Thinking of Getting a 2T and Have a Few Questions

So, my fascination with 2Ts has come to a head and I think I either need to shit or get off the pot. In order to accomplish that I've come to you guys for your opinions. Currently I'm running a pretty well sorted ex-race 05 600RR, but have always wanted a 250 GP bike. I've done some research and am worried about the potential costs of maintenance on one if I were to take the plunge. A few of my concerns are: cost to rebuild crank and/or top ends and the cost of having to run leaded fuel. The crank and/or top end factor I cannot escape, but the fuel aspect is a little more plausible. My questions are is it hard to find a 250 that's setup to run pump gas (I'm looking at 90s RS250s, but would ride a TZ250) and what sort of costs am I looking at if I were to run 10-20 TDs in a year? Thanks for helping me get peace of mind and ending this mental constipation I'm having.

 

http://forums.13x.com/showthread.php?t=150008

http://forums.13x.com/showthread.php?t=200777

http://forums.13x.com/showthread.php?t=174857

http://forums.13x.com/showthread.php?t=165615

http://forums.13x.com/showthread.php?t=114029

http://forums.13x.com/showthread.php?t=114190

http://forums.13x.com/showthread.php?t=101446

Cliff notes: Honda parts are expensive. Unleaded is possible but pump gas is unlikely. Toward the low end of your trackday estimate you can run a season on a single crank.

On my 250 I burn $50 of leaded race gas in a trackday. On my 600 I burn $50 of vulcanized rubber in a trackday. Pick your poison.

 

Much appreciated Yard. I must admit that I was lazy and should have done a bit more searching than I did already.

So, you'd suggest getting the TZ opposed to the RS as parts are cheaper and more TZs are out there? Also do the tires really last that much longer on a 250? I was reading that some people run Sunoco 110, which is substantially cheaper than VP gas. I didn't see that. That definitely makes it more feasible. You think that I can really get a full season out of a crank (on a RS or TZ)? Based off of people stating that you should change them every 1K miles, I was thinking I'd be lucky if it lasted half a year at most (using 2.1 track lengths*8 laps*8 sessions=~134 -> 1K/134=~7 Trackdays on a crank). Are my calculations way off? Speaking of cranks I saw that the TZ can be rebuilt, whereas I think I read somewhere that the RS cannot. Then again, my research (if you want to call it that) has been pants today. Thanks again.

 

I had many of the same questions as you. After weighing my options (Honda vs. Yamaha, 125 vs. 250), I opted for the Yamaha TZ125. The Honda 125s are more well-represented in the US, but I got a great deal on the TZ and haven't regretted it a bit. It really is the most fun I've had riding on the track.

My main issue was that I had never ridden nor worked on a 2T bike before, so there'd be a bit of learning to do on both sides. So, I figured it would be easier to deal with 1 cylinder, carb, pipe, etc. than with 2. Plus, the parts cost is cut in half with regard to pistons, rings, cylinders, etc. Fortunately, I'm short enough that the 125 isn't too painful to ride for 20 minutes at a stretch.

The ability to rebuild the TZ crank is nice - eventually I'd like to learn how to do it myself, but there are enough people out there that will do it for a reasonable price. You definitely will want to find some knowledgeable people to help you out, there's a whole bunch of things that you have to consider that are not an issue with a 4T; for example, don't even think about hopping on the bike at 3rd call for your session and going full-bore once you're on the track. Unless you like seizing engines!

 

TZ250 is a west coast thing I guess; there are more Honda 250s elsewhere. RS125 is more popular everywhere for sure. It's a moot point if you're hoping to find spares at a trackday; almost nobody rides these at trackdays. Hardly anybody races 250s anymore.

But I would get a Yamaha not just for the cost of parts, but also for their track record of keeping the parts available for many years, and the fact that Honda are evil scum.

Rebuilding a TZ250 crank costs $800 in parts and labor. A new crank is about $1200. A crank lasts 1200-1500 miles. Maybe only 1000 miles if you just race at Road America and Miller. That's the major expense. Tires last forever unless you're fast. You do need to spend a few hundred bucks up front on special tools like a leak tester, timing kit, and deck height gauge.

Cheap race gas like VP 110 can work. You don't need the $20/gallon oxygenated fuel to avoid blowing up the bike, you just need a bunch of octane because these bikes make a lot of compression with a lot of ignition advance. Speaking of ignition, you can run $6 spark plugs instead of the $25 or $40 spark plugs called for.

