Author Topic: The last roll of the dice.  (Read 5728 times)

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Offline Bigusdickus

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Re: The last roll of the dice.
« Reply #30 on: July 14, 2018, 12:25:13 AM »
Thanks for that T.Rex your eyes are better than mine I hadn't spotted that. To be honest I hadn't even considered the head gasket till now
It's a new gasket and it's torqued up right. There didn't seem to be any external signs of a leak there I will pay close attention to it when it goes back together.

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Offline Bigusdickus

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Re: The last roll of the dice.
« Reply #31 on: July 30, 2018, 06:08:17 PM »
Hi to all.
  I got my bits back this weekend so went through it all again befor the rebuild.
T Rex your head gasket theory even though compelling didnt stand up to scrutiny, the pictures are of the gasket
that came out, it has full contact both sides. The protuding stud threads turnend out to be my cock up, I had put the studs
in the wrong way up the threads are longer on one end than the other  ::) so the only other thing I found was a suspicious
splash mark on the back of the stator. Even though it had passed a pressure test I replaced the stator side crank seal.
So I am still scratching my head.

Rich.

Offline Bigusdickus

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Re: The last roll of the dice.
« Reply #32 on: July 30, 2018, 07:08:40 PM »
 So after all that,
 The squish band has been set to 1.2mm at the piston edge this increases to 1.6 at the inner edge
of the squish band. It was at 2.7mm at the piston edge and just over three at the inner edge. The interesting thing
is the difference between piston edge and inner edge mesurement, at first I thought that possibly I had built this in with
the Wossner piston. after comparing the the new with old they are the same so it is as its supposed to be. I have gone back
to a standard head with a decomp as before so the edge mod has gone.
So this is it so far the timing is right the jetting is close the engine is sound as in no leaks and now the squish
is right. is there somthing I have missed at this point  ;D

Rich.

Offline 4V5

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Re: The last roll of the dice.
« Reply #33 on: July 30, 2018, 08:29:12 PM »
if you're confident that everything else is right retard the timing a shade more and see if that solves it.

if that doesn't solve it satisfactory.. go one bigger on the main jet.. again see what it does.

sounds like something is close to being right without it being 100% right.



How about a good shot of the piston dome? Are you sure it's detonating and not something rattling? What RPM/Throttle opening is it occurring? What's the float level set at? Plays a major role in off idle mixture. You guys don't have ethanol in fuel do ya?


that ^ how is the crank? the main bearings and the cases?

and an out of the square thought...

is the breather in the cap blocked?



IT465x4 IT400C IT175F YZ465G YZ250C YZ250WR XJ650G RD350LC RD250LCx5 DT175Nx3 TW200x2 DT200L DT200R RT3 RX100G GT80F YZ80L PW50J KH250B1 KZ250D1 PE175C TS250ER TS185ER AG175B AG100

Offline 4V5

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Re: The last roll of the dice.
« Reply #34 on: July 30, 2018, 08:31:37 PM »
... and does the tap flow well?

.....ask me how I found that can kill an engine.

 :'(
IT465x4 IT400C IT175F YZ465G YZ250C YZ250WR XJ650G RD350LC RD250LCx5 DT175Nx3 TW200x2 DT200L DT200R RT3 RX100G GT80F YZ80L PW50J KH250B1 KZ250D1 PE175C TS250ER TS185ER AG175B AG100

Offline Bigusdickus

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Re: The last roll of the dice.
« Reply #35 on: July 31, 2018, 07:26:29 AM »
Hi Les
  The breather is another thing that hadn't crossed my tiny mind  :o I will check it.the fuel tap is new
with a new clean filter in line float hight is bang on. Like you say I am close to getting it right.
Now you have mentioned it you have to tell the story ;D

Rich

Offline 4V5

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Re: The last roll of the dice.
« Reply #36 on: July 31, 2018, 08:34:42 AM »
YZ250-WR.

freshly rebuilt with a few hours on it.. new OEM crank barrel piston and sundries. 1/2 the purchase price of the bike basically

riding with mates when I stopped turned the fuel off.. forgot it was off.

tap didn't shut off though.. just trickled.. so when I rode off it ran fine unless I opened it up then it would carry on knock and was getting hot..

so riding it slowly back to the car to grab the backup bike it cleared up.. last corner of the track where I could go to the car or cut a lap on a bike that had just cleared up.. nup... one more lap.

full noise in top it locked up.

it spent the rest of the day making metal contacting clunk noises. when it cooled down zero compression. it's then I notice the fuel tap being off.

that f__ken silly you have to laugh at it.

mates were concerned I was going to crack the shits.. nahh I've driven hours for my bikes to blow up.. doing it on the other side of town is actually much better it seems.

this is later on in the day I had 3 bikes there the other two were for my mate and his son, the TW200 and the DT175.. blowing the YZ up freed one of us for being the cameraman lol.

and I got to thrash the snot out of the DT lol

IT465x4 IT400C IT175F YZ465G YZ250C YZ250WR XJ650G RD350LC RD250LCx5 DT175Nx3 TW200x2 DT200L DT200R RT3 RX100G GT80F YZ80L PW50J KH250B1 KZ250D1 PE175C TS250ER TS185ER AG175B AG100

Offline Bigusdickus

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Re: The last roll of the dice.
« Reply #37 on: July 31, 2018, 09:08:06 AM »
Mate its a bummer when that sort of thing happens.
I have to say I'm a little gelous watching your vid, looks like you have a bit of space to play in.
Not so easy round here as we have to share green lanes with walkers and horse riders or go to an
enduro or MX, competition has its place but it would be nice just to muck about with some mates
for a change  :D

Rich.

 

Offline Cooky375

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Re: The last roll of the dice.
« Reply #38 on: July 31, 2018, 10:57:26 AM »
Great vid, looks like good fun. That soil looks nice, i?m missing loamy soil, mostly rocks and sandy/bull dust here in the NT.

Offline Martin I Henry

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Re: The last roll of the dice.
« Reply #39 on: July 31, 2018, 05:01:54 PM »

Quote
Not so easy round here as we have to share green lanes with walkers and horse riders or go to an
enduro or MX, competition has its place but it would be nice just to muck about with some mates
for a change  :D

...... And that's why I wish Vinduro would take-off here in the UK.
Twin shock scrambles are a bit too much for me, but I like to twist the throttle and get some speed now and again !

Cheers,

Dave.