needle jet question.

[sbjones73]

ok people, i have read alot of things about jetting and proper jets. i am down to my needle jet. mine is bent so i need another one.

i have an 84 250r that i am running a 86 pj 34 carb on it. from what i can tell the stock needle jet is a CEG (last parts of the needle code) the one that is in my carb right now is DGK., ok so my needle is richer on the taper but leaner on diameter and length.

my trike seized up again. so i am trying to cover all of bases here. is anyone out there running a pj 34 carb on there trike ? i would like to know what needle size they have. and also your opinions on what size i should go with. i am thinking about just splitting the difference and going with that.

need some help here!!!!!!!!!!! please. this is the last thing i have to figure out.

[sbjones73]

ok i may have gotten a little tooo technical. my question should have been this.

my trike is seaizing easily on hard acceleration through all gears . i am going to fatten up my pilot some. i have gone from a 160 main toa 162 and the top end is very doggy. my neelde is bent. i am going to fatten up my needle one size on the diameter and the length.

how much does one size of richening make a difference in carb jetting for the needle? (diameter and length) or should i go 2 sizes bigger?

that should have been my question from the start.

thanks

[sbjones73]

no help on this? come one now. i know there are some 2 stroke jetting guys out there !!!!!!! i for sure need help here!!!!!!!!!

[AutoXer]

seaizing easily? its been my experience that a "seized" motor needs to be rebuilt?
and your needle (obviously you need a new one as yours is bent) should have clip position's or groves to raise (ritchen) or lower (lean) out the mixture at half throttle... might be why you aren't getting much help. I'm no expert this has just been my past experiences

[sbjones73]

yes, the needle can be moved up and down on the clips. i am trying to figure out if i need a richer needle totally. mostly in diamter and length.

thanks for the reply thogh autoxer, i never really get to many when i post a thread, maybe i get a little to technical? i don't know. but some do help!!!!!

so thanks again!!!!!

[Jason Hall]

I would start by checking the piston to cylinder clearance. Is the exhaust bridge relieved? A needle alone shouldn't seize your engine. What size main jet Is In the carb?

[Daddio]

yes, the needle can be moved up and down on the clips. i am trying to figure out if i need a richer needle totally. mostly in diamter and length.

thanks for the reply thogh autoxer, i never really get to many when i post a thread, maybe i get a little to technical? i don't know. but some do help!!!!!

so thanks again!!!!!
I haven't gotten into changing needles too much yet. Everything that I've worked on so far could be jetted properly with the needle that was in the carb by moving the clip.:wondering

[sbjones73]

well to answer the questions here. i am running a pj 34 on my 84 250r. and as far as main jet. i was running a 160 in it when it siezed. i tried a 162 and it blubbered pretty badly at wot. pilot is a 48 and needle was changed from previos owner. it is leaner than stock( from what i can find info on stock jetting).

the reason for changing my needle is because mine is bent. my piston clearance is now .006 i honed the scoreing out of it, it didn't really take much with a ball hone. and cleaned up the piston. can't afford to buy all new piston and get it bored. and the bridge for the exhaust, it's and 84, don't have one. ports have been chamfered. it looks like a four corner siezure again, but i was riding the thing for nearly 30 minutes before it siezed.

i have done alot of reading about jetting and siezure problems. i have made a plate and cup so i can pressure test my engine for any leaks at the seals. i figured i would pressure test and vacuum test the engine this time (didn't do it before) i know that i did not have any leaks at the base gasket, head gasket or intake boot. but didn't even think of checking the crank seals.

i have a feeling that i have more than one thing going on here. bent needle. possible crank seal leaks. lean carb? i have never fouled a plug to date on this thing. a plug chop came out looking great (darker cappacino coffe color) but i am going to richen up the carb till i foul a plug then go from there. start rich and work my way down i figure.