overhauling an older xt350
Posted October 15, 2002 - 02:53 PM
Posted October 15, 2002 - 03:37 PM
Posted October 18, 2002 - 07:35 AM
I dont mean to mock on your bike. Its great that your ridding again. I just wanted to share my opinion of that bike.
Posted October 19, 2002 - 02:15 AM
Posted May 26, 2006 - 12:34 PM
Posted May 26, 2006 - 01:22 PM
The smoke is easy.
If it smokes MORE as the RPMs increase, your cylinder is worn. You will get cone-shaped pattern from normal wear on the cylinder. The higher the RPMs, the rings cant fill in the gap fast enough and oil blows by.
If it smokes when coasting the engine at any RPM (no throttle) that usually only means rings. Under load the rings are "press-against" the cylinder wall by the expanding gasses, thus they seal up to the cylinder wall and it wont let oil by into the cylinder.
If it smokes the worst right after starting it up it is valve-guides usally. Oil drips down off the valve-guides slowly accumulating....even when engine is off, thus the reason for more smoke when you start it. Under load the rings are "press-against" the cylinder by the expanding gasses, thus they seal up to the cylinder wall and it wont smoke under load
Why not try putting a set of rings in her? It would be better to bore it though and slide in a new matching piston. Not sure what that would set you back.
Maybe opening up the side cases (not splitting the case) for a peek? You will gleen much on the overall condition of the engine, clutch wear, etc, not to mention when you put her back together (new gaskets) you may fix some (or all?) of you leaks!.
This would take you and evening to do, not require any fancy tools other than a ring compressor and, if your like me, you would love every second of it!
Good luck, and post some pics!
Posted May 26, 2006 - 02:00 PM
The first place I would start is to get rid of that P.O.S.
I disagree. I had a 1987 XT350, which is basically the same bike. It was a great little trail bike. Furthermore, it had 6 gears and did well on the road. I went everywhere on that little bike. It was the last bike I used to ride 30 miles on-road to go trail riding then rode home. It was very reliable.
Here are pictures of my 1987 when I finally sold it in 2004. It ran great.
Posted May 26, 2006 - 02:34 PM
Posted May 27, 2006 - 12:22 AM
Posted May 27, 2006 - 10:30 AM
The cylinder head is the most fragile element in the engine. So check the valve clearance regularly. They don't need adjustment often, but when they do you must take care of it. That also means watching the cable adjustment on the auto decompression.
You might want to replace the front wheel bearings rather than "adjust". They had issues with some of them. Mine spit all the bearings out of one side of the front wheel at high speed one night when it was only a few months old.
Make sure the top of the fork tubes are flush with the top of the triple clamp. That was the factory setting. Mine came setup from the dealer brand new with the fork tubes up about an inch and it wanted to tuck and would even headshake.
I second moving up from 10wt fork oil to 15 or 20. I used 15wt and made preload spacers that helped with bottoming. I never did run air pressure. But there is no cure for them being too small and having pathetic damping.
I also second opening it up having the cylinder honed or bored and slapping in at least new rings and maybe a forged piston. Also, since it is shim and bucket valve adjustment that requires a special tool or cam removal to adjust the valves anyway, you might want to let a shop replace the seals and readjust the valves while it is apart.
If you do the disassembly and assembly work yourself you can freshen the top end for very little money. To me, anything over $400 or $500 in repair cost says start shopping for a new beater. That was why I parted mine out the last time the top end grenaded. With the head destroyed it was going to be pricey.
Posted May 28, 2006 - 11:12 AM
Posted May 28, 2006 - 07:28 PM
A Yamaha technician warned me of this issue. He said these bikes were never really designed properly due to lack of cooling ability for the output of a bigger bore. And that is why they stopped making 350's. Same for Honda and Suzuki
Honda XR 350 were only made for 3 years 83,84,85.
They did have some heating problems on the 83 &84 when going slow on tight trails. This was mainly due to jetting to lean.
85 Honda went to a dry sump motor and solved a lot of heat problems but were generally still jetted to lean.
Fatten them up and heat problems went away.
Also many riders didn't know how to start 4strokes and when stopped they didn't stop the engines= overheating.
DR350 was bullet proof. It came jetted to lean for all conditions. Damm ECO- RATS. Jet them correct no overheating.
YAMAHA XT 350
Yamaha 350 was made from 1985 thru 2000 with no changes except for the color of the plastic.
The Yamaha enginers know more than most motorcycle shop wrenches.
I think your Yamaha tech is wrong.
The barrels on the 250 and 350 are different!!
Again these bike are most all jetted to lean=overheat.
The EPA freaks cause the manufactures to jet them lean to get approval to sell in US.
I got a little windy, I have ridden XR 350 & XR 350 motorcycles in Baja at near race speeds for hours at a time in 100 + degree heat an had no problems.
GET YOUR JETTING CORRECT
Posted May 29, 2006 - 04:44 AM
Posted May 29, 2006 - 05:51 AM
a: it came jetted too lean
b: it is a wet sump engine
Too me, the only serious engine design issue is the overly complicated head. Shim and bucket valve adjustment in a low power DS bike is just plain stupid. A lot of people end up never adjusting the valves because of the complexity and/or cost. Which is why you almost never see XT350 heads on eBay. However, the up side is that the engine can be made to scream without compromising reliability.
As to the wet sump design, like I have said before I changed the oil after EVERY ride. And I only ran full synthetic. Even though the clutch cover got about as hot as the surface of the Sun, mine still had the original clutch and the cases had never been split after 17 years and 30,000+ miles. I did plenty of riding with the throttle pinned and grinding though ridiculous amounts of mud in SC heat with no reliability issues from heat.
That said, I wouldn't put much money into rebuilding one that I bought cheap. I kept mine going because I had bought it new and modified it to suit my taste so it had sentimental value. But starting from scratch I would buy a better bike to start rebuilding. IMO, both DR's and XL's have better suspension and an easier engine to work on.
Posted May 29, 2006 - 05:15 PM
as to the front rim shake carefully replace the bearings as i have just broken 2 hubs doing this on my bike. then check it with a dial indicator for out of round and side to side movement. i think Yamaha spec is like 10 thou or something ridiculous. get it as close to "0" as you can and it should make a huge improvement.
Posted May 30, 2006 - 07:16 AM
Posted May 30, 2006 - 08:39 AM
Where did you get this info???
"Just keep in mind the 350 is a 250cc cylinder that is bored out to a 350. This means the cooling fins on it were designed for a 250cc."
That isn't right. They are different cylinders. The 250 has an extra oil passage on the cam chain side. You can see this for yourself on one of the many sites out there that show engine blowaparts. That said, much of the 1984 XT250 and the 1985-2000 XT350 are identical (including the bottom end). In fact, I could be mistaken, but I think the only significant difference between an '84 XT250 and a '00 XT350, besides the cylinder, is the front end (forks and front disc).
Posted May 30, 2006 - 12:03 PM
Pay attn to carb boot leaks and anything else that gives you a lean condition, because that will make it run very hot. If you keep it cool, it will go forever. It may not be a motoxer, but it's a pack mule in the woods.
As far as the wandering on the highway, body placement on the seat and not keeping a stiff grip on the bars alleviated that. A tight hold, and sitting way back in the saddle caused it to oscillate and feel vague.
In many ways, it was better than my newer DR 650. Well, except for all the extra oomph.