new to the TZR, hitting the speed limiter. ? direct experience requested

[m in sc]

Hi,

so i have procured an 87 JDM TZR250 1kt. its bone dead stock w 10k on it.

for some background:

I have removed the 'speed' light bulb, cleaned the carburetors,  rebuilt the petcock and have stripped and lined the fuel tank with caswell tank liner & verified and cleaned that the cap vent is working correctly, so the fuel system is clear and clean.

all the wiring is straight, powervalve is adjusted correctly. runs fantastic. However,

today riding into work, and once before, I got it up around 100 mph and around 10k, and it felt like it was losing power. Like others have described. back off throttle, seems ok, and in 5th (and lower gears) pulls fine to 10K +

I assume this is the speed limiter. 

the direct experience is: does when the speed limiter come in, does it just go sort of flat like its running out of fuel? Of course at that engine speed, any loss of power is 'concerning' as no one wants to hole a piston.  I would prefer to remove the speed limiter signal tot he cdi if this is what it actually is, what exact wire do i need to remove?

I would prefer not to swap the gauges if that's the other option but would be ok to do so. I assume an FZR600 speedometer would swap in (and give mph) but the cable is in at an angle. so if i went this way i need to use an fzr600 cable as well since the end is angled?

I have a LOT of experience with air-cooled rds, lcs and rzs, but never a tzr so i need some assistance on this specific q. thanks!

-Mark (in S.C, USA)

[SeaR1ck]

Sounds about right for a 1kt 2ma they make power 7 to 10k gets to 100mph pretty quickly the last 10 it takes awhile.

Unlike my newer v twins that will rev to 11.5k and and hit 110mph easy the last 10 or so it takes a bit to build up to.

[m in sc]

yeah, i can believe that sounds... right.

at lunch i pulled the cluster and pulled the 3 pin plug from the speedometer, black plug going into the cluster housing. i assume this is the indicator for the speed light and possibly the limiter if it indeed has one? can anyone confirm this?

[SeaR1ck]

No limiter yet that stuff started popping up on the newer later models. It's just an indicator light that comes on at 88kph.
It doesn't limit the power or drop the speed. The cdi is limited to 45hp stock as it is.

Don't think it will even reach stock 120mph /180kph.

My friend has a 87 Canadian model which is supposedly the most unrestricted model. Which is now more a 2xt setup.
Wiring is the same as the uk models. With the 2my-50 cdi. Even with jolly moto

Still only gets to 100 mph and signs off at 10.5k rpm.

[m in sc]

yup.. think you're right.

just test rode it @ lunch, feels like its starving for fuel. 2nd gear pulls to 11k, well, then hit 3rd, drops. back off, let bowls fill, seems to do better... and, it seems to do better on prime. I have vacuum petcocks anyway, time to search for a manual one.

fwiw, i work out in the country so i have some good back roads to raise hell on. 

[Warwick]

Probably worth checking/cleaning the little sock filters in the carb intake stubs if you are feeling a little fuel starvation.

[m in sc]

they were removed when i rebuilt the carbs.. but good point.  I'll pull the tank tonight look at carbs & line routing.

[teezer250]

Rd350 ypvs clocks are the same as tzr250 if you want to fit a mph speedo,I did this to both of the 1KT's I used to own.

[busa1300]

With a bike that has a R1Z motor with TZR pipes and ignition...it has either 40 or 45 hp....but that is at the crank.
So it's not a lot of HP to the wheel.
My RZ350 would pull redline in 6th at about 120, but that was about it.
My RGV VJ23 will pull redline in 6th at almost 140....Stock had 40hp at the crank, but added a pipe and Zeel to put over 62 at the wheel now.
Pipes and ignition will wake your bike up some, I think.

[m in sc]

i get that, but that's not what its doing. its not that its slow.. it pulls well, and will absolutely pull it in 1st and second wot.., but sliding into 3rd wide open, it physically stops pulling the revs and then back down it comes back in. I rode home from work, and tested it with this in mind & revs staying high in the 1st 2 gears looking for that... it def did it again. im 99% sure its fuel starving. On my lc hybrid, i did the same thing when i was sucking the bowls dry into 6th gear at 120 or so, had to put in bigger needle and seats. 

what confounds me is its dead stock and everything should be in order. 

and it will def get a zeel and pipes down the road, i just want it sorted in stock form before i start modifying. 

