F3 TZR

[ypvskeith]

I'm in the process of getting a F3 2MY ready for the Australian Historic Titles in November.
It has F3 Ignition, crankshaft and pipes. The top end is only blue printed but I think I'll rrun out of time to get it to F3 spec before the races.
Not sure how it will run as it is though. Waiting for Log Book from MA and it will need new slicks.

This is how it arrived - paint jobs is changing:

Nice tzr!
What seat unit do you have on there?

[mboddy]

Sir Al (in Australia) made that seat unit mould by combining a TZ250S seat unit with the original TZR side panels.

Where are you located? Can you add it to your Profile.

Are you closer to Poly26? http://www.poly26.com/carenage-moto-tuning-yamaha-250-tzr-1988-1991_5-115.html

[jools]

Ah yes that's my bike - I forgot all about it with all the other stuff happening....

One day I'll get back to it. MBoddy has the fairing now as I bought a TZ250S for it.

[mboddy]

Duncan has the fairing with the TZR I sold him.

[jools]

Pat is selling a 2XT complete if you are interested Mark ?

[mboddy]

No thanks Jools. I have enough motorbikes.

[jools]

Ok
Having finally got the 3MA running reasonably well, now joining the list of bikes that "I don't really want to sell now...." it was time to pay attention to this poor old F3 hoping that a lengthy break would sharpen my focus.

I did recall that I needed to check the squish clearance which turned out to be around 1.35mm so I set about reducing this to around 1.0mm as a starting point.



This machining wasn't as difficult as I imagined - as usual the setting up was 80% of the time required.

On reassembly one of the water jacket studs sheared off.

fortunately there was enough of the broken off part to grip and remove. I turned one up from some stainless threaded rod I had.

All re assembled and a measured squish of 1.05mm on both sides. A good starting point. It was at this point that I started to install the PV pulleys. I noticed that there had been a bush installed to remove the slack from the cable. This didn't seem right. I always removed this as an assembly and replaced the same way. On closer inspection I noticed that the cable 1 from the servo went to 2 on the pulley housing. this seemed crossed and the manual confirmed this. So this could have been the problem all along - operating the servo it cycles to the open position and sticking a finger up the exhaust port to adjust would not have identified this problem if it was actually rotating the wrong way to close. Swapping the cables and looking up the port with a torch while the servo cycled confirmed the problem was now solved.
Lets hope so, this was a basic error and in any future assemblies I will make sure that the PV cycles correctly.

Fully assembled the bike started up easily enough but now there were problems with the throttle cables not seating correctly which will be todays job.

Fingers crossed this time.

[Eric_TZR_TDR]

You are right. The cables have to cross. My tuner warned for this during reassembling the engine. Luckily I sticked a number on the loose cables :-) Good luck tinkering

[jools]

Yes Eric, never take anything for granted.

I replaced the throttle and cables with an old used TZ350 one that I had used on the Spondon as the one fitted to thye bike was a single pull with a splitter located too close to the carbs causing the shorter cables to have an undesirable bend.
This TZ item used universal cables which I had to shorten the outers by 10mm to get the correct throttle opening & closing.
With these cables installed the engine would consistently start much more easily but not pick up off the throttle and stall. Its almost like there is no fuel.

Not sure why this should be the case, so tonight I'll remove the carbs and give them a clean out.

I had changed the static timing back to 0.84mm as per the F3 manual but this shouldn't have affected it.

[iron chef]

The majority of the guys who race 2ma/1kt in the UK are limited to standard carbs/ignition/PV and are edging towards 60 rear wheel horses (well upwards of 55). Will any of you Aussie/Kiwi/French classic racers share your power curve that you've managed with alternate ign/carbs/F3 kit etc?

C'mon make us jealous!

[Toop]

It makes no sense, 60 hp at the rear wheel on which bench and which calibration?
The bench passing my motorcycle does not show much with ignition, power valve and carb original. . . . but by changing the setting of the bench I can get twice carefree ...
It is only to draw your attention to the relativity of this things.

[jools]

The majority of the guys who race 2ma/1kt in the UK are limited to standard carbs/ignition/PV and are edging towards 60 rear wheel horses (well upwards of 55). Will any of you Aussie/Kiwi/French classic racers share your power curve that you've managed with alternate ign/carbs/F3 kit etc?

C'mon make us jealous!

As Toop says, but there is no harm posting up stuff for reference and personal benchmarks for development.

My 3MA was dyno's at the track in NZ at 53 HP or so but it was walking away from trick RGV's in a straight line drag.

[mboddy]

I haven't put it on the dyno. But I have played around a bit and track tested it to get it how I like it.
In the class I race in the bikes to beat are reverse cylinder TZ250s and Honda RS125s.
My top end power keeps the TZs close and I have broad linear power from 7 to 12 so I am happy with the engine performance and won't be playing with it further.
It gets off the line fast.

What I do need to work on now is further improving corner speed to try to match the RS125s.
I think the F3 fairing will help corner speed over 200kph as the screen gets a vibe at those speeds.
And for general corner speed I am working on reducing fork stiction by fitting some NOS fork tubes as all the used ones I have are not absolutely perfectly straight and shimming the front wheel spacers.

[yanw]

...... I am working on reducing fork stiction ......

I have seen some production factory bikes running without dust seals (just oil) to try to achieve this). YMMV.

[iron chef]

Cheers guys, I'm aware that max power is relative in the dyno.

I'm intrigued to see what difference that carbs ign etc make  to the shape of the full load curve and the peak.

I know that reverse TZs make at least 15 more than my tzr, my 4DP makes 23 more on the same dyno!

If you're hanging on to TZs, you must understand my curiosity