Re resurecting my old XT600

[mangocrazy]

That's one tough old bird to keep running in that condition. I think you arrived just in time...

[Le_Fromage_Grande]

I had a XR250 with a worse barrel and piston than that and it still ran, but that needs at minimum a new piston and rings, but I'd be going for a rebore, it only adds £40 to the bill, apart from that the rest of it looks pretty standard for a well used trail bike, I'm surprised the footpegs aren't sagging like an old woman's boobs, XT usually kill the footpeg mounts.

[Skub]

Keep the piston as a spare. Ya never knows.

[Bustaspoke]

Seeing as I had got this far & it was obvious the bike had suffered a hard life & neglect I decided to split the cases & see what lurked inside.
This is where things took a turn for the worse.All the gears worked & the gearbox seemed good,however



Every gear & pinnion was pitted...



At this point everything else seemed to be alright but I knew the gearbox was going to be a few hundred pounds,if I could get one.
After doing some research I decided to get the gearbox sorted,this wasn't straightforward as the early gearbox's had an issue with the hardening of the gears.The work around is to fit a later XT600E gearbox,but this requires some machining as there's an extra gear for the starter motor drive & I didn't know what needed machining.
After browsing the forums I took the disassembled motor to a Paris Dakar mechanic,he pronounced the gearbox toast but he could do the machining,
He also reckoned that the bike was an import as externally the barrel looked a lot better than a typical barrel from a UK bike,some good news!
The bore was already a couple of sizes oversize but he had a barrel with damaged fins on it's standard bore,so we agreed to fit the good sleeve from the damaged barrel into my barrel & bore it to +0.5. I left it all there & got on with sorting out the chassis & carbs.

[Skub]

Once you start needing gearbag parts,is it not more cost effective to buy a decent engine,or are they too rare now?

[Bustaspoke]

Once you start needing gearbag parts,is it not more cost effective to buy a decent engine,or are they too rare now?

This was back in 2009,I thought about getting another motor but I would be buying something unknown & probably lived a life similar to this motor so I decided to bite the bullet & do it properly.

[Skub]

Once you start needing gearbag parts,is it not more cost effective to buy a decent engine,or are they too rare now?

This was back in 2009,I thought about getting another motor but I would be buying something unknown & probably lived a life similar to this motor so I decided to bite the bullet & do it properly.

Makes for a better thread anyway.

[Mr. Dazzle]

Once you start needing gearbag parts,is it not more cost effective to buy a decent engine,or are they too rare now?

This was back in 2009,I thought about getting another motor but I would be buying something unknown & probably lived a life similar to this motor so I decided to bite the bullet & do it properly.

Makes for a better thread anyway.

Already know the ending though, s'in the first post

[ChrisW]

Have to admit I misunderstood at first - thought this was going on now. Actually pleased to know we'll get to see it through to a successful end.

[Bustaspoke]

Seeing as it's raining again,here's todays episode
I took the fork yokes off the frame,even the bearings were worn out



Got the coil mount sorted



How do you break a coil mount?

Got the frame & a few other parts powder coated



Took the carbs apart,repeatedly soaked them in carb cleaner & got new jets.
The big singles of this era often ran twin carb set-up's,notice how the nearest carb doesn't have a float bowl.There's a link pipe between the two carbs.I read at the time that it was to minimise the lag between opening the throttle & the power coming in on a big single.I'm sure someone more knowledgeable than me can elaborate.



Note the YDIS logo- Yamaha Dual Intake System

[KungFooBob]

Iirc the yam srx had the carb and a half thing, because it was cheaper than two proper carbs.

[Bustaspoke]

Here's a short write up on this model XT600 https://ridermagazine.com/2014/11/11/re ... 1984-1989/



This is what they looked like.Classic 80's trailie.Hopefully if I get the bike running again I'll attempt to get it looking like this one

[Le_Fromage_Grande]

It's a twin choke carb, not two carbs (some Honda XRs have two seperate carbs) from memory of XT350 carbs, the primary choke is a slide carb and the secondary is vacuum operated and opens when the vacuum is strong enough, they don't work brilliantly even when new, a big slide carb gives better throttle response on XT350s

[Bustaspoke]

It's a twin choke carb, not two carbs (some Honda XRs have two seperate carbs) from memory of XT350 carbs, the primary choke is a slide carb and the secondary is vacuum operated and opens when the vacuum is strong enough, they don't work brilliantly even when new, a big slide carb gives better throttle response on XT350s

On forums I've seen people mod the XT600 carbs by swapping them for either a couple of Keihins or something from a snowmobile.
I'll do some research after I've rebuilt it.. again

[Le_Fromage_Grande]

Does it have a single inlet port to the head or a twin?

If it's a single go for something like a Keihin FCR39, they're a really good carb, but it's a bit over the top for an XT600, I can't remember what setup the TT600 ran, but the TT has the same basic engine and makes about 5bhp more, I preferred the TT600 to the XR600, it was definitely easier to start.

[Bustaspoke]

It's a twin port head. I read about people using a couple of Keihins of some 'Ninja' & also I think some were experimenting with carbs from a snowmobile.I think it was on the ADV rider forum.For the momment I just want to get the bike up & running again as I parked it to one side as a retirement project.The carbs are the least of it's problems..
I just did a Google search & dual carbs from a 660 raptor fit,& the big money upgrade is a pair of keihin CR's
https://power-barn.com/yamaha-tt600-or- ... retor-kit/
It's getting rebuilt with the original carbs...

[Le_Fromage_Grande]

Interesting, a pair of CRs, they work well, but they're expensive, I may be able to get you a good price for them, but they're still going to be about £700. Mikuni RS flat slides are as good and less money, I would think about £450 for a pair, a set of four are around £800, the CRs are £1200ish for four, FCRs about £1500, and for lottery winners, Mikuni TMRs

[Bustaspoke]

I got the chassis sorted & after what seemed forever the mechanic said that the motors done,so I hired a van & did a 300 mile round trip to fit the engine & put the completed bike in the van.The mechanic took the bike for a test ride & pronounced that everything was working as it should do,but being an old bike there was no warranty as something that hadn't been swapped out might fail
I got the oil pump upgraded as part of the rebuild,there are 3 generations of pump on the XT600 & from what I read the flow goes up by 50% with Gen II 3AJ & 100% with Gen III 1VJ oil pumps.Hopefully this should keep the gearbox lubed.
On the way home with the XT in the back of the van there was a smell of petrol..


Even now after putting it all back together it still wasn't right



The fuel pipe from the float bowl to the other carb had split

I got a new pipe ordered & took the bike on a few local test rides as I still didn't trrust it.The plug was really lean so another seesion cleaning the carbs was required.After this the bike was great,just what I expected from a old 80's trailie.
I then decided to fit a new exhaust & bought a Predator system,took a while to turn up but I liked it
Nice headers







No concours show pony but I'm happy with the outcome

[Bustaspoke]

After riding it with no problems for a year,I took it to the Picos D'Europa



It was great on the easy gravel tracks that I rode,unlike my mate's Tiger.



After rebuilding the bike,the only issue I had was a few years later with the CDI unit failing literally as I turned into my street one day.
After reading good things about them,I bought a Zeeltronic unit & everything was great.
I even took it out on the snow,I fell off a couple of times but at this stage,the XT was just a good sound workhorse it didn't matter




Until I took the bike to the 2017 Classic TT...

[Taipan]

Great thread. Thanks for posting. I love stuff like this!!