What Size Jet

[slimeee]

Ok I have a new top end bored to next oversize and a rebuilt carb with boyesen power reeds. I run premix. I want to run with airbox lid off. Stock exhaust. What size jet should I run? It currently has stock sized jet. Also If I run with the airbox lid off and a stock jet will this blow my engine? Also how many turns out should the air screw be on the carb? Or do I need to adjust that with the engine running to get the best tune?

 

[tbrooks]

You will melt your piston with stock jetting. +2 for lid removed, +1 for aftermarket filter, plug chop to confirm. Temp and elevation make a difference. Air screw should be about 1.5 turns out. To set ensure no airleaks, confirm float level, plug chop jetting, set idle high 2000 rpm, turn screw little bit at a time allowing 10-20 seconds and go for highest idle

 

[slimeee]

You will melt your piston with stock jetting. +2 for lid removed, +1 for aftermarket filter, plug chop to confirm. Temp and elevation make a difference. Air screw should be about 1.5 turns out. To set ensure no airleaks, confirm float level, plug chop jetting, set idle high 2000 rpm, turn screw little bit at a time allowing 10-20 seconds and go for highest idle

If I run with stock jet boyesen power reeds air box lid on and a uni air fliter will i still melt the piston?

 

[dirtysquared]

If I run with stock jet boyesen power reeds air box lid on and a uni air fliter will i still melt the piston?

No one can really guarantee you will or will not. The best thing to do is check your jetting after any kind of changes with a plug chop.

I'd start at a 280 and work down. Its better to be to big, than to lean.

 

[slimeee]

No one can really guarantee you will or will not. The best thing to do is check your jetting after any kind of changes with a plug chop.

I'd start at a 280 and work down. Its better to be to big, than to lean.

Ok i got the stock main jet and trying to adjust idle, I have no air leaks. So i have boyesen power reeds, uni air filter, airbox lid has holes drilled in top. Bike seems to smoke a lot not from air leaks or tranny fluid. Does this mean its running lean? Is a 280 too big the only mods are the power reeds, uni foam filter holes drilled in air box lid, performance ignition coil.

 

[dirtysquared]

The reeds and coil aren't going to effect your jetting. The Holes drilled in the airbox lid will allow more air to flow into the engine.

Buy some main jets, a 280, 270, 260. Start at the 280, and work your way down.

Make sure the carb is cleaned well, the float level is set, airscrew is 1.5 turns out from lightly seated.

It could be alot of things thats making it smoke alot? What Ratio are you mixing your Fuel at?

 

[tbrooks]

What psi did leaktest hold? for how many minutes? Lots of smoke could be a crank seal. If you are pre-mixing you will have to adjust jetting for that to. Nobody can tell you exactly what jet you need. Every quad is a little different.

 

[Blaaster]

Ok I have a new top end bored to next oversize and a rebuilt carb with boyesen power reeds. I run premix. I want to run with airbox lid off. Stock exhaust. What size jet should I run? It currently has stock sized jet. Also If I run with the airbox lid off and a stock jet will this blow my engine? Also how many turns out should the air screw be on the carb? Or do I need to adjust that with the engine running to get the best tune?

Idle adjusting.

Set float level, make sure that all jets are clean and fuel flows freely from the float bowl drain when the screw is cracked open.

Start with air screw 1.5 turns out.

Set idle screw so that it has some sort of idle. With TORS it is the big screw under seat on top of unit. With no TORS is is the brass screw midway down carb body.

Warm up motor and then set idle screw for a faster idle, 2000rpm+

Adjust air screw either way to get the fastest idle.

Adjust air screw a little at a time leaving 10 secs or until the motor responds.

Re adjust idle screw for desired idle .

 

[slimeee]

The reeds and coil aren't going to effect your jetting. The Holes drilled in the airbox lid will allow more air to flow into the engine.

Buy some main jets, a 280, 270, 260. Start at the 280, and work your way down.

Make sure the carb is cleaned well, the float level is set, airscrew is 1.5 turns out from lightly seated.

It could be alot of things thats making it smoke alot? What Ratio are you mixing your Fuel at?

24 to 1 its a new top end and was told to run 24 to 1 for first 5 tanks. Thing wont even start now . Seems like idle screw isnt workimg right. Gonna order the jets and try them. I think right now im suckimg in too much air and top end isnt even broken in. This thing is driving i got way too much time and money in it.

 

[Blaaster]

If you are mixing at 24:1, did the idiot that told you to do that tell you that you need to rejet when you change an oil ratio.

By adding entrance oil you effectively lean out the mixture just enough to fry the piston.

 

[slimeee]

If you are mixing at 24:1, did the idiot that told you to do that tell you that you need to rejet when you change an oil ratio.

By adding entrance oil you effectively lean out the mixture just enough to fry the piston.

No he didnt but i havent ridden it enough to fry anything. Got some bigger jets on the way. Can i just use 32 to 1 during break in? I got ine tank of 24 to 1 thats old gonna get new gas too

 

[Awk08]

always use the same ratio you plan to run for break-in too, there is no added benefit to running more oil than required for break-in.
yes, run 32:1 so you can get the same jetting advice 99% of us on here , know, and successfully run.

 

[slimeee]

always use the same ratio you plan to run for break-in too, there is no added benefit to running more oil than required for break-in.
yes, run 32:1 so you can get the same jetting advice 99% of us on here , know, and successfully run.

Why did this moron tell me to run 24 to1?

 

[Awk08]

Why did this moron tell me to run 24 to1?

i think you just answered that yourself

 

[Blaaster]

It is not moronic to use 24:1, but it is moronic for one to advise you use it for break in without telling you to alter the jetting!

Running a ratio of 24:1 is perfectly fine, in fact it is beneficial as one can ride at wide open throttle for extended periods without fear of engine failure.

If you are at peak rpm all the time, 20:1 is a good idea. However for recreational level riders that don’t “scream” their engines constantly, leaner premixes will yield excellent long term wear.

The problem lies with the fact that if you use more oil in the mix, the carby must be re jetted to compensate for the lack of fuel in the mix.

More oil = less fuel = more heat = engine failure.

You have two choices, either use the fuel in the tank at 24:1 and re jet the carb to suit.

Or drain the tank and use 32:1 in a fresh mix.