Diagnosis Help

[Baley69]

Bike – 1999 Yamaha Blaster stock except a pipe. Had fuel, and oil in the injector reservoir.

Problem – My son was riding at the dunes on the flats, probably high RPM’s and the quad stalled. I jumped on it and could not budge the kick start. Towed it back, and got it to kick, but will not start. Have not touched it since.

I'm afraid it blew, but I have no experience with 2 strokes, and do not know what to do from here.

[fearlessfred]

you can do a compression check to confirm that you seized the piston,but if it was me i would go ahead and pull the topend.its very easy on the blaster.if you need instuctions just ask

[Baley69]

I have had this quad for over two years, and have no idea when the last rebuild was anyways, I think that is a good idea. Im I better off pulling the engine out of the chassis?

[trailrider894]

Originally posted by fearlessfred
you can do a compression check to confirm that you seized the piston,but if it was me i would go ahead and pull the topend.its very easy on the blaster.if you need instuctions just ask

He can't do a compression test if he can't kick over the motor. Take off the top end.. Chances are the pistons just seized and now it is stuck. Just yank the top ends off while its still on the quad and see what's wrong. If the piston is missing a skirt or pieces have fallen off, you will have to either split the case to make sure there isn't any hunks of stuff in the case that could damage any of the tranny parts. Check the cylinder for any deep scarring or damage. If there is any deep scarring or damage you will either have to get your cylinder replated or re-sleeved. Also check to make sure your crank rod doesn't have a lot of side to side play, if it does you will more than likely need to replace the crank. Hope that helps!!!

[ridehonda400ex]

Ive heard that those oil intectors can not work sometimes and cause it to blasters to sieze up. My buddy has a blaster and has never had the oil injector fail on him but is always a possibility it happened to you. Sucks too

[CJM]

Originally posted by ridehonda400ex
Ive heard that those oil intectors can not work sometimes and cause it to blasters to sieze up. My buddy has a blaster and has never had the oil injector fail on him but is always a possibility it happened to you. Sucks too

I dont even bother with them, I always mixed myself-I dont trust those injectors since they often fail.

It probably seized, as already explained yank the topend and see whats up.

[trailrider894]

Originally posted by CJM
I dont even bother with them, I always mixed myself-I dont trust those injectors since they often fail.

It probably seized, as already explained yank the topend and see whats up.

I immediatly unplugged the one on my ol PW80 ( makes a great transport to the showers when camping. ) I actually noticed a decent power gain...

[fearlessfred]

Originally posted by Baley69
I have had this quad for over two years, and have no idea when the last rebuild was anyways, I think that is a good idea. Im I better off pulling the engine out of the chassis? i would pull the head and cylinder off first with the the motor in the bike and determine the the damage is, before pulling the motor.it may not have to be pulled .on a .two stroke the transmission is seperate from the crank and very unlikly that there is piston parts in the transmission .dont assume that it seized from lack of oil. if it seized from a hole in the piston and the piston melted on the exhaust side,then the motor leaned out or the piston could have cracked and broke from wear only. most often ,any debri can be cleaned out without pulling the motor from the bike and the rod has sideplay in it ,but no up and down play in the big end rod bearing.beleive me when i say that there is very little if any extra effort to pull the head and cyinder first before going any farther .post what you find and we can help you get her running again

[fearlessfred]

Originally posted by trailrider894
He can't do a compression test if he can't kick over the motor. Take off the top end.. Chances are the pistons just seized and now it is stuck. Just yank the top ends off while its still on the quad and see what's wrong. If the piston is missing a skirt or pieces have fallen off, you will have to either split the case to make sure there isn't any hunks of stuff in the case that could damage any of the tranny parts. Check the cylinder for any deep scarring or damage. If there is any deep scarring or damage you will either have to get your cylinder replated or re-sleeved. Also check to make sure your crank rod doesn't have a lot of side to side play, if it does you will more than likely need to replace the crank. Hope that helps!!! baley 69 posted in his first post {towed it back,got it to kick but would not start} and the only way for piston parts to get into the tranny is for the cases to break and alltho it does happen, it is not very often

[trailrider894]

Originally posted by fearlessfred
baley 69 posted in his first post {towed it back,got it to kick but would not start} and the only way for piston parts to get into the tranny is for the cases to break and alltho it does happen, it is not very often

FUlly aware of that.... I am currently changing out 3 top ends of KX's, one of which grenaded so don't discount my knowledge.

