Hey, here's the start of my journey into working on the 1995 XT350 I bought back in January. All these posts are cross posted on another forum, so please forgive any odd formatting or discontinuities. I'll add original post dates in and split each post from that forum into another reply here. Enjoy!

Edit: forum must not like triple ellipses and having the w's in front of links, updated.

Feb 12 2025
Images link:

imgur.com/a/xt350-images-feb-12-2025-1fBdA7Q

Been wanting to get a dual-sport for a while now, with the conditions that it was: road legal, clean title, passable condition, around 300cc and under $1000. Bonus points were given if it was a Honda or had a square headlight.

This one fit most of the bills, so I ended up going to look at it. Not great condition, but I felt it was fixable. Didn't run, had sat for 2+ years, but turned over and had a lot of good parts to start with, along with brand new looking tires. All the plastics were also in good shape, other than the decals. That's about where the good ends, though.
First looks showed that it probably hadn't been cleaned since it was ridden, which while not detrimental, just seems lazy and like poor ownership. Entire bike was caked in mud, except for the tires somehow??? Why would you bother to replace the tires but not spray the bike with a hose? Battery had also cracked and leaked all over the side. The tank is a replacement from a Honda XL of some year, and included likely the worst paint job I've ever seen. The PO said he was proud of the paint job as well, without a single bit of irony. Headlight basket was entirely messed up and held together with zip-ties, haven't even bothered to test if the lights work yet. Rear blinkers replaced with some tiny and borderline unsafe LED junk, those will get put back to stock eventually. Carburetor has been messed with in some way, lots of hoses plugged with no less than three unique screws, and this carb seems much more complicated than the Keihin carbs from my Hawk. Exhaust is rather rusty, but the baffles are there, and it could be cleaned and painted just like the exhaust chamber I did earlier. Both front and rear sprockets are also heavily rusted and toast, chain too.

And now for what really set me off.
Started going through the checklist of getting it to start, changed out fuel, checked petcock operation, went through the gears, nothing out of the ordinary. I figure to check the airbox since it's a dirt bike; if the rest of the bike is covered in mud, there's bound to be some in the airbox.

Pasta. There was pasta in the filter. I really, really wish I was kidding about this, but no. There's an entire **** meal in the airbox. Along with what looks to be a human bite mark in the filter foam. The only inlets to the airbox are tiny, alongside being behind some flaps and plastic. I texted the PO, who claimed to have no idea how it got there, but I have my doubts on that. I kept thinking that if I found soup or something instead of oil, then someone was getting their teeth knocked out. The worst part? Bike still didn't start after removing it.

So I dig a little deeper, drain the oil: full of metal shavings, absolutely shining with them. Not a great sign. Remove the filter and strainer, also loaded with them. Then, remove both crankcase covers and find an interesting situation. The right cover has been practically milled by the crankshaft, where the retaining nut must have backed off at some point and rattled around for ages. Bit a massive section into the cover, thankfully without going through it, ruined the threads on the crankshaft and the retaining nut, and did some superficial damage to the clutch basket.

That leaves me where I am currently, in the process of getting the engine out of the frame and taking the whole lot apart in order to service the crankshaft. I guess if I wanted experience working on engines, I'm certainly getting it , no reason not to if I already need to disassemble the whole thing.
Sidenote: where do Yamaha engines hide all their oil?! Every time I think I've drained all of it, it leaks a bit more out like an untrained puppy.
 

Hm, my Imgur link was removed. Is there a restriction for new members? I can't find any info about it.

This sounds like it's going to be quite an undertaking.  Can't wait for the next installment!
 Jonathan

As a man of some experience in such matters, I await your journey with baited breath.
Must admit though, pasta in the intake is rather a novel experience.... Even by my standards.

IF ever there would be an anomaly in an adventure, you’d be the one to find it. (:

Maybe someone was thinking 'fasta pasta' feed that piston some carbs and go!!!

Really struggling to figure out how to add any pictures, text alone doesn't tell the whole story. Anyways, here's the next set of updates.

Feb 18, 2025

Images link: imgur.com/a/feb-18-progress-yufABfv

This was quite a process by myself, having the swing arm pivot as one of the engine mounts made it really difficult to remove. Can start going through the disassembly and labeling process now. I’ve ordered a bunch of tools that I frankly didn’t even know exist including a crankcase splitter, valve spring compressor and the particular rotor puller. More research is required first, though.

May 15 context: without the images this one doesn't make sense, I pulled the engine from the frame and got most of the frame stripped.

Here's a bonus since the previous one was so short.

Feb 23, 2025

Images link: imgur.com/a/feb-23-progress-gquPsUF

I've started the disassembly and cleaning process, with a little difficulty. I've already needed to go buy more tools twice, Overall the inside looks to be in pretty decent shape, I borrowed a calibrated micrometer set from work to check all the dimensions of the camshafts and piston, everything is within spec thankfully. The oil caps were hardened to plastic, along with a bit of discoloration on the valve cover. Valves and piston were absolutely caked in carbon, I don't really know what good valves are supposed to look like or what typical deposits should be with this being my first time, but I think these are exceptionally bad. I went at them a bit with solvent and a wire brush, but I'm not sure if they should just be replaced or not. Another odd thing is that when the head mounting bolts were removed, two of them seemed right and were oily, but the others were bone dry and starting to rust, along with some heat-welded bits on them. My current suspicion is that this engine must have suffered an oiling failure at some point that lead to overheating, on top of the crankshaft nut backing off. On the bright side, the gasket surfaces are cleaning up really well, so I can get those on order and ready for once I finish the lower crankcase. I need to either find a shop that could soak these for me or buy a large parts cleaner, these things could use it.

May 15 context: The entire engine was filthy when I got it, the outside looked like rust even though it was aluminum. Just tons of caked on dirt. Valves were terrible, very caked in deposits.

You need to use a third party host such as Imgur in order to post photos.

Some " guesses".
It may well be that the oil path up to the top end is via the bores that those oily two bolts run through.  I have seen a few yamaha engines like this.  IIRC TTR125 and SR125.  If so the dowels at the top and bottom of these two bores will be significantly larger than the others.

You do not state the mileage or I missed it, but excessively carboned valves are usually down to worn valve guides and or a badly fitting air filter. Since you already measured the piston/bore, I guess we can discount an oval cylinder / worn rings adding to the deposits on the piston.  Without pics it is hard to determine excessive.

Pasta in the intake. I will adopt an american accent. Yes sirree Bob, seems you had a
critter living in your airbox.  Edit.. Take care removing the pasta, it may well be rodent poison.

I had a quick look at the XT350 carb and it appears to be an odd double choke design.  It has also been branded as worse than garbage by most owners from what I can see to press.  This may be why it has been tampered with.
A common  and  much better performing replacement appears to be the mikuni TM34 single choke flatslide carb and fitting kit.

speedmotoco.com/yamaha-tt350-xt350-and-x...carb-conversion-kit/


Images. Open a flickr account. Upload your pics to flickr. Click on the pic you want to display, go to the small curved arrow that opens up a few share options. Select "BB code". Copy the file path and paste it in the paste box on this forum.
Takes 30 seconds once you get used to it.