be used, but don't get any into the engine, and avoid using it where the bottom case halves are joined. Then stuff a rag in the case to keep it clean in the meantime.

Repeat the process for the cylinder, bottom and top if necessary.

Check with your dealer for torque specs.
The piston kit should have instructions. Remove 1 circlip (don't lose it in the engine- (rag is in there right?). Slide the wrist pin out (long socket+ light tapping on it from the opposite side if you don't have a puller). CAUTION: I do not know if the wrist pin bearing is caged or not (check the new one when you get it) if it is not a caged bearing all the little roller pins will fall everywhere if you are not carefull. There is like 25 of them!
Now remove the piston, leaving just the rod. Prep the new piston (gap and install rings...line up gap with ring keeper pin...also, pay attention to orientation...some have an angle on the upper side of the ring. Install one of the circlips, rotate it so the gap does not line up with the hole, gap should be up or down not sideways. Install the wristpin bearing in the rod, slip on piston (usually arrow points to exhaust port...check instructions). now lube up the wristpin bearing and pin, slide pin through, and install the 2nd circlip.
Remove the rag, add a capfull or two of 2stroke into the bottom at this point. use a little break cleaner on a rag to make the gasket surface is clean.Throw down the new gasket. Line up ring in groves, Squeeze with one hand, and slide the cylinder down the piston. Once partway up, rotate the crank so the cylinder lines up with the studs. tighten nuts appropriately. Rotate it slow by the kickstart with the kilswitch held in the off position. Everything should be smooth. With the piston at the bottom throw a few capsfulls of oil in it to lubricate it as you rotate it through slowly. now clean the top, install topend gaskets and the nuts. Reassemble the bike in reverse order, make sure the carb is on tight, and don't forget to ADD COOLANT at proper ratio. Break in mix is gonna be 15:1 or 20:1 somwhere in there, for the first few hours riding anyway. Vary the throttle lots don't be afraid to run it though, just don't hold it WFO for more than a few seconds till everything gets happy. also, Especially when using FORGED pistons. Make sure the first time you start it, only let it idle, don't ride it. Let is get all the way up to temp, then let it cool completely. Do this heat cycle twice.
then continue normal break in.

I don't think I left anything out. Good luck.

May 17, 2009 | Suzuki RM 250 Motorcycles

1 Answer

Bike siezed up.rocking it frees up and starts but locks up

The piston seize destroys the piston, rings and cylinder wall. Bad enough, and repeated seizing, can get metal bits into the crank rod bearing and crank end bearings and seals. This is serious stuff. Sorry to be the bearer of bad news.

Seizing is caused by friction. Not enough lubrication means friction that creates heat. The heat builds and the piston and rings "weld" to the cylinder. A faulty cooling system can also cause heat. Any oil will break down and loose it's lubrication ability when the heat gets too high. A water pump malfunction or plugged coolant lines, leaking coolant hoses, plugged radiator and bad gaskets can create heat.

Other sources are > timing is off, air leak causing the fuel to be too lean, incorrect spark plug heat range, carbon buildup on piston and head causing detonation, motor oil used in gas instead of 2 stroke engine oil and over revs on the engine. I have probably left a few things out but these are the usual causes. Be aware that combinations of small problems can add up to a seize.

The engine needs to be rebuilt. Normally I would just rebuild the top end but since you have had multiple seizes the bottom end is probably contaminated. New crank bearings and seals should be installed. If the cylinder can't be bored then you will need a new cylinder. New piston and rings are also required. Bear in mind, you must find the cause or causes of the heat and fix those problems also. If you don't, the new piston will quickly seize up.

Top rating for this answer! Thanks Kev...

May 06, 2009 | 2003 Yamaha YZ 250 F

1 Answer

While riding my yz 125 it just died and won,t kick up again

  • If a hole in the piston then install new piston and rings. Next, clean the carbon off the head and install a new head gasket.
  • If cylinder wall is scared the piston has seized up. Pull the cylinder off and take it to the dealer. Have them bore the cylinder and return it along with a new oversize piston and rings.
  • While at the parts counter, get a new stock spark plug and a supply of Yamalube Two Stroke Motor Oil. You need to add 4 ounces per gallon when filling up. This will be a 32/1 gas to oil ratio. NEVER ride the bike without at least the needed 32/1 mix.
Please rate the solution as a "FixYa" if able. Thanks!

Mar 23, 2009 | 2003 Yamaha YZ 125

2 Answers

Possable Engine Seize

Use Marvel Mystery Oil, it will loosen the rust that you may have incurred while the bike was sitting. Just one word of caution, if the mystery oil does get the pistons free I doubt seriously that you will have any significant ring seal left. You may be better off removing the heads to see if there is serious damage. You can easily bend a rod if you are not careful and it's not worth destroying the engine because of the rust issue.
What most likely has happened is your cylinders suffered from condensation which will promote the rust. The pistons will not rust, (they are aluminum), but the rings and the cylinder walls will. You may need to simply remove the pistons and run a quick hone through the cylinders, put new rings in and be good to go.
By no means should you attempt to push start it or anything remotely close. You can take a wrench and try turning the motor over by wrenching on the end of the crankshaft where the electrical stator is. A small amount of rust will stop the starter motor from turning the motor over.
Let the Marvel Mystery Oil soak over night before trying anything like turning the motor over. You may be very surprised and lucky if it works.
Best of luck to you.

Dec 08, 2008 | 1991 Honda ST 1100 Pan European

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