Tuning/trim setting help? TRX 3.3

[BSPOT]

And I'm back. Finally got a hand me down truck to start (sorta). I have to prime every time I start it (finger covering exhaust method) and have to pump the throttle as well. If I let off the throttle fully the engine dies. It wont idle. 1/4 to 1/2 throttle and the engine is roaring so honestly a bit scared to open it up. It shifts to 2nd gear way too soon but it's not on the ground so no resistance. Not sure if the early shift is related to the throttle sensitivity or just lack of resistance. I've reset HSN, LSN both to factory setting and made minute adjustment until it started. Do I need to mess with idle screw given it wont stay running without throttle? Please bring on the feedback/suggestions. I plan on taking to LHS when the whole virus quarantine thing dies down but whose got time for all that noise?

 

[BSPOT]

Also def have an overheating issue. Temps were low but after running maybe 2 mins combined on 3 starts engine temp was mid 280s.

 

[olds97_lss]

Do the tires spin when the starter is starting it? Could be your clutch spring has died and it's dragging. That will make it less likely to idle at all.

 

[BSPOT]

They do indeed. Not full on but they do start moving when the engine first turns over. I've got a spare clutch spring. Think simply replacing the old one might resolve?

 

[johnnydmd]

Hmm possible air leak?

 

[D3MON]

what is the idle gap? should be around .5-.7mm at break in settings it will be on the wider side maybe even up to 1mm, are your trim settings all set to fully close/open the throttle? at neutral position on the controller is the throttle fully closed? is a chance at an air leak as well tank, fuel tubing, engine needle o-rings etc. make sure the exhaust is connected tightly as well as a loose exhaust will play havoc on tuning/running.

 

[cbaker65]

First of all ,setting the engine back to factory set is not going to solve the issue ,as those sets are for breaking in the engine an
is a very rich setting ,even though those sets will calm the engine down from a high rev!

After breaking an engine in ,the engine is retuned to a leaner fuel supply in which will cause it to rev higher ,in return ,you
would need to adjust the idle down with the idle set screw on the carb.
If the throttle barrel does not close enough after the set screw is backed off ,then you need to adjust your throttle linkage ,
but also could be in the trim of the radio ,with that being said ,you would have to take steps to re-set up the radio gear!

If this is the case ,then there maybe a chance that there was not anything wrong with the engine to begin with!....

 

[BSPOT]

Hmm possible air leak?

Possible but I dont think so. The engine is nearly brand new and I've replaced all fuel lines and filter. Have clamps on all points of attachment in the line. Maybe fuel tank but I'm able to get it running...

 

[Rolex]

Overheating that quickly is a sure sign that your LSN is too lean.
All 3 adjustments work as a team. LSN for idle and punch off the line. HSN for WOT and idle to keep it running at low RPM. When all that is doing well the trans adjustment is next if you feel it still needs it.

 

[BSPOT]

what is the idle gap? should be around .5-.7mm at break in settings it will be on the wider side maybe even up to 1mm, are your trim settings all set to fully close/open the throttle? at neutral position on the controller is the throttle fully closed? is a chance at an air leak as well tank, fuel tubing, engine needle o-rings etc. make sure the exhaust is connected tightly as well as a loose exhaust will play havoc on tuning/running.

Thought I could upload a video but looks like extra steps needed. I'll send pics later. Carb isn't fully closed at neutral. Maybe .5mm gap. At wide open its def open all the way. All fuel lines are new and secured with clips that came with lines. Engine is almost brand new so doubt brings are worn. Trim settings are a mystery to me. They're currently at 100%. Should they be reduced? Exhaust is secured with zip ties on both ends

 

[BSPOT]

what is the idle gap? should be around .5-.7mm at break in settings it will be on the wider side maybe even up to 1mm, are your trim settings all set to fully close/open the throttle? at neutral position on the controller is the throttle fully closed? is a chance at an air leak as well tank, fuel tubing, engine needle o-rings etc. make sure the exhaust is connected tightly as well as a loose exhaust will play havoc on tuning/running.

Neutral throttle pic attached

 

[BSPOT]

Throttle open. Not sure it's needed...

 

[BSPOT]

They do indeed. Not full on but they do start moving when the engine first turns over. I've got a spare clutch spring. Think simply replacing the old one might resolve?

Took the engine out and removed bell and clutch shoes. Spring and shoes look great. No stretch and no noticable wear on the shoes. Was hoping for that simple fix lol. Thanks anyway.

 

[BSPOT]

Overheating that quickly is a sure sign that your LSN is too lean.
All 3 adjustments work as a team. LSN for idle and punch off the line. HSN for WOT and idle to keep it running at low RPM. When all that is doing well the trans adjustment is next if you feel it still needs it.

Got it - Richen LSN. Any suggestions as to how many turns? What should indicate I've got LSN dialed in aside from temp? I actually took out the trans and took it apart 2 weeks ago. Nothing broken/excessively worn. Cleaned and added lithium grease. Checked it over bc I thought it wasn't shifting to 2nd but after cranking it yesterday heard the shift (just way early as mentioned). Thanks for the advise! Nowhere aside from the experts online to learn from these days with the virus...

