Carb main jet settings CB750 K1

[750rideruk]

1972 CB750 K1 with HM241 pipes. Currently running with 110 mains and 40 pilots but it is bogging down on 1/2 to 3/4 throttle.
Never did this before the top end rebuild I have recently completed.
When I restored the bike back in 2003 I had to change jets to 110 to make it run OK so why the change now?
Any comments from the experts out there?

[750rideruk]

Typo, The pipes are HM341s

[hairygit]

The cycleserve manual says 120 mains for the K1, 110s are possibly the cause if you've fitted a new air filter, running weak will make it feel like it's bogging down. Do a plug chop and check the colour.

[steff750]

    the k1's also had hm 300 exhausts the 120 jets are suited better for them.so 110 jets would be ok on  hm 341 exhausts (off the top of my head),i dont think that is your problem ? we need a bit more info. and yes check colour of the plugs to see where you are at now
you want to check the carb rubbers for air leaks dont discount anything like ignition timing  valve timing fuel supply you need to go over what you have done already its all part of the fun init
BTW just came back from a friends garage hes had the carbs off his cbx 1000 ten times and you have to drop the engine too get at them lol he has the patience of a saint 

[Green1]

My K1 came with a set of HM300's and 120 mains when I swapped over to HM341's I changed over to 110 jets and it runs perfect.
I would say most likely an air leak.
 
Mick