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Discussion Starter · #1 ·
Hi Guys,

When I ride, my 450cmx tends to hold back sometimes, like it doesn't get enough fuel. My carbs are recently been ultrasound cleaned and all rubber parts exchanged ( not diagrams for gas needles because they where good according mechanic ) allot of time it runs smooth and accelerate easy to 80 mph but also allot of times it runs rough and pops in the exhaust with fire coming out of the exhaust when full throttle doing 65 mph. Whilst idling I spayed 'break cleaner' on the outside of carb inlet boots, no increase of rpm's.
Exhaust are tight installed, no leaks. Airfilter and inlet are fine. Riding with stock filter open exhaust 130 jet. Tried without filter but no increase. Choke isn't enabled checked that also. What can it be..?!
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1985, 86 CMX250C, 81 CM200T, 74 CL360, Invisible to cages, treat them accordingly. Avoids Road RAGE!
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If it were me, I'd start thinking about the spark coils and the wires. After all the bike is at least 30 years old, and so are the coils.
I say this because I had a car that did the exact same thing.
 

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Discussion Starter · #3 ·
If it were me, I'd start thinking about the spark coils and the wires. After all the bike is at least 30 years old, and so are the coils.
I say this because I had a car that did the exact same thing.
I think you might be right in that, either this or the cdi is where I narrow it down to. Wires look on the outside ok but that's no guarantee. Gonna run a test with the cdi and or coils and wires (step by step) from te 450 of my dad and see what it can be.
 

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Although they come w/112's, I believe 130 jet is (way) too small. You need to stage up like crazy.

I think bigger jets will solve your problen. While it is cheap to invest in new wires and plugs (I suggest making your own-Revival Cycles in Austin TX sells kits and has all the colors!), I do not thinkmthat will solve your lack of top end and occaisional sputtering problem. It will help though. Also, I always recommend a new CDI box. All are +30 years old and since new are available, makes sense (to me). All my 450's get a new one, good investment.

Try some 138-40 mains and maybe 40 slows. I went hrough a process of pulling carb-new jets-install carb-test ride-repeat until the bike ran like it should. I wrote it down somewhere, but recall I have 142 mains and 40 slows in Gin-Ba and she only has fishtails (maunted to OEM double walled pipe) with an OEM air intake. Idles perfectly, no misfire, good throttle response, and top end.

Try some bigger jets, I think you will like!
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