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Tuned zetec on carbs
richard munnis - 23/1/17 at 06:01 PM

Hi folks
Just wondering has anybody out there run a tuned zetec on motorbike carbs if so did they gain much bhp I was thinking of gas flowing the head and fitting cams too mine and using the zx9r carbs I have already attached to my standard engine
Cheers Richard

johnemms - 23/1/17 at 07:26 PM

Injection - as the revs rise you need to have another set of injectors further away to keep up with the progression.
Carbs 40's - need to have the right size choke fitted which would favor either high or low revs - pull.
Bike - nice and big with sliding variable chokes so great for high and low pull - revs.

I like bike carbs - off and stripped in 10 mins - back on in 10..

SPYDER - 23/1/17 at 08:09 PM

Hi Richard. Injection doesn't NEED a second set of injectors. The benefits would be marginal. Loads of Zetecs coping perfectly well on a single set. My 3SGE engine only has a single set.
You do need the right size injectors though.
I suspect that with head work and cams that you may be getting to the point where your ZX9 carbs become the
weak link. Having said that I would be tempted to run with them at first. A rolling road run will show you how
well the carbs are working. Blackbird carbs are 42mm IIRC and may provide a "least cost" alternative.
Ultimately, injection is the way to go.

kingster996 - 23/1/17 at 10:25 PM

Depends where you are starting from and what you want to achieve I guess.

But I'd start out doing what I did and create a spreadsheet with realistic costs against a list of options.

So I started with a silvertop on gsxr throttle bodies with an st170 manifold that put out 168bhp and 133ftlb.

I fancied about 190bhp (which I though would be reasonably affordable) and looked at various options including tuning the existing silvertop.

Then I snapped the cam belt and so options needed to be adjusted and I opted for less power to allow me to buy a new engine.

Anyway to cut to the chase I ended up with a new crate blacktop, new DanST manifold, hayabusa injectors, 90mm trumpets with my existing gsxr bodies and MBE ECU.

Had it mapped and was blown away by how much more power and torque it made. 185bhp and 173ftlb and felt like a different car with a very noticeable kick in the pants. Plus with the engine still bog standard there's more to come if I fancy it.

Sorry it doesn't answer your question but food for thought on moving to injection :-)

[Edited on 23/1/17 by kingster996]

Paul Turner - 24/1/17 at 03:06 PM

quote:
Originally posted by johnemms
Injection - as the revs rise you need to have another set of injectors further away to keep up with the progression.


I have read about 8 injector set ups and how they give better power delivery but its only with mega spec engines using very high rpm plus it appears to work correctly they need quite a lot of sorting.

My common or garden 4 injector set up on a Zetec had worked beautifully with a 208 bhp engine, a standatd silvertop and a standard blacktop. The same 330 Pico injectors have been used on all 3 set ups and its smooth form tickover to max rpm.

quote:
Originally posted by johnemms
Carbs 40's - need to have the right size choke fitted which would favor either high or low revs - pull.


When I had 45's on the Zetec they were fitted with 36mm chokes which gave a good compromise between drivability and outright power. The carbs were the normal 45's with only 3 progression holes and I never really had the issue some people find. My tuner had experienced issues with some engines and initially I was keen for him to mod my carbs but he suggested I wait and see. There wasn't so money saved. Unfortunately he retired.

Injection is definitely way better than carbs but I do not think its £1000 better (what it cost after selling the carb set up). But once its mapped it stays perfectly in tune whereas Webers do need a fettle every couple of years to keep them perfect.

If you are starting from scratch go injection its very little extra.

quote:
Originally posted by johnemms
Bike - nice and big with sliding variable chokes so great for high and low pull - revs.


Its probably different now but go back 15 or so years there were very few people out there with bike carb expertise.

Last time I looked for a good old boy who had loads of Weber experience locally I had to give up and travel 60 miles. The previous time a spotty 18 year old made a right balls up, despite working for an acknowledged Weber specialist he did not have a clue and his boss had no interest in sorting it.

FASTdan - 15/2/17 at 09:51 AM

quote:
Originally posted by Paul Turner



Injection is definitely way better than carbs but I do not think its £1000 better (what it cost after selling the carb set up).


The price gap is not so great (at least not with our two comparable carb and throttle body kits). £1000 for a plug and play Zetec deluxe carb kit (with NODIZ ECU) or £1500 for the equivalent Throttle Body kit (with ME221 ECU).

coozer - 15/2/17 at 07:27 PM

quote:
Originally posted by richard munnis
Hi folks
Just wondering has anybody out there run a tuned zetec on motorbike carbs if so did they gain much bhp I was thinking of gas flowing the head and fitting cams too mine and using the zx9r carbs I have already attached to my standard engine
Cheers Richard


This in hindsight is exactly what I should have done instead of spending £2k ditching the carbs....

I gained 12 bhp for 2k.... up from 166 on zx9r carbs to 178 on injection......

Took it to the rolling road and they had a westie in with as you have described a 2l zetec, gas flowed head, Kent cams and blackbird carbs. It made 210 on the rollers...

Needless to say hindsight is absolutely marvellous doh😈😣😣