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Discussion in 'Thumpers' started by TimberlineAdventure, Mar 29, 2008.
Hey XT fellas, question for y'all. What do you keep in your tool roll when you ride? Local and LD?
Lot's of good info here for anything and anywhere you ride.
A Yamaha TT 400? Thats is "TOP SECRET!! Does Yamaha of Japan have wind of this bike???
Love the event!! Thanks for posting!! BIG ED XT&TT 600 FAN!!!!:eek1:eek1
same here it good for me ,good to see you here as well plugeye
I have a question for the XT gurus:
I have a 1978 xt500, with only 1,200 original miles on it. I know the original owner, and it sat inhis basement from 1991-2012, when I got it.
It has 140 lbs compression and runs great. I did a full service (oil, carb clean, tank clean, plugs, points, condensor, adjusta nd clean everything) BUT, it smokes like a steam train. It usually takes about 1-2 minutes for the smoke to START after I start the bike cold. If the bike is hot, it smokes right away. It never stops until i shut it down. I ahve gone on a few 20-ish mile rides and it runs great, but burns a little oil.
I know XTs usually smoke for a bit after startup if they are wet sumping... but mine is doing the OPPOSITE. It takes a minute or two for the smoke to begin, and then it never stops...
I'm thinking this is valve stem seals.
What do you guys think is causing my smoke?
At 1200 miles, the old girl is barely broken in. Got to imagine the 35 year old seals are pretty hard, but I'm wondering if it could break in a bit more too. If it were me I would change the stem seals and watch for leaks at the other places. Oh, and then ride the heck out it. Good luck.
Watch to see when it smokes.
get up to speed and cut throttle and coast down...more smoke or less?
Accelerate hard...more smoke or less?
The coast down test is pretty definitive test for valve seals.
I bet you have glazed or stuck piston rings.
More info on my smokey 1878 xt500:
It does not smoke at idle, or if it does its VERY little.
When I give it any gas at all, it starts smoking. More throttle = more smoke.
When I'm cruising or riding with the RPM's up and snap the throttle shut it smokes more. (The bike is constantly spewing smoke when I ride it or give it gas, but snapping the throttle closed makes the cloud get even bigger).
After returning to idle, the smoke stops within about 10-20 seconds.
I have put about 100 miles on it so far... and noticed no change in the smoke. I even poured some of that No-smoke magic stuff into the oil for the last 20 miles. No change in smoke. I'm usually afraid of that stuff causing more damage, but I figured i was going to tear the motor down anyway...
When I got the bike, it had 40 psi compression. After a good soak with ATF+ Sea Foam in the cylinder and in the valve inspection covers and a bunch of good kicks, the compression returned. Now its about 130-150, depending on how hot it is and how mant times I kick it. (3 kicks gets 130 lbs, 5 or 6 kicks gets 150 on a warm motor).
So, yeah, it had stuck rings. I'm tearing into the motor this weekend. Its already pulled and sitting on my bench. I will definitely replace the valve stem seals, and lap the valves. I'm also thinking that hitting the cylinder with a hone is a good idea to get rid of any glaze.
I ahve used a 3 stone hone for an electric drill on MANY motorcycle motors. I understand that is it just for de-glazing. I will of course be measuringt he bore and roundness of both the cylinder and piston first... but at only 1,200 original miles I really doubt that my cylinder or piston are past tolerances...
Sounds like your ring is still not seeding itself well. Yamaha makes a product called "Ring Free" that deposits through your fuel. Similar to seafoam, but probably a little bit better.
Does it make any knocking noises or sound like it's worn? I have a TT with about 500 hours on the top end; it knocks because the wrist pin bearings are shot, but I used the Ring Free and it alleviated a lot of the smoking, hot and cold. Even yet, rings for them are cheap.
Just make sure you put your cam in the right way. Last time I had a motor rebuilt, we screwed up and put the cam in 180 out. Luckily, rotating the points plate 180 alleviated that issue.
I used stock gearing for everything. On the highway it really wasn't powerful enough to pull anything taller, and because of the torque and heavy flywheel it was pretty forgiving in the tight stuff. Mine topped out around 90 mph indicated, pre GPS so couldn't say how accurate that was.
Can't say that I have a dedicated obsession for the 2 valve Yamahas, But I've certainly built and abused a few over the years.
<a href="http://exoskeleton.smugmug.com/Vacation/Out-and-Back-2007/4509916_3HDJSv#!i=265483633&k=FgHfZQT&lb=1&s=A" title="......some more rocks in the middle."><img src="http://exoskeleton.smugmug.com/Vacation/Out-and-Back-2007/i-FgHfZQT/0/S/IMG_1361-S.jpg" title="......some more rocks in the middle." alt="......some more rocks in the middle."></a>
Should never have let this bike go. What it lacked for ugly, it more than made up for in with sheer will.
<a href="http://exoskeleton.smugmug.com/Vacation/Out-and-Back-2007/4509916_3HDJSv#!i=265483957&k=dPF89nm&lb=1&s=A" title="When the human race is past and the cockroaches and trillobytes are finally gone, the XT will remain."><img src="http://exoskeleton.smugmug.com/Vacation/Out-and-Back-2007/i-dPF89nm/0/M/IMG_1366-M.jpg" title="When the human race is past and the cockroaches and trillobytes are finally gone, the XT will remain." alt="When the human race is past and the cockroaches and trillobytes are finally gone, the XT will remain."></a>
Had some others over the years......
