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Please help yamaha 350

733 Views 31 Replies 4 Participants Last post by  Mech
Hey everyone. New to the forum. Have used it just a bit here and there for some advice, but this is my first time posting. TLDR at the bottom. First a bit of backstop.

Got a cheap non running buggy with a yamaha 350. Got the engine out torn down and cleaned. Heads, piston, and jug were absolutely trashed. Went ahead and split the case to look for any further damage, but everything looks clean. So with help from a shitty online manual and multiple YouTube videos everything is put back together the way it goes. Shifts through every gear, forward and reverse work. Everything was fine. Test fit the other crankcase half, bolted 4 or 5 bolts down, got the shifter arm on, everything was fine. Took it back off, put some yamabond 4 on there, torqued all 15 bolts down to 10 ft lbs ( I know torque spec is 7.2, we'll get to that in just a moment). The main shaft is locked. It maybe moves an inch and a half both directions but won't go further.

This first time I thought what the hell, it's whatever I took it all back apart thinking maybe I had screwed something up. This was my first time working on one of these, so I am liable to **** up. Got it apart, and everything was working again. Cleaned it, put yamabond back on, and this time I set the torque wrench to exactly 7.2 lbs. Tightened everything up, and what do you know, still locked. Backed the bolts off to where they are barely touching, and it's tight but spins, back them all the way off, and it spins fine.

Any one else been in this situation? I want this thing back together and running again, but at this point I'm so tired of cleaning this yamabond off the case it's not even funny. I pretty much know its a tolerance issue, but i am unsure of where to go from here. Any assistance would be vastly appreciated. More than happy to upload pictures if needed.

Tldr: When I tighten the bolts on a yamaha 350 even below torque spec, things refuse to move freely.
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Sounds like the end float on one of the shafts is wrong.. A misplaces shim perhaps between a gear and shaft or two gears.

Get yourself a tube of loctite master gasket.. Brilliant stuff. Doesn't harden till you clamp things together, doesn't harden in the tube, ever, really economical to use because of the syringe it comes in, doesn't leave strands of hardened sealer inside the engine, the excess just wipes off with a rag, fills gaps up to thirteen thou, good for air, fuel or oil. Never leaks.. no matter how old it gets.
Appreciate the response a ton. Noted on the locktite for next time. Already spent 12 bucks on this tube of yamabond, so I'm going to make it work haha. Trying to keep this as budget as possible without skimping too much. Paid 100 dollars for the buggy as it was someone's wood toy they used and abused then left to die.

As for end float, could you explain that a bit more. Any common places to see that. I did have one washer that I couldn't figure out where it went, because it came flying off when I split the case. I found a video, and he has it exactly where I put the missing one. I'll snap a pic real quick if possible. These 3 here have washers, and the one on the left has a washer on the top and bottom. I did replace the bearings on this case half, as they were locking up. They seemed to go all the way in at the time, but just to be sure does this photo look correct? I know it doesnt look perfectly clean as it is, but everytime i put them together with some new oil a bit more of the old stuff finds its way in. As i said before, really appreciate the help.
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Don't really have an exact year on it. It was bought already fitted to a buggy, as such I don't have the code that would have been on the frame. Just an engine code. The bearings all look flat on the other side.
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Don't really have an exact year on it. It was bought already fitted to a buggy, as such I don't have the code that would have been on the frame. Just an engine code. The bearings all look flat on the other side. View attachment 4248
From what I've read online and seen it looks like most of the transmissions are very similar if not the same in these things.
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I'm more suspicios of that shaft with the circlip on.. I bet that's meant to have a washer against it.. Possibly one of those washers on the other shafts...

You need to tell us the exact year and model prefix or suffix so we can check it in a book Fish..
Went back to the only manual I could find online, and it looks like that gear is proper. I've got pics of what I could find.
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Okay guys, I've had a bit more time out in the shop today. I think it's definitely this "drive" gear. If I hold the shaft of it, I can get just about the same type of play as when I have it together. It moves back and forth an inch or two and stops in both directions. This shaft has to be getting pinched somehow.

