I wouldn't bag him just yet until you prove if there is in fact a leak there & it's not a carb issue or crank seal problem [ok should'nt be seals if replaced]. Do you think he's added the gasket to the original--ie--not removed original. i know its not right but doubt its leaking there. Maybe he just greases his gaskets [as i do] no sealer unless there's a obvious surface fault. So, if greased it might look oily now you've removed it--or was it dripping while running. I'd run it up & squirt something around there while running. If it's that bad you might feel it by running finger across under & around the 4 sides. Not had it ported & its porous there somewhere around the transfers sucking air?, i've seen that but from a faulty casting on a yamy 100. Or base gasket sucked in. Sorry probably all been covered.

the spark plug colour looks good. The original gasket is stuck on the reed cage with what looks like Permatex Grey and is never coming off...Looks real solid. The second gasket may have had oil to seal it but not grease. I'm going to seal the Nitrile gasket to between the old gasket and the CLY. with Yamaha bond 5 The surface here looks to be in great shape. I think this would do it or I will now shortly after my ride. Within the 5 or 10 minutes it takes to warm up the bike there is a gap creating at this joint. The wg40 at idles indicates some thing is not right here. there may be yet undicovered issues though but for now this is the easy most logical solution to try,


spring is 3 months away..

IF it were not for this website I would not have known to spray down the intake area wit WD 40 to determin where it was leaking from

While looking on ebay for reed cages I see a reference to a #1 or a #2 reed cage. What does a stock 1975 DT400B require?
I see no markings on the one I have. The engine is stock. Well bored one size over. I have a new rubber intake on the way and if I can pick up a used reed cage in really good shape, I would go with that

The part number I have is 363-13610-00-00

Not sure if it's relevant but i see on ebay "75 showing 6 petal reeds & "77 showing 8 petal reeds. Doubt they reed block would swap between models though as the 8 petal is probably wider but shallower as well [not as tall].

Na, what it will be [found it on a canadian seller] i guess he has two the same for sale & is just foe his own identification of which one sold. Nothing to worry about.

Great to know, thanks. Mine is in great shape but there is no way to separate it from the rubber intake and i have a new rubber intake on the way. Debating if I should pull the trigger on a NOS reed cage but $150 is steep. I think I will reinstall what I have with proper sealant and see if it fixes the issue. If not then a leak down test is in order