Ok guys here it is, the Results of my recent Dyno Time!

I first thought I had a problem with my Carburettors and simply could not sort it out myself after 6 times having the carburettors off and adjusting this and that!!! I also determined that I did not have the correct tools to accurately set them up and so i had to take it to a specialist.
In came Kevin at Projex in Cradley Heath. Few emails and telephone conversation and my bike was booked in to be fully set-up using the Dyno Machine.


We did a first run to try and find out what the problem might be... It turned out it was an electrical fault to do with the de-restrictor Module under the Speedometer. With that then sorted we did a first full power run to see what we were dealing with.

The red line on the graph shows this first run. It was clear that the Carburettors were unbalanced and the fuelling was all over the place. So we removed the carbs and investigated. After checking the spark plugs, we thought it might be necassary to increase the jets by one size. Going from 116F/118R to 118F/120R. (Completely Factory Standard Bike). We checked the float hieghts and found the Rears to be almost perfect and not needing adjusting, and the fronts were not only too low, but were also out of balance form each other which doesnt help. We reset all the float hieghts to Factory Standard 6.8mm. I also asked if the bike could be made to pick up quicker and have better response, and Kevin suggested the 2.5mm Vacuum hole mod on the slides which I had already done by this point.
With all that done and the bike rebuilt we put it back on the Dyno and performed another Full power Run. the blue line is the result of this second run!
You can see just how much smoother the power delivery is! And how consistent it is aswell. the difference is unbelievable! And the response is incredible! A completely different bike than what i took up there thats for sure.
As you can tell from the graph, almost 90% of the time the bike is producing and holding a lot more power through the rev range. the flat spot is no longer there, just a ballistic amount of power instead! Overall I am really happy with the result. (Im just a little bit annoyed a tthe Peka power output, but the bike is 15 years old now, so i will forgive it. LOL

Although the graph is showing peak power output to be 45.26bhp and 45.65bhp AT THE WHEEL, the second run actually produced an extra 1.8% on top of that due to the differenc ein air pressure in the Dyno Room between the two tests. So peak power on the second run is actually 46.47bhp. (AT THE WHEEL) Not a bad increase just by setting the Carbs up properly wouldnt you say?


Sorry about the Missing bits of the Graph, My scanner is seriously playing up and that is the best i could get it to scan after an hour of trying. LOL

how long did you spend at the shop ?? how much did it cost ??

I was there all day from about 10am to 4pm, but during that time he was also working on a lot of other bike whilst I fettled with mine to one side! If simply working on a single bike we could of had it all done in under 2 hours easily.

I payed £165, but that was for three runs on the dyno, full set-up and tune of the Cabrurettors and also the finding of the fault with the electrics and its repair. I also got a set of Carbon bar-ens in with the price aswell, as I kept on begging him for them. LOL

I believe for a single power run and quick assesment he charges about £30. its well worth it for the knowledge this guy has on setting them up right, and would make an Ideal days ride-out at some point.

not got much time right now - but you want to be seeing at least 10 more bhp than that....

Mmm... Where do I start. Well, with the obvious. Your bike is very underpowered and must be running poorly somewhere. So other than 118f/120r and 2.5mm slide hole what else is on the bike and what is its history? The factory standard is 58bhp, and even after 20 years, 46bhp is poor numbers.

The good thing is the graph is pretty smooth, but peak power is astray. 12,500rpm is the standard peak power from a standard CDI. We need more info to help start putting it right, like when was the oil and filter changed, last new air filter, are the valve clearances done, what exhaust/system is fitted, is the bike sucking air or are the collars rusted away etc???

Yeah not so sure about the results myself, but they could be well in the ballpark depending on the dyno.

If the A/F ratio scale was visible it would be easier to add comment.


Not to burst your bubble in any way, but for the benefit of others reading this the work the dyno operator performed is what most peeps on here recommend as a good base setup and it takes less than an hour to do in your own garage.

FWIW as a comparison this is the graph from our 1994 NC35 with 55000km on, std engine, jetting etc only change is ART race can (Original downpipes), should really do another dyno run on it now, it's on a different engine!



If you can't read it that's 57.73BHP at the rear wheel.

The Standard figure that everybody seems to be throwing around is 58bhp. I agree, it is. but that is at the Flywheel!! Not at the rear wheel! The figures quoted in my Dyno graph are REAR WHEEL POWER and so you should compensate this into the equation. I am not entirely sure how much this equates to at the wheel, but i do know the bike has lost power over the years. It is 15 years old now for god sake!!

It has just over 13'000 Miles on the clock, It had a complete service about 1000 Miles ago, roughly at christmas last year. it had New Oil, Filter, Air Filter, Carb Rubbers, Carb Rubber Clips, New Spark Plugs, new Chain and Sprockets etc and Also a new Sub-Air Cleaner. It also had New Coolant and the Brake pads were changed along with the enitire amount of brake fluid. Its not as if this bike is in poor condition or not looked after. In my opinion, it doesnt get any better than this. As for Valve clearences, I dont think I need to do them yet!! Not for at least another 3'000 miles anyway!

If your all telling me that my bike should have 10 more bhp AT THE WHEEL, then every single VFR400 NC30 that i have ridden with has been faulty or down on power! Ive ridden with about 5 other ones and theyve all performed about equal to mine. I think I would notice if theres were running 10bhp more at the wheel. LOL As i have never had any problems keeping up with all the ones Ive ridden with, and most of them were tuned a little bit. The one person I know fitted an Exhaust, tuned the Carbs with modified filter etc and Id like to think my bike is now faster and pulls stronger than his since I last rode with him and my bike was not tuned and running rough.

jesus, yours only has 13,000 on the clock!

mines now on 47,000 (and ive put 29,000 of them on it) and ive never had it set up or owt, so mine must be well down on power then, haha

This is what I got from a Blueflame can and a blowing exhaust.

THIS IS REAR WHEEL POWER!!! Just a smidge over 60bhp



The Honda figures are actually RWHP, on the old forum I had stickied a dyno chart topic and the average power at the WHEEL is high 50, low 60 without any proper modifications.

Also, my bike has had 44,000kms on the clock for the last 3 year, its simple to remove the speedo cable.