TZR mixture issues?

[Timmeh]

Hey all.

It's my first post so forgive me if this has been done before.

I've just bought a rather insane '93 TZR125RR SP 4DL, the Belgrada variant which is essentially a 250 racing bike with a full-power 125 engine and road fairings. It goes like the tits and handles better than any other 125 I've ever ridden, including derestricted NSRs and Mitos. It runs fine when its warm, the engine is really responsive and happily revs away, however it currently doesn't run at all because it doesn't start. I had the RAC guy out to it on sunday, and when he looked at the sparkplug it was drowned in fuel and covered in black, sticky soot. We stuck a new plug in and it instantly started and I happily ran it for another 20-25Ks before it wouldn't start again. I haven't looked at the plug yet but I know it'll be covered in gunk.

I think I'm right in saying that it's running stupidly rich, does anyone have any ideas how to get it right without having to take it to a garage and using an oxygen sensor? Bit skint at the moment, having saved all my pennies for the bike.

It's done 18K so I think it may be time for a rebuild. I just want it going well enough to drive the 8K to work and back everyday until I can get it done.

Cheers!

[Kickstart]

Hi

Firstly check the main jet and needle jet. It does sound like it is running very rich, but this could be a very obvious carb problem (with a Gilera CX125 which uses the same carb we had the attomiser tube shear off from vibration, giving a hideously rich mixture and bending the needle jet).

Unfortunatly the owners handbook for the 4DL does not list the standard jetting.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Timmeh]

Thanks for the quick response matey.

I'm going to have the bike in bits this weekend, it's driving me nuts!

[Kickstart]

Hi

Just had another thought as well. The CX has basically the same carb, and the floats slide up and down 2 pairs of pins (rather than pivoting). On the CX this was prone to sticking. Check the carb is not overflowing (possible that if you turn the petrol off when you park then this problem would be disguised).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Timmeh]

woo ta!

Another question if I may.

Are there any symptoms that would indicate a rebuild is in order? Would I start to suffer from lack of performance or is it strictly a mileage thing?
____________________
GSXR400 x2 | '94 RVF400 | '93 TZR125 4DL (again)
20:22:30 BLUEX5: i would love to be forced to undergo a**l plugging with different sizes
20:48:18 Temeluchus: comp you hunk of smouldering homos3x you

[Kickstart]

Hi

Performance is likely to drop off, and maybe starting would get harder.

The worry is if a worn ring snaps and scores the barrel.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Timmeh]

cool.

As soon as I can afford it I'll get it done.

Thanks again
____________________
GSXR400 x2 | '94 RVF400 | '93 TZR125 4DL (again)
20:22:30 BLUEX5: i would love to be forced to undergo a**l plugging with different sizes
20:48:18 Temeluchus: comp you hunk of smouldering homos3x you

[Timmeh]

OK, here's an update:

Had a really good look all round the bike, found several breather pipes blocked with dirt including the carb drain hoses and the one that goes into the bottom of the tank. Cleared the blockages, dismantled the carb, cleaned it out, got a colortune.

At idle the colour's a nice deep blue with the odd flash of yellow which I know is what I'm looking for. I've got instant off-idle response and more power down the bottom end, but the power band isn't as defined and I think I'm missing some top-end performance.

Would I be right in thinking that the needle jet is now too lean? At the moment the clip is one setting towards the top rather than in the middle, so would putting it back in the middle help?

The air screw is a full 2.5 turns out so should I put it back in a quarter of a turn to make it slightly more rich?

Thanks for all your help btw, I'd be a bit lost without some sterling advice I've found on here.


____________________
GSXR400 x2 | '94 RVF400 | '93 TZR125 4DL (again)
20:22:30 BLUEX5: i would love to be forced to undergo a**l plugging with different sizes
20:48:18 Temeluchus: comp you hunk of smouldering homos3x you