So they emailed me back. The 10mm wrist pin on the hoca minarelli IS 26mm from the crown, so no cutting required, just insert and enjoy! HOWEVER the piston set is 4.7 oz, which is 133 grams (23 grams heavier than our assemblies) and the wrist pin is 5g heavier than our wrist pins (20g), so without balancing, vibrations will get worse.
Is there any other piston that will work with this engine?
- Thread starter mrfubs
- Start date
Awesome! but isnt the overall length 48mm? ours are 45mm right? And if its 23g heavier i think i should be able to drill 11.5g off each side of the crank to make up for the weight? and that is if i get a new crank assy.
well.. i enjoy doing this stuff so ill order a crank with the removable weights that has the shorter con rod length. i think ill have it all said and done in 2/3 weeks. are you gonna beat me to it mew? lol
well.. i enjoy doing this stuff so ill order a crank with the removable weights that has the shorter con rod length. i think ill have it all said and done in 2/3 weeks. are you gonna beat me to it mew? lol
Sadly no, I was interested until I heard the weight. If I end up needing a new piston then I may dive in, being a piston from a real scooter it should be better quality (as most 47mm pistons seem to be 133 grams anyway). If you use the titanium wrist pin I linked to, it should reduce the weight to 120 grams which isn't too bad. I'm surprised though, my understanding was our piston and wrist pin were heavy for their size, yet everything else seems to be heavier.
As for the length of our pistons, they're 47mm, so if these new pistons are 48mm, you *may* have to chop 1mm off the skirt, though I imagine theres more than enough clearance (if you have the crank out, see how close the piston skirt comes to the crank. If you have at least 1mm you should be fine as the aluminum will only expand about 0.3mm at running temp).
Thanks for all your help mew. I called dax and he still doesn't have any bottem ends in yet but he said he should on the 18th.
So everyone I will be experimenting with this as soon as dax gets some lower ends in and I'll buy that hoca piston shortly. I'll update soon as I get everything.
So everyone I will be experimenting with this as soon as dax gets some lower ends in and I'll buy that hoca piston shortly. I'll update soon as I get everything.
Ive been reading this post and if Im understanding you guys right and from what I seen of the first piston it should be a direct bolt up to the dax balanced bottom end. The worse thing should/could be takeing a max of 3mm of the bottom of the piston? Also with the titatum wrist pin it should be with in 10g of our stock set up? and best of all already set up for reeds
Now have either of you thought of the jug the piston came from to start with? any ideas on it I know you would want a diffrent carb set up but that could help also.
Now have either of you thought of the jug the piston came from to start with? any ideas on it I know you would want a diffrent carb set up but that could help also.
yup thats the worst case scenario and yes give or take 10-15g which isnt a big deal for me, ill just drill more out of my crank and also gives me an excuse to open it up to see how things are going.
and what do you mean the jug the piston came with? Im going to use the same jug iv been using and maybe deglaze it at the very most because the plating is so thin.
and what do you mean the jug the piston came with? Im going to use the same jug iv been using and maybe deglaze it at the very most because the plating is so thin.
guess what I should of said is the jug the piston would normally be with. I was also looking at the topend kit jug head and all that that piston was inm
yeah, I checked, our bolt patterns are way off, spanning across like the site measured, our jug is 65mm, 10mm short, sadly that wont work. HOWEVER there IS a puch jug out there foureasy used, with a spacer, and got great results with! Only problem is I have no idea which jug it was.
As for the piston, at most we'll have to shave 1mm off, the piston wrist pin (according to the emails I got back from them measuring them) is perfectly matched to the type D motors (dax, speeddemon, etc.), but it is 1mm longer. The thing I'm afraid of is if that 1mm will end up cutting into the reed ports. For sure let us know, though, I'm interested in the vibrations and the power (shouldn't leak compression as much and the extra weight may net you some torque and idle ability)
As for the piston, at most we'll have to shave 1mm off, the piston wrist pin (according to the emails I got back from them measuring them) is perfectly matched to the type D motors (dax, speeddemon, etc.), but it is 1mm longer. The thing I'm afraid of is if that 1mm will end up cutting into the reed ports. For sure let us know, though, I'm interested in the vibrations and the power (shouldn't leak compression as much and the extra weight may net you some torque and idle ability)
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So iv still been hunting around for pistons and came across this. I cant seem to find just the piston but it looks to me as if it would fit in the engines with the longer con. rod, what do you think?
http://www.monstermarketplace.com/s...-more/morini-47mm-big-bore-cylinder-kit-185-6
im not looking for a different cylinder but i went ahead and measured our bolt spacing and reads 45.72mm and the one in the pic is 46mm thats pretty dang close!
http://www.monstermarketplace.com/s...-more/morini-47mm-big-bore-cylinder-kit-185-6
im not looking for a different cylinder but i went ahead and measured our bolt spacing and reads 45.72mm and the one in the pic is 46mm thats pretty dang close!
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The only bolt hole listing I see on that page is exhaust bolt hole spacing. Compression height (crown to wrist pin) is 2mm too high as well. The cylinder IIRC is 85mm as well, whereas that one is 78.5mm It's very close, would need a spacer (woo), and the piston would sit 2mm lower than stock on the longer conrod (grubee) motors. The piston is also 2mm shorter than ours. With some shimming and maybe cutting of the piston skirt, it could possibly work though.
well crap
Here is a listing on ebay for it and shows a little more info infact they list this one as 46mm bore not 47 i think because the bore is 46.96 A little tight for a forged piston that we have. An the part that the cylinder has a case intake port and the actual intake port looks like a transfer port but is routed into the case.
http://www.ebay.com/itm/70cc-big-bo...Parts_Accessories&hash=item35cba6eb3f&vxp=mtr
Here is a listing on ebay for it and shows a little more info infact they list this one as 46mm bore not 47 i think because the bore is 46.96 A little tight for a forged piston that we have. An the part that the cylinder has a case intake port and the actual intake port looks like a transfer port but is routed into the case.
http://www.ebay.com/itm/70cc-big-bo...Parts_Accessories&hash=item35cba6eb3f&vxp=mtr
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our pistons arent exactly 47mm either and our cylinders are almost bang on 46.96 (I think we have 46.97, but due to variations in productions, your could be different). Pistons will also be slightly smaller. Unless you have a way to pre-warm the cylinder similar to F1 cars though, it'd be dangerous to have an exact-fit piston, thats what the rings are for. however the better fit the piston is, the closer those rings will have to be, less blow-by, and better compression and performance. But the nature of 2-strokes demands a slightly sloppier tolerance due to the rings speeding by holes in a cylinder (ports), contrary to a 4-stroke that has a smooth surface the entire distance.
Alright so i got my piston in and am very happy with how everything has turned out, so far it looks like at least 1-3mm needs to be cut from skirt and i also weighed the over all weight of our piston and the Hoca. The hoca weighed out at 111.8g and ours was 106.9g so very close AND the wrist pin the Hoca piston came with is thicker so right off the bat we can just use the original pin for weight savings.
First pic is the Hoca with the reed port windows centered in the intake port and looks great. Second pic is piston at TDC.
First pic is the Hoca with the reed port windows centered in the intake port and looks great. Second pic is piston at TDC.
hahaha i would have it right now but! i concluded that im going to buy a new cylinder and the Dax lower end that way i basicaly have a new engine and every thing will wear the same, give or take a couple weeks because dax is still waiting on the lower end shipment to come in on the 18th. Right now my con. rod is too long thats why im looking into the dax bottem ends because they have the shorter con rods.
