Jetting the carb 1991 mk2

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Northy272
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Jetting the carb 1991 mk2

Post by Northy272 » 06 May 2020, 22:19

Evening all,

New to the forum. Have had my mk2 for a couple of years now.

I'm getting spluttery/jumpy running at low revs, soon as throttle is half-wide open it jolts very slightly and absolutely takes off, so my thinking is it may need a richer pilot jet??

Recently had new crank bearing and seals, carb clean along with full inspection.

Bike has a full DEP exhaust system and racing reeds.

This issue makes the bike quite hard to ride on the road unless I'm flat out and breaking speed limits with ease lol.

Any help would be greatly appreciated.

xstian81
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Re: Jetting the carb 1991 mk2

Post by xstian81 » 08 May 2020, 07:28

I'm running a FMF pipe with a Dep can, on my mk3. I can't remember if I changed the jetting at all, if I did I would have thought I would have just changed the main jet.

Your problem does sound like it could be the pilot jet. It might just be partially blocked. Sometimes when cleaning carbs you can dislodge some muck which doesn't get flushed out and when you put fuel through it, it blocks another jet. I would check that first. Also worth checking the needle clip height and making a note of what size jets are fitted in there. Someone may have already be in there swapping stuff.

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Northy272
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Re: Jetting the carb 1991 mk2

Post by Northy272 » 08 May 2020, 19:30

Thanks for your reply,

I've not had a look at the carb as yet, but i did try a different spark plug, it had a B9EVG and i swapped it out for the standard BR8ES and it seems to be running alot better. I took the plug out after a quick blast to see how its running and it came out a perfect colour. Checked the oil pump and that's set perfectly too.

I will defo be taking the jets out and give them another clean and take note of what they are. Am i right in thinking you can access the jets through the bottom of the bowl without removing it?

Cheers

xstian81
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Re: Jetting the carb 1991 mk2

Post by xstian81 » 09 May 2020, 06:49

I always just take mine out. Its not a big job.


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