Saturday 5 March 2022

The Everyday TR1 - I'll just... CARNAGE!

 It all started so innocently: After being tangled up in all sorts of other projects (not that they are finished and you missed out, no worries...), I thought about two things: First the old trusty girl could do with some love in the form of a bit of maintenance and secondly, if I shimmed the needles on the VM38s I should be able to get rid of the lean spot in the midrange, which caused some ever so slight yet annoying lean stutter, when "power-cruising".

With the carbs installed, sync'ed and jetted 17.5, 175 with the airscrew 0.75 turns out the AFR-probe showed some very nice results. The slightly lean midrange had moved to 11.5 to 12:1 afr, which should result in a lovely strong midrange and the added benefit of some nice engine cooling, when cruising. The jetting on top could probably do with a 180 mainjet, but the engine rev's nicely to 8500 and then it seemed like the carbs hard run out of fuel, which was fair enough as I wasn't planning to use the old girl whilst there's still salt out on the roads ... WAIT A SECOND 8500rpm and beyond? Yup, at this point I was absolutely convinced that the old girl died of natural causes. 

When the starter clutch slipped, I then just thought to myself: Guess, I am one lucky fella as that could have happened right when I was out and about with the old girl last time and I had that smug grin on your face. (Which only happens, when something terrible is about to follow...)

Due to a severe lack of starter clutches, I chucked the presumably broken one in the lathe, removed the backplate, realised that this was totally unnecessary and welded it up.

As a matter of fact you only have to weld the shaft to the backplate and the job's a good un'.

Gave the old starter bit of its annual clean as the carbon dust isn't exactly helping in getting the most out of my starter.

Now I'll skip the part, where I swapped in an already semi-burned out starter and found out that one of the solenoids I had on the shelf was broken as well and head straight to the more interesting part. Now the starter gearing on a TR1 (and for what I know on the XV1000) is 19:35. As you can see below Yamaha changed this to 18:36 on the XV1100, even though this should be a bit slower on paper, it also means less strain on the starter motor and thus effectively resulting in a higher starting rpm. (Fun fact: the starter clutch pictured on the right was taken out because it slipped - I forgot to mark it on the box or the part and had to pull it out again and weld it up.)

At this point I still didn't know that the bike wouldn't start because it had two bent valves, but after finding the isolation completely destroyed on the alternator and ignition pickup loom I was pretty sure it was all down more of a no-spark situation. (To be fair, certainly didn't help...)

In case you're running into the same issue - this is the original pinout for a twin-pickup loom.

If you lean the bike far-enough to the right, you can do all that starter work without draining the oil.

Bit of sealant on the rubber pass-throughs to keep things nice and sealed.

Didn't have any of the orange/brown cable so yellow has to do.

Next I took multiple starters apart to build a single good one. As in really good. The shaft was slightly to thick, so it was polished until it slid into the starter clutch without force. 

And here you can see the locked-out (welded) 18-tooth starter clutch during one of the numerous test-fits on the shaft. (Smart me welded the clutch straight on the shaft, which caused some ever so slight distortion and meant that I would return to the lathe a few times...)

This was roughly the point where I was convinced that it should start no matter what... So I did a compression test and it read 0 (Z-E-R-O), I checked the gauge on the SR500 and even though it only read some funny numbers, it didn't register zero, so it was holding pressure. Logically I tried a leakdown test.

At this point I went over to my dad's and had a little break - only to return with my endoscope in hand. And without the hint of a doubt, that valve kissed the piston.

But there was another problem: I had no heads left except for the welded up heads, which I retired about 4 years ago because of valve stem seal issues. After cleaning them up I found that the welded up portion showed no signs of discoloration, pitting or any other signs of fatigue.

 They were missing a vacuum port though.

With the heads ready for install, I took the 700 heads off, swapped the cams into the "new" heads and had a look at the carnage. The pistons hadn't taken any damage, the valves on the other hand were beyond hope.

Luckily the bike didn't fire up again or I probably would have needed cylinders and pistons as well...

... and as we all like a happy ending:

Strictly speaking the welded up heads have done about 1200km so far, which isn't a lot, but last time a failed valve stem seal ruined the party - I hope that it was just a faulty seal and not the retaining lip, which wasn't the greatest and which would ultimately mean to replace a valve guide. A quick blast (about a quarter-mile up and down the road outside the workshop) revealed some slight losses in the midrange department, but the engine becoming VERY lively once it got past 5000rpm.

Ultimately these heads will go onto the engine that is currently in the Turbo as that bike will become my test-mule and the 700 heads will go back on onto the old Tractor... that is unless an extended testride in the coming days doesn't change my mind.

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