500 Two-Stroke Tech

As if eleventy five bike & car projects are not enough, I figured getting a pair of clean ready to show (and maybe go) GP gems was not such a bad idea. Hopefully these will actually increase in value over time.

1987 TZ250T 2KM





1988 RS250R NF5

Did you buy them? Do they run? And will you ride them? Just bought an FZR 400 and going to sell my Bandit. I have told myself enough is enough to keep all running, licensed, and insured.

Yep - bought em. They should be here in a couple months. They may run right out the box, but I should imagine after having been static displays for many years they need to be given a mechanical once over.

I would like to have the RS250 in good thrashable condition and the TZ just for the occasional parade lap.

These 'build from scratch' bikes are exhausting, it would be nice to have some complete very presentable bikes on hand.

I am also on the look out for a pukka 500 GP bike. Probably end up getting a real RS500 or XR35/40 RG500 at some point. In the end it will probably cost about the same as the cost of a decent replica.

They look splendid .

The bikes have been here for a while now.

The TZ is waiting on a couple consumables and a 17" rear wheel.
It is like a time capsule. Someone pulled into the pits in 1988 after a club race, wiped the bike down, drained the fluids and parked it inside for the next 25 years.

With everything being so original I might do a photo essay for anyone who wants to restore a 2KM to original state.






The RS has been given a cosmetic once over and even brought to life.

A couple before, during and after painting pics. The 17" HRC wheel is installed and makes tyre choice a lot easier.

And Its ALIVE!!! Video ---> https://youtu.be/FXjXvkxVul0" onclick="window.open(this.href);return false;

Before





[During















After

All dressed up with the new decals, fresh off an 8psi leak down test and ready to go

Just waiting on new tires and brake pads.

New startup & warm-up video.

https://youtu.be/thn7bMEGZqY" onclick="window.open(this.href);return false;

Took the chance to take some photos with the DSLR.

The Van








The Bike

Are you OK. A bike that runs. Kidding. I like it. Good finds. Get the tires and see you at track. MSR next weekend.

Went out to the country to try some straight line runs to do a couple plug chops.

Decided to try various video setups as well.

1st up, a push start video from an unusual perspective - 360* panorama
https://www.youtube.com/watch?v=RnYixnW577U" onclick="window.open(this.href);return false;

Next up - an onboard 360* plug chop run. Fadng light, bumpy country road, 10 year old slicks, close ratio road race transmission and small sprocket make for chasing "5 to 10s at full throttle" an interesting experiemnt.
https://www.youtube.com/watch?v=IZ1xWEgH0NA" onclick="window.open(this.href);return false;

This one is a road side view of the outbound run for the 1st plug chop
https://youtu.be/KdQkBPhClNw" onclick="window.open(this.href);return false;

Same as above, just onboard looking back through the haze of 2 smoke
https://youtu.be/6qeykEweavA" onclick="window.open(this.href);return false;

Our road side pits and the volunteer pit crew



The Plugs - very hard to tell - down in the plug the porcelain is coated in a coffee color, but the rest seem swashed off. I am not looking for ultimate power, just reliable not lean setup.

Finally got around to doing some controlled plug chops and AFR checks on the dyno.

Picked up the bike form the local Honda dealership where it is on display...


Took the bike for the dyno runs down to a local bloke that builds and tune some crazy Banshees and other 4 wheelers


Warm-up video..


The Dyno Run video

The pistons - a little washed out byt he flash.

Lower cylinder


Upper cylinder

Well, it was another afternoon on the dyno.

Dyno Run 2


Dyno Run 3



The bike again posted some amazing results, different conditions to Saturday but very similar results.



49ftlb and 95hp & 50ftlb and 96hp. This appears to be one very healthy RS250. ALmost too healthy And without getting too caught up in the numbers I was again really interested in the jetting and health of the bike during the runs.

AFR numbers showed the bike to be running on the safe side at WOT and below 7,000, with a bit of a leaner patch from about 7500 to 8500 rpm. Leanest was 17:1.

But once the revs picked up it starts to richen up again and pulls as far as the throttle jockey is willing to go. We did one run almost to 12,000 but the rest we dint go past 11,000. Did not seem to the be a need for it.

Now I guess all that is left is to go ride the damn thing

RC45 wrote: Now I guess all that is left is to go ride the damn thing

With those numbers you should bring a parachute

Put it on the track. Missing another COTA event.

Yep, now that all the t's are crossed and i's dotted the bike is ready to use. I will look into a day in the near future. I would have probably foregone this next COTA day as I have zero interest in rain riding.

I spent lots of years commuting in the rain on a motorcycle back home - I am a great rain rider I just detest the rain itself so much there will be no fun to be had, for me at least.