Sunday 18 June 2017

The new TR1 motor - Introduction (part1)

As you might have guessed by the apparent decrease in posting frequency: Exam time is upon us poor students. The mere mentioning of these perilious times sends shivers down the spines of even the most brave students... but I digress.

The XS Triple isn't even remotely done (yet) and still, there's a new project dawning on the horizon. I have recently started to gather the parts for a new motor for my trusty old everyday TR1. Originally I had only planned to bore the cylinders to the next oversize and slap the engine back together. But truth be told, the most worn out part of the whole engine are the cases. Nearly every thread of a bolt holding on the sidecovers has been stripped and helicoiled and there must be some small crack on the left side somewhere between the alternator cover and the neutral switch.

Luckily I still have a good set of cases under the bench and then I literally fell over a parted out XV1100 engine that I managed to pick up really, reallly cheap.

 Together with some new (used) rods and fresh bearing shells the bottom end is pretty much sorted. Additionally I also managed to score a set of XV700 cylinder heads, which I got today, cleaned up and inspected and then put next to an old XV750 head I still had lying around to show you the differences.


The interesting feature about those XV700 are the two squishareas, whereas a normal XV750 only has got one (larger) squish-area, which also creates an uneven load on the piston and that can be seen with the small ends of the conrods wearing out unevenly. 

Of course, one of the new heads came with the mandatory damage to one of the fins... Guess we'll see a bit of ally welding soon.

As you can see the on the new XV700 heads, the combustion chamber is basically shifted 5mm to the right. I haven't cc'ed the combustion chamber, but I suspect it might be a bit smaller, but it's also recessed by about 0.5 - 1.0mm so overall the compression ratio should end up the same or only marginally higher.

An absolutely essential part is to clean up all the parts. One of the best methods (I found) to remove old carbon deposits is to use some industrial gasket remover spray, let it do its thing for five to ten minutes and then just brush it off with a soft brass brush and the combustion chamber cleans up nicely.

The other part (as you might have noticed in one of the first pictures) is that one head was increadibly oily and dirty and I found typical kitchen cleaner to be the most effective way to clean off that grime.

As I mentioned before: the next two weeks I'll mostly spend with my books, so only expect some minor updates (if any at all). The next update on this project will most likely be, when I measure the crank and rebuild it with fresh bearing shells and some good (used) rods. To be fair though, it'll probably be at least another four weeks until you hear about this project as I really want to get done with the sidecar before I start a new project.

Saturday 10 June 2017

The XS Triple Sidecar - making oilcooler mounts and finishing the rear subframe (for now)

It might have seemed like there was no progress on my own XS-Triple-Sidecar, but I did in fact get quite a few things done, but only in baby-steps. To be fair, I only realized how much I got done lately, when I compiled this post.

First step was to modify my early '77 frame to accept a stock XS750/850 oil-cooler. I made some steel bungs, tapped M8 to weld to the frame.

A bit of shrinkwrap should seal up the tach-cable for a while until I can get hold of a slightly longer tach-cable. 

When removing the old exhaust most of the old studs (all but two) came out, so the threads in the head had to be recut and new studs cut from some left-over M8 all-thread bar.

Last part of the subframe-mods was to reinforce the rear-subframe by adding an extra lower brace that will take the sideloads of the rear mount as this proved to be a bit too flimsy during the first tests.

So with those issues out of the way, I am pretty convinced that now I can finally get to assembling the old girl and get her ready for a proper testride.

Monday 5 June 2017

The Dre-XT-Stück - first tweaking of the carbs

As some might have guess, with the upcoming sale of Ms. Braaaap (my XT500) I needed something else as a substitute. Well, my dad wasn't entirely happy with the Dre-XT-Stück and I wanted something cheap 'n' cheerful and a bit more modern than a XT500. So a deal was struck, I'll take the Dre-XT-Stück off my dad's hands for the price he paid, fix his other XT500-4-valve, which is smoking like mad and everybody (in theory) should be happy again.

The Dre-XT-Stück suffers from a few issues, the most pressing one is some rather unpleasant cutting out when cruising at part-throttle to almost full-throttle starting at 4000 rpm.  Unfortunately this one is the 500cc equivalent of the very first XT600-model, a so-called type 43F. This in itself isn't the unpleasant part, but the fact that Yamaha changed the Teikei-carb a bit and not all of the carb-jets are available anymore for this version. Especially the mainjet of the secondary is no longer available.

I tried playing around with the mainjets first, as the one fitted to the carb isn't marked and looks a bit like someone already messed around with it. So I swapped it for a #124 Hitachi mainjet, which remedied the cutting out quite dramatically and limited it to a small rev-range between 4000 and 4500rpm. Unfortunately it also seems to run out of puff at around 110kph or 6000 rpm.

Mainjets (for the main-carb) are also a bit hard(er) to come by, so I was looking for alternatives and whether I may have some other mainjets that would fit.

The original Teikei mainjet on the left, Hitachi in the middle and Keihin on the right. All of them are a DIN M5 thread and are interchangeable. Even though the hex on the Teikei jets makes it considerably easier to change the jet.

Sunday 4 June 2017

The other XS Triple Sidecar - adjusting the carbs

... and finally getting the old girl ready for sale.

Funnily enough the stock mainjets on a XS750 with Mikuni Mk.1 carbs are #145s, which turned out to be too large to be used with pods and I had to swap them out to #135s. But now the old girls runs like a champ and revs to the moon...

Can't beat a magic box with tons of jets. 

And it would have been rude, NOT to check the synchronization of the carbs. 

The somewhat sad part: With the old girl now fixed up properly, she's ready for a new home. So if you're in the market for a technically well sorted bike, give me a shout. 

Saturday 3 June 2017

Boring yokes of Tom's RD400

My mate Tom recently passed by and asked me for a favour: He had just bought a RD400, but the original forks were completely shot. But as a true Yamaha-connoisseur he used to own several SR500s and had some good fork legs sitting around. The only problem: RD400s run 34mm forks and SR500s 35mm forks. Which is exactly where I came into play.


The thing with such jobs is, that it takes longer to have everything centered under the boring head than the actual boring job and even that takes quite a while. All in all it took the better part of two hours to have the yokes bored out to size.

There'll be an update on my XS Sidecar very soon, but I've been working a lot on my other XS Triple Sidecar and the XT to get them ready for their respective sales and had to do some fixing up on my car. So there's not that much to show as of yet.