Interpol 2 uneven running

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jgn
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Location: Denmark

Interpol 2 uneven running

Post by jgn »

Hello, I have an Interpol 2, which presents a few problems for me. When picking up speed from slowing down for a turn or for a crossroad, it runs very uneven - I have to turn the throttle, increase rpm and slip the clutch in order to get it going.
When running at constant speed, 50-60 mph, it misfires occationally, but acceleration when at speed is no problem, and idling is also fine. Spark plugs are new.
I have renewed the O-rings for the large suction tubes and also the O-rings in the carburetors for the idling tubes. I have also checked the float levels this Winter but found them inside limits.
Can anyone help me on this matter?
Kind regards
Jorn Gaardsvig Nielsen
Denmark
johnbirchjar
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Re: Interpol 2 uneven running

Post by johnbirchjar »

Has this problem occurred since you fitted new plugs?and what electronic Ignition box is fitted to you bike?J.B.
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Interpol2471
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Re: Interpol 2 uneven running

Post by Interpol2471 »

Have you serviced the carbs especially replacing the choke o rings?
Various rubbish in various states of decay.....
Anthony Duffield
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Re: Interpol 2 uneven running

Post by Anthony Duffield »

Jorn,

Your comments, below seem to contradict each other:

When picking up speed from slowing down for a turn or for a crossroad, it runs very uneven - I have to turn the throttle, increase rpm and slip the clutch in order to get it going. I would have said that this was a fuelling issue, turning the throttle causes the pistons to rise increasing fuel.

When running at constant speed, 50-60 mph, it misfires occasionally, but acceleration when at speed is no problem, and idling is also fine. Spark plugs are new. But as acceleration when at speed is no problem it would suggest fuelling is OK??

However I would still suggest that the issue is fuelling, when slowing down for a crossroad the pistons will be at their lowest point, turning the throttle to increase the vacuum to lift the pistons to provide enough fuel and to quickly pick up speed seems to be the issues, unlike when at constant speed the pistons are someway up the suction chamber so able to provide enough fuel to increase speed.

I would inspect the movement of the pistons in the suction chamber, they need to be free to move, check the springs they should be the same length, make sure that the oil in the dash pots is the same as you use in the tank i.e. SAE 40 and while you have the carbs off give everything a good clean check the needles are not varnished and the jets are clear and blow everything through with carb cleaner and compressed air.

And as suggested by Interpol 2471, make sure that the choke (fuel enrichment valve) is clean and the O Rings are renewed.

Good luck
jgn
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Location: Denmark

Re: Interpol 2 uneven running

Post by jgn »

Thank you all for your replies and tips - I will take a look at the carburetors and the O-rings at the chokes - I have not renewed them.
With respect to the ignition unit, it is a Minimag unit.
Jorn
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Interpol2471
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Re: Interpol 2 uneven running

Post by Interpol2471 »

Minimags are normally pretty good and if not sure can be tested by mini magneto on the IOW
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Ian Mc
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Re: Interpol 2 uneven running

Post by Ian Mc »

Is the problem only when the engine is hot ? Sounds like it could be an air leak. Make sure the idle pipes are fully into the engine casing, a light tap with a blunt screwdriver will do. Try a smear of instant gasket around the pipe to see if it helps. If your bike has the crank case drain modification, disconnect it and block both ends to see if that helps, you will see a second pipe coming off the left hand spigot if fitted. It can allow air to leak into the inlet. Make sure the oil scavenge pipe is tight on the spigot.
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