[rz500guy]

Definitely be sure about fuel. You sure do not want to seize it. The main issue I had with mine was you do not know what was done to it in the past. I would start with doing a pull till it stops and do a plug reading. Have you tried pulling the choke on when it starts or run it with the choke? When I installed fuel filters my lines partially kinked from being too long. Have you replaced all the fuel lines? What about the fuel filter in the tank? I installed a Zeel because I was tired of trying to figure out what was possibly could be wrong with mine. It eliminated an issue with a 30 year old piece of electronics that sits above a hot engine. I have a 3MA and almost have it done.

[m in sc]

all good points for sure. Im 99% sure its fuel.

all the lines are new and the correct size, the tank is spotless, and lined with caswell since it had a pinhole or 3 in it. (it sat a lot, was in a collection). tank screen is in place and good.

it doesnt feel like ignition, been through bad cdis with rzs in the past. also, the cdi on the 1kt/2ma is on the back framerail so its nice and cool.  I do plan on a zeel though, make no doubt.

My plan is to replace the needle and seats i reused the ones in there. they seem ok but i do get an occasional piss out of the LH carb when riding it, so not good. New ones are on the way.

I hate to admit it, but i sort of eyeballed the float settings. Im going to set them to 15mm and see how it does when the new needle and seats come in, and take a hard look at the fuel line routing from the petcock to the carbs.   


the carbs are spotless inside, i ultrasonically cleaned (in actual carb cleaner) them after a complete disassembly, and even got new power jet feed line that fits tight.

i did NOT try the choke thing, I've been shaking the bike down for a few weeks and felt comfortable enough to do some long pulls, and this is where i am. Good idea though.


My plan is, after the rain passes through and Saturday is clear, i'll tear into it and nth degree the float settings, carbs and line routing since ive put about 100 miles on it since the intial 'go through'... and make sure nothing additional worked its way into the carb, kinked a line, or whatever. I also plan on modifying the stock petcock to have an actual 'off' position, mostly due to my loathing of vacuum petcocks in general and trying to avoid running an inline cut off.

-M

Definitely be sure about fuel. You sure do not want to seize it. The main issue I had with mine was you do not know what was done to it in the past. I would start with doing a pull till it stops and do a plug reading. Have you tried pulling the choke on when it starts or run it with the choke? When I installed fuel filters my lines partially kinked from being too long. Have you replaced all the fuel lines? What about the fuel filter in the tank? I installed a Zeel because I was tired of trying to figure out what was possibly could be wrong with mine. It eliminated an issue with a 30 year old piece of electronics that sits above a hot engine. I have a 3MA and almost have it done.

[teezer250]

Both of the 1986 1kt's I had have a restrictor metal tab which passes through a sensor inside the kmh speedo that restricts it to 180 kmh (112 mph).
They would get to 160 kmh in 5th gear around 10k rpm and when put into 6th gear would be very slow to go really much faster.
I cut the tab off completely and then could reach speeds nearer to 200 kmh (118 mph).

You have to open the clock (speedo) from the rear prising up the metal lip carefully all the way around to gain access inside and later close up the metal lip when all is done.
You have to rotate the speedo knob the opposite way to loosen and unscrew it from the body first.
There is a bit of wiring linking the speedo to the tacho.

Later I put a mph clock on and left any spare wires unconnected from the loom.This I found was a better solution and gives you mph readings.All experimenting to find and remove the restriction,

I previously had a uk model 2ma which would reach 120mph as standard but bored out by .75mm so I knew there was some extra power in the 1kt,just a matter of finding it.

[tzr-v4]

According to the 1KT wiring I don't see how the bike is restricted !!!

No wire coming from the dashboard to the CDI unit (item 23).

I suppose that speed light is the item 16 on the diagram and the little box beside is the tab switch.

The only wire between the CDI and the tachometer (item 13) is the grey one which is connected in the loom to the wire going from CDI to YPVS box (black yellow).

My 2XT 1988 bike was restricted using rings in the exhausts.

Olivier.

[teezer250]

I first did the metal tab removal back in 2004,so my memory is a little vague now,so the metal tab may have been to activate the speed light in the tacho.
Anyway it run better with the tab removed.