Monday, 29 February 2016

The Turbo TR1 (part 1)

Now I am not the first one to build a Turbocharged TR1 (check out Edgar's Turbo TR1 straight back from the 90ies or his absolutely awesome Topfuel supercharged TR1) and quite honestly it wasn't even remotely in the cards to build a turbo bike, but I am getting a bit ahead of myself.

Edgar's legendary supercharged TR1 Topfuel bike

It all started out with an ad on the German TR1 forum, that said something like: Have flood damaged TR1, needs to be gone. ASAP.

I don't have any pictures of the initial state, but very grim was an understatement. On the other hand it was a low mileage bike that was well maintained, only had two owners and even had some goodies on it like steel-braided brake hose and was a Mk.2 TR1, which meant it already had the bigger oilpump in it and all the innards that weren't suffering from water damage should be in pretty close to perfect nick.

It took me about a month to break the engine loose again, but it turned out, it was only the rings of the front pistons having rusted to the bore. A constant attack with penetrating oil, heat guns, diesel and a socket on a breaker bar finally broke up the little love affair and made it possible to take the engine apart.

Engine out
One of the very cool features of the TR1 frame is the fact that it is only held on with six bolts, which once removed, mean you can roll away the whole front end with elegant ease...

Sunday, 28 February 2016

My everyday TR1

 Some pix of my everday TR1 in its 2016 guise. It currently sports a polished GreasyGreg Mk.6 exhaust (yep it took me a few attempts to get it really right) and Mikuni VM38-9 carbs, which amazingly only needed very gentle re-jetting to make them work. It's (of course) taken to the full 1063cc via a Virago 1100 crank and pistons, but in order to my the old girl fly I run it with XV750 heads to bump up the compression to a  healthy 10.1:1 instead of the stock 7.8:1 for a Virago 1100.

Yes, the right sidepanel is missing in the picture...

Showing off a shiny downpipe and a sporty VM38

XS400SE rear mudguard

XT600 43F/2KF rearshock
Oh and that V-twin does sound quite nice too...

Saturday, 27 February 2016

Why TR1s always blow their headgaskets (and what to do against it)

I currently own two TR1s. One is the Turbo Bike and the other is my slightly more conventional everyday ride.

Now truth be told, a stock TR1 is a pretty rubbish bike. Firstly it is relatively slow for a 1000cc v-twin and secondly it is pretty unreliable by Japanese bike standards.

The first thing you have to be aware of with a stock TR1 is that they have a really weird headgasket, made from a pressed asbestos ring, which sits neatly in a groove. It wasn't exactly the world's worst idea, but on Mk.1 TR1s (the ones marked with 5A8) there was no separator between the groove for the headgasket and the rubber seal of the camchain tunnel.

It's a pretty rubbish design

Luckily later XV1000s and XV1100s sport a conventional style fibre or multi-layer metal headgasket. The 1100s even sport the same bore, but it's not that easy. If you want to go for the full monty, you have to go for an 1100 crank and pistons as well. 

But you don't necessarily have to go for a later cylinder, there's two alternatives for you to modify the stock cylinder, yet both involve a bit of machine-work. Number one is to have the gap between the headgasket groove and the camchain-seal welded up and then machine it back the correct height. This is the bolts 'n' braces way to do it and exactly what Yamaha offered to upset customers in 1981 and 1982 and made stock for the Mk.2 TR1s (marked 19T). A more simple way is to cut a very thin slot with a 1mm-disc on your angle grinder into the space between the headgasket groove and the seal and then stick in a bit of stainless steel sheetmetal.

Bit hard to see, but this one doesn't have a groove

Monday, 22 February 2016

Carb boring 101

A while back I wanted to fit flatslide carbs on my old Kawa Z1000J. Bearing the prices for a nice set of Mikuni RS34s in mind, I was looking for cheaper alternatives. The first generationof 750cc GSX-R's actually sported a set of very, very proper OEM Mikuni flatslides, which go by the name of VM29SS. Now putting 29mm flatslides on a bike, which was originally delivered with 34mm CV carbs yielded some nice performance gains, but not quite what I had hoped for.

After going through a lot of literature I can to the conclusion that all this carb boring isn't all that difficult, if you have access to a lathe and bear a few things in mind. Interestingly enough, the throats are already at 33 (and a bit) mm, but the backplates are choked to 29mm.

The thing that makes this whole job a lot easier is that you may take the backplates off the carbs and as such the bodies can stay where they are and you only have to remove the slides.

Next step is to put the backplates in the lathe for boring them out to the same diameter as the front. Now the only thing you have to bear in mind is to bore the carb eccentrically, as you can see, I did this with a few strips of copper sheet wrapped around one of the jaws on my lathe. If you bore it centrically (which is of course possible and would yield larger gains in terms of maximum flow) you have to lower the needle jet and recut the grooves in the carb body that make the slide seal at the bottom. Furthermore this would really upset the idle mixture, so basically it's not really worth it...

And this is the finished product. Yes, it did work but the gains weren't as drastic as I had hoped. I should have offset the carb less and bored it in a wider circle as I ended up with an oval carb.
(By the way something Mikuni did in the early eighties on a round-slide carb intended for the Suzuki DR500!)

My path towards (not exactly) Yamaha's greatest engine

This story goes back way longer than actually me driving motorcycles. Years ago, I was about 15(-ish), I saw my very first flat-black v-twin motorcycle in my hometown. It took a while to get to know the owner and years later I happened to become the owner of said motorcycle. The bike in question was a Yamaha TR1. Yamaha's very first attempt at building a V-twin but back then not exactly aimed at the cruiser market, but meant as a big naked touring bike aimed against BMW's R100 and the big Guzzis of the era.

A TR1 named Faust from the side ...

... and from the rear.

 Over the course of time I ended up with multiple of those unreliable heaps. And just to make matters worse I started tuning the buggers and ultimately sticking a turbo on one. But this is another story...

The TR1 Turbo

Who's this GreasyGreg guy anyway?

Pretty good question Wattson. Well, the name's Greg, I am from Linz, Austria and I love bikes and other wheeled vehicles, which are proper fast or at the very least feel fast.

I admit I've got a soft spot for older stuff, mainly not only because it's what I can afford, but it's simple to fix and it's what I played around with in the last years. Therefore my stable's mostly home to assorted old two-wheeled junk, none of which was more than 1500 Euros, when bought. I am not in particular a fan of a certain brand, but I do admit that all of my active bikes come from the brand with the three tuning forks. I did have the odd rocket from other oriental and even European manufacturers under the belt of my ownership, but there's only a very few, I've stayed for a longer period of time.

Truth be told, I am also strongly into engineering of all sorts and as such you'll find the odd post about lathe- or milling-work and welding-techniques, etc. on this blog.

Now if you fancy employing my services, you can either leave a comment under one of the posts on the blog or send me an email to