How do you know you got your jetting right ?

K

Krisden

New member
I've just replaced my exp pipe because of a nasty crash crushing the old pipe
Now my bike seems faster and uses less fuel but the first part of the pipe have turned a gold color (heat ?)
I'm new to gas gas and im now questioning if my jetting was or is now right
how would i gauge that ? is there a right sound or ping ?
being new to gas gas i cant really tell if the power is right
any help would be nice six year off a 2t has made my a noob again :)
 
Hot topic. How lean is too lean?? Poor power, high temps, easily boils over, white spark plug, not much piston wash. Pinging under load. IMO a well jetted exhaust note sounds crisp and clean. A lean one sounds too tinny but more so lacks power under load. A rich exhaust note sounds wet and dull.

The easiest way to tell is to richen it up and see if it makes more power. If it does then it was a bit lean. If it gets too rich and starts to break up then switch back.
 
its not over heating at all
sounds more crisp but band is weaker but that could be a pipe as its an
fmf gnarly
i was just worried as im getting 140 out of a tank when i only got 120 before
I just have nothing to gauge it off hence the question
 
Is that on the stock tank?? If so thats about twice as far as most people get. No one really has anything to compare against with their jetting, apart from other settings they have tried, which is why I suggested richening up the needle one clip and experiencing the change (which may be better or worse). Its all a very personal experience depending on what you want from the bike and the way you ride. When I jet I tend to go to somewhere with an incline and do runs in different gears at different throttle positions. Basically I'm looking for good response and having the engine take revs easily. As things get leaner the bike will rev faster but may also start to lack torque and take on more of a 125 feel where its weaker below the band and super responsive on it and needs more clutch work. As they get too rich you'll get a lot of 4 stroking and burble at light throttle or part throttle. Ideally I want my bikes to fall in between these.
 
sorry fair call
have a Clark 12.5 tank gnarly pipe standard scotties jet set up i was after jetting info just after how do you know you got it right :)
 
Ha.. pfft. I know nothing about it other than what I've read and experienced.. If it feels close and you just want to confirm best method is probably to index the throttle and go and rip a few plug chops at varying throttle positions. From memory scotties was setting their Euro models up with 42 N3EJ#3 178 after setting the floats a touch lower than stock. I'd say its fairly safe even if the pipe did lean things out a bit. Especially if you haven't increased the compression ratio or tightened up the squish (IE stock engine). For me I just say the jetting is right when it feels right, and come to this by experiencing what is too rich, and what is too lean.
 
i hate not knowing gas gas aust isnt too helpfull when you ask questions they just have a standard answer
and that's right what does too lean sound like :)
i hate not knowing
looks like i will have to rebuild soon just to be safe
 
How many hours you at now?

No one can really jet a bike for you on the phone or online, or tell you the answer. Its really one of those things you have to experience or feel for yourself, and once you do you'll know. My advice is that if the bike is still taking throttle and accelerating well when given throttle at any rev then the bike isn't too lean. Pinging will happen if you go too lean and will sound like bolts in the ehxuast and will be evident with the engine under load, and usually with flat power as well. I also think the turbinecoreII silencer produces a much raspier sounding exhaust note than the Q4.

If you're worried richen everything up until it rides like crud, then lean it off until it runs well.
 
thanks obi-wan
i was a big fan on lean on 4ts
being an old 2t yz465 rider i think i have it right im just asking questions to see if I realy have it right as it sounds realy angry
 
Angry is good isn't it?? :D

Here's a short clip of mine for you http://www.youtube.com/watch?v=zEzCyCoDiQY

Just out of curiosity, has it shown any signs of being lean? Hanging idle? Hard starting? Have you confirmed what jets are in the carb, or made any changes? Take note the vid above is with the 250 top end, but the 300 sounded very similar. Just had more grunt in the bottom to mid.
 
Doesn't look like there's anything wrong with your riding abilities mate! Bike sounds fanastic.. Looks like a bit of wildlife around in your riding areas too! You shouldn't need to do a top end for a bit more yet. I did my first at 75hrs and the rinsg were still well within spec.

Here's one of my older ones using the 300 top end http://www.youtube.com/watch?v=rKBVJOLuufU
 
i can see the use of the 250 setup 300 is so much different more 4t like
but thinking of going to a 250 top end
but once you get your head around the 300 you can mess with the 4ts youngens
 
if it makes it better it was my bike that was stacked first go :(
never lend out your bike :)
And yes im a first aider :)
 
Good watch! Some funny offs there. Hope no one was too injured. The dude with his dacks pulled down gave me a laugh. Haha! To be honest the 250 and 300 are very similar. The 250 revs a bit quicker. The 300 makes more power just about everywhere except top end where they feel the same. They'll both give any of the 4T's a run for their money. Most can't even hear you sneak up behind them.
 
sounds like i have the jetting about right
close enuff that is doesn't matter
i love messing with the younger ppl on 4ts that cant work out how an old 2t with a 50+ year old is still on there tail
i do see they are faster but i have more fun :)
 
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