[Jegs87trx350]

Hey everyone! So I'm not too far in but I've got some questions... firstly, are the piston rings supposed to be fairly loose on the piston? I've never dealt with them before.
And I cannot seem to decide whether or not there is play where the connecting rod meets the crank because the gears all move and make noise when I push and pull on the piston. Honestly it feels pretty good to me. I can't discern any movement that shouldn't be there.
And how do I check if the wrist pin is bad?
And then lastly, since both of my 350's are making similar noises from the crank (or so it seems) is there any part that often wears out on these that would a cause a noise like that? Can a wrist pin not make any noise at the piston but have that sound travel down the connecting rod to the crank? I've tried many times with my stethoscope and the noise is always loudest when I've got it near the crank. I'm taking it out anyway because I want new crank bearings in it. I'm just trying to get ahead if it turns out not to be the crank or rod bearing. Thanks a bunch!

 

[Manny]

rings should rotate freely with no hangups in the ring grooves.

if your moving gears trying to check for lower rod bearing play, you are moving the rod too much, just a real small gentle straight up and down will give you an idea if there is play, it is usually obvious when there is a bad bearing.


consult the manual for wrist pin specifications to see if its past its service life (I always replace these anyways when apart)

with the top end tore down you can measure your small end of the rod for wear, also, make sure your one way bearing isn't making all the noise from the centrifugal clutch.

make sure and check that your oil pump isn't worn either while everything is apart.

 

[Jegs87trx350]

Thank you for your response! The rings do move freely that's for sure. I will check the oil pump when I take the clutch cover off. I didn't check it last time for some reason. I did however check the one way bearing and it seemed just fine. Didn't look worn at all and spun freely and smoothly.
I'll be more gentle when pushing/pulling on the piston and see how that goes.
In your experience, can a worn wrist pin make noise through the crank? But no sound at all at the wrist pin?
The cylinder walls look pretty good. If I'm not mistaken I think i can still see honing marks?
I really wish I had some experience with this stuff. I learn quick but not in the dark. Thats why I have to ask questions that probably seem obvious to you guys. I'll be working on it more tomorrow so I'll have more pictures( and more questions). Thanks again!

 

[retro]

Its easier to feel slop in the lower rod bearing after the piston is off. You can slide the end of the wrist pin into the rod just enough for the pin to barely poke out the other side of the rod... then use that wrist pin stub for added leverage and control while pulling and pushing on the rod. If there is any up & down slop felt at all, the rod bearing is bad.

Same goes for the upper end of the rod... if you can feel slop or wobble with a new pin in it, its junk. Measure it though... if it measures bad its junk no matter how good it feels/looks.

Check the end play on the lower rod bearing with feeler gauges. Should be about .015"-016" range... but the service limit is high... about .030 or so I imagine. Specs are in the manual. If end play is high I'd suspect a worn out bearing or worse.

Piston ring grooves wear (they get hammered out over time) can be checked with feeler gauges between the upper edge of each ring and its respective groove/land. Specs are in the manual I think. You can yank the top compression ring off from the piston and check its end gap in the bore (square it up in the bore near the top of the bore where wear is highest) too... to get an idea whether its at the end of its life or not before measuring the cylinder.

How far are you intending to go with this rebuild? Splitting cases? Fresh bore & piston? Or just fixing and freshening what you have to?

 

[shadetree]

looks like its burning oil to me from your pics^^^. stick wrist pin into the top of connecting rod ( with piston off ), just the end of the wrist pin, reason: the ends of wrist pins don't wear like the center does !. once in just enough to be flush with other side, lift up, and push down on the other end of the wrist pin, you should not feel any movement !. if It does ?, then you connecting rod is bad where the wrist pin is, which means, the whole rod is bad.

 

[Jegs87trx350]

I will do fresh bore n piston if I need to. I'm planning on at least rings, wrist pin, rod, all bearings in the the crank case, maybe valves, guides, seals and springs etc. I'm gonna wait on the stator,i can replace that anytime. I may end up waiting on the valves too. Compared with pulling the bottom the top is easy and I really don't have the $ right now or the tools for even removing the valves let alone reaming and all o that stuff. That's why I'm kinda going slow with this project. Normally I'd have torn everything apart real quick but I'm determined to go slowly and be thorough. Besides lack o funds. I just got another roof yesterday and I still have a lot of work lined up but winters are usually looooong here in Maine.
And a question about it possibly burning oil? I never saw smoke and the oil level would stay unchanged for the whole time until I changed it. I never had to top it off. Could it still have been burning some oil? Shade you thought it looks like its burning oil? Is that considered really bad carbon deposits? I'll admit its pretty thick! Thanks guys and I'll be doing more on it today for sure.
Unrelated question, do you fellas have county fairs that come through yearly by you? Do you attend? I'm just curious. We've got one about a half hour away and a different one an hour away each year.

