F1 Sport poor running

Posts: 28
Joined: Fri Mar 06, 2009 7:09 pm

F1 Sport poor running

Postby barney » Fri Jul 24, 2015 1:43 am

Hi all,

It's a long time since I posted to this group, but I hope everybody is well?

I tried to contact Richard on the old email I had for him, but it's a couple of years since I spoke to him and I'm guessing his email might have changed, so I thought I'd post here instead!

Here's a snippet of the email I sent him incase anybody knows how to reach Richard or even may have had a similar issue!!


You might remember that in 2008 I bought the F1 Sport that you rebuilt for Alan Sykes?

I had a few problems with it between 2008 and 2010 just getting it running right, but since 2010, it's been running like a dream!

I don't do huge milage on the bike, may 300-800miles a year, but it's been a delight!

Until now!!!

I put the bike away at the end of last summer with no problems at all. I fished it out in April for it's MOT. It started fine, but was running like a dog. I managed to get it to the MOT centre and back, but only just.

It starts fine, but runs really rough. It feels like it alternates between running on one and both rotors. I cleaned and changed the plugs, but to no avail!

Yesterday I took it for more of a run, thinking it might just be stale fuel in the tank/carbs.

The symptoms where really odd,

At first it was so rough it was almost unridable.

After a while it was usable, but very lumpy.

After about 50miles, it would run fine at low revs (500-3800rpm) and higher revs (over 4.5k) but inbetween was a nightmare.

The means you can cruise at motorway speeds no problem, but if you back off the throttle, and then reopen it, it almost feels like it will stall, if you wind the throttle past about 25-35% open it picks up again.

The other thing I noticed was if it's running hot, say around town with the temp gauge reading over 50%, it's pretty good, you don't get the flat spot or missfire.

If you stop, say to get fuel, it can be running nicely before you stop, but when you start again it's really bad.

I wondered if I could pick your brains as to where to start to look for the problem.

I'm thinking it must be fueling related?

If you remember back in 2008/9 I had huge problems with a similar missfire. You even loaned me a spare development ECU you had.

In the end it turned out to be the float jets and needles that had eroded due to unleaded fuel. This meant the bike was running massively rich and actually flooding.

I replaced the jets and needles with new ones from Burlin which are supposed to be unleaded resistant.

I'm suspicious that I might be having the same problem again.

However, before I pull the carbs apart, I wanted to check in with you to see if you had seen any similar issues?

I remember you said that the o-rings on the engine side of the carb inlet duct could wear, and also the o-ring in the coke mechanism of the carb Would this give a similar symptom?

If I'm going to pull the carbs off, is there anything I should check/renew?

Sorry to bug you, but I feel I should always come back to the oracle with problems on this bike!!!

Many thanks in advance and kindest regards,


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Richard Negus
Posts: 870
Joined: Mon Jun 18, 2007 5:11 pm
Location: Wilds of Lincolnshire

Re: F1 Sport poor running

Postby Richard Negus » Fri Jul 24, 2015 7:59 am

Hi Barney,
Here I am! We moved from Staffordshire to North Lincolnshire just over three years ago and changed email address then.
Your fault sounds very much like time for a carburettor clean / re-set :
.viton-tipped float needles, if you don't already have them
.replace the O-rings on the cold-start mechanisms
.clean the fuel needle, particularly, close to the piston (a light application of Scotchbrite)
.check the float height (0.5 mm)
.replace the dashpot oil (SAE 40)
There's not much else to go wrong, but it's worthwhile checking security of the inlet and idle pipe hoses.
You have a Norton digital ignition, I believe?
PM me if you'd like my current contact details.
Slower slower, no faster faster - the joys of old fogey mode to hooligan mode at the flick of a switch

Posts: 28
Joined: Fri Mar 06, 2009 7:09 pm

Re: F1 Sport poor running

Postby barney » Tue Sep 08, 2015 9:37 am

Sorry Richard and all, I forgot to post a reply to this!

Cleaning the carbs was all that was needed!! I didn't have the dreaded jelly in the float bowls, but a sort of limescale had formed on the needles. This was pretty easy to remove and the bike runs lovely again now.

Spot on again Richard!!

Thank you,


Posts: 28
Joined: Fri Mar 06, 2009 7:09 pm

Re: F1 Sport poor running

Postby barney » Sat Apr 15, 2017 1:06 pm

Hi Richard (and all),

I'm back with carb problems again!!

This time the fuel pump keeps running and over flooding the carbs!! It's obviously the float needles, but I thought I'd rebuild and clean the carbs completely.

Do you have the correct burlen part numbers for the kit, or for the various parts?

Also any tips or techniques for initial set up and tuning? I think I'll change jets and needles this time, as the clean up in 2015 will probably only have lasted so long!!!

As always, many thanks in advance,


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