Revo Tuning Q

[ThunderTiger]

I Recently fitted a brand new complete carb to my 2.5 Revo engine and now i'm having tuning problems.

I installed the carb with the settings un-touched to see if would fire ok, but no go, so tuned to the settings of the old carb, those being 4 3/4 out on the HSN and flush on the LSN.

While it will start, it tends to be "boggy" on the top needle despite leaning down to 3 1/2 turns out.

I've looked at the settings on the original carb and the needles were LSN flush, HSN 4 3/4 out and that was how it ran and it ran well on those settings, Yet despite my efforts, i can not keep the engine running and avoid the flame outs with this new carb. I did seal the carb, so it is not an airleak as the engine too has been sealed, the fuel tank is airtight and all fuel / pressure lines are new as is the inline fuel filter. The head is down tight and the exhaust is well sealed, so I can see no sign of a "False lean" setting causing the issue.

The glow plug is also new and being lit by a fully charged ignitor and just to test that it wasn't my ignitor being funny, i tried my other four ignitors and my spare new glow plug.

yes i know the engine is an older one, but it has loads of compression still and pulls strongly when it's running.

It's just this tuning issue since i fitted the new carb on is giving me a headache.


ADMIN: Could this thread be moved to RC Engines and Motors please. Thanks

 

[2revo1maxx]

Must be some crap in it somewhere. Have you tried changing out the hsn?

 

[ThunderTiger]

the HSN is brand new.

The carb was a "Complete" one, aka TRX Part #TRX 5252, So no blockages on the HSN or LSN, I checked the carb over before I fitted it anyway.

I have been through and checked all the usual area's for problems and all is ok, hence why I'm asking.

 

[2revo1maxx]

That doesn't mean there isn't a rogue piece of plastic in there. I would give it a shot. Remember the new revo tanks with the bits of plastic in them? Just trying to help.

 

[ThunderTiger]

the HSN is brand new.

The carb was a "Complete" one, aka TRX Part #TRX 5252, So no blockages on the HSN or LSN, I checked the carb over before I fitted it anyway.

I have been through and checked all the usual area's for problems and all is ok, hence why I'm asking.

And by checked, I mean carefull stripped including needles, checked for dirt particles / debris and put it back together. properly.

I know your trying to help and I am very thankful that you are matt, I appreciate it.

I have been round the block more than once with carb's on nitro rigs so I am more than aware of a few little niggles that are carb specific, I'm also aware of some of the TRX QC issues..........but this is testing my patience to it's limits.....

*****UPDATE*****

Just tried to run the engine again............

Primed up as normal and engine ran then died out..as normal since i fitted the new carb.

Seems like fuel starvation, but lines are clear, no blockages, no kinks in fuel line, Fuel filter is clean as well. Plug is brand new.

*****UPDATE*****

 

[ThunderTiger]

OK, managed to get it running by running it rich as heck on the LSN and richening out the HSN.

Run 1:

Tuned it out to near a good tune, ten minute run and blew a plug. Tell tale compressed coil = too lean at 4 3/4 turns out on HSN & 1 1/2 out on LSN.

Run 2:

Brand new plug, HSN 5 1/4 turns out LSN 1 1/4 turns out from flush. Another run, this time 12 mins, plug blows. Again compressed coil at 5 1/4 turns out on HSN. Stuttering at take off and lacking power at the upper end of the rpm range.

WHAT ???

Run 3:

Running on OS#8 plug (blew my only two TRX long life medium plugs). Same settings as run 2, allowing some mild tuning. Final tune after 15 minutes hard running (and I mean WOT) equates to 5 1/2 Turns out on HSN, 1/2 turn out from flush on LSN. Running but STILL stuttering from standing start despite a little leaning, Running temp at peak = 245*f

I Do NOT understand this......The only thing I have changed is the carb (as a complete unit with needles, slides et al) and now i have all this hassle.

If I go leaner on the HSN, it's bye bye Glow plug. If I go leaner on the LSN (to flush with housing), it will not start. PERIOD. What am I either doing, or not doing (whichever the case may be) that could be causing this ?

Any ideas anyone ?

 

[2revo1maxx]

You probably are too rich, that will compress a plug. You can tell a leaned out plug by the coil, it will have a grey, kind of deteriorated look to it. If I were in this situation I would forget about the needle turns and just tune it to run. It's already broken in, start at 4 turns on a cool engine and go from there. I also have to run my trx engines out from flush on the lsn, up to about 1 turn out.

 

[ThunderTiger]

2 revo, i did use the original settings from the orig carb (LSN Flush & HSN 4 3/4 out), as stated above, but it was no go. I am aware of a rich setting screwing up a plug and I know how to tune to avoid being too rich or lean, hence my frustration since fitting this new carb.

If i go richer on the top end, it's boggy, if i go leaner on the top end, as in start from 4 turns out, it flames out or kills the plug.

The bottom is still a little boggy from take off, but not as bad as it was......if i richen out the LSN it gets really boggy.

 

[2revo1maxx]

You'll never know for sure til you really lean it out for a minute and try it that way. It's too rich. And besides, you keep asking questions.....I keep suggesting things. They're just suggestions, take 'em or leave 'em, I just wanna help you, I know what you're going through. It's frustrating.

 

[ThunderTiger]

2revo..........I've had the carb every which way but blocked off.

I ran the HSN down to 4 turns out over a 20 minute run, as soon as i hit 4 turns out, it killed the Glow plug outright. Brand new plug too.

I think, that i'm just gonna run it as it is for a while and tune on the fly and get to the best settings i can so it's not boggy or flaming out.

 

[2revo1maxx]

Still running those trx plugs?

 

[ThunderTiger]

yup £5 each..........can't find another type of long reach plug anywhere otherwise i would be running a different plug.

can't stand how much the TRX plugs cost.

 

[2revo1maxx]

I don't know if O'donnell #77 is long reach or not, but that's what I run in sb engines, they work great and take a beating too. I have 5 different types in stock all the time. I'll never buy trx plugs again.

Also I've had very good luck with LC3's and 4's.

 

[ThunderTiger]

I like what your saying, but if i could fine 'em in the UK, trust me I would STOCK UP on them.

 

[2revo1maxx]

I like what your saying, but if i could fine 'em in the UK, trust me I would STOCK UP on them.

Gotcha.