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no tickover on 604 sm; carb prob
Topic Started: May 21 2012, 08:49 PM (2,372 Views)
richyrich
Commoner
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my 604 ccm splutters at full throttle. has standard can. last year i swopped its 185 main jet for standard 175, made it worse so refitted the 185.
last week tried a 190, still spluttered at full throttle but 8 mpg less!
so i put the 185 back in.
while i was messing i tried moving the jet needle clip in 2 new positions, up and down. messed with idle and fuel mix screws- no tickover!
put clip back to original position- one up from bottom. still not able to get tickover. mix screw and idle have no/little effect.
it was not very tunable with mix screw before, but least it ticked over.
will try from cold tomorrow, but poss thinking pilot jet is wrong size?
any ideas welcome?
i don't fancy messing with float cos i think its ok... :chin:
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watts
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Duke
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floats do seem an issue they were for me , i think. but also my exhaust valves werent seating snug. as a matter of coarse check the compresion. :dirtbike:
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too old
Earl
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watts
May 21 2012, 10:24 PM
floats do seem an issue they were for me , i think. but also my exhaust valves werent seating snug. as a matter of coarse check the compresion. :dirtbike:

This is a must do ,then float level , thats critical,and make sure throttle slide
moves freely in carb: body,
Thats 3 probs out the way then :sweat: :sweat: :sweat:
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richyrich
Commoner
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i will get mate to help me check valve clearances cos i think they never got set properly. then i'll check float level after that- 18mm?
thanks :chin:
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too old
Earl
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Mine is 17 mm
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Monty
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Charlie Big Banana's
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manual says 18mm. but every one sets them up at 17mm, this has cured many running probs.

As has been said, do a comp test, the rotax suffers badly from leaking exhaust valves, a simple compression test is all that is needed.

test dry first, make a note of result.

then squirt a few cc's of oil in the bore and repeat test. if compression the same. then valves leaking, if compression goes up, then rings are letting by, as the oil will temperary seal the rings.

The head should come off whilst in the frame, you may have to reomove starter motor and front mounting bolt so engine can tilt forward in frame to give a tad more clearance
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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richyrich
Commoner
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set valve clearances- 0.05mm- different to what you said on my other post, so just a bit confused over figures- rotax manual defo says 0.05
float is 17.14mm- that will do for me.
just gonna try a 45 pilot ( got a 40 in ), to see if any difference.
if that fails i will buy compression tester and take from there.
thanks :what:
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Cuz
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God
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which cam have you got fitted (number on end of shaft behind cam wheel). Don't set your valves to 0.05,its to tight and will cause problems.
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richyrich
Commoner
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Cuz
May 24 2012, 11:55 AM
which cam have you got fitted (number on end of shaft behind cam wheel). Don't set your valves to 0.05,its to tight and will cause problems.

i will have to check that...
will have to redo clearances as well.
just checking- is top dead centre where the flywheel has that notch about 2mm wide?- the rotax manual is bit diff to follow- it shows this with reference to this notch being 3 degrees off tdc, and it being to to with timing measurements!?

its the only mark i could find, so took it to be tdc? think sommat lost in translation?!

sorted tickover prob with the bigger 45 pilot. starts with just a slight bit of throttle- (should be none?), and ticksover nicely. mix screw and tickover still have little/no affect- would this indicate bigger still pilot? ( will prob leave as is though ) not tried to tune when warmed up yet...
had bike nearly 2 years and always had a few carb issues, so if half decent that's ok.
thanks :what:
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richyrich
Commoner
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tickover sorted with 45 pilot and valve clearance widened. thanks for advice regarding clearance.
not sure why rotax manual says 0.05mm (quote ' 0,05mm' ) :what:
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