Airhead

you need a new (used airbox) that one is completely untrustworthy in my opinion, no wonder you holed a piston, am I right in thinking thats a big hole near the rear stop switch? and you downsized the main jet with this airbox?

it burned a hole in the piston because it was seriously lean...either from a bad air leak (unlikely because you would have noticed the engine racing)...or the jetting was lean, yeah I would say around 150 / 155 /160 with the Gianelli because mine runs ok with a 150, so can you post a pic of the airbox butchery?

just oil your filter yourself, get a paintbrush and spread some engine oil all over it, knead it in then let it stand a while, then squeeze out any excess and fit (do not wring it, it may tear if you do), I am a bit unsure about your airbox picture I can see a square swing arm (mk2)yet the airbox looks like a mk1, somehow the back of the airbox (left of the picture) looks a little unclear? I will have to guess that the original 160 jet was correct, I would re-fit that one for now, what jet size is in now...did you say...did i miss that? anywaywere getting sidetracked here talking about main jet sizes, main jet size isnt causing your issue with engine racing and dying with the choke off do the oiling and exhaust gasket and air leak checks for now Sam

just noticed it's a mk1 airbox, so would have had a 130 as standard, sou then yours would be similar to mine now with around a 150 jet with a Gianelli pipe (and an oiled filter)

yeah but get that exhaust gasket done as well Sam is the filter well oiled too, well oiled but not soaking...definitely not dry?

I wouldnt fit jets from yambits in mine, I prefer to stick with genuine mikuni jets, my mk1 has a Gianelli pipe and at the moment is running a 150 mikuni jet as opposed to the standard 130, the mk2 would run a 160 as standard and so with a gianelli would likely need a 170 (ish) can you really trust that a pattern jet is an exact match for a genuine one?...I couldnt and the risks are high

Oversize jetting? be very cautious about downsizing, it may have been correct in the first place and downsizing can be catastrophic! what did it have, what does it now have, what exhaust, filter box intact and not drilled?? is it a mk1 or a mk2?

no it will not be the seal at the airbox (though this needs to be good anyhow) its the seal to the inlet rubber you need to check and the seal from inlet rubber / reed cage / cylinder, try spraying with WD40 when the engine is racing (choke off) to see if it makes a difference

yes choke is on when pulled out I disagree with your reasoning Sam, when a 2 stroke engine runs lean (air leak) it will race so pull the choke with this and it will enrich the mixture quite a lot so the revs will drop and settle more. Thats why I questioned the oil feed blanking and the exhaust gasket

Best get the gasket ring in place first...pretty crittical on 2 strokes so we'll see how it is after that's fixed. Have you done any work on the engine...like replace the crank seals? You say you are premixing now, so have you capped off the spigot on the carb that was originially an oil feed?

Superb

Oh yeah, you'll have to catch em first

rab...again this forum is for intros only

Greetings rab, this forum is for intros there are others for Q's

obviously theres something wrong with you de-compressor as has been said, no amount of 'start ya bastard' (love that name ) is gonna fix that, Oh and stopping it by stalling isnt a great method is it!

Greetings moose and

Greetings and what a great little stroker you have there

Greetings and thatsjustdandy

Greetings Mark

Greetings dato I'm totally umfamiliar with the bike other than i know its a single cyl dirt bike However I expect there may be some sort of compression release to aid starting, either manual or automatic. I would say check your owners manual for clarification yep, i just checked the manual and starting procedure is in there as expected see my sig line http://www.yamahaown...om.au/index.php

crypyic titles!!!I'm with you NEO, dont like them at all and useless for searches as said!! Me I just smear gaskets with silicone grease both sides it helps them not to stick, Ive had the clutch cover off my DT twice now and not replaced the gasket...it's on it's 3rd tour of duty lol

OK PM me your name/address

I have a spare bottom yokeset which some bright spark has sawn off the horn mounts! If you send me your yoke I will fit the stem from mine into yours FOC (I have a hydraulic press at work)

I take it you disconnected it from the horn before measuring this ? yb_newbie mmm

could be serious consequences if you dont recover every last piece of the cage and roller bearings...for example I only count 5 rollers!!