Thunderace Carb emuslion tube question

[Tazzkiller]

Do thunderace's wear out the emulsion tubes like the exups?

mine has done 70k and the carbs engine running rough, no amount of balancing or air screw adjustment seems to help.

[Goshreally2]

If you are sure your motor, ignition and fuel delivery system to carbs is ok then the carbs will need at least a minor strip down. There are a number of points within the carbs including needles, emulsion tubes, jets, pilot screw setting and leakage and diaphragm splits. It would cost a bit and take a bit of time but unless you know which part is causing the issue your guess is as good as anyone else.

[Goshreally2]

Forgot to add I changed the needles and emulsion tubes on my genesis after asking about carbs on here a while back. There was an improvement in the carbs so I am thinking downdraught carbs wear in this area but I did other work. I decided to change the tubes and needles after a visual inspection.

[YAMAEXUP]

The intake is the same to all intents & purposes as the earlier Exup-Rs but the 'O' rings between the intake rubbers & the cylinder head are the same that can & do split, allowing excess air to weaken the air/fuel ratio leading to uneven running.

https://www.fowlersparts.co.uk/parts/41 ... 0-a/intake

Even if they look ok, it's worth smearing something like Blue Hammerite on to the mating surfaces, just to be on the safe side.....

I had a problem with what I thought was down to the emulsion tubes on my Exup. Having fitted new ones, even though the originals looked ok, it didn't fix the situation. So I thought it was still a problem with the carbs, so I replaced the strange shaped seal that goes between the carb body & the jet holder, but it still had the same problem.

In the end I looked more closely at the silicone leads & OEM plug caps from the high output Dyna coils to the DR8EV plugs. I replaced the leads with copper core stuff from M&P & the OEM plug caps with new NGK ones, having removed the internal resistive element....& wham, suddenly I have full power again, with a decent tickover & good pickup on the throttle above 4k. It transpired that the original plug caps were expanding with engine heat & the enhanced spark energy was leaking out to the cylinder head via the molding seam.

While looking up the fiche for the T/Ace I noticed that the inlet manifolds are different to the earlier Exups in that there's a vacuum takeoff for the balance gauges, similar to the Morgan Carbtune kit that I now have fitted to my R1 & Exup. Yamaha must have listened to the painful shreeks of countless bike mechanics attempting to remove & reinstall the small blanking plugs on the earlier bikes.....

[Tazzkiller]

The intake is the same to all intents & purposes as the earlier Exup-Rs but the 'O' rings between the intake rubbers & the cylinder head are the same that can & do split, allowing excess air to weaken the air/fuel ratio leading to uneven running.

https://www.fowlersparts.co.uk/parts/41 ... 0-a/intake

Even if they look ok, it's worth smearing something like Blue Hammerite on to the mating surfaces, just to be on the safe side.....

I had a problem with what I thought was down to the emulsion tubes on my Exup. Having fitted new ones, even though the originals looked ok, it didn't fix the situation. So I thought it was still a problem with the carbs, so I replaced the strange shaped seal that goes between the carb body & the jet holder, but it still had the same problem.

In the end I looked more closely at the silicone leads & OEM plug caps from the high output Dyna coils to the DR8EV plugs. I replaced the leads with copper core stuff from M&P & the OEM plug caps with new NGK ones, having removed the internal resistive element....& wham, suddenly I have full power again, with a decent tickover & good pickup on the throttle above 4k. It transpired that the original plug caps were expanding with engine heat & the enhanced spark energy was leaking out to the cylinder head via the molding seam.

While looking up the fiche for the T/Ace I noticed that the inlet manifolds are different to the earlier Exups in that there's a vacuum takeoff for the balance gauges, similar to the Morgan Carbtune kit that I now have fitted to my R1 & Exup. Yamaha must have listened to the painful shreeks of countless bike mechanics attempting to remove & reinstall the small blanking plugs on the earlier bikes.....

they are good idea, apart from the yamaha tube plugs, they corrode like crazy.

[Tazzkiller]

i'll tear them down at the weekend, it's getting almost un-rideable. The clutch slave cylinder has just given up as well. it's almost like it's telling me something.