 

[Rolex]

No such thing as "How many turns." Warm up the engine, richen the LSN just slightly and blip the throttle a few times. Run it in a little circle to let it clear its throat and adjust it SLIGHTLY till the performance is at its peak. Temp has really nothing to do with the tuning other than it will be too hot if you're too lean.
When you've got the LSN dialed in start with the HSN for WOT. (Wide Open Throttle) Once the LSN is set you won't have to change it unless you change the glow plug temp or the fuel ratio. The HSN usually needs a tweaking according to the ambient temps and humidity. You always want to see a trail of white smoke to know that it's not too lean on the HSN.
You might have to adjust the idle while making changes to the carb just to keep it from stalling or revving too high.

 

[BSPOT]

No such thing as "How many turns." Warm up the engine, richen the LSN just slightly and blip the throttle a few times. Run it in a little circle to let it clear its throat and adjust it SLIGHTLY till the performance is at its peak. Temp has really nothing to do with the tuning other than it will be too hot if you're too lean.
When you've got the LSN dialed in start with the HSN for WOT. (Wide Open Throttle) Once the LSN is set you won't have to change it unless you change the glow plug temp or the fuel ratio. The HSN usually needs a tweaking according to the ambient temps and humidity. You always want to see a trail of white smoke to know that it's not too lean on the HSN.
You might have to adjust the idle while making changes to the carb just to keep it from stalling or revving too high.

Great info Rolex. YouTube has suggested similar but not with the same level of detail. One thing I've noticed is little to no smoke on start/idle but when throttle applied there's smoke/exhaust. Supports your lean LSN diagnosis I suppose? Should there be blue(using TRX20% fuel)/white smoke at idle?

 

[Rolex]

Since you're not putting a lot of throttle into it there won't be much but you still get a little. If you're spitting oil everywhere it's too rich. I always left a minute or two for warm up before running. Cold starts would stall out on full throttle. Rule of thumb... If you start it cold and it runs like a bat instantly, you're too lean.

 

[BSPOT]

First of all ,setting the engine back to factory set is not going to solve the issue ,as those sets are for breaking in the engine an
is a very rich setting ,even though those sets will calm the engine down from a high rev!

After breaking an engine in ,the engine is retuned to a leaner fuel supply in which will cause it to rev higher ,in return ,you
would need to adjust the idle down with the idle set screw on the carb.
If the throttle barrel does not close enough after the set screw is backed off ,then you need to adjust your throttle linkage ,
but also could be in the trim of the radio ,with that being said ,you would have to take steps to re-set up the radio gear!

If this is the case ,then there maybe a chance that there was not anything wrong with the engine to begin with!....

Lot of good advice Cbaker65... one of my learning opportunities is the transmitter. Everything is digital except throttle and steering and the manual is in Chinese so learning from the internet as much as possible. I think trim and tuning are likely my culprits. Be great if I could get it in front of a pro and learn hands on.

 

[cbaker65]

Lot of good advice Cbaker65... one of my learning opportunities is the transmitter. Everything is digital except throttle and steering and the manual is in Chinese so learning from the internet as much as possible. I think trim and tuning are likely my culprits. Be great if I could get it in front of a pro and learn hands on.

Lol....I am harly no pro ,but been involved in RC's for over 20 years an can hold my own on them!

Radio gear set up is the one of the most crucial ,if it isnt right ,then it can give you false readings as much as
a dirty filter inside a tank ,or a dried up needle seal or even a leaky cylinder head!

When setting up a radio ,the throttle horn should be removed from the servo ,then power your system on ,then
make sure your trims knobs or if it is a digital set up ,they need to be set in center ,like[RIGHT -CENTER -LEFT]
$
Then you put the horn back on in relation with your carb barrel in the closed position ,you also might have to
alter the linkage as well ,some have collars & springs on them an a threaded ball joint for adjustments as the
throttle linkage works in conjunction with a brake system!

We all can help you do that if needed ,some times I am not on line ,but the other folks here can ,but anyway ,
you will need to learn that part of RC an that should be the first thing to check ,then work your way down to the
other stuff ,like dirty tank ,carb leaks & ece.!.....

 

[D3MON]

Thought I could upload a video but looks like extra steps needed. I'll send pics later. Carb isn't fully closed at neutral. Maybe .5mm gap. At wide open its def open all the way. All fuel lines are new and secured with clips that came with lines. Engine is almost brand new so doubt brings are worn. Trim settings are a mystery to me. They're currently at 100%. Should they be reduced? Exhaust is secured with zip ties on both ends

trim is the location of the servo rotation at neutral position. (i.e throttle trigger is not pressed or pushed/idle position.) if you are not touching the throttle, and the carb is closed as far as it physically can (leaving the .5mm gap) your trim will be ok. if the trim is adjusted too far one way, the servo will hold the throttle open, but when you brake it will close. if its adjusted to far the other way, it will hold the brakes, and be pushing against the throttle slide further than necessary.