FG MT G260RC Porting

[shorey nz]

your tuning backwards always set your top end neadle first then bottomend if you have pico switch run one full lap around your footy pich then kill it dead at full tilt dont back offjust hit the kill switch retreave car and check the plug repeat till plug is buiscuit coulor short bread is good or crisp chip colour also listen for doubeling a slight splutter at the top end iff this happens back TE out.once youve got this done you might have to dile 1/16 turns hear and there. now you can start setting bottom end youl  find once top is set the bottom willbe a piece of cake
setting bottomend
set idel screw so that you can see about 0.5mm under butterfly in carb set neadele to stock .start engine run as above til warm bring car to stand still wait 5 sec then jam wide open and it should just launch off the line if not observe what happens stutters then pulls badly or dies your prob too lean.and idle will be high
if pulls badly with lost of smoke too rich.remember as you lean out the bottom end the idle will go up so back the idle out and vice versa.

goodlluck

[Benckie]

thanks for all the info guys.

shane, i was actually thinking about the big bore kit the other day. i read about the zen 29.5cc big bore kit, what do you think about that? if I attach it to the 668 and the billet spacer?

i took the mt out last night, it started to cool off around 8ish so i headed to the local footy ground. started by taking needles 2 turns out. couldnt get it to idle for a while. obviously very rich.

kept adjusting the ls and idle screw until it was isling where I wanted it. started off ok, take off was ok and top end was boggy down, leaned it off slightly, saw instant difference, leaned if off some more and was hitting good rpm, after about 10 - 15 mins of running, mainly flat long straight runs full throttle the take off started to suffer severley, it would bog down before taking off. if it was idling still I would mash the thottle, there would be a hesistation, for a good second before it slowly took off for another second and then it would really open up, break traction and start screaming.

Any idea's how I can address this? I tried richening and I tried leaning???

There's no more air leak it gotta be tune related.

the zen 29cc top end kit will not fit your motor, you motor is a g260rc with 2 bolt head.

the zen 29cc is a 4 bolt head it will not fit and will not work with your motor.

to use the 29cc zen 4 bolt top end kit, you would have to buy a new g240rc or a new g270rc motor and then buy a zen 29cc top end kit and install it or buy a complete 29cc zen motor either way your looking at over 430 aud with post.

this is why i sugested a gp290 28.5cc head kit, they are the best cy head out they, they do make gobs of power and rev realy well.

http://powerslideracing.com.au/index.php?main_page=product_info&cPath=15_17&products_id=1627

you might have to cut the little tab of on the crank case, but thats easy, use that with a 668 carb and a billet carb spacer and you will have a 28.5cc head kit, the same size as the zen 29cc top end kit.

now with tune, most manuals videos and so on will tell you to set the low end first, since the low and high end both operate and feed the engine fuel and full throttle, if you set the high first then set the low, this will effect the high end, if you have to lean to low end out after setting the high end, this will make your high end run leaner, so always tune the low end then the high end.

i think since you ran over a tank on the g260rc with an air leak and kept running it, i say you have worn out the top end, i think you will find you ring would of worn out and you would of worn down the platting on the head.

i think that motor is spent to be honest and you where lucky no more damage was done, i think its time for a new top end, you might get a bit more life out of it with a new ring and or new ring and piston but i thinik yourll find the life still will be very short.

my honest opinion is new 2 bolt top end kit of your choice, but dont worry about race ported, new 668 carb, new billet carb spacer and get the screwing driver out and have some fun

[sperera]

thanks everyone. shane when I had the motor apart the ring looks like there's plenty left, as for the lining I dont know what to look for so you could be right, it might be worn.

i think ill run it as is and maybe next month opt for the top end kit you have recomended, believe me I plan to stay away from porting for the time being.

just out of curiosity why have you recomended a carby change from the stock 813? not saying your wrong I would just like to know why.

thanks again

[Benckie]

a ring looking fine to be fine is a bloody big difrence to me, i hear this lots, shes got lots of compression, when i hear this i know the engine is rooted.

say with the rings, people say shes looks like its got lots of meat, well the difrent to a new ring to a stuffed ring is fark all.

the diffrence from a new ring to a worn ring is 0.2 mm can you eyes see if a ring has the extra 0.2mm needed to run good ? i sure as hell cant !

