High revs

[watty51]

Hi,

Any ideas of what causes this problem I encountered on my CB350F today.

Sunny day took bike out, after about 3 miles of running fine the revs rose to 4000rpm and just stuck there. I pulled over to see if there was issues with cables/throttle etc but everything was working fine. Left bike turned off for about 10 mins. Started the engine and it went straight to 4000 revs again ?

The bike has been starting fine on the choke and had been idling fine when stationery. I must say this is the farthest the bike has travelled so not sure if it was getting to hot. The run was on country roads with no traffic.

Cheers

[kevski]

Air leaks between carbs and head head.

[Rob62]

What happened next? Did it settle down, could you ride it home? Is it ok now or still the same? We need more info. Sounds to me like something has happened to the throttle control cables, either  snagged or not located properly in the carb or the throttle tube.... were you negotiating a turn have you routed the cables correctly. Apologies if you've  already checked all of this...

[Trigger]

Hi,

Any ideas of what causes this problem I encountered on my CB350F today.

Sunny day took bike out, after about 3 miles of running fine the revs rose to 4000rpm and just stuck there. I pulled over to see if there was issues with cables/throttle etc but everything was working fine. Left bike turned off for about 10 mins. Started the engine and it went straight to 4000 revs again ?

The bike has been starting fine on the choke and had been idling fine when stationery. I must say this is the farthest the bike has travelled so not sure if it was getting to hot. The run was on country roads with no traffic.

Cheers

Make sure you have non resistance spark plugs fitted

[watty51]

Thanks for the replies.

The bike didnt settle down after the high revs but luckily i wasnt far from home so pushed the bike home. Having checked all the cables they are all new and correctly routed ( on both left and right lock) so don't think that's the problem.

I will check for leaks as suggested, but the post from Trigger is interesting.

I have non standard ignition coils form DS, and I am using NGK D8EA spark plugs. ( are these spark plugs non resistance/ compatible with the coils from DS  ?

[Trigger]

The plugs are non resistance but, have not got a clue about the Sliver coils . You will have to check for leaks .

[watty51]

What is the best way of checking for air leaks between carbs and head as suggested.
I've had a good look and everything still looks secure.

[hairygit]

Spray some carb cleaner or easy start or even wd40 around all the joints from carbs to engine while its running, if there's a leak, it will get sucked in and the revs will increase slightly for a moment. If it's only happening when hot, it could be the o rings in the alloy intake stacks where they bolt to the head, the leak being caused by hardened o rings not taking up the expansion of the metal.

Sent from my X6pro using Tapatalk

[watty51]

I sprayed some wd40 around all the carb joints as suggested, but the engine revs didnt increase.

The idle was around 1200 which is what it should be so could be the o rings when the engine is hot as suggested by Hairygit.
Will give that a go next weekend.

Does the fuel/air mixture setting have any reference to the idle ? also my Clymer Manual is saying 1.5 turns to 2 turns out, seems a lot ?

Decided to get the ultra reliable  1996 VFR750 out for a Sunday ride. Lovely