Blaster locked up

[blasterisfaster]

Ok so my blaster runs like a champ, it fires up first kick 9 outta 10 times, runs all day without bogging or dieing out, idles smooth, has awesome throttle response. So basically it runs A OK.

Also, i Premix my gas at 32:1

Well today i fired it up after putting on my new clutch cable and let it warm up a bit then took it for a spin, in about 10minutes of running it locked up. I tried kicking it and nothing. I got off the quad and put it in first gear and jerked it forward and back about ten times then i heard a kinda like pop and the engine freed up and fired up first kick, i continued to drive it around for about 30mins and it ran just as it ever did.

Now i just bought the quad and the previous owner had paperwork from yamaha that it had a new topend, (he claimed it had about 2 hours on it, he could be full of it but who knows) Ive put about 6 hours on it after i bought it.

Im a mechanic and i can tell you anything you need to know about 4 stroke engines, All i know about two stokes is how they work, i dont have much experience with them and dont know common issues.

So basically is it just in the nature of two stokes to every once in a while lock up and be fine or do i have something to worry about?

 

[scotj77]

probably an overheating airleak. not a huge airleak but enough to overheat it durring hard riding. need to get a leakdown tester and check her out. that will forsure lock up and run again like that. as soon as it cools it will come free and start right up.

slickerthanyou has them for great prices

 

[yamaha28]

They should never ever ever ever lock up....something happened there. Check compression? Do a leak down test?

 

[blasterisfaster]

I rode it HARD for 3 hours straight the other day and not a single issue, Is it possible that a gasket/seal just happened to break just within the recent few days. And even after it did lock up i rode it hard for another 30minutes and all was good.

 

[blasterisfaster]

Also, when i bought it the oil pump lines were cutoff and they premixed, the people i bought it from looked like they didnt know anything mechanically related so i figured it was never rejetted for the premixed gas. could this lean it out the the point of overheating and locking up?

 

[yamaha28]

Premixing would not requite rejetting. Failure to properly delete the injection system the right way could cause some problems though

 

[blasterisfaster]

how could not properly deleteing the oil injection cause problems?

 

[yamaha28]

how could not properly deleteing the oil injection cause problems?

there is a hole in the carb for the oil injection line, that has to be plugged. Also there is a gear inside the clutch side cover that spins for the injection system, that has been known to fail if you don't use the system, and leave it in there. None of your problems seem to stem from those kinds of failures though, I would just double check it

 

[Blaaster]

A small air leak can make the motor go like a dose of the craps, I mean even better than with the correct air/fuel ratio.

The problem with a little leak is that it creates a too lean a mixture which will over heat the piston crown and can cause a slow piston seize.

Hopefully no damage has been done, but the problem has to be rectified before it is too late.

You defitnatly need to do a compression test and a leak down test before you ride again!

Make sure the oil injection line fitting on the carb is well plugged and the plastic gear is removed or the oil pump may seize up.

 

[Larry's Shee]

Little tip for all who desire to gain knowledge/experience is if you encounter an experience such as this is "limp" it home and investigate as to what/why, not ride it like a cheep whore for three hours It could make the difference between a cheep fix and catastrofic failure.


Spell check: it's CHEAP whore I:I

 

[blasterisfaster]

yes i plugged the injection line well, i was just wondering what just cutting the lines would hurt, would a locked up oil pump cause the engine to seize? or would it cause the little plastic gear to chew up and throw plastic everywhere that can get between things and cause it to lock up. And i rode it for three hours BEFORE the day it seized, only 30 minutes after, still a no no i know. Also i planned on taking the engine completly apart here soon to put all new gaskets/seals in it(it leaks a bit of crankcase oil out of the sproket) Looks like ill be doing this a bit sooner than expected, but its worth saving my motor and some peace of mind

 

[blasterisfaster]

I pulled everything apart today, turns out that one of the screws holding the magnets in the stator came off, i think the screw got wedged in between the gold wheel and the case and caused it to lock up, now the magnet that screw was supposed to hold broke apart and is in peices, it also chewed up the metal edges on the pickup/contact inside the stator a bit, im thinking it may be fine because it still ran and function perfectly after it did lock up and i got it to start. But i figured id fix it right and get all parts that got their share of damage. The inside of the motor is spotless, and has a brand new piston and a clean bore(so the kid didnt lie he got a new topend). Tonight im ordering all new gaskets and seals, the spring for the kickstarter(the kicker didnt come back up), and then the stator assembly.

 

[Blaaster]

The magic word is "Loctite".

 

[blasterisfaster]

oh trust me, i use loctite all the time. this case just happened to be user/builder error from the people i bought it from. Never would happen if i built it, and wont happen when i do build it this time

 

[Larry's Shee]

Glad it wasn't major I:I though can't think of any reason those screws would ever be removed so I blame the factory on that one X(