Siro 18 tuning problems

[comeonstart]

I will start from the beginning. I bought my t-maxx 2 days ago, It had a Siro 18 in it then with a bad one way bearing, I paid $250 for it and a whole lotta extra parts. The next day it was kinda raining and wet but I installed the one way bearing, new glow-plug and new fuel and the T-MAXX started right up and ran great with enought power to rip the tires off the bead lock rims. The next day (today) I tried to start it up and it would run a little at an idle but only rev up for a split second before it would die. I called my local shop and they said "its too rich, lean the high speed out some." So I tried doing that and I turned the high speed about 2 turns with no results. Then it would not start or do anythign so I refered to the Traxxas site and their FAQ said to turn the needle all the way in, then back it out four turns. I did that and it started up again but it revs uncontrollably and spits fuel out of the carb, the only way to get it to slow down is to hold the brakes. The high speed screw seems to have dome nothing as far as getting it better in both directions. I really need some help getting it going again.

PS. I live in SC where its about 85-90 degrees and 85%-95% humidity

[Duster_360]

I don't have this motor but remember from having been an active member of the trx forums when it was real popular that its HSN settings are more like 7T out from closed, but there were 2 versions - one they called the "original version" and a later version. Look down the page here - tower shows them both.

http://www2.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=sirio+18&FVPROFIL=++&search3=Go

There was a confusing difference in the needle settings between the 2 versions if I remember correctly. I don't think its the same as the 2.5, which is 4T out from closed. Guess you didn't get a manual with it either?

Have you tried going to Trinities site and seeing if you can find out what its supposed to be for both needles? Be careful, if you run it too lean, you may wind up needing a new P/S which I think for this engine was pretty expensive.

[comeonstart]

I tried 7 turns and its was spraying nitro all over the place, I talked to another hobby shop that siad they would tune it for $10 next week, thanks for the help.

[Duster_360]

Get them to show you what they set the needles at so you'll know if you ever need to reset them again.

Guess you had the Sirio that used diff needle settings. Hope it doesn't set you back too much to get ity done. That hobby shop prob sold that engine and hopefully sold the one you've got. Good luck, hope they get you running.

[JoeMAXX]

I tried 7 turns and its was spraying nitro all over the place, I talked to another hobby shop that siad they would tune it for $10 next week, thanks for the help.


Drop a new glow plug into the engine then try again. That would be my first thought. The fact that you were spraying nitro all over tells me you may have fouled the plug or fried it on the previous run. Pull the plug then hook it and see how it glows. It should be bright orange from top to bottom. If the first few rings are red or dead replace it.

Second thought is Make sure your glow starter or battery pack on the easy start is fully charged this is a very common mistake when an engine will not fire.

[comeonstart]

well the truck did fire at 7 turns out, the glow-plug light on the starter did flitter a little. It would just start for a few seconds and then quit like it was flooded. Nitro was coming out everywhere, the carb, and pipe. when it did start it was all bogged up and you could tell it needed to be cleared badly. Its probly a good thing it doesnt run right now because I am at the beach and running it in the sand would be aweful tempting. again thanks for the help.

[Quinton]

When you richened it and said that you opened it up 2 full turns that was a mistake.

You only want to make adjustments in 1/8 turn increments. I would start it and as soon as its running pinch the fuel line by the carb. It should die within 3-5 seconds. If it goes much longer then lean the LSN by turning it clockwise. Once that is set then try to get the HSN dialed in.
Is your air filter clean?

[comeonstart]

I opened it up 2 full turns in like 15 degree increments. I will not run for 5 seconds as it is.

[Quinton]

Start it and pinch the line. It will either die immediately (way too lean) or it will idle up and sound better in which case it would be too rich. Then adjust accordingly. Keep stairstepping your way to a good running engine.

How is the compression?

[comeonstart]

that sounds like a plan, I am 450 miles away from my maxx right now but i will tyr that when i get home

[ososlow]

I have the manual for the maxx .18 Sirio installation and tips and the pull start .18 Sirio instructions (rotary carb).
.18 Maxx break in settings are:
low end: 2½ turns out
high end: 7 turns out

.18 pullstart break in:
low end: 2½ turns out
high end: 7-7½ turns out

Pullstart after break in recommended settings:
low end: 2 turns out
high end: 6½ turns out

I could scan the back page of the Maxx .18 manual that has tips and tricks if you want. I could also scan the whole manual if you need it :)

This is a great little motor. If you can get it running properly, and don't own one already. I recommend buying a Sirio big bore pipe to compliment it. It really brings the motor to life compared to the drilled out stock pipe.
Also, if you are confident with a dremel I recommend doing some work to the sleeve. I made some serious power by smoothing the angles and polishing the sleeve and crank. :cool: Do alot of research here before you start though ;)

[comeonstart]

The would be great, I have the Maxx version, I have some sort of tuneable "twin" pipe already installed also, I do not really knwo the history of this motor. But I would really appreciate a scan of the manual. I know very little about these and I even thought about going back to a 2.5 so I could get more help. I think I will also try new fuel lien because you can see air bubbles in the line. I already have a fuel filter on it also.

[ososlow]

Alright, here you go:

I had to re-write the line that is in the fold.
Page one (http://gamma.applepics.com/7/userfiles/42dd792425a29.jpg)
Page two (http://gamma.applepics.com/7/userfiles/42dd79429d438.jpg)
Page three (http://gamma.applepics.com/7/userfiles/42dd79552335d.jpg)
Page four (http://epsilon.applepics.com/52/userfiles/42dd8114e226d.jpg)

The fuel filter might also be causing you problems. I had one on my burned out 2.5 and it just made it run worse and I installed it on my Sirio and it just made it run like crap as well.