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DH1900

Joined:

Oct 12

Posts: 11

DH1900 says:

Screen reducing top speed?

I recently purchased a YBR125 custom. It came with a GIVI A604 screen. I haven't been able to fully open up the taps yet as it's still in its break in period but it struggles to do much over 50 mph. Am I expecting too much from a 125 or could the screen actually be harming the aerodynamics of the bike? It doesn't seem to be keeping the wind off me at all.

I know that the custom isn't the most aerodyamic bike but I don't have the lumbar spine or shoulders for anything with a less upright seating position.

Thank you.

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  • Posted 2 years ago (26 October 2012 23:13)

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SlowLearner

Joined:

Feb 10

Posts: 1953

SlowLearner says:

Screen limiting speed

At 50mph, a screen is not likely to make a noticeable difference to performance.   Not unless it's a massive 10-foot by 20-foot double-glazed window you've got on the front. 

You should be able to get more that 50mph out of a 125cc, though... my old 100cc way back in the day could do half that again.

Then again, is your bike is geared down?  It is "custom" after all.   The MCN review reckons you should get 70mph out of it:

YBR125 review

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DH1900

Joined:

Oct 12

Posts: 11

DH1900 says:

Re: Screen limiting speed

I had a look at the manual and compared it to the standard, the only difference is in the secondary reduction ratio which is 43/14 (3.071) on the custom and 45/14 (3.214) on the standard. If the standard one can do 70 that would mean that the custom should be able to do 66 if all things are equal. The bike has a wet weight of 4kg more.

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jaffa90

Joined:

Mar 09

Posts: 8925

jaffa90 says:

top speed

How much do you weigh?

What year mileage is the bike?

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DH1900

Joined:

Oct 12

Posts: 11

DH1900 says:

Re: top speed

I weigh 80kg. It's currently got 310 miles on the clock, which I'm working on increasing.

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jaffa90

Joined:

Mar 09

Posts: 8925

jaffa90 says:

top speed

I used to be 80kg:upset:,the screen you have is for a naked bike and not for a cruiser,i suspect your bike has been thrashed and now under powered.

Test it with your head down a little, on a calm day, on a level road, full throttle for 30 seconds,if you do not reach 60mph then change the bike.Your bike is booked at 65mph with a 60kg nip with a tail wind. 

 

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SlowLearner

Joined:

Feb 10

Posts: 1953

SlowLearner says:

Jaffa:

What do you mean "it's been thrashed and is now underpowered" - did you read the dude's post at all?   The bike is brand new!

But DH1900 - if it's only done 310 miles, you really shouldn't be trying to do more than 50mph on a bike like that!   It the top speed is 66,  you're 75% of your way there already - break the engine in gently, and you'll get the best out of it.

You're trying to crack that thing in way too quickly, and it's probably only doing 50mph because the engine is still brand new and very tight.

Take it a lot more easy for the next 600-odd miles, slowly increase the revs you do, and keep it under halfway to the redline until you've done 500 miles.

Just hope you haven't ruined the poor damned thing already.

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DH1900

Joined:

Oct 12

Posts: 11

DH1900 says:

Slow learner

At 50mph it's doing 6000rpm in 5th gear and I've got the throttle about three quarters open. The manual says not to take it over 7500. It redlines above 100000. I haven't taken it to that speed for more than about 30 seconds.
Should I take it even easier than that and, if so, how easy?

[This Reply has been modified by the Author]

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cairnsie13

Joined:

Jan 11

Posts: 267

cairnsie13 says:

If its not run in it

wont be producing all its power yet anyway. probs why its slower. I have never had a new bike but i have had many new cars and you can definately see an increase in performance and fuel consumpsion when run in.

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SlowLearner

Joined:

Feb 10

Posts: 1953

SlowLearner says:

DH1900:

Sorry mate for being slow in responding.

I'd give it at least twice the run-in distance stated in the manual.   The revs/mileage given are for a occasional maximum - not what you should be giving it full throttle on a sustained basis.

It sounds like you're being sensible, 3/4 throttle and all that - please continue to be patient, and it'll pay off.  You'll have a sweet engine that gives you the maximum in the long run. 

Besides rebuilding blown engines,  I'm currently running in my third brand new one.  Taking it particularly easy too, because I want to hang onto it - you'll never regret being patient in the process.   For smoothness, MPG, power output, longevity the lot - run it in very easy, you'll thank yourself later.

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