TOPIC:

Hello
Just installed a new out the box set of rs 34 with 17.5 pilot and 115 main as it comes just replacing the 29 smoothbore I had on it since I wanted better performance,
the 29 are running good and 4 cylinders fire.
with the smoothbores 3 cylinders are exempt #4, I have checked the coils and swap spark plugs from the cylinders I even put a new spark plug and do not fire. came out clean.
the engine is new not even 100 miles on it and 4 cylinders have 135 psi compression.
the strange thing is that I poured gasoline in the filter and still did not fire.
could someone give me suggestions to where to look.I mean the reason I bought new carbs is that I don't like fiddling with carbs to much but I think there might be an issue with them
thanks

Doesn't sound like a carb issue. Maybe you upset some of the coil wiring during the install.

So No 4 is not firing even after swopping No1 plug lead/ cap with No 4 and No1 fires with either lead cap? I think thats what your post says? So if no 1 fires with either and no4 doesnt with either lead it must be a fuel issue. Something sounds blocked in no 4 carb then. Even new there is a possibility, remote admittedly, they left the carb factory like that. Could be a bit of dirt, could be a bit of machine gunk, could be a manufacturing error. Who knows, all you can do is take number 4 carb apart and see if you can find whatever it is.
The alternative is to take them back and swop for a different set.

Can you see if you have a spark coming out of #4 ?

If you do then it probably has to do with the #1 carb. Can be a blocked passage like Warren said.

Are you sure you see a real visible spark on #1 and 4??? The engine has to be run/start on #1 cyl (all cyl) with break cleaner sprayed into the air box. If not something blocked the fuel/air flow in # 4 carb. Do you have fuel in the bowl of carb #4 ???

I think its no 4 thats not firing guys?

I took another carb from my brothers bike and 4 cylinders fired straight away and fitted back my 29 and all cylinders fired so def it was the carb, must have been some manufacture defect.
by the time I did the post I have checked spark really well. I will stick with my 29 for now. thanks for your input but to be honest did not have the patience to deal with much of the issue I did open and did not see anything visible.
thanks,