spents shorty roofchopper rail build

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Seandonato73 said:
Pop off is a pressure test. You have a compressor and regulator. Aim for 20psi pop. Around 15 psi reset. It's a wet test so make sure you have fuel in the carb before testing.
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yeh will rig sommat up and test that as well sean (y) ,
i remember you did a quick how to not so long ago for the pop off as well,
i did take notice (y):LOL:,
and you explained it spot on as well,
 
Rep732 said:
I'm sure it's been covered but how and what do you do with those plates?
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gonna pressure test the 34 reed ryan (y) , trying to find out why it runs like a bag o shite when warmed up,
runs fine when cold then bogs like feck when it warms up, ruled out the carb as the problem, thinking i have a leak when engines hot somewhere (y)
 
Ahhhhhh now I get it. I wonder if you could have a bad crank seal? I would think its going to boil down to crank seals or a base and case gasket... can't say there's much left other than maybe a worn ring? How hard is it to start for the first run?
 
Rep732 said:
Ahhhhhh now I get it. I wonder if you could have a bad crank seal? I would think it would its going to boil down to crank seals or a base or case gasket... can't say there's much left other than maybe a worn ring? How hard is it to start for the first run?
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yeh already have new seals, bearings etc here in case it needs em ryan (y),
its obr 34 reed case so doesn't use a case gasket, just a smear of sealant on case halves,
have a new ring here as well, not sure what it will need and if it doesn't need the above at least i have spares ryan (y),
it starts fine and idles fine as well, low needle is spot on, just when ya give it wide open it bogs as it gets to normal temps,
add fuel on high and its fine till it next idles, then bogs again when ya give it the gas,
i also noticed the last time i had it running that there was a misfire at times, but not sure if thats just cos theres so much fuel going in there or the coils breaking down when it gets hot, so have a new coil here as well,
new plug was really rich after i had it running, but was just adding fuel all the time,
sean said pressure test it, so am gonna do that first and see what happens , then go from there (y),
also had three different carbs on as well, two that are known good ones, does the same thing with each carb fitted,
 
so pressure tested the 34 reed,
straight away theres three significant leaks at roughly 15psi 🤦‍♂️,



heated the whole engine to around the 80 degrees c mark which is what it basically runs at a t full warm up idle,
well its close anyways :LOL:,
aaaaaand leaks get worse,you could feel the leaks when cold and hear the leaks when hot, then just feel the leaks again when it cooled off,



let the engine cool down till it was easy to hold in hand, so above ambient but not hot,
dunked in bucket of hot ish water and yep, bubbles galore,
not just a few bubbles, it was like a jacuzzi in there :ROFLMAO:,



circled are the two main leaks,



and the third is from one of the top end side cover plates,
now the cover plates are my own fault cos there sealed with black rtv, and have since found out that ya shouldnt use rtv to seal the plates cos it doesn't sela properly there,
the case halves are sealed with threebond though as they should have been,



sooo, its apart fully now :ROFLMAO:,
not sure how to tackle this yet,
maybe lightly lap the case halves to see if theres a low spot or sommat,
needs to be done lightly though, pain in the arse that obr don't use a case half gasket on the 34 reed cases,
bearings are spot on super smooth still, seals seem fine as well, but may change em anyways as i have new ones, and there cheap anyways,



the one main issue i do have is the cover plate screws seem to be made of cheese and the heads are turning out of em straight away,
gonna have to heat the scews up a tad and see if that helps, both plates need to come off anyways to be re sealed with threebond,
so hopefully i can get all four screws out of there (y),

 
Least you've found air leaks Spents, means you can resolve them and hopefully resolve your issues without playing shotput with the longblock.
Also seems to be a relatively simple fix, hopefully it goes well.

As for the seals and bearings, think that's gonna be personal choice for changing them, if you have even the slightest doubt about them swap them out.
Good luck fella
 
DougStar said:
I have been using the 1211 sealer on all my rebuilds works a treat👍🏻
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almost the same as what i'm using then doug, i'm using 1215 (y),
and yeh i really should clean the crud off the tube so the cap screws on proper :LOL:,
i do keep it in a plastic bag as well though to stop it going off,


KevTrem said:
Least you've found air leaks Spents, means you can resolve them and hopefully resolve your issues without playing shotput with the longblock.
Also seems to be a relatively simple fix, hopefully it goes well.

As for the seals and bearings, think that's gonna be personal choice for changing them, if you have even the slightest doubt about them swap them out.
Good luck fella
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yeh should be easy enough fix kev (y), lmao, i wont be playing shotput any time soon kev, am having a slight shoulder issue at moment, i could get mrs spents to shotput it over the fence if it does get that bad though :ROFLMAO::ROFLMAO:,

yeh seals will get done for sure kev, bearings i'll have a closer look at em and replace if theres any sign of play or roughness etc (y),
 
took forever to get the port covers off :ROFLMAO:,
all four screws the heads turned out of em 🤦‍♂️,
so torx bit tapped in and a tad of heat and three of em came out,
the fourth needed the screws hez hole drilling a tad deeper but 0.3mm smaller than the torx bit, then torx bit could be tapped a little deeper and that worked out fine(y),
turns out i had used threebond to seal the port covers and not rtv,
musta done a crappy sealing job, so my bad :ROFLMAO:,
new better graded screws found and old ones straight in the bin so i don't mix em up,



then screwed the case halves together, went out in the dark with a light and could not find any sort of gap anywhere,, around the surfaces,
again, musta been a crappy seal job again by myself, reed block slides in nice and doesn't cause any gaps to open up etc,
gonna do a better sealing job this time :LOL:(y),
also removed crank seals and bearings, one bearing does have a slight rough feel to it, so fresh bearings can go in,
and the seals felt really hard compared to new ones, so new seals will go in as well,

 
reight then, got the 34 reed back to a long block again (y),
new seals, new bearings, thought screw it and fitted a new ring as well, all sealed up, triple checked etc etc,
if this engine don't run right this time its getting retired and i'll use the +2mm crank and build a 34 non reed i think :D,
just thought i'd point out that i'm the third owner of this engine and previous two owners both had running issues with it,
well first owner blew it up on meth, second owner blew it up on petrol/gas :LOL:
cant find anything wrong with it though, if there is a fault its with the cases cos everything else has been replaced,
have now also named the engine brick top cos its a horrible cu** :ROFLMAO::ROFLMAO:,
letting the threebond go off overnight then need to make a fresh reed block gasket and can then get it fully back together (y),

 
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