Some things about a 250GP: Very uncomfortable, even though I'm short with a short inseam. Very physically demanding, particularly on the brakes, which are just unreal. Light weight magnifies every bump. Somewhat mentally demanding. 3K RPM powerband isn't as difficult to manage as it might seem, perhaps due to the gearbox. When you work on it, you realize you have a Grand Prix motorcycle designed by engineers, not accountants, for racers and their mechanics. When you ride it, you realize you have a Grand Prix motorcycle designed for expert racers, not trackday chumps or novice racers, and you feel kind of inadequate.

 

Thanks again for all the info Yard & Cyclox. The plan is to move out west this coming spring, so I see a TZ in the future. The cheaper cost to maintain and the parts availability alone make it a wiser choice over the Honda. :up:

 

I would get a Suzuki RGV, but that's just me

It's expensive to keep running, even on street duty. I think I put more money in maintance this year then I did on my RC51 in 3 years.

The RC51 ate tires like it's job though, so in the end the RGV is actually cheaper, it just doesn't feel like it due to all the little chicken pecking of the bank account rather then a large sum every once and a while.

Top ends are cheap and easy to do. $300 and a few hours getting your hands dirty.

RGV's use the same motor as the Aprilia RS250 cup bike.

 

I forgot about that. Which means you could upgrade to this:

http://www.twostrokeshop.com/two_stroke_shop_engines.htm

:wow::wow::wow:

The leak-down tester, deck height and timing gauges are all essential. Also, spares of cylinders, pistons, rings, etc. etc. etc are all good to look for.

When I was doing some engine work on the TZ, I fully appreciated the engineering behind these GP bikes. They're a totally different world than a race/track prepped street bike, let alone a stock street bike. Everything is there for a purpose and everything is easily accessible. It's a dream to work on compared to my 4T streetbikes. Oh, and no oil/filter changes (apart from the gearbox oil)

I bought my TZ with the intention of doing only trackdays. After riding it at 2 trackdays, I wound up entering my first race last month. Came in dead last, grinning from ear to ear and hopelessly addicted.

 

Just a normal suzuki 500cc swap would make me plenty happy!

 

That's what I'm kinda' expecting to happen and I figure if I'm going to be racing it ought to be on a proper race bike.

 

For 250, TZ all the way. 125, RS all the way. The biggest and most awesome thing is that you can order TZ parts from any Yamaha dealer. With the RS, you have to go HRC (=$$$).

I've never ridden a 250, but I do quite dream of it. I have, however, ridden my son's RS. I can say this, I've never ridden a bike that handled that well. Words simply can't describe it. And...I'm 210lbs and it was setup for 85lb son. I can't imagine riding it with suspension setup for me!

Working on them is intimidating to start with. Jetting is very important. Once you get it down though, it's not bad at all. We're on our 4th 2-stroke now. I never want to touch a 4s again!!!!

 

I started with a Aprilia cup bike. Over the last 4 seasons I have been able to slowly learn more and more about the 2T bike world, and that I like it, a lot! The upside to the Aprilia or RGV 250 is that it is not very tuning sensitive. You can get a season out of the pistons and I have been going 2 on each crank and probably could go longer. I describe it as two strokes for dummies I am finally at the stage where I feel I could maintain, tune, and ride a real GP bike with some confidence.
Friends who went right to GP bikes have had mixed results. I suspect because of the very steep learning curve. I did get a ride on a Honda RS250 and there is nothing like a real GP bike, and I will be getting one for myself soon.

 

I'm just a track day chump but would be more than happy to mentor/help ya out with your journey over to the dark side.

Sold my 125 last year but am running my 250 this season...
I'm located in Eastern PA and run with Absolute cycle, TPM and Nesba.

NJMP thunderbolt
http://www.youtube.com/watch?v=yYc8J8U1FHk

Not particularly fast but pretend I am :up:

If you decide to make the leap.... I'll do what I can to help you out.
PM or email me jz at jzracecolor dot com

 

How does maintenance of a 2T gp bike compare to a 2T dirt bike? I bought a 2T dirt bike and I was wondering that.

No threadjack intended, this is on topic right?

 

Never owned a 2t dirtbike, but it's not hard to keep a gp motor running on the road.

 

I would hesitate to call an RGV/Aprilia 2t a GP motor, but agree that the maintenance required to keep these "road worthy" is far less involved (maintenance intervals). These are street replicas Not GP bikes....
I started out on an Aprilia..... VERY FUN and a good choice for a light trackday bike/2 stroke introduction.

