500 Two-Stroke Tech

Ok. Finally all of them came out, without breaking cables, but plungers surfaces are a slightly scored. I am going to UT all carb components, anyway for the time being none of them plungers is happy when I try to make them do their job again. One of them is quite prone to jam again. Maybe UT will bl...

You refer to aluminum slightly superior thermal coefficient respect to brass.

Thanks, Silverstrom, I'll try it.

Hi. Rebuilding an engine. Engine closed, now at carb cleaning stage. They have been sitting for 4 years, I disassembled them for UT, but found all 4 starters sets stuck into carbs seats. I unscrewed brass nuts, tied little springs to their sheath in order to get clearer view (springs kinda rusty wit...

With Mitaka non-offset TZR (2MA/1KT) pistons I read 2,5° difference right now between rear and front.
But I did not take the reading with stock Yamaha pistons before dismantling.

phildu31 wrote: ↑Tue Jun 04, 2019 5:29 am On mine, I found these :
front bank : 1,6 ~ 1,7 mm
rear bank : 1,4 ~ 1,5 mm
Obviously, original values I think.
Heads lowered by 0,6 and 0,4 mm respectively to get 1,0 mm on all cylinders.

And what Vcc at TDC, Phildu, please?

When I got my all stock 500 it measured 120-125 psi and .065" squish. For 15 years its been 135-140 psi and .028" squish. It definitely runs better this way. 125 mx bikes run on the rev limiter don't get piston to head contact until .024" or less squish. I like tight squish but run p...

Well, i am not afraid of detonation, bere 100 octane gas is easy to be found.

I am worried top of piston touching squish head area while working, e.g. due to Mass producing tolerances in conrod lenght etc.

Hi guys. Machine shop went a trifle further. Now I am at 0,75 mm squish height. I'm feeling uneasy. Supposing I mirror-polish top of pistons to avoid things deteriorating due to carbon deposits, should I rebuild the thing as it is, or should I target 0,8-0,9, just for safety reasons? I did not figur...

These are figures I found yesterday on the bike I bought second-hand in 1991:
front bank: 1,0 mm
rear bank: 1,2 mm.

I am in rebuilding stage, aiming 1,0 mm for all of them.

Tks, Luther. I'll post my findings soon.

Hi.

1) what squish height are you on?
2) this figure of yours is related to stock engine or what kind of mod?
3) what squish height is/was your engine, when in stock form?

Hi.

In store pics I can see gas tank, but they're not giving customer a tank too, is it?

Hi.

Does somebody know a good internet dealer for 500 single petal reeds (stock cages & carbs)?

Thanks.

Franco.

Danke.

Franco

Hi.

I need to know factory cylinder gasket thickness for 500 engine, please.