 

[retro]

Yep, still have small county fairs here. Still old-school traditional too... like stepping back into the 1960s. Its cool because the folks like to show off their old farm equipment and I love really old stuff that still works!

Your wet carbon buildup in the combustion chamber (& on the piston crown) is caused by 30 years old valve seals finally giving up. No worries, its expected and easily fixed. If you can find a small calibur gun cleaning brush that will fit down the valve guides clean them out good with solvent and a bore brush. Then oil them & fit new valve seals on each guide before reassembly of the head. You'll need to get eyeballs on the valves and valve seats to see how bad they are wore... it only takes a few minutes to take valves out, so borrow or rent a spring compressor for an hour or so... you'll probably want to lap them all (very) lightly if they are still in good shape. Mark the valves and springs as you take them apart so they'll go back in the same hole....

Yer gonna have fun!

 

[Jegs87trx350]

Hey guys. Not much to update but I figured I'd post just the same. I'm kinda stuck for now because I'm thinking it may even be next spring/summer before I can afford the parts and I don't want to tear everything apart and lose stuff or forget how things go back together. The manual is awesome but its good for me to have that stuff fresh in my memory if possible. So I'm really going slowly this time. Unfortunately there's no rush this time! Its a real bummer too because I really want to get back riding! Or fixing. Anything is preferable to doing nothing with the wheelers. I probably should've waited to start this post but you guys did give me some good advice and tips already.

The top of the connecting rod is definitely bad. The end of the wrist pin has play when I put it in the rod. So I know It needs to be replaced regardless of What shape the bottom is in.
How in the heck do you clean off the piston? That stuff is REALLY baked on there! I soaked it in carburetor cleaner for a night and used a wire brush, then put it in engine degreaser(ran outta carb cleaner) and tried brillo and steel wool with plenty of elbow grease with almost no effect.
I've removed the center driveshaft and the starter gears/starter is next.
I've been lugging my firewood up from where I've had it stacked and drying since last March. Almost all nice red oak. Between work and that and reading I'm plenty busy but just not busy doing what I like best. Its all good though. Maybe I'll get a couple more bid jobs after that roof I'm doing and I'll be able to get the parts after all. Have a great night guys! And thanks very much as always!

 

[shadetree]

bench grinder with a wire wheel is how I clean pistons.

 

[retro]

Easy-off oven cleaner (or gasket remover in a spray can) usually loosens the carbon buildup so you can get it off too. Only thing is... that stuff is nasty... if left on aluminum for a long time it will etch it, and sometimes discolor it depending on the alloy. If you are going to replace the piston anyway (I would, since the wrist pin and rod are shot) ya got nothing to lose...

 

[SamUK]

Hydrochloric Acid is great for cleaning aluminium, 50/50 acid/water ratio I would advise though followed by washing with boiling water afterwards. I use this on nearly all alloy parts now with great results.

 

[retro]

... So I'm really going slowly this time. Unfortunately there's no rush this time! Its a real bummer too because I really want to get back riding! Or fixing. Anything is preferable to doing nothing with the wheelers. I probably should've waited to start this post but you guys did give me some good advice and tips already....

My best friend says (all the time) it doesn't ever pay to be in a hurry... and he's right when it comes to tackling projects. Take your time, think things through, compile lists, label parts in bags as you take them off, take your time researching part numbers and shopping for parts... and talk about stuff all ya want to! Everything you do helps to keep your head in the game and taking your time generally provides fresh thought and new opportunities. Plus, we like to read all we can about this stuff... can't get enough... so go ahead and hit us with it...

