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Discussion Starter #1
Hey guys and girls!

im having an annoying issue with my 39cc blata rep,

its hard to explain but when i start it and i leave it run for a few secs jump on to ride and it flys loads of power im 80kg and it tried to wheelie me!

after maybe 30sec it sounds the same but the "pep" is gone and struggles to build up and speed, some times it surges a bit too!

anybody know what i should look at to sort this? I was thinking the carb but its new ill put a pic of it (looks identical to the one that came off it)

I also though fuel starvation so i put on a different fuel filter which is higher flow than the other! Im a bit stumped, it starts first pull of the cord even when cold its very easy to start.

C9D4ECDD-A7C5-4B4A-A864-A886698423F0.png
 

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The rep bikes are known for water pump issues

That carburetor kit is for a Cagllari Daytona
 

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Discussion Starter #3
Thanks for the reply, my waterpump seems ok as the radiator is heating up, i just used the carb as the manifold was too small for my bike but the carb itself looks the same as what was on it.

i think i found the problem! I put a new clutch in and it seems like the springs were set too loose and when the clutch bell was heating up it was causing too much friction if that makes sense, i adjusted the clutch and it seems ok there approx 21mm each now.

i wont be fully sure until i try it a bit more but looks like that was the problem.

i also seem to get oil weeping where the exhaust is joined to the head its only head up by springs, im running 33/1
 

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The oil is normal, 1:33 is good. You can put some heat resistant silicon on the exhaust to stop it.
What's the color of you spark plug? White, brown or black.
And I can say the 14mm carb is to small for these engines, try to get a phva 17,5mm or if it's easyer to get a 19mm PHBG. The 17,5mm carbs runs great on these engines.
 

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Discussion Starter #5
My spark plug is clean yet bike only running for a couple of minutes at a time as was having issues, will cleck tomorrow as it had a better run after I adjusted the clutch.

i thought that carb i bought was 19mm ill have to measure it but i don't want to take it off it's awkward to access.

added a pic of clutch i have, the one they sent wouldnt fit my bike wouldn't go over the keyway, so i took the fingers off and fitted them to my old backing plate, the springs where also bigger on the new clutch i used the old ones I didnt know how tight or loose the adjuster was spose to be so i had them quite loose that seem to cause the problem is that normal?
 

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Set the springs to 21,5mm "normally" but better to measure the rpm at the engaging rpm with a gaug.
 

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Discussion Starter #7
thanks chrisi, i have the springs at just under 21mm so in the right neighbourhood now at least, i didnt know to use the bigger springs or not so i used the springs that came with the bike not the new clutches springs.

i looked online i will have to fit a bigger intake to change to the other carbs you mentioned so im not sure if ill change ive put a nice few €€€ geting it this far!

is there a big improvement with the 17.5 carb would one from AliExpress be ok are they hard to setup some have two fuel pipes maybe im looking at the wrong ones lol
 

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Discussion Starter #8
Hey all, the clutch definitely was he problem, sadly though it has lead to a new issue, my new clutch has half its lining eaten away already! Not sure what I should do about this?
 

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This clutch is dead, you have to buy a good clutch like BZM, CS or something like that.
Also a origin Blata clutch have better lining.
I think your Clutchbell is to big, there should only be 1-1,5mm gap to the clutch pads.
Then you have to run it in, run a few rounds then let the clutch cool down and do this again 3 or 4 times.
It's also important that all three or two pades engage at the same rpm and you must stop riding immediately when the clutch start slipping, a slipping clutch produces a mass of heat and that destroy the springs of every clutch.

It's also possible that your transmission setup is wrong and that's the problem.
 

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Discussion Starter #11
Thanks chrisi, it's probably dead yes :-( I bought it off red circles which usually have good quality spares, i have bigger springs maybe i should have used them, the clutch bell came with the bike so it might be worn but the clutch was fine but the linings fell off from ten years of sitting still!

my front sprocket is 7 tooth rear 68 I haven't changed any of that only the clutch ive got no real riding out of it yet so many problems for something so little!
 

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I've added you two pics to show the different between 79mm and 81mm Clutchbell, that's so much, you can't adjust it with the springs. You have to change the bell when the clutch is worn more and more. That's the big mistake of much riders. As more as the clutch is worn as more it slips and as more it slips as more it will be worn. A deadly circle for a clutch, if seen 130€ clutches burn down in 30min.

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Discussion Starter #13
That is a massive difference! I will have to look into mine maybe i should have set the clutch before i fitted it?

im really annoyed with it now i see original blata clutch for €89 plus ship €16 but I'll probably set it up wrong lol
 

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Discussion Starter #14
I measured the clutch bell it is just under 80mm across the clutch in your pics is a bit different to mine, what size should my 3 finger clutch be? are the two shoe clutches any better?
 

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A new clutch should fit in a 80mm clutchbell with about 1mm gap.
The italian clutches use a other style than the blata or blata rep. I am not enthusiastic about the blata clutches.
When i reline a clutch i´ve go with the clutch on a mille and prepare it for a 81mm or 80mm clutchbell, depends on the wishes of my customer.
Usually I calibrate the clutch to 0,5mm gap.
For the run in time I recommend always a rpm gaug, 8000-8500rpm is a good starting point. At the first hour you won´t have the full grip, the clutchpads don´t fit 100% to the bell and have to run in.

I run both, 2 and 3 shoe clutches. 3 shoe has better grip and is better for high power engines and short karttracks.
 
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