[CJM]

Just because you dont think anything got into the cases-it isnt always true. When anything grenades like you had its entirely possible.

[fearlessfred]

i think we all agree that baley 69 should pull the topend and see whats up before pulling motor out of the bike?

[trailrider894]

Originally posted by CJM
Just because you dont think anything got into the cases-it isnt always true. When anything grenades like you had its entirely possible.

I had tried to rinse mine out the best it could, but ended up splitting the cases on my KX250 and got some nice hunks of piston skirt. Its really the only option.

[Baley69]

Thanks guys! I will pull it sometime this week and post what I find when I do.

[rrguy]

IDK without hearing what it did before it stahled, but Sounds like a light seize if you can kick it over once it cooled down.



Simply pulling of the exhaust you might be able to see the piston an its condtion. Luckily the blaster is a simply top end an once the head + cylinder is off you will be able to see if rod an crank bearings are ok or piston an cylinder cond etc...

I understand it got towed back but simple notes like if you can kick it over in neturel but not while in gear help locate if its motor or trans issue. It sounds simple but sometimes in the excitment people forget it stahled while clutch was engaged an in gear an then put it in netural an pull clutch to move an try start then all of a sudden you can turn the motor over. just a check worth doing before tearing into motors.

[Baley69]

UPDATE....

Thank you all for your input! I took the head off, to find a warn piston and messed up cylinder...

I took the cylinder to my local shop, and they measured the bore to find out that it was still stock, so they will clean up the cylinder, and I will install a new piston and be good to go.

2 questions now...

The top of the piston was eaten away on the exhaust side of the cylinder. (I can post some pics if that would help) Does this indicate anything? Does this mean that my oil injector failed? Either way, I'm going to disconnect the oil injector and just mix from now on.

Is there something I should look for, or do with the cylinder head off of the engine?

[fearlessfred]

no ,your oil injecter did not fail.the motor for what ever reason leaned out on the main jet (that is if it failed when throttle was held wide open) or you have an air leak some were. you need to detemine why it leaned out before repeating the same thing.other things could have caused the lean condition
1, airbox lid removed
2. really cold temps
3. different fuel (fuels can be diff. winter to summer )
keep in mind, that when you premix your oil,gas you will probaly have to increase the jetting, because with the oil injection the oil does not go thru the main jet and when you use premix, the oil goes thru the main jet and that leans it out

[fearlessfred]

you still need to check the bottom end while it is apart and make sure it is clean and the crank spins freely with no gritty feeling,the rod should have no up and down play,but does have a little side play (dont confuse side play for up and down play) see if you can look into the oiling slot at the bottom of the connecting rod and see the bearings are shiny or dull. a motor that has had sand ran thru it can have the hard shiny surface taken off the roller bearings

[Baley69]

Ok, thanks guys! So I am picking up the parts today to put it back together. Any tips or heads up for puting the top end back together?

[fearlessfred]

Originally posted by Baley69
Ok, thanks guys! So I am picking up the parts today to put it back together. Any tips or heads up for puting the top end back together? first of all,i would make sure everything is clean.make sure you clean the bore with soap and water ,dry quickly and apply wd 40 or twostroke oil. make sure the bottom end has plenty of two stoke oil ( a small puddle at the bottom is ok) put one side wristpin circlip in the piston,make the rings are in there correct groves and the correct side facing up. install piston part way into cylinder.make sure the rings dont hang up on ports. you want to leave enough of th piston hanging out to get the wristpin clip on the other side. put a clean rag over the crank area ( this so if you drop the clip it doesnt go to the bottom ) have someone help you hold the cylinder as you slide wristpin into piston and connecting rod and install circlip. there is another methed of putting the piston on the rod first ,but i dont recommend it