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Projects - TYGA Doohan OK MC21

TYGA Doohan OK MC21
By Tyga Europe 3/18/2018 11:09 AM Comments

By tygaperformance.com

The ‘carcass’ consists of the MC21 test bike that we used to develop the Ohlins rear shock exclusively sold around the World by TYGA Performance. This started life as a lowly ‘R’ model with wet clutch aluminium wheels and the non-remote gas reservoir rear shock (which of course was removed for Ohlins testing) Anyway, on completion of suspension testing it had been put in storage and pretty much ignored for the last year.

The next bowl of left overs came when we put the NSR300 Rothmans together. Previous, it had an NX5 RS250 front end and an old Ohlins rear shock from circa 1998. These were carefully wrapped up and kept in storage for just such an occasion. The final thing that triggered this dish was a GP-T bodywork kit which was getting painted in 1994 HRC colours to be used as an alternative for the Rothmans scheme. It was only when we used the Ohlins bike as jig to get the graphics properly aligned that I started thinking about a different plan to just having a change of clothes for the NSR300. One thing which was niggling was that the wheels needed to be black and not white so this would be troublesome if not expensive to have to swap back and forth wheels as wheel as body colour. I was also having second thoughts about wanting to do any changes at all to the 300 just because it was so well known (plastered all over the internet in June 2015) and was now becoming part of TYGA history. Anyway, when we put the bodywork on the Ohlins bike for the first sitting, they looked like they belonged there and as everyone who reads these project bikes can relate to, I am sure, you can never have too many bikes.

Now, the Ohlins bike might have looked quite neat and tidy doing laps with Matt hanging off in the corners, but up close, it had the scabbiest frame that I’ve ever seen on an MC21. The wheels were dinged and chipped and worse so they needed to go. The swing arm was not great either, now that we are looking at it in a picky kind of way. Luckily we had more scraps in the larder, so to speak, and Matt produced a really clean frame and swing arm that had belonged to his 300 which had been scavenged for parts over the years, to the point that not much remained except for the chassis. Perfect!

Next job was a total strip down. This took only a couple of hours once Matt saw what was going on and gave me a hand. Just as well, as my memory is not as good as it once was, and I forgot a couple of obvious things even though I must have stripped down 40 or 50 NSR250s back in the day. Once the parts were spread across the floor, we could separate them out. All parts were inspected and bolts and brackets were prepared for zincing in their original colours of black, silver or gold. Other parts were separated into a pile for cleaning and painting, and another pile of parts which we wouldn’t need. The last pile was pretty big and included the wheels, the front end, all bodywork, tank and subframe. Now came the fun part, I spent an entire Saturday just trying to clean all the corrosion and staining off the engine. I am not sure if it was the right decision looking back. It might have been quicker to strip the engine down and blast the parts but anyway, it wasn’t supposed to be a major project just a leftovers bike, so the decision was taken to just clean it up a bit. My back was killing me the following Sunday (getting too old for this!) and I still hadn’t even began to clean the other parts. The good news was the frame off Matt’s bike was like new and the swing arm, although it had been stripped of the anodizing, was easy to freshen up with some light wet sanding and scotchbrite.

While the cleaning was going on, and the metal parts were being zinced, we sent a pair of stock MC21 wheels off to be painted black and dug out of storage a pair of tyres taken of the RC390. We also had a look around to see what else we could use and found a carbon hugger from the Rothmans MC21 which was surplus to requirements and substituted a few parts such as instruments, air-box, auto-lube container and some stays for better condition ones which we had squirreled away. Now came the fun bit; shopping on the TYGA website! Even with a leftover project, it is nice to add some choice components. We replaced the TYGA step kit with  the latest version, chose some GP two carbon/Kevlar silencers up the right side exhaust, 50 mm handle bars, a 40T TYGA rear sprocket, TYGA meter stay, LED indicators and some carbon parts such as the radiator shrouds, front brake reservoir stay, fuel tank filler cap and instrument rings. We also went shopping at Honda and bought a new front brake reservoir, hand grips, chain rubber (yes now back in production so that is good news!) and a few fasteners which were non stock.

After cleaning, the radiator, side stand clutch and brake perch, along with a few other bits and pieces, were painted to make them look like new. Matt rebuilt the front forks which had been leaking and while he was at it, fitted newly anodized adjusters to freshen up their appearance. Once installed, he made custom brake lines to link the Brembo calipers to the stock Nissin 14 mm master cylinder. The original plan was to use VTR1000 Firestorm rotors but the ones we had tucked away were pretty badly warped. Not a big deal, we had some spare RS250 ones which perfectly compliment the calipers and pads. The rear suspension, as previously mentioned was taken care of with the used Ohlins rear shock. We resisted the temptation to put a Brembo on the back and had to stay disciplined to the idea that we were using up what we had, not trying to make the ultimate NSR. It is too easy to get carried away and install RS250 magnesium wheels, a 300 motor and this and that but we had to keep the budget down.

After waiting a couple of weeks for the zinc parts to come back, the chassis went together very well. We had the engine soaked in WD40 during this period and this helped to lift the corrosion that I hadn’t managed to remove with scotchbrite and brass brushes. We replaced all the nuts and bolts on the engine with either ones we had re-zinced or new Honda ones. These shiny parts helped to freshen up the engine, and along with the scotchbrite work and the WD40, it was transformed to an object of technological 2 stroke beauty and was now ready to be installed in the frame.  Matt had some NSR250 F3 engine rubbers which we used instead of the worn stock ones. All went well with the build, and so it should because this stage in the procedure was more or less stock.

The issue we had with the chassis was with the Ohlins rear shock and the GP-T bodywork. Either works fine by itself but when you put them together, the hose, where the banjo bolt is, clashes with the battery box part of the subframe. One choice would have been to turn the shock round but then have issues with the banjo bolt and air box clashing. We therefore decided to cut a section out of the battery box to allow the subframe/battery box to fit and lay the gel battery on its side on a foam block above where the banjo bolt was; problem solved! We also had to trim the front section of the undertray for clearance with the shock hose too but that was pretty simple.

The wiring and other components were installed without drama and it now came the important and exciting moment to fire the NSR back to life! Normally, with these builds, if the bike is mostly getting a cosmetic makeover, it should start right up the same as it did previous to dismantling. I say normally, because every now and then you get a stubborn bike which refuses to start and this was the case with our MC21. We quickly discovered that we didn’t have a spark on either plug but why this was the case was not so easy to discover. After hours of running through the electrical system (I was feeling guilty because I had re taped up the harness and was worried I had broken something), it turned out to be two things, a defective pick up and dodgy connection in the connector coming off the pickups. Once these were replaced, it fired into life right away and we were now ready to move to the next step.

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