Superbyke weak 5th gear and other problems, updated info after lot of changes

Well, theres a lot of time passed, I was riding my Superbyke RSR to work, and such, here's the results:

in gear 5, 50-55mph is the max,
but in gear 4 I can squeeze out 55-62mph.

This max speed ( in 5th) compared to what the factory and all youtubers claim, and visually achieve: 75-80mph, 50mph is very low.

Air filter was clean, took out the carburettor needle once, seemed crystal clean, aswell as the tube, but I yet to have it taken apart fully.

I have a new CDI, I try to install that, but other than the weak 5th gear, I have no clue about a bad cdi.. So I only going to put it in because I have a new, so why not..

Changed starter igniting unit and spark plug to brand new, no results, nothing changed.

Brand new oilt filter and oil, etc.

I'm starting to think that there's a fault in the engine, or that my idle speed or any carburettor setting is bad, but without a working tachometer I can only ask one of my bike expert friends to have a look. Idle seems to be a bit low rpm to me by the sound of it...


Other problems, might be related:

The bike was running fine until I rode it every day,
but when the fuel meter dropped down to 1/3, (at least a few blocks away from the last two red bars) sometimes my engine started to stall, and refused to kick in, like theres no gas... I kept on trying, and once a loud bang occured XD so I started to push it home instead... (spark was fine) As soon as I reached an elevated surface BIKE POINTING UP, I gave it another try, and the bike was started right away without any problem. Then when I was braking, (bike putting its nose down a little bit) it stalled again.
I switched to reserve, it didn't had the right effect at once, but after a few minutes it kicked in nicely, and remained stable.

next day I went to the fuel station, and filled it, NO PROBLEM SINCE THEN.

But after I left the bike in the garage for 2, or 2 and a half weeks, and tried to start, (with choke) battery was ok, as the starter was spinning teh engine hard, but nothing...

After half a MINUTE of igniting, I recognised, that it kicks in, just very very weak and does not stay ignited. I almost gave up, then it kicked in very weakly...

Somehow managed with choek on 80% and using throttle to warm it up, then when It all looked good, tried to decrease choke, then it died out, and took MINUTES to get it stay on.. after that I used heavy choke, and after long minutes I achieved a steady idle without choke.

I rode a bit, and the idle RPM was sounded faster than usual, bike restarted after 15 mins without choke nicely.

As the battery was ok, I cannot imagine WHAT can cause this horrible weakness after 2 weeks in the garage.

Maybe it's related to the ever-weak 5th gera, I dont know.

I cant take apart the engine, so, is there anything I can try to try to raise the top speed?

Riding in 55 mph on a 60 mph road in England is dangerous, as people keep cutting on you dangerously- they teach here to always travel on the max legal speed, so noone going to cut on you unless they break the law... It's still not that bad on a 60mph road, but dual carriageways have a 70mph top, and 55-60mph there is outright dangerous...

Many guys told me that nbot reaching 70mph is very very bad, as even 50cc scooters can go near that, and this machine is regarded as a strong enough 125's.

Also: one of my bike expert buddies tried it, and he says, that compared to it's weight, i's accelerating wonderfully! So it seems that the problem only persist at 5th gear- as I think 55-60mph top in 4th gear is -very- remarkable...

In 5th, it rides steadily, but the engine rpm stay low-middle, does not goes up like in 4th, and no matter that I slowly increase, or open fully the throttle, it rides with 50-55mph
with small throttle, or with full throttle aswell.

Can you have any clue for me for this problems, what can I check?

Needle crystal clean ≠ Main jet not blocked...
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What's the teeth # of current sprockets... There's 80kph version for German, if fitted those wrongly by factory from day 1...
Valve gap OK?

Quote:

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Originally Posted by humanbeing

Needle crystal clean ≠ Main jet not blocked...
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What's the teeth # of current sprockets... There's 80kph version for German, if fitted those wrongly by factory from day 1...
Valve gap OK?

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I don't know how to check the valve gap, and any other settings of the carb yet :(

I'm going to count the teeth in the coming days! :)