mac star .28 running problems fixed but some questions

[craig911]

hey guys, so after all the headache this engine gave me i got it figured out

so to fix my running problems i glued the Mid range screw, ( kept unscrewing when up to temperature ) messing up my tune
also my fuel had gone bad ( not making much power )

how often have you guys had an engine thats needed the MRS to be glued in some way?

also since converting the engine to a turbo button head it seems to make a bit more power,

the turbo head came with a standard hobao T4 plug, what would be a good plug to replace it with when it eventually fails?

using 25% hpi optifuel RTR

 

[cbaker65]

hey guys, so after all the headache this engine gave me i got it figured out

so to fix my running problems i glued the Mid range screw, ( kept unscrewing when up to temperature ) messing up my tune
also my fuel had gone bad ( not making much power )

how often have you guys had an engine thats needed the MRS to be glued in some way?

also since converting the engine to a turbo button head it seems to make a bit more power,

the turbo head came with a standard hobao T4 plug, what would be a good plug to replace it with when it eventually fails?

using 25% HPI optifuel RTR

I had to on my hyper 21 engine.
It leaked real bad,but eventually just put a Ae 28 pro carb on it with 2 needle setting.
Its all molded aluminum carb with no composit material.

I hate the ones made out of composite ,they eventually start leaking around the aluminum
parts that are simply pressed on them ,poor design!

 

[olds97_lss]

I had to on my hyper 21 engine.
It leaked real bad,but eventually just put a Ae 28 pro carb on it with 2 needle setting.
Its all molded aluminum carb with no composit material.

I hate the ones made out of composite ,they eventually start leaking around the aluminum
parts that are simply pressed on them ,poor design!

The old picco 28 was plagued by that too, from what I've read. Most guys were able to fix it for the most part by cleaning it really well where the alloy meets the composite, sanding it a bit and putting a thin layer of RTV or JB-Weld on it.

 

[ninnon]

What type of glue did you use?

 

[craig911]

What type of glue did you use?

i used some generic super glue i got from lidl,

set the screw flush with the housing applied some superglue unscrewed it slightly then back to flush to get some glue around the top edge of the screw so it's sealed tight, runs perfectly now

 

[ninnon]

i used some generic super glue i got from lidl,

set the screw flush with the housing applied some superglue unscrewed it slightly then back to flush to get some glue around the top edge of the screw so it's sealed tight, runs perfectly now

Super glue will eventually split and crack, but for now it's fine. You don't want anything permanent since you may want to start tuning the engine later. I recommend loctite blue, not red, that is permanent.

 

[craig911]

Super glue will eventually split and crack, but for now it's fine. You don't want anything permanent since you may want to start tuning the engine later. I recommend loctite blue, not red, that is permanent.

problem was the threads are quite far into the carb to use lock tight, i didn't want to risk it getting anywhere it shouldn't

i was going to get a standard car that only had high low and idle but was not sure what would fit

 

[olds97_lss]

Generally, most engines that only have two needles were poor runners and difficult to tune.

Not sure what you mean. I've only had issue with single needle carbs. My 2 and 3 needles ones (except traxxas 2.5/3.3) all tuned fine.

 

[Rooky78]

I almost questioned that too. I've always heard 2 needles to be preferable to single or 3 needle carbs. But I've only ever had 2 needles.

 

[olds97_lss]

I almost questioned that too. I've always heard 2 needles to be preferable to single or 3 needle carbs. But I've only ever had 2 needles.

I've had all 3 and the 1 needle carbs suck. Best you can hope for is a decent mid-range, low end that doesn't die and high end that doesn't bog so bad that it's unusable.

 

[craig911]

i personally prefer only having a low and high speed needle to worry about, never had an issue until i got an engine with a mid range needle

 

[cbaker65]

i personally prefer only having a low and high speed needle to worry about, never had an issue until i got an engine with a mid range needle

I like these first gen Ae carbs,they are 2 needle ,I run this on my Ofna 21 hyper.
Easy to tune ,an keeps a tune!

 

[olds97_lss]

OS's old 21RG was like that. Instead of adjusting the needle for the lower range, you adjusted the seat. Man was that thing easy to tune and held a tune all day long. Which is what a 3 needle carb lets you do, but a 3 needle also lets you adjust the needle on the end of the throttle barrel.

Most other 2 needles (if not all) that I've had have the typical HSN and the LSN in the throttle barrel. And the idle stop screw of course.

 

[ninnon]

Not sure what you mean. I've only had issue with single needle carbs. My 2 and 3 needles ones (except traxxas 2.5/3.3) all tuned fine.

I almost questioned that too. I've always heard 2 needles to be preferable to single or 3 needle carbs. But I've only ever had 2 needles.

I've had all 3 and the 1 needle carbs suck. Best you can hope for is a decent mid-range, low end that doesn't die and high end that doesn't bog so bad that it's unusable.

My mistake- that's what I got confused with. Deleted it.

 

[craig911]

had the truck out today engine ran quite nicely, just looking for a good pipe to go with it

I'm using this at the moment, not sure anything else will give much better performance unless i went with a ERCM pipe

vid of the truck running (youtube edits are in progress)

 

[Rooky78]

Looks pretty good. What tires are those?
As far as pipes, I'd say either stick with what you have or go ERCM.

 

[cbaker65]

That sounds pretty good ,But it sounds like your spur is slipping alittle......Not sure though!
Always make sure that your gear mesh is good with the clutch bell & spur..

Great vid!....

 

[craig911]

Looks pretty good. What tires are those?
As far as pipes, I'd say either stick with what you have or go ERCM.

i believe there from a ofna/hobao pirate but haven't been able to confirm it,
this is the closest i came to finding a mach http://www.modelforceukrc.com/hobao-pirate-wheel-and-tyre-set-17mm-hex-15289-p.asp

but searching part numbers showed different wheels that tapered in before reaching the spokes some sites showed wheels that matched mine

the tyres are also quite tight fitting on the wheels so i haven't needed to glue yet and may not bother since they were a PITA to get unmounted to remove stones from the inside (bought used)

the wheels just over 4.5 inches wide with a diameter of 6 inches, i bought them for the offset over the standard savage wheels and using the integy axle extenders ( standard X axles ) it's nice and stable turning, I'm currently running 17/52 gearing and its been fine even 19/47 has not been an issue if i wanted more speed

here are a few pics of the back and front

That sounds pretty good ,But it sounds like your spur is slipping alittle......Not sure though!
Always make sure that your gear mesh is good with the clutch bell & spur..

Great vid!....

when i set gear mesh i take my time to make sure its perfect, i run with my spur tightened all the way down and only use steel spur gears
sometimes after using reverse it doesn't fully engage forwards properly so its like its in neutral for a second allowing it to rev up and jump forwards (linkage is fine just the reverse sticks at times )

would like a 3 position switch to actually have forward neutral and reverse

 

[Rooky78]

Those tires are tough. I like those.
I don't know how you'd get a neutral. Never really thought about it much, but neither of my nitro rides have reverse either.

 

[cbaker65]

Oh ,then that's what I heard then,it didn't sound quite right.

Yea,its like a neutral when the throw of the servo is off.That would happen in my mgt when I had reverse.
That sometimes gets a lot of newbies sometimes when there reverse servo gets out of adjustment...Lol