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why inlets tulip

Taffy

Taffy

Joined Nov 2001
17K Posts | 774+
Ely, England
a careful look at an inlet valve from the side and up close to the seat face should show you that nice 45d angle. but the widest part of the diameter of a valve should be almost 1mm wide with a slight radius to it. but there it should be all the same - a thick edge which then rolls around into the front face of the valve on the combustion side.

with husabergs as well the valve is seated on the absolute edge of this widest part!

with me so far?

well the hammering effect of the seat is trying to get the valve to fold in and go into the inlet port because the metal at the leading edge DOESN'T HAVE THIS 1MM OF EXTRA METAL.

a husaberg valve goes down to a sharp '>' wedge. edge too thin = tuliping. what should happen is that a37mm balve should sit with the outside diameter of the cut seat in the head being 36.5mm + or - a little. that way a more thickset part of the valve would be in contact.

regards

Taffy
 
Its not just Husabergs Taff :D

All enduro bikes do it here in Oz- Its given Honda absolute fits as the CRFs have become bit of a laughing stock as they are the worst offenders.

Blame valve material/seat material designed to be run with leaded fuels (ie race fuels, AVGAS etc) being expected to run on unleaded.....just one of the many reasons :wink:
 
in my opinion i think that you're wrong!

we have excellent fuel here in the UK and they still occasionally have the problem with the hondas, not half as bad as the rest of the world. so i think it's a honda design fault. they burn out - ours don't. also is it honda exhaust valves? i thought it was - i may be mistaken...

this is however - a design fault i think. the cam flanks and those nasty conical valve spriongs are to blame.

but i do like a good debate and we're only three posts in!

regards

Taffy
 
Taffy said:
in my opinion i think that you're wrong!

we have excellent fuel here in the UK and they still occasionally have the problem with the hondas, not half as bad as the rest of the world. so i think it's a honda design fault. they burn out - ours don't. also is it honda exhaust valves? i thought it was - i may be mistaken...

this is however - a design fault i think. the cam flanks and those nasty conical valve spriongs are to blame.
but i do like a good debate and we're only three posts in!

regards

Taffy
Click to expand...



I agree Taff- its a multitude of factors.

I cant help but wonder how much a high lead content fuel could help minimise it though.
 
cryo science

has anyone heard of this company they claim to increase material strenght by up to 50% there on the web links on the uhe site has anybody tried this or is it a furfie might solve a lot of problems who knows
 
RE: cryo science

ok i can think ahead for you pitt. you're thinking "you don't add 1mm to the thickness of the valve at it's widest point because the face of the valve would be nearer the piston by that 1mm causing V to P problems. right?
so we need specially heat treated valves instead.

BTW, the additional valve material adds to the compression ratio but it also becomes a heavier valve and whatever might go with that?

regards

taffy
 
RE: cryo science

I dont know where you get the extra material from ,no where did i say extra material have you seen their site it looks interesting have a read if you like :)
 
valve problem

The valves have a problem from all the dirt that is sucked thru the carb. George at UPTITE Husqvarna has fixed the problem with carb filters. Till he found the fix Husqvarnas were having valve problems too. Any bike with a FCR is going to have the problem.
 
RE: valve problem

i was mocking you pitt! i know you didn't say it and i even say that you didn't say it you plonker!

my point was that all you need is extra material - job done! no need for special heat treatment.

Geoff, they've been tuliping valves for years dell ortos or keihins etc. interesting idea about the filters but i'm not convinced.

regards

Taffy
 

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