Bike Throttle bodies on a zetec
Discussion
PLanning the fitting throttle bodies onto a 1.8 zetec. want to do it as cheaply as possible but maintainnig reliability.
Looking at Gsxr1000 TB's, we currently have it on weber dcoe 40's, will the manifold fit the bike throttle bodies post k3? as I understand thats when they stopped making them as indivudal TBs and built them in pairs.
Looking at Gsxr1000 TB's, we currently have it on weber dcoe 40's, will the manifold fit the bike throttle bodies post k3? as I understand thats when they stopped making them as indivudal TBs and built them in pairs.
Ideally you need to re-space them....but I suppose it depends on how you propose doing the interface between the TB and the existing manifold - you may be able to do the offset there perhaps.
Used some GSXR600 TBs on a 2.0 Silvertop on our Westy - work a treat. Prior to that, they were on the Xflow that came out to make way for the Zetec. They've done 6 or 7 years service now - not missed a beat reliability-wise.
Do be aware that you might get some mapping niggles around idle/throttle just open on a stock motor and MC TBs. Depends on whether you can define your own load site vs throttle number in the ECU or not - you want to make the first few load sites VERY close together so the ECU can 'see' the very small change in throttle angle that gives a big change in airflow at the very bottom end.
Problem goes away if you are going to use lumpy cams. Speaking of cams...or at least sepc, if the 1800 is stock and likely to stay that way, I'd suggest you think carefully about whether you need the bigger TBs - smaller ones might work better for you. Unless it's monster sepc, I'd look at using GSXR600 TBs TBH, you'll get slightly better torque and throttle response and they flow plenty for at least 170bhp.
Also do make sure you do a decent job of extending the thottle links between the TBs - you need to retain the easy adjustment and still make them stable.
HTH
Used some GSXR600 TBs on a 2.0 Silvertop on our Westy - work a treat. Prior to that, they were on the Xflow that came out to make way for the Zetec. They've done 6 or 7 years service now - not missed a beat reliability-wise.
Do be aware that you might get some mapping niggles around idle/throttle just open on a stock motor and MC TBs. Depends on whether you can define your own load site vs throttle number in the ECU or not - you want to make the first few load sites VERY close together so the ECU can 'see' the very small change in throttle angle that gives a big change in airflow at the very bottom end.
Problem goes away if you are going to use lumpy cams. Speaking of cams...or at least sepc, if the 1800 is stock and likely to stay that way, I'd suggest you think carefully about whether you need the bigger TBs - smaller ones might work better for you. Unless it's monster sepc, I'd look at using GSXR600 TBs TBH, you'll get slightly better torque and throttle response and they flow plenty for at least 170bhp.
Also do make sure you do a decent job of extending the thottle links between the TBs - you need to retain the easy adjustment and still make them stable.
HTH
Cheers, some good info there, it's got Kent cams, fairly lively , dosnt get going until 5000 peak power at 6900... but we don't know exactly what spec. We've just had it dynod at about 155 crank on the carbs. Were Pretty happy with it but hoping for 20lbftish more everywhere, and the improved fuel consumption to boot, were just looking into the choke sizes at the moment.
Given those cams, you probably won't see the issue I did at the bottom - it's down to the fact the stock 2l Zetec sucks like mad 
As I mentioned, never saw it with the same TBs on the old 1690 Xflow - that had a Kent 234, big valves, 11:1 CR...the usual, so it was a bit of a surprise when it came to light on the Zetec.
I know there's always this big-is-best thing...but honestly, I think the slightly smaller GSXR600 bodies would suit you better. Unless you plan on fitting a bigger and more highly tuned engine...in which case, perhaps go big now, but it would hurt torque a wee bit.
I got the biggest improvement on the old Xflow going from clockwork to 3D ingition, but the final step from carbs to TBs really made it sing...it was great - the old flat spots were gone and driveability was brilliant throughout, fuel consumption improved loads. Wouldn't go back to carbs on anything now (unless they are the original ones like a BEC perhaps).
Which ECU do you have by the way? Just curious.
As I mentioned, never saw it with the same TBs on the old 1690 Xflow - that had a Kent 234, big valves, 11:1 CR...the usual, so it was a bit of a surprise when it came to light on the Zetec.I know there's always this big-is-best thing...but honestly, I think the slightly smaller GSXR600 bodies would suit you better. Unless you plan on fitting a bigger and more highly tuned engine...in which case, perhaps go big now, but it would hurt torque a wee bit.
I got the biggest improvement on the old Xflow going from clockwork to 3D ingition, but the final step from carbs to TBs really made it sing...it was great - the old flat spots were gone and driveability was brilliant throughout, fuel consumption improved loads. Wouldn't go back to carbs on anything now (unless they are the original ones like a BEC perhaps).
Which ECU do you have by the way? Just curious.
Edited by CorseChris on Thursday 26th July 12:38
I had gsxr750 TBs an 1800 zetec and had exactly the symptoms Chris talked about. I ended up with 1% increments for the first 5%, then opened up the gaps between load sites progressively after that. It was never perfect but pretty good. Currently swapping to a 2.0 so hoping that they suit the larger capacity slightly better :-)
There is a load of info on my website at www.mymojo.co.uk!
There is a load of info on my website at www.mymojo.co.uk!
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