Ott's 1VJ

[j0epere]

So over the coming months(years likely) I plan to bring my 1VJ back close to it's former glory. As I don't have the budget to do everything in one go, I will try to work it step by step. My first plan was to fix-up and repaint the plastics, get the huge dent out of the tank and have it repainted/stickered, but i discovered that the headgasket was leaking so i will have to dive in the engine first.

As a start I did a compression test for the engine, with the warmed up engine i managed to get 90Psi, a whopping 63 Psi short of the value stated in the manual. Seems incredibly low, considering that the bike was starting/idling OK.

Second thing I did, was draining the oil. Luckily didn't find any metal shavings, but i sure found a lot of oil, 3.5LT to be exact. Also draining the oil reservoir was quite a mess.

Next week I'm planning to remove the engine and start taking it to bits. Hoping to take many pictures along the way and keep this thread as a diary for myself and future generations. Feel free the chime in!

[j0epere]

I got the engine out of the frame and the top end disassembled. Fairly sure that the rocker box was screwed tight with the Torque gun, as it was a bit of a bitch to unscrew these bolts.
Haven't yet measured all the tolerances yet, but from visual inspection the results are as follows:
The barrel has some scorches which seem to be deeper on the bottom. Also according to the second picture the barrel seems to be more wore down in the middle. In any ways looks like it needs to be rebored and a new piston to be put in. The piston itself looked fine without any marks on the sides.




As for the conrod, the big end didn't have any up-down play, but the small end has wore down quite oddly. Cannot feel the difference with a finger, but does it looks like a new conrod will have to go in as well?





Looking in to the engine I couldn't notice any pitting in the gears, but the view was quite limited. I will likely still open the cases to see what more surprises this engine has to me.

Ott

[jibber]

[j0epere]

Another day of digging into the engine and quite a few interesting things popped up, bear with me:

Bore size and piston:
According to the stamp on the piston, i expected this to be 2nd oversize(+1.00mm), but measuring the piston with a micrometer, the diamater on the top was around 96mm, and the bottom of the piston was 97mm, the piston seems to be Yamaha OEM. Is there supposed to be a difference like that?
Also measuring the bore(4cm from the top of the cylinder sleeve as the manual suggested), i got a result of 97.07mm.
This makes me wonder if I'm measuring/doing something wrong, or am I really running of O/S Piston kit's to fit in there. Pro-X doesn't seem to sell over 97mm.




Camshaft:
The camshaft dimensions also see to be out of spec as per the picture below (0.1mm for intake 0.2mm for exhaust). Would you consider to change the camsaft in this case? If yes, how is the interchangeability with other XT models?




Counterbalance shaft:
Counterbalance shaft seems to have an odd wear on the same side as the weight is on. Definately can feel this, but still seems to sit nicely on the bearing without any excess movement. Does it seem wise to change this one out as well?



Gearbox:

The fifth gear didn't seem to have any pitting as I was afraid, but there were some scorches and very minor pitting on the third gear. Not sure if i should look for a replacement gear for that.





Main bearing:
I also planned to change atleast the main bearings once the cases are alerady halved, but the camchain sprocket seems to be on the way. Is there a way for mortals to remove it and put it back(So it's still properly alligned?



Overall It wasn't too hard to open everything up, but the tricky part will be ordering and waiting all the spares to arrive. Luckily I found a used 3AJ oil pump available in Estonia so atleast one thing i can aquire close by :)

Ott

[scottieh]

I also planned to change atleast the main bearings once the cases are alerady halved, but the camchain sprocket seems to be on the way. Is there a way for mortals to remove it and put it back(So it's still properly alligned?



Ott

I recently removed mine with a large bearing splitter and a three jaw puller (two jaw will work too). It takes a little work to keep the splitter fully behind the bearing as you start to pull it off.



Then to put it back on i used a drift and worked it back on the shaft until it hit the end. I suppose you could use some feeler gauges to measure the gap between the sprocket and the crank if you wanted to be sure.

[jibber]

Pistons measured at the skirt, 90 degrees to the gudgeon/wrist pin, there are pictures in the service specs, look in the links section under manuals.

[Mezo]

Pistons measured at the skirt, 90 degrees to the gudgeon/wrist pin, there are pictures in the service specs, look in the links section under manuals.

Didn't Actionman make a little jig to align the crank half's? i tried looking for it but no luck.

Mezo.

[jibber]

Yes, more of a pot iirc to help align the 2 halves in the press. There's a bloke on e Bay who charges £65 labour to rebuild a 660 crank, add postage and parts about £200.

[Mezo]

Yes, more of a pot iirc to help align the 2 halves in the press. There's a bloke on e Bay who charges £65 labour to rebuild a 660 crank, add postage and parts about £200.

I do remember (back in the day) that guys were simply buying whole new crank`s as they was only $300 brand new from Yamaha, not sure if that`s still the case or if there any left?

EDIT: Just looked, all gone now.

Mezo.

[jibber]

They dried up a few years ago Mez, I think they worked out to £180 plus shipping and charges still worked out quite cheap........