Bike not pulling away as it should

[cbrcol]

Hi I have a Honda Cbr600f3. 9k on the clock N reg.

I took the bike out for a ride yesterday and trying to pull away at junctions etc felt like the bike was miss firing, once going it was fine no problems at all, until I slow down for a turn or junction then the revs seem to hang around 4k. When I start the bike it will idle fine.

 

The bike is standard with no mods.

Things I have done:

Cleaned carbs - taken off bike fishing wire through jet holes, soaked in cleaner, compressed air through to clean and dry.

Cleaned air filter.

New fuel

New petcock and filter

New fuel filter and pipes

Fuel pump seems OK.

Changed plugs

Trimmed back coil end of plug leads - the other end is sealed. Resistance tested ok.

Although when checking spark its not a big fat blue spark. I have checked wiring, all looks OK.

Sprayed WD40 around inlet boot and vac hoses etc. No change in revs.

 

Where would you start? Any advice will be appreciated so that I can get back out on the bike.

 

[Ian Frog]

Just a thought  given that everything you mention sounds sensible I would start looking for air leakage as what you describe could be a leaning off of the mixture and it`s an easy check.

Just sit the bike idling and spray carb cleaner around the joins of the fuel supply system and listen for changes.

Funny it`s the second time I have mentioned this in ages.

Good luck

Cheers

Ian

[Mississippi Bullfrog]

How old are the HT leads? They don't last forever. 

[cbrcol]

3 hours ago, Ian Frog said:

Just a thought  given that everything you mention sounds sensible I would start looking for air leakage as what you describe could be a leaning off of the mixture and it`s an easy check.

Just sit the bike idling and spray carb cleaner around the joins of the fuel supply system and listen for changes.

Funny it`s the second time I have mentioned this in ages.

Good luck

Cheers

Ian

Thank Ian, I am going to have another go in the morning.

[cbrcol]

1 hour ago, Mississippi Bullfrog said:

How old are the HT leads? They don't last forever. 

They are originals, I'll spray around the air and vac pipes tomorrow, if that doesn't cure it, I will get an aftermarket lead and cap set to try to see if it helps. 

[Tinkicker]

Are you sure all the linkage springs between the carbs are still in place?

 

Also have you had the carbs balanced since they were apart?

 

The little rubber slip on boots/ screws on the intake stubs used to block off the balancing ports, are they still in place?

 

Does it spit through the exhaust when opening the throttle?

 

 

 

 

Edited June 23, 2024 by Tinkicker

[Hairsy]

7 hours ago, Tinkicker said:

Also have you had the carbs balanced since they were apart?

 

 

 

 

This.

From your symptoms, I'd say pilot jets and balancing. If you're certain that you've got completely clean pilot jets then try a balance. If you're not 100% certain then double check your pilot jet cleaning or replace them with new OEM ones - and then do a balance.

I've had exactly those symptoms on a CBR600F3 and this was the solution.

Edited June 23, 2024 by Hairsy

[Stu]

And don't discount float height too as this can also have an affect