Carburettors can seem a bit like black magic and voodoo if you are not familiar with them and how their internals work.
Here’s a diagram that shows the throttle ranges that the standard components that can be adjusted affect, there are other factors than can be changed but that’s getting into more serious modifications.
I have deciphered the voodoo of carb tuning and now after countless hours of fiddling with jets float hights and mixture screws have it 100% sorted. I ring Brett Roberts 0274031119 he has a dyno and knows carbs . For $50 he tunes and has instant proof of improvements or other problems clever bugga.He generally gains about 5 hp on a tune well worth the money and time saved.A clean air filter new plug and fresh gas and a thick skin are all thats required (hes a sarcastic bastard)
Us KLR guys talk about this a lot, they come a touch lean in the emission range, needle mostly, and rich in the main to compensate, so when you change the needle only, they end up using to much gas if you don’t go down on the main, good old fashion fun and tinkering.
Where is Brett based? for that money I’d put my bike on and get the fuelling sorted.
The dyno is in Otahuhu
Does he have a company website/facebook page or anything?
I wonder if he’d be interested in running a Adventure Riding NZ dyno day?
Best ring him and organise direct i am sure he will be keen.I don,t think he has a web site probably too busy rebuilding motors and restoring bikes to bother.
I’ll try find the link 2night but there was i page i read that had good trouble shooting tips when tuning carbs. Not that i’m storted mine fully yet…
thanks eddie!
What’s a ‘carb’?
Checking the colour of your spark plugs is a good way to see how your bike is running and whether your carb tuning is correct.
I’ve pulled my plugs to find the bike is running a bit rich so I’ve leaned it off a little by dropping the carb needle one clip position and it’s running heaps better.
Will the spark plugs change colour to reflect the change and if so how long/km’s will it take to reflect the new tune?
I like most am happy when I turn the key, it starts and runs! If I start dicking around with all of this magic, Voodoo stuff I am sure to F**K something up either in the dismantling or the OMFG, where did that bolt go, or what is that thing on the floor and where does it belong syndrome….
Nice to know, thanks….
If I was buried in snow 7 months of the year I would know my bike as well as Bruce Jenner knows his willie…
Oh wait, that’s not a good simile…
I would know my bike as well as anyone that tinkers for 7 months on ADV rider….
🙂
If a bike has any intake, engine or exhaust modification from stock then the fuelling should be looked at the get the best performance and economy from the changes.
My bike is heavily modified, airbox, carb and exhaust and some exhaust porting so getting it to run right has been an ongoing process of tweaking. I think I’ve got it pretty good now. It’s a lot stronger than a stock DR.
You should take it for a spin up the road at Taumaranui.
Here’s a better diagram about what parts of the carburetter affect it’s performance at different throttle openings.
If there was a group carb-tune session on that dyno I’d be interested.
Thanks
Yeah I’m quite keen to get the Dr on the dyno too for a baseline before I put a high compression piston in.
So, my bike stopped idleing recently and at the same time the midrange improved HUGELY, it now comes on in a big rush.
On investigation I discovered the extended fuel mixture screw has unwound itself and dropped out of the carb.
I want to get the bike idling again but not lose that huge midrange rush. With the fuel screw removed that means more fuel is getting in through the idle system, so I should go up a size on the idle jet?
‘@Badjelly dyno day in 2 weeks, $40 per run.
https://www.adventureridingnz.co.nz/forums/topic/auckland-dyno-day-saturday-march-25th-2017/
I found this nifty video on how a CV carb works. This type of carb is stock on the DR650, KLR650 and many other bikes.
https://www.youtube.com/watch?v=IBFq9nHVmks
Dyno day seems to want to cover 1/2 of your video….
??? post a screenshot? it looks ok to me on my pc and my android phone.
https://youtu.be/toVfvRhWbj8
Excellent vids Eddie, thanks for posting.