What happend to the XT550?

[Wired1]

I've just acquired an XT550 hybrid - basically an XT550 motor squeezed into a TT250/350 frame - and have been looking around as you do for manuals and parts etc. Thing is, it looks like they only made this bike in 1983? What happened after that? Was it such a disaster that they quickly got rid of it or did it morph into the XT600?
From what I read it has a weak clutch but other than that sounds pretty reliable, although my one has no connection between the kick start and the rest of the motor from what I can feel.
I am in the process of pulling the head off to have a look but in the mean time if there are any members out there who are experts more or less on this beast I would like to make contact.
And, as always, if anyone has a manual in pdf format, or any parts I would like to know too.

I haven't made up my mind yet whether or not to use the TT frame, I could do a nice SR kind of thing if I could find the right donor rolling frame ...

[Motu]

The XT550 used the old monoshock frame with the shock under the tank and the triangular swingarm.It morphed into the XT600 with a better frame and beafed up engine.There were XT500's and 550's made for other markets I think,same as the XT400 we get here as imports.

[AllanB]

Pretty sure it started as a XT500. They were around for a few years in the 80's as I remember them being very cool, as was the XR500 thumper.

Just had a look at www.bikebandit.com XT550 is listed for 82 & 83, prior is the 500 and after the 600.

Good to know to can take it out to 600cc ....:niceone:

Post some pictures please.

[What?]

The "weak clutch" comment interests me. The 550 I had certainly had no issues, and I rode it fairly hard. Braking was another issue, though...
Overall, a bloody good bike; it was anything but a disaster, and Yamaha's decision to take it out to 600cc was probably more a fashion thing than anything else. I replaced my 550 with a 600, and am quite convinced that the 550 was quicker. The 600 had better brakes and long travel suspension, which made for a more comfy ride, but that's not really a concern of yours, is it...

[Wired1]

Thanks for all the info guys. The 550 is not a rebored 500 though as the 550 is a dry sump and four valve head, but the 600 thing makes perfect sense. The only photos I have seen are of them are '83 bikes with a frame and tank that looks like my old 1980 TT250's. These would have had a drum front and back and would have been heavy I'm guessing. The TT350 frame this motor was shoe-horned into is lighter, has a better monoshock set up, bigger forks and travel and the all-important disc front end.

I will pull the head off the motor today and see whether it is worth rebuilding then decide if I am going to put it back in the 350 frame. The problem with the 350 frame is it hasn't been done very nicely so i will end up rebuilding it tidier for sure. I have a spare 250 frame from the same year so it might be easier to start again and do it neatly.

[Wired1]

Pulled the head off, comes apart real nice - I like the split head thing, makes changing your cam a breeze.
The piston is stuck solid in the barrel and it's halfway in so I can't just disconnect the conrod and pop the whole lot out. It's also far enough in that I can't split the crankcases as the studs are still in the barrel.
Whats the old-school way of freeing the piston? I have heated the barrel and sprayed lots of CRC around it, the conrod still moves freely but the piston is solid as.

[Sketchy_Racer]

Block of wood and BFH*





*big fucking hammer

[Wired1]

Block of wood and BFH*
*big fucking hammer

Thanks for the small print. I whacked f$*k out of it with a hammer then gave up and sprayed it with carb cleaner. I figure I'll soak it overnight and try again tomorrow.

[Ixion]

Place donk under a solid thing. Hydraulic jack upside down, top of jack inside cylinder on top of piston. Base of jack on SolidThing. Pump up jack, then put socket and honking big power bar on crankshaft end nut and bash the hell out of it, at the same time trying to increase the jack pressure. Be sure to check which way the conrod is going, and choose the appropriate end of the crank. Beware that this can twist built up cranks. If necessary leave overnight under pressure (with lots of CRC).

If the bottom of the piston is sticking out the bottom of the barrel (once you remove the barrel holding down stuff, and pull the barrel up), then put a couple of steel blocks across the crankcase mouth between piston and crankface, and pul the barrel down so the piston is sitting on the blocks. This will leave the barrel not actually down on the crankcase face. Now tighten the barrel down , using its usual bolting down stuff (choose suitable thickness blocks). Alternate tightening, like bolting down a cylinder head.

[Wired1]

Day two: BFH used several times but no movement yet, will soak overnight then try again tomorrow. I have a larger BFH (FBFH?) if that fails.
After that I'll try the jack idea, but I need something to jack against...
After that I'll melt the f#&ker out and buy a new piston...

[DEATH_INC.]

My memories of the ole XT550 was it was a bit of a tank....not a bad roadbike but shit suspension and waaaay too heavy offroad.....good engine though, they certainly seemed to go ok in their day...
Good luck with getting the piston out :confused:

[Wired1]

I've been away for three days and left the piston soaking in CRC. When I got back today I got the old block of wood back out and smacked it repeatedly with the BFH and lo and behold it moved! After half an hour with my trusty hammer I had the sucker out - awesome. The bore is a little marked and the piston is probably not reuseable so I'll probably go for a first size over piston and rebore.
Now all I need is a clutch inner, and the missing kick start idler - and of course, a frame to bolt it into.
I'm on the hunt for an SR500 roller and I might have found one, only problem is it's in Auckland and I'm on the mainland.

[awayatc]

Hi, The xt400 was the Japanese local version off the XT 550.Many (maybe all?) engine parts where interchangeable....
Had one, was very reliable, started 2nd kick after weeks and weeks of neglect...
Good luck

[Wired1]

Hi, The xt400 was the Japanese local version off the XT 550.Many (maybe all?) engine parts where interchangeable....
Good luck

Great info, I'll put that to the test. I'm scouring ebay for a clutch and a few other parts so I'll try for XT400 parts too.

[Badcat]

I've been away for three days and left the piston soaking in CRC. When I got back today I got the old block of wood back out and smacked it repeatedly with the BFH and lo and behold it moved! After half an hour with my trusty hammer I had the sucker out - awesome. The bore is a little marked and the piston is probably not reuseable so I'll probably go for a first size over piston and rebore.
Now all I need is a clutch inner, and the missing kick start idler - and of course, a frame to bolt it into.
I'm on the hunt for an SR500 roller and I might have found one, only problem is it's in Auckland and I'm on the mainland.

i have a bunch of xt/tt/sr engine parts if you need.
i know your have the four valve 550 - but just in case your plan changes.....
ken

[Wired1]

i have a bunch of xt/tt/sr engine parts if you need.
i know your have the four valve 550 - but just in case your plan changes.....
ken

Thanks Ken, the XT550 is proving to be a rare beast, they only made them for a year so there are'nt a lot of them around, and they don;t look anywhere near as impressive as the older TT500's.
I used to own a mag wheel SR500 back in the day as my boy says, so I am planning on getting another one as soon as I can. I have been offered an SR500 rolling chassis for my TT350 one but it's in Auckland so it might be a bit of a stretch to get it to Nelson easily. If I get this I could put the XT550 motor in it but it would be nicer to put the correct motor in it.
I've been reading the VMX magazine series on the TT/SR500 motor rebuild and it gets me craving for one of these motors again.