Alittle help with engine tuning plz.
 

Whenever I give it full throttle the engine rapidly bogs. It never dies just doesnt want to go anywhere. But if I give less throttle is takes off fine. I tried leaning out the needles and riching them,but doesnt seem to help. Unless im just not adjusting them far enuff. Just seems weird im only having probs when I try to give it full throttle.

RE: Alittle help with engine tuning plz.
 

Start by setting both needles to stock. From there, start leaning the HSN by 1/8 turn at a time. Once the HSN is tuned, move on to the LSN. Note: most new nitro users get too carried away with the LSN. Most of your tunning is going to be had with the HSN.

RE: Alittle help with engine tuning plz.
 

Is one needle more for full throttle? Like the high speed, or do they both control it. I've never experienced this kind of hesitation, was wondering if something was wrong with my carb. But ill go back to stock settings and try it again.

RE: Alittle help with engine tuning plz.
 

Yes. All the low speed needle is for is so you can lean your idle so it doesn't load up and flood as fast at idle, but you still get enough fuel at full throttle... All of the fuel comes in through the high speed needle, and the low speed needle simply restricts it further, but only until about 1/4 throttle, once you pass that, the low speed needle has absolutely no effect. If you have a slide carb, you can see this. With the engine NOT running, take off your air filter and look inside the carb. Now slowly open the throttle and look down inside the hole the opens up, you will see a little bar inside the goes into a hole when the throttle is about 1/4 open, that's the low speed needle. once that comes out the hole, its no longer affecting engine operation at all... That's why you tune the high speed needle first, because the low speed needle just further restricts the fuel that's let in by the high speed needle.

RE: Alittle help with engine tuning plz.
 

About 90% of the time the low speed needle never has to be touched and when it does usually only once for the life of the engine. The tune is done with the HSN as the primary target for the running functions. The whole set up is based aroung that HSN and when it runs the best it can without being to lean and if there is still a problem then you look to your LSN and idle stop needle. Take a look [link=http://www.xtm-dealer.com/breakin.html]HERE[/link] there may be some usefull information there for you ;)

RE: Alittle help with engine tuning plz.
 

Something is definatley not right. No matter the settings of both needles I keep getting a bog, hesitaion, at full throttle. Im gonna take the carb apart, see if I find something wrong.

RE: Alittle help with engine tuning plz.
 

what engine, fuel and glow plug?


Perhaps your issue with the clutchbell? If it was really loose it could bind when the shoes engage.

RE: Alittle help with engine tuning plz.
 

Mach 427, trinity 20%. Ya I got the clutch fixed. Im in the process of sealing and cleaning the engine and carb. I did fid a small piece of debris in the high speed needle tube, im thinking that was probaly what the prob was, but well see after I get it all back toghther.