yz 400d tope end

[hagon_84]

just curious to know whether i can put a barrel back on without using a base gasket and using loctite 510 gasket eliminator instead or do i need both, i seemed to have a airleak somewhere as it was revving up on idle so i decided to pull top down and re seal all again to make sure it 100%

[Montynut]

new gasket everytime.

No gasket can also increase compression and alter port timing if it should be a thick gasket say a 1mm gasket left out will have an affect on both.

[Iain Cameron]

check the inlet manifold they have a tendency to crack . Iain

[Montynut]

crank seals also

[Iain Cameron]

ignition side seal yes forgot that one Montynut they are another air leak source .

[hagon_84]

Thanks heaps for advise I thought it would make a compression difference gasket don't seem to be that thick compare to some, the inlet manifold has got some hair line cracks starting to appear so I thought I could sika it up till I can chase up a replacement one new as for crank seals bottom end was done up less than 5 hrs run time so the seals should be ok but can they be a reason for air leak and high idle ?

[Big Al]

They have a tendency to pull head and barrel studs. If it is the case you will find oil residue where it has leaked

[Iain Cameron]

Air leaks are your main problem with high idle to just flat out revs if the oil seal goes on the clutch side you will have heaps of blue smoke . manifolds are easy to get (speed and sport ) ignition  side oil seal can be replaced with out splitting cases  use a good gasket and torque down to specs

[Lozza]

just curious to know whether i can put a barrel back on without using a base gasket and using loctite 510 gasket eliminator instead or do i need both, i seemed to have a airleak somewhere as it was revving up on idle so i decided to pull top down and re seal all again to make sure it 100%

If the base of the cylinder and cases are nice and flat it will be fine, you can make gaskets out of corn flake boxes if your desparate. Have used greased on both sides manilla folders as well. A set of wad punches from Super Crap Auto and you will never buy a gasket again. A company called James Walker seld OEM quality gasket paper in large sheets, the shopp will sell off cuts of various thickness.

[hagon_84]

Got gaskets yesterday went to put it back together but dumbasses sent me a base gasket for a f-g model no d mod ones in stock anywhere up and down coast I tried was keen to hit track this weekend I got a roll of gasket paper pretty well spot on for thickness if I replicate the base gasket is there any reason y I can't make on does there need to be a specific pressure rating on the gasket paper for a base gasket?  If not ill be back in action tomoz 

AL.

[oldyzman]

Al,
you can certainly make your own base gasket. Use the same thickness as before if it squashes 0.2mm smaller than the one which came off it, it probably will not matter. Have you considered squish. this might be a good time to think about it. you should find a thread regarding squish on here. There are a few factors to consider but the bang for your buck makes it an easy way to find more horsepower... I am not a bike mech - so i do struggle with some things but I can assure you its not rocket science...
Brett