General TZR250 Engine Characteristics

[srxburns]

hi, I'm in the process of restoring a 2ma. I would like to know what are some of the bikes engine characteristics. I have some experience on 2 strokes bikes but not that much. I guess I'm trying to figure out if I need and carb tuning. The bike used to be raced it has been ported and polished. since this is the case should I expect to have not much on the bottom end. what is the average rpm range for starting off in first gear 2000, 3000, more, less? it seems boggy if I'm under that, I'm a 200lbs guy so that comes into play. I don't want to start changing things if that is what to expect from this bike.

Thanks
James

[srxburns]

Maybe I posted a silly question or too general as I haven't got any replies but if someone could answer it would be of great help. for example does your TZR pull clean and crisp from a slow roll in first gear up to redline or is it a little hesitant till you get to 4000rpm.

Thanks
James

[Crank]

I would say a 2 stroke motor by design will be boggy until 3 grand, depends on the state of tune, pipes etc. Also if you come from valved background it'll take awhile get the hang of a true oil burning 2 stroke. As far as TZR's go, the powervalve is only fully open at 6 grand unleashing any potential power the motor might have.

[Crank]

Just re-read your first post, if the bike is prepped for racing it will only perform in the upper part of the rev range!

[srxburns]

lots of 2stroke experience with sleds here in Canada but they are clutched so you don't see any bog. just recently got into 2 stoke dirt bikes as my son wanted to race so as you can tell they are on the smaller cc range. I wasn't sure what to expect with this bike seems to work well in 3000 rmp and above range but boggs out under that. might just have to get used to it or double check what the gearing is and maybe raise a tooth in the rear to make it easier to drive slow without stalling around heavy traffic.

Thanks
James

[teezer250]

If the bike is going to be used on the road and it has a race tune AND race pipes,then it will work better in the upper rev range(8-10,500 rpm) as this is where most race bikes are operating and it WILL be boggy in the lower-mid range revs.
Putting standard exhausts on for road use will make it more driveable in the low-mid range as well as giving a good top speed.
You have to give it about 3-4,000 revs when setting off from a standstill,otherwise it may bog down.

[srxburns]

Thanks all for the help. It does have datona pipes etc etc will have to get used to it. looks like it is operating fine then.

James

[James P]

James,

I remember you replying to my topic about carburettors. Would you be able to let us know what jets etc. are fitted in your carbs? Specifically:

Main jets
Atomisers (type/series and size)
Needle (type and clip position)
Pilot jets
Throttle slides

Is the jetting identical on each side?
Have you still got the power jets connected?
Are you using the standard air box and filter?
Are you still using the autolube oil pump?

For your info; My own TZR will pull from 3000rpm, but has standard porting and carb settings (my autolube oil pump has been removed). Although I'm not sure exactly what brand of pipes I've got, I am sure they are "road" pipes, as the characteristics are user-friendly (it will even pull from less than 3000rpm on flat or downhill roads). The pipes are also much much lighter than standard ones!

Thanks & regards,
James

[srxburns]

Both jets are the same, the power jet is connected, I have the standard air box with the filter but the top plastic part of the box isn't on and I'm running on premix. The sizes are in your post. I striped the carbs down again drained the tank cleaned the fuel cock put in new fuel and connected another filter after the cock. I put in sea foam fuel additive and changed the plugs and now it is running great no issues idling and the pickup is night and day at low rpm. I think the system had lots of sediment  even after all the cleaning I saw a chunk of varnish at the second filter as soon as I turned on the fuel. I plan on running the second filter till I'm sure all the crap is gone. Very happy with it now. thanks James

[James P]

...I think the system had lots of sediment  even after all the cleaning I saw a chunk of varnish at the second filter as soon as I turned on the fuel. I plan on running the second filter till I'm sure all the crap is gone. Very happy with it now. thanks James

Thanks for the info James (see my reply under the other topic also). You may like to consider cleaning out and sealing the tank - I did mine with a POR-15 kit.

Regards,
James

[srxburns]

Thanks I might do that, we will see if it clears up. When i drained out the gas and looked it the tank with a light I was surprised that there wasn't a spec of rust I guess another benefit of running premix the inside of the tank get a constant oil bath.
James