Hitchcocks Forum

I hope that someone can help me with a question.

My 2018 C5 Euro4 is the first bike i have had which is fuel injected. If i ride to the top of the rev range in any gear when i hit the top the bike suddenly flattens its acceleration and hesitates and loses power until I pull the throttle back and ease he revs off a bit and then it picks up. Is this usual fuel injected behaviour?

On naturally aspirated bikes I would expect the power to stay the same at the top of the rev range until you move up a gear.

My example is, if i go to overtake in 4th gear and pull the throttle all the way back in overtaking, i find it hard to know when i am at the top of the rev range to move to 5th gear as the bike is pulling well in the overtaking manoeuvre and then suddenly plateaus/bogs/loses power until i change to 5th gear and pull away again and complete the overtake. it feels a bit unnerving, but maybe its just my riding style!

With that riding style I would want to know what revs Iwas doing. Perhaps a small electronic tacho would be useful? It is a 500 single after all so it's not going to rev so very high.
I tend to ride on the torque rather than the peak power.

Sounds like the rev limiter cutting the ignition circuit?

It doesn't feel like i am riding hard or taking the bike too far.

Is there rev limiter on these bikes?

It seems like the ECU has a built in rev limiter, the post below on the classic motor works forum is old but interesting.

https://forum.classicmotorworks.com/ind ... ic=14571.0

The problem doesn't happen very often mostly when i am overtaking from a junction or roundabout, so maybe its my riding to blame!

I suppose a Carburetor replacement system would get rid of the problem as it seems that the ECU rev limiter cuts the fuel flow in and out.

The ECU has a “hard” rev limiter ie it just cuts the fuel at specific revs rather than gradually reducing the power. Apart from a rev counter or a carb conversion you could always gear it up one tooth on the gearbox sprocket if you are not too heavy, don’t ride with a pillion and don’t live in a very hilly area. A lot, including me, have done this. Are you sure you’ve got the right sort of bike?

Just noticed it's Euro4. They went down to 17 teeth for Euro4 which seemed very low to me. I went to 19 and it still pulls away at tickover as well as reving out well. I never carry a pillion though.

I've made the step from the standard 17T front sprocket to the 18T a few weeks ago. Possibly my problem is that I've moved up from a 90cc, 125cc and 200cc bikes in the past 12 years all that revved to about 9000rpm and needed to be ridden at those revs to go up slight inclines or keep up with traffic, so i suppose its me getting used to the lower revving but more capable C5 now. I never used to get to overtake anything on the previous bikes!

AS far as fitting a tacho goes I quite like the look of this https://accessories.hitchcocksmotorcycl ... ters/34921. Not sure what it would look like fitted though

If you want to just check your revs then for under a tenner you can buy, Tiny Tach Digital Hour Meter / Tachometer on ebay. No wiring required, you just wrap the sensor wire round the ht lead and select the correct number of cylinders. But your obviously riding like you stole it

Thanks for the tip Haggis