Air Leak?

[wax]

I went for a ride on my rapido 250 yesterday. Harry Barlow set up the carb for me on Thursday, and all seemed fine. After a few miles the tick-over started to rise. I noticed that the revs took a few seconds to die down between gears too. I adjusted the tick over to a more acceptable level, but that's not really addressing the issue?

Does this sound like an air leak? It's a reed valve LTH manifold with one of those fancy rubbers that bolt on to the manifold.

I remember a few years back, when I took my scooter to a scooter shop with another suspected air leak, the mechanic sprayed some kind of aerosol around the manifold and confirmed that it was indeed an air leak that way. I have no idea what spray it wAs or what the symptoms were when he sprayed it.

any advice would be helpful......

[Darrell Taylor]

i found in leakdown tests the lth reed inlet rubber leaks everytime,it has a raised rubber o ring cast into it and the tightening of the 2 bolts pulls down either side and lifts the middle causing a leak
i generally flatten off the raised sealing rubber and seal down the manifold with loctite 5910 and leave it to cure overnight
the 25mm version inlet rubber is too small and fails to seal at all

[wax]

I have just stripped it down and found that ridge in the rubber. I smoothed it off with a fine file then siliconed it on with loctite. I hope this cures the problem. I will give it 24 hours to set before trying it again.....

Thanks Darrell.

[coaster]

i found in leakdown tests the lth reed inlet rubber leaks everytime,it has a raised rubber o ring cast into it and the tightening of the 2 bolts pulls down either side and lifts the middle causing a leak
i generally flatten off the raised sealing rubber and seal down the manifold with loctite 5910 and leave it to cure overnight
the 25mm version inlet rubber is too small and fails to seal at all

Thanks for that Darrell, I have one of those on my TS1, I'll give it the treatment.....and I must get round to buying one of your kits soon

[boris]

My small block ts1 ported kit never run properly.After having an lht reed valve fitted. 400 mlies later a holed piston.

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[Darrell Taylor]

my referance was to the reed valve conversion kits and specifically the inlet rubber used ,the lth inlets for ts1 are generally fine but still need careful sealing between reed and inlet and rubber as do all ,the little 4th fixing is a major problem for sealing on the ts1 type inlets ,a leakdown test is a must!

[boris]

Yep the people who fitted my reed should have known better.
I ask them to to test it. Just before the piston holed they just changed float pin and played about with the mix screw then blamed it on the fuel.
Like I said it never run properly after the valve was fitted. And have you ever heared of the engine cutting out when the bike is tilted to the right.

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