There is some kind of seal that I put back behind the bearing pic for reference that I thought could have played a role, but I put weight down on it, and It's not locking up in that bearing.
Pic attached of the gears I'm talking about, seal, and bearing with seal underneath
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Appreciate the input yall. I'll try removing the washers when I wake up in the morning. It's a 350 off a warrior as far as I know. From looking at it, the forks really only have one place to go in for each. I took good pictures pulling it apart of each of the designations, and where each code went. I'm leaning towards washers or something of that nature at this point.
Guys I think I figured it out. I really don't want to believe this is all that was causing the headache the past week. The gods were on my side, and I traded a kid a 3ds and a few xbox games for another parts engine to compare too. It had a blown rod bearing, and metal everywhere in the case, but I've been at this most of the night and all day today. I think I've got it. This counter drive gear... something was up with either the shaft being bent or this inner trace being out too far. I put this other one in, and she cranks just fine. I'll keep you all updated on how it goes from here. Also @Mech If you're the same from quadcrazy, I saved your guide on timing to use whenever I get to that point, as I'm sure to need it. Besides that I really appreciate the wealth of knowledge you all bring to the table. If it wasn't for you all, this probably would have been on the bench a lot longer. As for me, it's time to get some sleep haha. Also, if anyone is interested, I'll take a snapshot of the shitcart this is soon to be attached to. I know it doesnt look like much now, but at 100 dollars, I couldn't say no. Once this engine is done we'll be getting her painted, fixing some of these dog s**t welds, among a few other things. Will update in the coming weeks with how she's going.
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Like he'll, just like the rest of it😂 Electrical should be fun too. Most of the connections didnt even have wire nuts or but connectors. Literally just wrapped together and taped, but im thinking i may just get a kit i found on ebay that has the stator, computer, some power control box, ignition coil w/ wire, ignition, and harness for 150 instead of decoding this rats nest and hoping all the electronics are working. Who knows how long its been outside before it got here. And the kit is only 135-150.
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So that thing had a briggs or such originally hunh? Yeah toss the rats nest. Not much to rewire really, if you'd like I'd help over the phone, maybe draw you up an electronic map.
That would probably be really helpful, but I'm just worried about all the components working. I mean it did crank before, so it should be fine?? My main worry is that one of their power connections was on the frame, and burned it out. You can kind of see the burnt pin on the silver box in one of the pics. Not sure on the past configuration. But do you guys see those welds😂😂😂. I do not know what happened there... the worst was on the cargo thing on the back, but we cut it off when taking the motor out. I'll have to grind them down and re weld them
I threw up in my mouth a little when I saw those pictures.
And I agree, Mech is really helpful.

Haha, don't blame you one bit, but 100 dollars. I have plenty of time on my hands, so... WORTH IT.
Well dude! What's up with this thing.
Haha, duude... I know. I've been so busy. I got the jug and piston back on the other day. All the rest of the electronics came in. Debating whether or not to lap the valves before putting the head on. Guy claimed the atv it came from was running. Unsure of how well. Between basically a job, 2 businesses, and a antique shop booth we opened the week before last this has gotten shoved to the back. Also realized I lost a cover for it somewhere in the garage or outside while we were working on it. Idk how the he'll that happened. This week though I'll decide and get it back on track again. I guess we decided on not painting the frame for the time being as I'd rather make sure everything is 100 before worrying about cosmetics
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Oh heck yeah, always best to get things going and have a ride before deciding how much time or money to spend on them if they are unknown..

And I don't think I'm much help to anyone today.. One son came around yesterday at 4:30 and didn't leave till a bottle and a bit of bourbon later at 4:30 AM..

Coffee please..
😂😂 Sounds like a good night
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