Laser ProDuro "Legal" carb settings?

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bluesman
Berichten: 266
Lid geworden op: ma jul 21, 2008 16:46
Locatie: hoegaarden

Colleagues,
One of my friends in my home country - Ukraine - bought himself DR800 SR43A.

There seems to be problem with carb settings. Bike came with street-legal Laser Produro, but had "hole" in engine characteristic, when you quickly turn trottle it would "shut up" for a moment then start to gain rpms.
When my friend took carbs apart - all seems OK but idle jet was 47.5 instead of expected 45 - no big problem, but main jet was 125! :shock:
When stock is 130!
He tried to change it and play with needle position, that "hole" dissapeared but now bike too smooth, e.g. slow and top speed down too.
I am running out of ideas what could cause it because I do not have "hands on the bike" and have to help him remotely.
Any ideas what is correct jetting for E-approved Laser Produro or what is your experience?
zappa.suzuki
Berichten: 8373
Lid geworden op: do apr 06, 2006 11:32
Locatie: Bij Utreg

My BIG with the legal Laser run good with stock setting exept the gas needles 1 groove up..

Bad gas respons could be solved with playing with the idle jet setting
Suzuki DR 800 1997, KTM Adv 640 1997
bluesman
Berichten: 266
Lid geworden op: ma jul 21, 2008 16:46
Locatie: hoegaarden

That's what I expected too! The mix screw is adjusted actually...but here is what I read on German DR Big forum - they all say that Laser Pro Duro E-approved requires change from 130 to 125 jets! :shock: I mean - it will cause LOSS of power! What the hell...is it true??? Laser E-approved model will kill some of DR power instead of helping it??? :shock:
zappa.suzuki
Berichten: 8373
Lid geworden op: do apr 06, 2006 11:32
Locatie: Bij Utreg

i believe the reason for it is the air out take is more open, but the air intake not..
So the motor tries to suck more air in and the vacium in the carb grows and sucks more gas true the main jet and the mixture gets to rich..

So when you increase the air flow in and out with say a K&N air filter and a race use laser you have to go to a bigger main jet

But to get a bike set up proper after changing somting at the exaust or/and air filter you should do a dyno run.
And the setting a just good for that bike, its not a general setting for all the bigs..

And there goes it wrong by the Germans, they take Stefan as a all knowing man but there is no such a man, specialy not a man so arrogant en stuborn as he :wink:
Suzuki DR 800 1997, KTM Adv 640 1997
bluesman
Berichten: 266
Lid geworden op: ma jul 21, 2008 16:46
Locatie: hoegaarden

I had same idea about airflow actually. I adviced my friend to take quick test run on clean road without airfilter and see what happens.
I just hate idea that he will lose bhps just for shiny exhaust :(

Actually Stefan was very nice to me, I can't complain about work he did for me. So - no comment on last part :wink:
I think we all like that when it comes to bikes. It's a passion! :lol:
Shifty-PK
Berichten: 1594
Lid geworden op: do jan 25, 2007 14:04
Locatie: Zoetermeer
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I had this problem with my old carbs on my sr41(60kkm). When i put on sr42(35kkm) carbs it was gone.

The problem accured when i was driving at constant speed and I rappidly pulled the gas open it would 'halt' for les then a second. Like it was choking or something. After it had picked up again all was o.k.

I suspected the membrane's to be too rough because they where a bit rough because they where worn. No holes, just a bit sanded by all the dirt coming past the lowsy airfilter. The problem would be that they could not move up and down very smooth anymore. So when allot of pressure in a short amount time was put on them by opening the gas they could have given some resistance. But this is just a theory.

The only thing i know for sure is that I replaced the jets needles and all the little parts, just not the membrane's.
Suzuki DR 750SK Big '89

Innovation distinguishes between a leader and a follower.
bluesman
Berichten: 266
Lid geworden op: ma jul 21, 2008 16:46
Locatie: hoegaarden

thank you! Will try to look into it - it sounds exactly like problem my friend is having!
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