its safe to say you have killed it, when you run lean the motor is not getting enough fuel, it runs hot, since there is oil in the fuel, if you not getting enough fuel for not getting enough oil, if you not getting enough oil your getting more heat and more engine wear.

it is very safe to say, even if you dont think so the engine is worn out, due to running for over a tank in a very lean state, you said so your self it wasnt running right and you said you ran a tank thru it.

when tunning you only hit a lean period for a few seconds then back of you dont keep running for over a tank, so its 99.999% likly that the ring is worn past the zenoah replacment figers and that the head would have worn quicker due to the lack of lubication and the extra heat.

now i sugest a 668 carb for a few reasons for one the 813 for some is hard to tune, it does not always hold top end tune and can be fiddle and some guys (not me) have trouble starting and tunning the 813, so since the 668 is cheap, holds a tune and is very relible i sugest that carb.

this is another reason why i will not sugest a 813 carb,

http://ozlargescale.com/index.php?topic=837.0

if you jsut look around this forum you will find the 668 to be popular and alot of people have witched back to the 668 carb from the 813, so just dont take my word for it.

i sugest you buy a good set of calipers, a good set of feeler gagues and have a good long read of the zenoah g260rc manual, then you will know whats worn and when its time to replace engine parts.

then buy a good torque wrench in 3/8 or 1/4 with some bits, and follow zenoahs torque settings, then you will not have to worry about warping carb spacers, leaking head gaskit and air leaks and you will never bag out a 2 bolt head and you should not ever have the common engine troubles most have, including me befor i pulled my finger out and got serious

[sperera]

shane,

once again mate i think your spot on, i didnt realise the difference between a good ring and a bad ring could be such a small difference.

ill order the 668, spacer and cy big bore kit, ive got access to all the tools you mentioned through the workshop at work.

other than the 3 items above do you think i need anything to get the mt back up and running to her former glory? just to be on the safe side i dont want to miss anything.

[Benckie]

to be on the safe side and if it was my truck and motor i would go, crank seals (one big one small), all new gaskits and an ada billet manifold and mabe even a new fuel filter just to play it safe.

i would use your zenoah manual for all the torque settings for the crank, carb abnd carb spacer with new gaskits and you should be right for any air leaks.

[sperera]

thanks shane, ill start hunting these bits down later in the week. keep you posted on my progress.

[sperera]

looking through PSR for some parts to rebuild/upgrade mine. came accross this, what do we think?

http://powerslideracing.com.au/index.php?main_page=product_info&cPath=15_17&products_id=307

[Redline]

I installed this kit on a CY26 bottom end last year. Went really well.

[sperera]

thanks, deciding weather to go this one or the 28.5, any other opinions?

[Redline]

Well the 28.5 is the same kit just without the 2mm crank and copper gasket.
But power will obviously be slightly different between the two.

[sperera]

cool I didnt know that, thanks for the info.

[Benckie]

as redlines says they are the same same, there is endless option, it jsut depends on what you want to do.

i used the 28.5cc head kits with 30mm crankcs (30.5cc) on 20 pluss kg all alloy baja 5b,s they are alot heavery then a all alloy fg.

it depends on what you want


http://powerslideracing.com.au/index.php?main_page=product_info&cPath=15_17&products_id=2351

[sperera]

nice find shane, tempting but my confidence in porter products arnt the best at the moment 

so either the 28.5 or 30.5 kit should be durable and powerful in my MT you think?

i honestly dont want to go nuts with the FG, just want it back to what it used to be when new maybe a little bit more if I can get it. want to be able to lift the front on flat ground which wasnt a problem within the first 5 litres.

im seriously considering the 30.5 kit, its a good price (one I can afford) and as long as we all think it will work well and last a long time when treated right ill try and get my hands on one next week.

i am also considering getting a 4WD FG Baja later this year, I want something more suited to track work but still keep the FG MT for the ultimate basher  ;D

[sperera]

well I took the FT out for a run at the footy ground last night. overall went well, i did some tuning (new experience for me) and the results are much better than what it was running.

its almost back to normal. almost lifting the front on the flat. still got a slight bogg to it down low but once its moving it sounds sweet, spesh up top.

half the prob is I am partially colour blind so its a bit of guess work when it comes to plug colour but I dont think its lean. sounds good, idles nice, will run it like this till I change the top end.