Reed Block Question

[usmcdoc]

Reed Block Question...when holding block up to a light...should I be able to see light through tiny gaps at the tips of the reads? Having a fuel flow prob and I think the block is bad. Carb is clean...low tension fuel switch(fuel pump...petcock) works when you suck on vacuum line.In order to create a good vacuum..it seems the reed block should seal tight and have no slight gaps. Anybody got a pic of what it should look like held up to a light?..

[vvtr]

they should seal pretty good but remember that when the piston is on it's way down it creates a positive pressure and pushes against the reed, forcing it shut.
if you have any doubts, change the petals as they dont cost that much.

[usmcdoc]

vvtr....petals must be shot....I know they open during vacuum......but these I can see light through when holding the block in my hand. Tried to bend the petals to make them flush.....just won't work...so must be the reed block itself is worn as well....

[vvtr]

yeh i wonder if its warped by overtightening it to cure an airleak?

had one a while back and it would just about idle, but any slight whiff of throttle it would bog & die.
thinking it was the crankcase seals, i took the engine out & filled the crankcase with fuel...
the only place it leaked was the reeds.
so if this is the symptoms you're seeing it could well be that you've found the fault.

i reckon if the block has been overtightened, or unevenly tightened, then heated up, it could be wrecked.
only cheap though - see it as an opportunity for an upgrade!

[moore716]

try flipping the reeds over.

[usmcdoc]

Clementine's..did that....just made the gaps larger..even tried to bend them...then flatten....same thing. So the block they ride on must be worn and have low spots?...If I shoot staring fluid in the carb...it will barley 'pop' on occasion... Brand new top end with 8 miles on it...so maybe compression is low as well? Ran VERY well...sister went down road...gently about 30 mph....it died..won't start. Placing hand over carb and cranking..I get no suction from the intake. Suck on fuel valve hose...and it works fine...so that is not the prob.

[jmkjr72]

i would get a new reedblock with cf reeds

stainless steel are fine on non moded engines but if you run more the 8grand they will start to chip and maybe even chunk and destroy your top end

i dont think i have a spare reed block laying around but ill look this weekend

and if you want to stay ss try just getting an oem yamaha one with reeds they are only like 20 bucks + shipping from boats.net or cheapcycleparts.com just get the zuma one the vino one is diffrent

[vvtr]

Jan 6, 2012 8:11:25 GMT -5 usmcdoc said:

Placing hand over carb and cranking..I get no suction from the intake. .

yup the reeds / block is borked.
can you feel it like pulsing in & out?

try this.... empty the fuel out of the carb with the drain screw under the bowl.

clamp the fuel pipe so no fuel can flow, or turn off the fuel tap.
or remove the vacuum pipe and plug the hole.

when you cant smell fuel (when it's evaporated away) get a lit cigarett or hippy joss stick and hold it near the carb intake (with air box off)
get someone to crank it over while you watch the smoke.

it should be drawn into the engine.
if the reeds are leaking, you will see the smoke being pushed in & out of the carb.
this is exactly what is happening with the fuel mix - and nothing is getting into the engine, its just being puffed in & out.

* be careful not to set fire to your engine lol!!! dont do this if you can still smell petrol!


the symptoms you describe - no suction at carb, also sounds like the crankcase seals could be shot.... or the crankcase itself has been badly assembled and has an air / vacuum leak.

replace the reeds & block first though if you suspect they are leaking.

[jmkjr72]

and if after new reeds and reed block it still wont run then its time for a leak down test

we know that by seeing light your reeds arent sealing right