Yamaha XT500

Discussion in 'Thumpers' started by TimberlineAdventure, Mar 29, 2008.

  1. Thomasrh

    Thomasrh Been here awhile

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    Hey, what do people know about the 1T1 60 carbs? I've read it was for an earlier model TTs, but I want to get one for my '78 XT500 to replace the lousy original pumper carb I have now. Any information would be appreciated!

    tempImageeEl7vS.jpg
  2. Dtx915

    Dtx915 Long timer

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    I ran a Mukuni VM and now a Lectron both work well
  3. Mairp

    Mairp n00b

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    Hoping to pick up another 1980 XT tomorrow and the guy I'm buying it off of just had the top end rebuilt (501 now). Bikes in Nebraska and he said the work was done by a guy up there that's pretty big in the Bultaco scene. Anyhow the bike only has about 80 miles since the work and I'm curious as to the break in period. The opinions seem to be all over the place but 500 miles is bandied about a lot. I'd like to get at least 3 or 4 full days riding in before the weather turns but that seems unwise.

    Any advice would be much appreciated
  4. Dtx915

    Dtx915 Long timer

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    Rebuilt mine and took it to the track and raced it that weekend and its been fine for the last six years, I do the same thing to all my motors.
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  5. Mairp

    Mairp n00b

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    Great news. Glad this thread is still alive

    Any more input would be much appreciated!
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  6. Jzxt500

    Jzxt500 Adventurer

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    Whats the general opinion on carbs? Is the stock carb a problem? I hear alot of negatives about the stock carb.
  7. plugeye

    plugeye MC rescue

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    usually problems from neglect, age and wear. or someone worked on it before you got it. also, the ones with the diaphragms aren't worth messin with in my experience.
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  8. motocrossross

    motocrossross Been here awhile Supporter

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    Just for kicks, on my front porch a few days ago. IMG_20210902_075115818_HDR.jpg
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  9. motocrossross

    motocrossross Been here awhile Supporter

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    Get a genuine Mikuni VM36, i have jetting specs. The only problem is you cant run the stock air box with this carb. The bell on the back of the carb is about 10mm bigger than stock. The stock intake manifold is a tight fit, but can be done. The easiest is to get a 36 mm intake from Hoos racing, it moves the carb back about 30mm, which lets the throttle cable escape the conglomeration of frame tubes above the carb. You'll need a Gunnar Gasser throttle and cable, the intake manifold, a uni filter, and the different jets(the jetting you will need is about $50-60). All total about $200-$250. Mine starts first kick every time, cold or hot. Doesnt hickup anywhere, and makes a little more power everywhere. One other downfall is fuel mileage, im only getting 35-40 mpg. Which sucks with a 2 gallon stock tank. But it runs fantastic.
  10. Jzxt500

    Jzxt500 Adventurer

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    I have remembered your recommendation for that carb - Mikuni VM36. Sounds like the replacement carb to get for these bikes.
    Hopefully the 1T2-60 carb I bought for my XT500D will work well with no problems. Tried to keep the bike completely stock. I’ll put in the rebuild kit and hope for the best.
  11. Old Smokey

    Old Smokey Long timer

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    I’ve got a TM36-68 pumper. Also starts well. First kick cold and warm, first kick hot if I crack the throttle a bit to mimic a hot start button. Though I’ve found it actually runs best with the pumper bypassed hah! So maybe not worth the money in the end..
  12. Old Smokey

    Old Smokey Long timer

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    I get about 40-45 MPG (US gallons), riding gravel roads. That’s with a 530cc wiseco piston and a megacycle 25140.
  13. motocrossross

    motocrossross Been here awhile Supporter

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    How does the 25140 cam do? I have that same cam and a pair of hard faced rockers that i bought last January for my XT. I put the 25130 cam in my flat tracker project(which is on hold at the moment because of a strange engine noise.... I think i got a bad bore job... Piston slap), so i bought two cams and 4 rockers and havent really got to use them yet. IMG_20210903_183941172.jpg
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  14. Dtx915

    Dtx915 Long timer

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    I put a Lectron on mine two seasons back, have to take it off to adjust the rod as space is a issue and no air box. I just ice race it now so I run a twin air filter.
  15. Dtx915

    Dtx915 Long timer

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    51240393_1971770566460922_4372252805834997760_o (2).jpg
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  16. Old Smokey

    Old Smokey Long timer

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    I like it quite a bit. The megacycle description is pretty accurate. Lots of bottom end grunt. The top end isn’t bad either but the cam is definitely designed for that lower RPM oomph. Much fun on tighter, slower trails. I do feel like it picks up a bit around 5k though. It’s more than enough to keep me smiling.

    What kind of strange noise do you have? My xt has always been noisy on top. I did a new bore job, cam and rockers, valves and guides, new OEM tappers then later the flat ball, new cam chain and tensioner, and finally the grub screw mod. All those things helped, but it’s still noisier than some XTs I’ve heard. Some almost sound like they have zero lash they’re so quiet.

    Here’s mine with some before/after the grub mod.


  17. motocrossross

    motocrossross Been here awhile Supporter

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    My XT is one of the quiet ones. The Flat tracker is very noisey, to me it sounds like piston slap, it has new everything, flat ball foot tappets, the only thing i did not check clearance on was the piston/cylinder after the boring work... The machinist was confident that he had it right at .003".
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  18. Old Smokey

    Old Smokey Long timer

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    I think my Wiseco box actually said 0.0035" on it. I'll have to double check. Using a mechanic's stethoscope though sure has it sounding like its rocker related. But I'm the same as you - new everything and still noisier than usual.
  19. motocrossross

    motocrossross Been here awhile Supporter

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    I used a J&E 90 mm 11/1 piston, it was too pretty to put in a motor, almost lol. I guess i have 2 motors to work on... XT gets new cam and rockers, and some mild port work, the flat tracker gets the top end disassembld for inspection. One possiblity on the flat tracker, we put a kibble white exhaust seat in, the original had been loose at some point in a previous life,( It's a SR500 head, was in a pulling tractor, no shit) and whoever fixed it botched it bigtime, they flipped the seat knurled it and put it back in, must have still been loose, because they 'staked' it in.
  20. Mairp

    Mairp n00b

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    The 1980 I checked out is in great shape. Dude couldn't get it started for a couple minutes but he hasn't had it all that long so I can relate. Tearing around the dirt roads rekindled my love for this bike. It just fits me really well. So I'm going to get it tomorrow.

    Going to need regearing as I'll primarily be using it on the street and occasional fire roads as well as highway riding. I can't remember how I had my last one set up but it would do 70-75 all day but still got my through the Sheetiron 300. Any sprocket suggestions would be great.

    Thanks all