 

[Jegs87trx350]

Thank you! Really kind of you to say. I will try those things to clean off the piston. I have a bench grinder but no wire wheel for it.
Will I get into trouble if I unbolt and remove the drive output assembly from the lower left crankcase before taking the crankcase out of the wheeler? It looks to me to be easier that way but the manual says to pull the crank case with it on and remove it after.
That's where I'm at now. After that I'll pull right and left covers off and then take the crank case out. I've been sanding and painting rusty parts and just working on it a little at a time. Lugging a lot of wood too. I bought an old jonsered 455 from the same fella I got the foreman from. I guess they are the least popular jonsered's? Part of the "520" family whatever that means. I know its a step up from my poulan! That thing really winds up and cuts like a devil. I just had that one question about the output shaft assembly for now. I think I can just take it off but I figured it's smart to ask. Thanks very much all! This site kicks @$s.

 

[shadetree]

Thank you! Really kind of you to say. I will try those things to clean off the piston. I have a bench grinder but no wire wheel for it.
Will I get into trouble if I unbolt and remove the drive output assembly from the lower left crankcase before taking the crankcase out of the wheeler? It looks to me to be easier that way but the manual says to pull the crank case with it on and remove it after.
That's where I'm at now. After that I'll pull right and left covers off and then take the crank case out. I've been sanding and painting rusty parts and just working on it a little at a time. Lugging a lot of wood too. I bought an old jonsered 455 from the same fella I got the foreman from. I guess they are the least popular jonsered's? Part of the "520" family whatever that means. I know its a step up from my poulan! That thing really winds up and cuts like a devil. I just had that one question about the output shaft assembly for now. I think I can just take it off but I figured it's smart to ask. Thanks very much all! This site kicks @$s.

do not remove the output shaft from the motor !!!, unless your tearing it all the way down ?, your gonna kick yourself in the nutz for removing the output shaft !!!!!!!!.

 

[Jegs87trx350]

See! I'm glad I asked. Even more glad you answered! Do I just have to loosen the rubber boot then to get it to separate from the rear driveshaft once I'm ready to pull the crankcase?
And this question is way early but; Do I actually need a press to remove the crankshaft? I saw that in the instructions.

 

[shadetree]

See! I'm glad I asked. Even more glad you answered! Do I just have to loosen the rubber boot then to get it to separate from the rear driveshaft once I'm ready to pull the crankcase?
And this question is way early but; Do I actually need a press to remove the crankshaft? I saw that in the instructions.

your correct, just unscrew the boot band, slide the boot off the output shaft, there is a u-joint inside, it pulls right off the rear output shaft to the drive shaft. no, you do not need a press to get the crank out. I just use a 2lb hammer, block of wood laid on the end of the crank, and go to town, lol. DO NOT HIT THE END OF THE CRANK WITH ANYTHING SOLID !!!. if you were to use a press ?, then yes, it would rest on the crank, but you can't whack on anything hard laying on the crank when using a hammer. I bought a 20 ton shop press awhile back from harbor freight, about 170 out the door I think it was back then ?, well worth the money if your doing stuff like pressing ball joints, bearings, that kinda stuff, money well spent, not sure how I got by all these years without a shop press ?..but I did !..lol.

 

[retro]

...I bought an old jonsered 455 from the same fella I got the foreman from. I guess they are the least popular jonsered's? Part of the "520" family whatever that means. I know its a step up from my poulan! That thing really winds up and cuts like a devil....

That old Johnny is a 44cc model from the 80s or early 90s I think. It was not a bad saw in its time... its a vertical cases design, homeowners grade saw. Folks bashed 'em because they were inexpensive to buy and they don't have a Husqvarna or Stihl sticker on them is all...

I'm a Stihl pro saw guy myself... but I used an old 44c saw I rebuilt for many years cutting firewood, pulling an 18 inch bar and chain. I say if it gets the work done every time you put it to work, its a good saw no matter the brand name. If it was priced cheap you can just smile at the bashers... or cut their saw in half with yer ole Johnny when they won't shut up!

 

[Jegs87trx350]

Hey guys! My internet is barely working at my house and I don't have enough cell service there to use the net. So I'm just writing real quick from my work to let you know I appreciate your responses. Hopefully the company will get it straightened out soon and I'll post more. Not much to update anyhow. Take care n thanks again!

 

[shadetree]

Hey guys! My internet is barely working at my house and I don't have enough cell service there to use the net. So I'm just writing real quick from my work to let you know I appreciate your responses. Hopefully the company will get it straightened out soon and I'll post more. Not much to update anyhow. Take care n thanks again!

lol, no rush, i'm sure one of us will be around here to help..lol.