Pistons made to order

[tomitch]

Is there a company out there that makes pistons to order?? iv just re-built my mk2 with a autisa bigbore and and matched piston these had not been used since the rebore i fitted a 230 main jet into a tzr carb and it didnt run all that well low down in the revs but high up it started running great then...... it seized we have now realized that on full throttle the fload bowl is draining faster than it fills so is then running lean. Luckely it was a 4 point seazure so i got away with it. can anybody put some pics up of the inside of a mk2 petrol tap as the transfer holes in mine are at least half the size of the input from the tank and the out put from the tap!!!

Anyway back to the pistons made to order question.. im guessing my piston will go bang at some point so i was wondering if i could send off the dimentions of my autisa piston somewhere and get one made to save doing the banshee conversion.

Any one have any ideas??

[Norbo]

First you need a Hi flow tap and posably a biger carb TZR125 carbs are not biganough . You need a 28mm carb .

I dont know of any place that can make pistons but im sure one could be made . I suspect however it would be a lot of money .

[carlos]

Go with the hi flow tap! and make sure the carb is nice and clean! I've seen the internal pipe work block up with rust from the tank slowing fuel to the bowl

[ally]

hi

there is a bloke on ebay flogging bigbore autisa kits for £70 for RD80's (you don't say if yours is 80 or 125

hope it helps


ally

bay id: 280259086812

[twostroker]

ive got a 66mm bore liner in my 125lc barrel and im using a dt175 air cooled piston from circa 1979,no need for a special piston,to make your big bore run at its full potential you will need a decent one off exhaust designed for the 66mm bore size and exhaust port duration,28mm carb and pre mix oil as the pump wont be up to the job with the 175cc kit.

i tryed running mine with a ledar kitted 12a carb and swarbrick pipe and it wasnt any better than with the standard liner but with the decent pipe and 28mm carb id say it will beat a rs125/mito.

ps what do you mean "the banshee conversion"?

[twostroker]

im in the progress of fitting a larger 5 spring,7 plate clutch with 50% more friction area as my 175cc motor simply produces to much power for the standard clutch set up,even with heavy duty springs,can you tell us the exact spec of your engine and il try point you in the right direction of getting it running properly.

[tomitch]

thanks for the help guys right (twostroker) its an rd125lc mk2 iv go an micron pipe (the one with the little tail pipe that turns) i have a tzr carb fitted (26mm) and could fit a 12A carb if better still on the standard clutch but i will be thinking about fitting the tzr clutch instead and a autisa barrel with genuine autisa piston and a skimed dt125 head

[twostroker]

you will need the head re-profiling to the same 66mm diameter as the bore,i personaly wouldnt have it skimmed as it will have more compression from the extra 50cc,
the 26mm carb might be ok but id go for a 28mm flatslide(mines machined out to just under 30mm).
as for pistons id run any decent jap piston kit ie prox or matika,the standard clutch will be fine for now but i highly recomend a 28/30mm carb and a specialy desighed pipe.if you do decide to get a special pipe ask norbo if he can get hold of one for you.
as for clutches the biggest and best one to fit is a dtr125 clutch,the tzr clutch has the same size plates as the rd.

[racerd]

could you not use a sdr 200 cc piston kit

[twostroker]

Nov 9, 2008 22:19:30 GMT 1 racerd said:

could you not use a sdr 200 cc piston kit

that sounds like a good idea,whats the diameter of a sdr200 piston?it may require a 1 off liner being fitted to a barrel if its much bigger than the std 66mm big bore liner.
it would certanly be a good conversion as long as the sdr piston fits?

them sdr200's look realy nice,take it they were import only cos being 200cc there couldnt be much of a market for them in the uk?

[Norbo]

Not sure if you could fit a 200cc piston in a 125 barrel even with a new liner you would not have a lot of room for the fuel to flow around the ports.

[tomitch]

i think it could have already had the conversion cos there is 2.4mm squish from tdc to the lowest point on the head and it has 0.007 written on the head which makes us think it could have already been changed i was playing with jets yesterday and its at a 300 at the mo and still not 4-stroking with the choke on past 5000rpm when the throttle is wacked open but gave me a little scare as it wheelied and i only had one hand on the bars lol

[twostroker]

does it run ok with the standard 24mm carb with say a 240 main jet?,seriously it will run well with a 24/26 mm carb and have nice botom end and mid range power but if you slip a nice 28mm/30mm carb on you will notice a big improvement over the smaller carb,mine had very little top end power with the 24mm carb.

theres even a pair of pwk 28's for sale on here,this is the carb i run with my big bore,originaly from a kawasaki kr1s,these carbs fit the inlet perfectly and being flatslide are better allround,convert it to manual choke and mod your throttle cable and your away.

[racerd]

Nov 11, 2008 16:20:24 GMT 1 tomitch said:

i think it could have already had the conversion cos there is 2.4mm squish from tdc to the lowest point on the head and it has 0.007 written on the head which makes us think it could have already been changed i was playing with jets yesterday and its at a 300 at the mo and still not 4-stroking with the choke on past 5000rpm when the throttle is wacked open but gave me a little scare as it wheelied and i only had one hand on the bars lol

squish is measured at tdc with lead solder, the squish standard is 1.50mm this is because of the head gasket is 1.00 mm thick and there
is 0.5mm lip on the cylinder head as well, a sdr 200 cc piston kit is 66 mm