<a href="http://exoskeleton.smugmug.com/Hobbies/Misc-racing-shots/4510379_WBnxLQ#!i=266219720&k=CfKHJSB&lb=1&s=A" title="A bygone era of lightweight superbike. The fun remains."><img src="http://exoskeleton.smugmug.com/Hobbies/Misc-racing-shots/i-CfKHJSB/0/M/racer2-M.jpg" title="A bygone era of lightweight superbike. The fun remains." alt="A bygone era of lightweight superbike. The fun remains."></a>
Made a few mistakes...
<a href="http://exoskeleton.smugmug.com/Hobbies/Misc-racing-shots/4510379_WBnxLQ#!i=265506210&k=mNVFBgp&lb=1&s=A" title="Then again there were bad days."><img src="http://exoskeleton.smugmug.com/Hobbies/Misc-racing-shots/i-mNVFBgp/0/M/MC8-M.jpg" title="Then again there were bad days." alt="Then again there were bad days."></a>
before you judge.....that was a very cool hairstyle at one time.
<a href="http://exoskeleton.smugmug.com/Hobbies/Misc-racing-shots/4510379_WBnxLQ#!i=265506172&k=7ggNbJf&lb=1&s=A" title="Bad hair decade."><img src="http://exoskeleton.smugmug.com/Hobbies/Misc-racing-shots/i-7ggNbJf/0/M/MC4-M.jpg" title="Bad hair decade." alt="Bad hair decade."></a>
There is an easy fix that doesn't require the points plate being set reversed or pulling the top end. I don't think you can get the points cover back on, or at least easily otherwise if you flip the plate 180.
When you place the points cam gear and line it up with the dots originally, make sure it is on the proper stroke or the timing will be out 180. It may have not been the cam that was installed improperly, but the points gear itself. I know it is super easy to mix it up as I recently did this myself. Just pop the clutch side cover off, and rotate the gear to the proper stroke if you run into the issue.
It's the gear in the bottom right of the pic.
I had a 78 xt500. Couldnt ever get it to run perfect tho. had a 38 mikuni, 540 kit, 81 xt head, bassani pipe and other stuff. My old man has one similar in the garage he never has parted ways with. xt500's have some of the best exhaust notes ive heard.
38mm Carb is to big even for a 540CC.
a 36mm would have been better.
Please help me.
Does anyone know where I can get a really big tank for my XT500? around 30 LITRES? Does a XT600 Tenere tank fit a XT500?
you might have better luck making one, or modifying a stock tank.
the larger clarke tank isn't even close to that.
if you do find one, please let me know, the VJLA death valley ride is is 2 weeks.
Hi Allen, for a large tank try ebay germany or put a wanted add on the XT500 Forum http://www.xt500.co
I found a beaut at last a week ago!
Now i cant post a pic??:huh
Just done a deal for this gorgeous beasty......
A good mate of mine had a TT500 from new back in the early 80's. He emigrated to OZ in mid 1980's and left me with his bike - to sell & send him the cash. I regretted not buying it off him - only got £350 back then as although it was road registered, he had lost the reg docs, etc!
Anyhow, it looks ace - apart from the naff front muddy - this one should be in my garage on Friday
I just now got around to going through my motor. When i got it it smoked like a train. It puffed at idle, but give it any gas at all and it would make a HUGE smoke screen. So, I tore it down:
I cleaned up the head, lapped in the valves, and replaced the valve stem seals. The guides seemed to be good, the valves didnt have any 'wobble' in them, but I didnt have a bore gauge small enough to measure the guides...
Th piston looks brand new and is .5 mm over. On my micrometer, it measured 87.51 mm. I measured several different points. My cylinder measures 87.56 mm. I got the same reading at the top, middle, and bottom using a bore gauge. I'm comfortable with my tools, and with measuring cylinders and pistons, so I'm pretty confident in my readings.
The piston, rings, and cylinder hone looked brand new. There was no carbon, scoring, or heat discoloration anywhere to be found. There was nice even cross hatch all over the cylinder, no glazing or scratches.
I also measured the ring end gaps, and they are all within spec.
I did find that all of the rings (both top compression rings and the oil ring) had their gaps lined up when I took the motor apart, with gaps facing forward. I assumed this was causing my extreme smoking. I staggered the gaps 120 degrees during the re-install.
I put the motor and bike back together, and started it up. IT STILL SMOKES!!! I rode it about 25 miles, and it never stopped. It smokes 50% LESS than before, but it still smokes a lot and makes a big cloud.
So, it smokes a little from idle to 3000-ish rpm, but hardly any at all (the very little amount it smokes at idle through 3000-ish rpm is acceptable to me). It does not smoke more at start up, and does not seem dependent on engine temp. Above 3000 RPM it smokes like a steam train. The smoke looks white, and has very little smell.
Ok guys, I'm stumped. Its NOT wet sumping... my oil level doesnt change after sitting... and the smoking never stops, even after the bike is warmed up.
Any suggestions from the Xt500 gurus?
also, I could not find any markings on the rings to indicate a top or bottom side... they looked like they were the same on both sides. Is this true?