malossi, cant get it to move. some advice please

[baap_cp]

I melted a piston on my cast iron the other day, slightly scrantched the bore, but got it honed and scored a piston from a buddy. I bought new rings slapped on the bore it starts but won't move. N e help? The piston has a SLIGHT grove in it. Wud that b my problem? Kus the manifold I got is new with new reeds and new spark. So n e sugestions plz?

[bakaracer]

Check how much compression you have with a gauge.more thsn likey with a groove on the piston and s over honed cylinder to get the seized scratches out, now your cylinder is over sized and piston to cylinder wall clearance is to big and ring end gap is way to big which will make the motor have a low compression or major blow by. Check the compression first to confirm its low . Then go from there.

[baap_cp]

Check how much compression you have with a gauge.more thsn likey with a groove on the piston and s over honed cylinder to get the seized scratches out, now your cylinder is over sized and piston to cylinder wall clearance is to big and ring end gap is way to big which will make the motor have a low compression or major blow by. Check the compression first to confirm its low . Then go from there.

ok thanks baka the hone wasn't to bad it was jus miner scratches. Wut shud the compression b at? N where can I get one of thoes gauges at? N if I honed to big cud I get a bigger piston?

[bakaracer]

Compression tester can be found at any auto parts store. As for over sized piston , you first have to find out how big the cylinder is now after the hone. That's where measuring ring end gap and piston to cylinder wall comes in to play. Can be from .25mm to .5mm over size. You can check online for all the malossi dealers or get ahold of red and see what size pistons he can get.

[baap_cp]

K so I never got the compression tester, but I took off my head n noticed there's some play with the piston wen it sits in the cylinder, is that normal? Fahk I sound like a beginer but I've been thru couple motors, jus never delt with honed out bores.

[bakaracer]

It should move but very very little. Clearance between the piston and cylinder wall near the wrist pin should be around .004mm. The top going have more because the piston is tappered from top to bottom. That's why I said to check the piston to wall clearance and ring end gap clearance.

[kingkamehameha]

Who is this?

[baap_cp]

I gotta slap my motor back on to my bike n ill try do the compression test. N shut up safir it non ur buissiness. Haha nah its cameron. Who has a cherry bore for sale for cheap

[Wheelman-111]

Greetings:

No need 2 slap u motor onna bike to comptest. It b e z r to do onna bench. Jus bring battery n hot war 2 st r ter. Even can do with kicker build biceps.

[baap_cp]

Haha nice I need some bicept building, nah I mite jus spin the fan, dat shud work right? And wut shud the compression b at? The guy that honned it out sed the device he used wudnt b able to over hone, n he sed I jus need to use * oil to get the piston a little gunked up, cud that b the case?

[baap_cp]

*cheap 2 stoke oil

[bakaracer]

What????? That guy is full of it. Any hone tool can over hone a cylinder. Now if was getting bored out then the machine can be exact on the size. If the scratched was deep enough where your finger nail can get caught in it, most times thats a 1 over piston needed. (.25 over)

[baap_cp]

Hahahaha yah dude that's wut I sed when he told me that. But the scratches wasn't to bad, it wudve ran still I'm pretty sure, I'm thinkin I shudnt have honed it. But yah ill keep u posted on this problem. I mite even jus get a new bore

[bakaracer]

Just measure it. That way you know what size it is now. Then just get the right size piston. Malossi has 1 and 2 over pistons. Or might just need a straight 47mm piston now. Original size is just under 47mm

[baap_cp]

Wut am I suposed to measure it with? That's a pretty small amount to meassure .001 of a mm das super small. Haha.