Garry45 Posted September 28, 2014 Share Posted September 28, 2014 (edited) Hi guys Just want to mention 1st that my rc runs fine after pete (scrumpy jack) sorted it out but like us all we like to tinker as its the only way we (break things) learn. After watching tons of vids and reading god knows information and watching pete tune my rc i feel ready to tune it myself (got pete,s settings written down) I must of spent an hour last night tweaking the LSN/PINCH TEST which everything ive watched and read bangs in about, On pete,s settings it runs rich and bogs down on instant pull away with lots of smoke but once it clears its fine (set that way as its safer) but on the pinch test it takes a year and a day to cut out!!!!! I started to once the engine was at running temp adjust the LSN clockwise to lean it out but only a few mm at a time as i no this needle it mega sensitive,i would take it for a run and then let idle for 10 seconds or more then pinch test and it would cut out in a nano second but it pulled away rapidly with a nice trail of smoke and looked so so quick off the mark but the pinch test was saying it was running lean???? My idle is set correctly and my HSN is still at factory setting so it its rich enough and the top end of the rc is great and seems spot on again with a nice smoke trail.. I adjust the LSN ran/idled pinch tested and it never once did what ive seen/read doing the 3-5 second/idle rises and dies. Im absolutley stumped with this pinch test/3-5 second/idle pick up then die and mine dies in a second or so???? was wondering if the LSN is cracked/faulty and is there any way of testing it??,its a stab in the dark as there isnt much info on this but ive managed to source another LSN so if it comes to it i will just replace it with a new one and try again, Am i doing something wrong??? I just cant get over that you can adjust the LSN a few mm and go from boggy to a sharp pull away but the pinch test just doesnt work. Also getting a temp gun as the thing im using is saying my rc is running mega hot but i cant be certain if its accurate or not Sorry for the long drawn out post but want to explain the best i can, Garry Edited September 28, 2014 by Garry45 Quote Link to comment Share on other sites More sharing options...
chrisknights Posted September 28, 2014 Share Posted September 28, 2014 when i set my LSN , first set my HSN and then for LSN i run it up and down then bring it back and let it idle for 8 seconds then full throttle off if it boggs then i slighty lean it again and if it dies as if there is no fuel then i richen it , i keep running it up and down and let it idle till i get to the point where it shoots off like a rocket and then slighty richen it up and run it and check temperatures but always make sure there is smoke Quote Link to comment Share on other sites More sharing options...
Garry45 Posted September 28, 2014 Author Share Posted September 28, 2014 Thanks for the reply chris and what you just described is exactly what I did It was taking off like a rocket with a nice trail of smoke My issue is with this pinch test as its in everything I read/watch and is a safe gaurd so you dont run the lsn lean and cook the engine My temp was showing 300 plus which is not good but again the temp gauge im using is cheap and cheerful Not gonna mess till my proper temp gun arrives Garry Quote Link to comment Share on other sites More sharing options...
Anthoop Posted September 28, 2014 Share Posted September 28, 2014 The pinch test is pointless.....it will not tell you if the LSN is set correctly or incorrectly. What you see and hear will tell you when it is set correctly. Quote Link to comment Share on other sites More sharing options...
Garry45 Posted September 28, 2014 Author Share Posted September 28, 2014 The pinch test is pointless.....it will not tell you if the LSN is set correctly or incorrectly. What you see and hear will tell you when it is set correctly. Thanks Anthoop Well if that's the case ive got a well tuned engine but going to wait for my temp gun to turn up before i venture out again And why the hell do so many people bang on about the pinch test and it's how you no if your LSN is set correctly because I couldn't get close to what is expected. Garry Quote Link to comment Share on other sites More sharing options...
Anthoop Posted September 28, 2014 Share Posted September 28, 2014 And why the hell do so many people bang on about the pinch test and it's how you no if your LSN is set correctly because I couldn't get close to what is expected. Garry I do not know why...but it is probably the fact that "tuning an engine" (as in making it work), is perceived as a black art or something complicated. It really is not that complicated with our small two stroke with a basic carb...if it is too rich/lean it stops.....it will be more powerful when lean than rich....way too lean will ruin it- running way too rich will not make it last longer. If you can understand the relationship between the HSN and LSN...and the LSN and throttle gap...then you are there. Where is lean..ah there...let me go back a little and not run lean for very long. Do not even get me started on people adjusting the mixture according to the temperature of the outside of the engine... Quote Link to comment Share on other sites More sharing options...
Garry45 Posted September 28, 2014 Author Share Posted September 28, 2014 I do not know why...but it is probably the fact that "tuning an engine" (as in making it work), is perceived as a black art or something complicated. It really is not that complicated with our small two stroke with a basic carb...if it is too rich/lean it stops.....it will be more powerful when lean than rich....way too lean will ruin it- running way too rich will not make it last longer. If you can understand the relationship between the HSN and LSN...and the LSN and throttle gap...then you are there. Where is lean..ah there...let me go back a little and not run lean for very long. Do not even get me started on people adjusting the mixture according to the temperature of the outside of the engine... I get the concept on LSN/HSN and as you say it's not hard to no what does what and the pinch test really threw me and made me seriously doubt my tuning (lack of knowledge) to blame but the car ran really well,my other doubt was temp as the crappy gauge I had was telling me I was cooking the engine!!!!! As I said just a few mm to richen made it boggy and slow off the mark but once going top end was good with plenty of smoke,idle was a little erratic but it did settle and doing a pinch test done my confidence right in as I'm a NOOB but not that stupid (I think lol) When my temp gun arrives the Sarga will continue Garry Quote Link to comment Share on other sites More sharing options...
scrumpy jack Posted September 29, 2014 Share Posted September 29, 2014 Yeah, I've never really bothered with using the pinch test either as a guide for tuning, I doubt your cooking your engine Garry...keep at it and give it another go. My truck should hopefully be back together soon (waiting on a few last past to arrive), so we will have a meet up and I can help you if your still having problems. 1 Quote Link to comment Share on other sites More sharing options...
Garry45 Posted October 1, 2014 Author Share Posted October 1, 2014 Yeah, I've never really bothered with using the pinch test either as a guide for tuning, I doubt your cooking your engine Garry...keep at it and give it another go. My truck should hopefully be back together soon (waiting on a few last past to arrive), so we will have a meet up and I can help you if your still having problems. Thanks pete Will feel better when mytemp gun arrives which should be Thursday and will run her again but just that few mm on the LSN makes so much difference, Thanks for the offer of help again but I'm determined to get it sorted and the only way it practice practice and more practice, Hope to catch up on Saturday Garry Quote Link to comment Share on other sites More sharing options...
scrumpy jack Posted October 1, 2014 Share Posted October 1, 2014 Yep, we are all go for Saturday may be worth unscrewing your LSN and checking the o ring is in the right place and all okay, also have a look at the end of the needle while you have it out, make sure it's not mashed up at the end or anything! I'm sure it's all okay, and we can see how it goes on Saturday. Quote Link to comment Share on other sites More sharing options...
Garry45 Posted October 2, 2014 Author Share Posted October 2, 2014 Yep, we are all go for Saturday may be worth unscrewing your LSN and checking the o ring is in the right place and all okay, also have a look at the end of the needle while you have it out, make sure it's not mashed up at the end or anything! I'm sure it's all okay, and we can see how it goes on Saturday. Will defo have a look at the LSN and luckily Ive got a spare :-) As for Saturday I might not be able to make it as I forgot ive got a bloke coming to buy my stringing machine and he wants me to teach him how to use it which is a long laborious task and I can see myself doing it for hrs and hrs and maybe some more lol. Will bell Paul once I'm done and if your still there I will come over even if it's for a chat. Garry Quote Link to comment Share on other sites More sharing options...
brit_bulldog Posted October 2, 2014 Share Posted October 2, 2014 I think Temp guns are pointless unless you are a serious on road racer! If the Cylinder head is too hot to keep your hand on, then its running too hot! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.