[chuckrussell]

my trx200sx runs and drives some what it idles fine but when I give it gas I can hear the topend I rebuilt the motor after the valves stuck and bent I put all new valves and cam chain and tensioners in it does anyone have an idea of what could be the problem I have done everything thanks

 

[SamUK]

Are the valves and timing set correctly? Possibly blocked jets in carb? Old fuel?

 

[chuckrussell]

That would make sence i can check all that im just not use to these small engines

 

[fishfiles]

I have had 200SX's and did an upper rebuild , the valve adjustment on that engine is kind of crazy with that lever and numbers , I would tell you to try and adjust the valves and just use the lever as a guide line and go by feel on the rockers , the rockers shouldn't be tight where they are making contact with the valve stem , and not so loose that they rattle

 

[chuckrussell]

Ive done that you go untill u feel it then go back one line and that didnt help. Im gunna clean the carb rn and check the timing again its like the 58 time i checked it but if its off that would make sence. When i got this bike and got it runing it had this same top end noise then the valve stuck and bent at.

 

[SamUK]

Stands a good chance the timing is out out then. Did you fit a new timing chain?

 

[fishfiles]

...I would figure if it bent a valve then the timing chain was heavily wore for that to happen ,

you might be fighting more than one demon , the carb may need some cleaning and / or have another problem

you may have missed the mark marks when reassembling ,

the sprocket could be severely worn , if you didn't already change it , and it be off from the pitch being worn

the rocker arms , rocker shafts or shaft journals could be worn out



you may have bent the connecting rod when the valve hit the piston , did you see the piston come all the way to the top of the jug deck when the head was off during your upper build ? a bent rod makes it run out of time and at a less compression , cause it won't achieve top dead center

 

[chuckrussell]

I did put a new timing chain in it and i sized up the journals and they where good

And the valves didnt hit the pisten they just stuck to the head and bent when i took the head off i didnt see any dig marks as their would be if the valves smack the piston it just dont make sence it sounds like a kitten on an idle but as i give her any gas i hear the topend

 

[fishfiles]

I don't get the bent valve thing ! Quote "they just stuck to the head and bent when i took the head off " Quote

 

[chuckrussell]

They stuck to the head and bent. When i took head off i didnt see any dig marks. I still have the old valves if you want me to take a pic of them and i could send a video of the bike running then ill give it some gas so you can hear it

 

[retro]

Sounds like a valve seat has loosened up in the head casting. Thats the only way a valve can get bent without hitting the piston. I take that back... if a guide is real bad, broken or split open, a valve can get bent. I'd yank the head and have a look at the valve guides and the valve seats before starting up that motor again.

EDIT: Replace the valve springs too. They are probably junk.

 

[chuckrussell]

When i put the new valves in it i put all new guides and grounded the new valves. I think the pre owner ran some nasty gas in it and it gummed up everything cuz the carb was all gummed up too when i got it.

 

[retro]

Refrain from posting adult language please. Thank you.

 

[chuckrussell]

okay thank you...

 

[chuckrussell]

Hey guys anther crack at the 1986 trx200sx ive ran into some more problems with it it still has the same top end noise :sad when i give it gas but when i started to mess with it last week it started right up and ran great rode it around for a couple of hours then when i parked it i let it run and idle until it died i tried starting it back up and its not firing i bought a new carb and coil for it its getting fuel and spark now but still wont fire itll fire when i spray some carb cleaner into the carb it'll start up and run for 5 seconds then die does anybody have an idea of what could be the problem thanks.

 

[fishfiles]

the tank could be clogged up at the petcock or old fuel

 

[fishfiles]

Sounds like a valve seat has loosened up in the head casting. Thats the only way a valve can get bent without hitting the piston. I take that back... if a guide is real bad, broken or split open, a valve can get bent. I'd yank the head and have a look at the valve guides and the valve seats before starting up that motor again.

EDIT: Replace the valve springs too. They are probably junk.

another couple of ways to bend a rod or a leaking fuel float valve ,
water or fuel ingestion on top the piston , you try and start it and BAM , bent rod

 

[retro]

Check compression, it may have destroyed the piston by now. It sounds like the cam is installed a tooth advanced and the motor is running some severe detonation.

 

[chuckrussell]

Thanks guys for the help after sitting and thinking and reading all the reply's i checked the timing and it was a tooth off so i timed it and its running like new i'm gonna order a new chain adjuster because this one i think is slipping but ill keep you guys posted if it happens again with the new adjuster.. thanks again