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  1. #1
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    jato tuning help

    Hi having trouble getting the tune right on my jato. Have been blowing glow plugs like crazy. Got it out today and tried to get a good tune, put a new glow plug in and it lasted about 3 or 4 tanks then blew. So I put in another new one and it lasted about 2 tanks. I have drilled the stinger on the exhaust to 5mm and my mixtures are set at hsn - nearly 4 1/2 lsn - nearly 2 1/2. It runs really well nice smoke trail and no bogging just keeps breaking glow plugs. I think the idle gap is correct to me looks like about 1mm(how would I get an accurate measurement of this). I was using a temp gun which said about 220 degrees f, but I stopped using it as it seemed to be all over the place and I didn't trust it to be accurate. And the pinch test seemed right.

    Photo's of 3-4 tank plug

    http://s997.photobucket.com/user/nsu...tml?sort=3&o=1

    Crap photo but shows the colour of the plug better

    http://s997.photobucket.com/user/nsu...tml?sort=3&o=2

    2 tank plug

    http://s997.photobucket.com/user/nsu...tml?sort=3&o=0

    Please help as I'm about ready to convert to electric or sell the car. I don't want too as I enjoy the car and would lose too much money as it's not that old and I just invested about $350 dollars in hop up parts. That said I can't keep putting $12 glow plugs in it.

    Any help greatly appreciated.

  2. #2
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    Those are the worst plugs I've ever seen. Your running extremely lean, but with very rich needle settings. That would suggest that your engine has an air leak somewhere.

  3. #3
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    dont go electric take it to ur local hobby store and have them tune it i did that with my nitro rustler and they fixed it instantly i promise they will find out whats wrong or even tune it right infront of u. dont go electric just do wat i said... good luck

  4. #4
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    Quote Originally Posted by Mark Ball View Post
    Those are the worst plugs I've ever seen. Your running extremely lean, but with very rich needle settings. That would suggest that your engine has an air leak somewhere.
    I had one let go last week Mark that the filament ended up through my engine and I had to clean it all out. Not trying to argue I appreciate your help and respect your knowledge as you have helped me with acouple of things already. I know the plugs look lean but the car produces quite a fair bit of smoke when its going(more probably than a lot of the videos I have watched of other jato's) which has me puzzled. But I will check for airleaks, this is done by simply spraying soapy water on the carb, backplate and in the head around the glow plug and turn the engine over right?

    Quote Originally Posted by Username4563 View Post
    dont go electric take it to ur local hobby store and have them tune it i did that with my nitro rustler and they fixed it instantly i promise they will find out whats wrong or even tune it right infront of u. dont go electric just do wat i said... good luck
    Yeah I am going electric wether it is my jato or keep the jato and get another more race ready car as I can't race nitro cars anywhere around where I live. They are elctric only tracks. I will have to take it to them after I check for air leaks and get them to tune it for me. Thanks for the luck the way I am going with this car I am going to need it.
    Last edited by cooleocool; 08-24-2013 at 09:55 AM. Reason: merge

  5. #5
    Marshal Double G's Avatar
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    Since you had debris in the engine, break it down again and make sure there's nothing dancing around in there. Seeing those plugs tells me that it was lean too. It could be that due to the stinger being drilled out the temps climb up at high speed and then come back down when off throttle; the LSN is 3/4 turn rich from factory and IMHO that is too much.
    http://www.nitroaddicts.com/forums/s...ad.php?p=69790
    The Super Derecho

  6. #6
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    Hi checked and double checked the engine for air leaks and none that I could tell. Checked the fuel tank seal as well. I agree that the plugs are showing indications of being lean, but am puzzled as I am running fairly rich hsn and lsn settings with a good thick smoke trail. One thing I thought of is I do tend to run it till the tank is just about empty and then refill and go straight away, should I let it cool off a little between tanks maybe. Have pulled the engine apart twice now and no debris was floating around inside. While apart checked the bearings and seemed ok. Did notice that the wrist pin seems to move up and down a tiny bit in the piston, would this be normal(my lhs told me that there should be alittle bit of play there).

  7. #7
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    Let me see if I can help explain what Double G is saying about your stinger.

    These exhaust systems are tuned like a speaker box. They are both using reflected sound wave's to get their desired effect. A speaker box is tuned for sound and a nitro engine is tuned for performance. Not just power, but overall performance. reliability and consistent running at all rpm's. If you make the port in a speaker box larger you lower the frequency by slowing down the internal reflected sound wave's. And with a nitro's exhaust when you drill out the stinger you lower it's tune, slowing the speed of the internal reflected sound wave. Which is changing your exhaust timing, not allowing for proper preload of the combustion chamber at high rpm's. Causing an extremely lean condition at high rpm's, but returning to normal safe conditions at mid to low rpm's.

  8. #8
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    Bummer had read a lot about drilling it and read that tuning changes were needed but no mention of any problems like this. Could I simply overcome this by running too rich for the low rpm running but good for high rpm or is it not that simple. I can't afford to buy a new pipe at the moment as I don't have a job.

    It has been suggested to run a colder plug and change gearing on another forum site. Could this help with my problem, was thinking revo gearing(20/40), as I really only do high speed runs most of the time and it hasn't been pulling wheelies for a while now so I would not be missing out on that. Could a chenge of rear wheels(only had to order in sets for the front, hard to get as they run the bearings not hexes) have also contributed, by throwing out my gearing as they are a bigger overall circumferance than the annacondas. I am running proline .28 badlands on desperados(offroad) and proline 2.8 streetfighters on desperados(onroad).

    May have fixed it am running temps of roughly 209 degrees f with the body off and have got 2 1/2 tanks so far. I will update later after a couple more tanks(have to go somewhere else my neighbours really don't like it).

    Changes I have made are:-

    Went back to the anaconda's

    Sealed the engine with high temp silicone

    Hsn - 4 3/4 Lsn- 2 1/4

    Seems to be running strong with good smoke. Will check temps with body on, but fingers crossed I have got it.

    Another four tanks and the glow plug is hanging in and the engine is running sweet. Took it to one of the local bmx tracks for a bash and bash it I did. I broke the back off the body where the wing mounts, lost a few screws and now have a clicking noise coming from the diff or tranny. Don't really care as it's been the first time in a while that it has run this good. Going to pull apart the transmission and inspect it.
    Last edited by cooleocool; 08-26-2013 at 09:31 AM. Reason: merge

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