A typical track day maintenance Schedule on my TZ would involve
Teching bike for safety
Engine prep
Piston top and bottom
Rings
Wrist pins
top bearings
BAse gaskets
Set squish
Check timing
Coolant
Top O-rings
Clean and gap plugs
3x heat cycles on 20:1 sunoco 112

At track
Charge battery (fuel pump/power valves)
Check air density and jet accordingly (I generally run rich...it's easier on all moving parts)
Check/set air pressure cold/base
Check notes and tape radiator according to ambient temp(I have a thermostat so I don't fuss with taping)
Mix fuel Sunoco 112 25:1
First session sighting 8k limit 4-6 laps
Watch temp
Pit in

Check cylinders with Bore scope
Check coolant level
Hot tire temps
splash of fuel
Run next session 10k revs max

Normally you'd do a plug chop in these first sessions to set jetting but again based on my notes I'll jet based on relative altitude (air density/actual altitude/humidity/temp) I also have EGT guages for both exhaust for top end jet tuning but running rich keeps the temps down. They will help you spot problems that might have you running too lean though
pit in
Check Cylinders with bore Scope.

Ride it like I stole it

After last session

DRain coolant
remove heads inspect cylinders
Replace inside O-ring
Reassemble
Add coolant/bleed

Next day
Jet accordingly
run sessions /fuel

AFter return home
Drain coolant
remove cylinders
dress high spots on pistons
Clean Scotch brite cylinders
Clean ring groves
New rings
Base gaskets
New O-rings
Set/check Squish
Set/check timing
Add coolant
Heat cycle engine/rings

Next weekend
First session sighting cycle to 10k

Sat.Jet/ fuel/ride

DRain coolant
remove heads inspect cylinders
Replace inside O-ring
Reassemble
Add coolant/bleed

Sunday ...Jet fuel/ride

Will sometimes do a single day based on number of sessions done on prior weekends.

Start all over again
Pistons top and bottom........

~10 -12 days
I'll do leak downs after reringing/pistons just to make sure all seals remain in tact. Reeds should be checked periodically as well ~4days


Check rod end play at seasons end and note. If in spec you can continue to run the crank but I would check for spec after each event after this.
It's just easier to send out for rebuild. There are several reputable crank rebuilders. I recommend Roland Cushway for TZ cranks. He is such a nice guy and will chat for hours with you on set up any other questions you might have

Tdub for Honda 125's..... thought I'd give him a plug too

Off Season
Rebuild entire motor
Setting up and breaking in the motor is a bit more involved

You can Agree or disagree with my methods but, They work for me and I don't relish the thought of being spit off because "it'll be OK".
I don't heal as fast as I used to :down:

It's pricey to run one. If you run rich and watch the overrevs you can get some good miles out of your builds. I often say what I save in tires I burn in pistons. But your burning fuel.....oil.....heheh your not saving anything

If you have to pay someone to do your work....... FORGET IT!

It's a labor of love to run one of these ...especially if your not racing it.

...........And the 2 stroke community has some of the best people on the planet......always willing to drop what their doing to help another stroker out :up:

 

Nice write up JZ. How've you been? Long time. Hope all is well.

 

No kidding. That's a lot more work that I was anticipating and here I thought that I had a clue. Obviously not. Damn. I guess I'll just convert my 600RR back to track duty and get an RD350 for the street. At least that way I'll be getting my 2T fix in a much less labor intensive manner. I appreciate the write up JZ. :up:

 

Buy a well set up RZ350, we used to do 6 hour endurance races with one and then race sprints on Sunday.

All season long. :up:

 

I just got a TZ250 after years on an RS125, and I'll tell you how I ran the 125. Completely rebuild the engine during the long, cold winter. That takes probably 8 hours of actual work, maybe a little more with cleaning everything else on the bike. The rebuild kit is like $600.

First race weekend give it 2 or 3 heat cycles to 65C without riding the bike. Go out in the first session and do 4 or 5 laps at 10,000 rpm or less. Next session I'd run it a little higher every lap until I'm at my normal red line of 13,500. Now it's ready to race. I generally put on around 225-250 miles every race weekend. Not quite up to the 300 mile limit Honda recommends, but a convenient time to change the top end. At the end of the weekend, drain the water, shoot some car oil through the carb while running the last gas out of the carb.

After getting home, pull the head and cylinder, replace the piston, ring, pin, bearing, gasket and o-rings. These parts cost about $210, and it takes about an hour to do a good job of it.

Next weekend do roughly the same break-in as with a fresh engine.

Reeds and chain replaced at every other top end change.

I ran the bike for 7 seasons and never seized or broke anything except the chain that I had nearly 1,000 miles on!

As some of the other guys mentioned, these bikes were meant to be maintained, so it goes real quick. The tank is held on by one pin, the bodywork by 4 pins.

The 125 is also very light, so you can pick it up and put it in the back of a pickup pretty easily! Maybe even the back seat of your car if the wife doesn't mind!:wow: