need help

[XxVASSAGOxX]

ok guys, lets try this again, ill give all info i can for better help.

HPI Nitro MT Nitro star .15

problem I'm having is....

hard to start, when starts up, idles good till warm first 3-5 highspeed passes its a monster, but if i bring it in to check for damage after say a roll over? it bogs and dies and will not restart so basicly when its hot it woulnt stay running, i have adjusted the idle screw a 100 times no luck with a happy idle.

no air leaks found. brand new glowplug fresh fuel..


there is NO lsn and hsp is just a tad rich, worn engine and its cold out.

 

[RC Addict]

There is NO LSN???

This is a .12 but the carb is the same. The red circle is the LSN

 

[XxVASSAGOxX]

hmm ok well i have been told by more then 1 person that the older hpi nitro mts did not have a lsn are they wrong?

 

[RC Addict]

Some carbs are two needle and therefor do not have an idle screw but ALL two needles have a LSN and a HSN.

When your engine dies have you pulled the plug? If so was it wet (not just damp but WET) or dry? Do you have a lot of oil/fuel coming out the exhaust?

Do you know what your temp is when it dies?

Have you done all the air leak checks?

Have you tested the fuel pickup for a leak (HPI tanks are famous for this)?

 

[XxVASSAGOxX]

yes RC Addict i did all the check u told me to do about air leaks, found none, and replaced all fuel lines and sealed bottom of tank to be sure, dont no exact temp my gauge broke, new one on order, when i pull the plug it looks normal there IS a idle screw on my carb and there is NO LSN if there is one its a ghost....

o yea i dont belive its over heating, its 40* and below latly and i did the water drop test and it seemed normal

 

[olds97_lss]

The old HPI 15 only had one needle called the "mixture" needle and a screw to adjust idle. I had one. It sucked to tune. Oddly enough, it was also from an HPI Nitro MT.
Take a look at the HPI tuning instructions for the older engine:
http://www.hpiracing.com/graphics/instr/nmt/n_mt-26v2.jpg

HPI NitroStar 15FE: http://www.hpiracing.com/graphics/instr/engines/1615p2.jpg

I put an OS carb on it (after drilling holes in the carb neck to mount it) and it was much better.

That said, normally when an engine is hot and will not start at all until it cools usually means it's worn too much. So when it's hot, the sleeve expands and you get excess blow-by and are loosing your compression and it can't fire.

The OS 18CV-R is a good engine for that rig. Plenty of power for it and not a real pricey engine. However, the stock pipe is very restrictive and you will find that even a cheap tuned pipe will make a new engine perform far better.

 

[RC Addict]

There is NO LSN on the side of the carb where the throttle linkage connects to the carb like the above picture? Can you post a picture of this?

 

[XxVASSAGOxX]

so there is no fix for this then? just replace the engine?

 

[RC Addict]

Must be a VERY old .15--the one on my Nitro MT had a LSN...

 

[XxVASSAGOxX]

no there is no LSN how do i post a pic for you? there is a nut with a rod in it were the lsn should be, this only has the mixture needed as he called it, anyone got a good .15-.18 for sale???

 

[RC Addict]

Wow. Not sure if I still have my .15 out of my Nitro MT or not. I will be home the end of the week. If I still have it I will let you know. It is a three needle carb... Oh, and it's a pull start.

 

[XxVASSAGOxX]

thats what i need i mean i could send it in ti hpi and get a replacment for $65 but maby i can find a better deal

 

[RC Addict]

So your mill looks like this?

Thanks for the info, olds! I had not a clue. Here is the OS olds is refering to: http://www.osengines.com/engines/osmg2104.html

 

[XxVASSAGOxX]

yea it looks like that with the upgraded cooling head and air filter

 

[olds97_lss]

So your mill looks like this?

Yep. That's the one I had. That phillips head just lets you take the arm off I think. Mine had the purple "upgrade" head though. I couldn't find a photo of it.

By the way, if you go with an aftermarket engine, you will need engine mounts:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXN373&P=7
The stock engine has stand offs on the bottom that bolt it directly too the chassis.

That's what I used when I put the OS in mine:

Didn't realize it, but that was a little over 5 years ago...

 

[XxVASSAGOxX]

yea i got the purple head on mine to

 

[RC Addict]

Well forgive me. I haven't been in this game long enough to know that HPI put out such an inferior carb. I learned somethin' new today! olds rocks!

 

[XxVASSAGOxX]

hey you learn somthing new everyday!!! what you think you would sell your old mill for?

 

[olds97_lss]

Well forgive me. I haven't been in this game long enough to know that HPI put out such an inferior carb. I learned somethin' new today!

I didn't mean anything by what I said. I just didn't want the poor guy trying to adjust an invisible LSN and have his throttle arm fall off on him! It took me a little bit to figure out back then that it didn't have a LSN. I just sat there with a "WTF" look on my face onder2:, then realized it didn't have it.

Just an FYI though, the old OS 15 rotary carb will fit it, but you have to drill/tap holes in the carb neck to mount it. Crappy design IMHO. Causes turbulence in the carb throat which messes up good tune. Then again, with a single needle adjustment, I'm guessing performance wasn't the point of that engine!

Might be able to find one on ebay for cheap, it will help your tune immensely:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXWY01&P=7

 

[RC Addict]

I didn't mean anything by what I said. I just didn't want the poor guy trying to adjust an invisible LSN and have his throttle arm fall off on him!

I didn't take it in a negative way. I said, "Well forgive me..." because I wasn't correct with my information. I am glad you came along and got it straightened out. Sorry if it came off like I was ticked, I wasn't! And I DID learn something new which is ALWAYS a good thing!

hey you learn somthing new everyday!!! what you think you would sell your old mill for?

If I still have it I will send it to you for a fair price. I am not sure if I still have it. I sold the truck before Christmas and don't remember if I sent the old mill with the rig or not. It had been replaced with a Fantom FR .15...