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Post Info TOPIC: Suspected vacume leak on bottom end. But cant find it


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Suspected vacume leak on bottom end. But cant find it
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I have a problem lol

Ill try to keep it simple. As ive done a lot... 

bike i rebuilt it last year with a replacment crank and bearings from a 12k miles 2004 dtr  it was a project and i got it running ok (stripped and rebuild everything with new seals and gaskets except for power, i honed the bore and got compression of 100, (old wossner piston and rings)  it never revved up properly really.. i blame this on the stator never being a good fit on the crank.. it seems slightly different size and i had to ad a few washers behind the stator to make it spark. It ran for 6 months... then as winter came it sat a few months and the head gasket gave out putting coolant in the bore etc... re honed it and noticed fresh scratches on the piston wihich i filed off, started it and it almost siezed again in the end i figured out it was the 2005 castrol  2 stroke oil had gone off (almost siezed my strimmer to). All good i reassembled and got 100psi compression again on new sythentic 2t. But now it revs right up to over run... the piston was shot anyway so i went the whole hog....

i bought the 170cc athena kit.. installed it correctly carefully, removed the 2t oil pump to run thru the tank oil mix.  Plugged the screws and oil inlet well (no crancks or holes and a good new gasket nicelly sealed to head... good carbon reed valves

 

Started her up expecting a nice normal bike... but no still has a vacume leak.... busy with work i handed it over to a bike repair shop... they checked my powervalve setting up and the seals.. and figured its the carb to be at fault.... i didnt think so as i went thru the carb with new gaskets and checked adjustments, all seals replaced and re sealed the car bodies of the flatside to be sure... 

 

Any way the repair shop mechanic insisted its the carb.. so i surendered and bought a 2004 flatside (exactly aame as my old one)  but low miles and gaurenteed working... so i fidded the new carb... and guess what still got the same suspected vacume leak over reving issue..... 

ive changed the carb the top end, the crank and all bottom gaskets done last year with a new clutch too. And im wondering what the hell could it be... ive sprayed it with wd40 while running... no change.. ive checked for leaks from the flywheel and anywhere on engine.. there are none. When i rebuilt her i did a good job on resealing the casings and installing the new gaskets... but it must be somewhere on the bottom end. As all the rest is replaced since. 

 

It doesnt leak coolant now or before but it started with the head gasket going and the barrel filling with coolant (i stupidly went with the chinese head gasket first time around... im using the proper ruberised one now... its got a new spark plut too and spare cdi fitted.

 

Anyone had this issue before?  It must be bottom end but me nor theyammy  bike shop can figure it out.... its wierd... never had a bike i couldnt fix til now.... 

 

Cheers rick

 

 



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cheers Rwszc rick...

Some say Live to ride, I say ride to live, and depending how you ride, decides how long u live lol



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all sorted.. oddly its the 6 month old flywheel crank seal shredded for no obvious reason... no more chinese quality rebuild kits thank you very much

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cheers Rwszc rick...

Some say Live to ride, I say ride to live, and depending how you ride, decides how long u live lol



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Sorry I didn't reply. My suggestion would have been crank shaft seal. I use Athena gaskets for my rebuilds. Top notch quality

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took me ages to get this sorted... v busy with work too....  even the yamy specialist couldnt find the issue (and i bought a spare carb thanks to his advice)  ive never seen 6 month old seal go and couldnt believe it...

its barly done 300km since full split gearbox and rebuild with probably 800gbp plus of new parts inc the athena 170cc kit. (i always wanted one of these bikes as a kid and never got one so wont be selling it anyway)

 

 If any one want to know the Flywheel seal can be got out with a screwdriver and a bit of prying it out and pushing the other side in... without spliting the engine. prof is in the pic.

 

put new continential tyres on and 1 more job to stop a leaky fork and she should be as new mechanically. (awaiting parts)

by the way if anyone is interested... I bought a crank and bearings a few years back off a 2004 (electric start) bike with only 2000miles on it. my bike is the 1998 version kick start, and the cranks are ever so slightly different, if you are using the 90s flywheel as i am, the flywheel will sit aprox 5mm further out and you wont get a spark... unless you get the taper of the shaft on a lathe or.. as ive done spacer out the stator to match ... changing the flywheel and stator to 2004 seemed to need most of the other components changing (hassle) so this is why i went for the spacer option.



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cheers Rwszc rick...

Some say Live to ride, I say ride to live, and depending how you ride, decides how long u live lol



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the bike athena head isnt noticeable to the naked eye and isnt marked with cc... not that it matters to much here... as i have a full licence and no road tax

 



-- Edited by Rwszc on Saturday 20th of June 2015 04:15:53 PM



-- Edited by Rwszc on Saturday 20th of June 2015 04:17:36 PM

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cheers Rwszc rick...

Some say Live to ride, I say ride to live, and depending how you ride, decides how long u live lol



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Aww what a mare!

An engine build on these is very straight forward and should only cost £200. I take it though it was the athena kit that was what made it expensice.

I wasn't too impressed with the Athena kit myself. The port timings are way off and a lad on here has had it corrected. His build should be very interesting!

Be sure to follow us on to our next forum.

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yea i heard the dt200 is what athena replicated.... but my old bore was shot and the wossner piston was sloppy with age (barly hiting 90psi pressure), so this was a quick off the shelf fix,

i almost went with the athena 125 kit but figured id give the 170cc a try, i have a 2007 honda xr200 4t (asian model) and fancied a simular power.

the only issues i got left to finish it is to hear from somone who re jetted for the 170cc to save me all the messing , some way of de-rusting the tank permanently, sprockets so i dont hit peak scream at 60mph, and perhaps a bigbore down pipe to replace the coked up, and leaky original.... or cut open and clean then reweld the yamaha one...



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cheers Rwszc rick...

Some say Live to ride, I say ride to live, and depending how you ride, decides how long u live lol



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My brother ran a YZ 38mm carb on his so can't help you there. Common conversion though and lots of lads on here use them so there should be something about

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thanks,

yea the parts thus far are

athena kit,
the 100quid original 2004, 2000miles on it, crank,
cdi,
the other black box under the tank (gold dust to find) near the cdi (forgotten its name both are spares from germany)
spark plug,
a new piston i never used,
2 new continental tyres,
forks seals n oil,
engine compression tester,
vaccume tester, (both bought for the bike)
and a spare carb i didnt need,
original yammy big end bearings & little end,
seals and gasket kit (chinese rubbish it turns out)
plus the fluids.
1 rear indicator
clutch kit
gold alloy oil cap
60£ worth of stickers
(exhaust down pipe to buy and im missing a coolant exspansion tank cap)


keep in mind i bought the bike a siezed lump of scrap with 40k miles on it for 300euro, it had been 4 or so years chained in front of a police station in nice city centre france, as it siezed up and the guy bought a new bike and left it there, until i bought it.

tank was full of rusty sludge, all plastics sun damaged, and mostly the worry was the oil filler cap was missing with the sump brimming with water and leaves.. Boy do i love a challenge... bringing the dead back to life..... been a steady away mega mission but the end is in sight now.....



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cheers Rwszc rick...

Some say Live to ride, I say ride to live, and depending how you ride, decides how long u live lol

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