Mikuni Carb Strip

[Bob the B]

Hi
I'm trying to get to the bottom of a poor running problem with my 2MA. I've had the carbs apart a few times but want to go through them thoroughly one more time. Up to now I haven't split the carb body so thought I would do this for completeness.

So, there are six screws fixing the plate on the side of the carb body, one of which has a strange head on it, it looks a bit like a torx head but has a small boss right in the centre which prevents you from putting a socket in there. Can anyone help me locate the correct tool to remove this screw?

Cheers
Bob

[chubba]

Look at security bits ( google it or security Torx ) you can get them all over cheaply , if that's what your after

[Bob the B]

Just ordered a set of security bits on eBay. thanks a lot.

[f3]

the security bolt is shorter than the other bolts make sure it goes back in the same place or you can damage the carb body with the longer bolt

[Bob the B]

Thanks for the tip 

[saltysealion]

I was under the impression that it's best to leave those as they are. I think there are discussions around here somewhere on that.......

You can dunk the whole unit in a ultrasonic cleaner without removing those security bits, at least, thats what I did

[yanw]

I think you can do it if you replace the gasket but the gasket is not an available part so you have to make one yourself IIRC.

[teezer250]

I think you can do it if you replace the gasket but the gasket is not an available part so you have to make one yourself IIRC.

You are correct that the gasket is not an available part.
I'll be putting my carbs in my ultrasonic cleaner soon as whole units with the jets,etc. removed.

[tzr-v4]

Reproduction TM28ss gasket is available...
MACCAS https://www.gasketguru.co.uk/product/yamaha-tzr-250-2ma-1kt-carb-body-gasket-premium-quality-pair/

[Kev]

Bob, I work a lot on TM28ss carburettors and have found most running problems are caused by blocked pilot jets and poor fuel supply when the bike is on the cold start cycle. You will need a very fine wire probe to ease down the brass tube that faces downwards when the float bowl is off. Regards

[Bob the B]

Thanks for all the input. I did take the front off the carb and it all looked fine I was prepared to make up another gasket if needed but the existing ones are in remarkably good condition.

Kev - I wondered if the brass tube could be removed but it looks a bit delicate! I did get a plastic brush bristle up through the bottom and through the cross holes.

I have another carb question. The clip position on the needle should be 2/5 according to the manual. Is that counting from the top or the bottom?

Cheers Bob

[Kev]

Bob, holding the needle in your hand sharp end downwards clip goes in 2nd last slot, don’t leave out any plastic washers if fitted. No the brass tube in the carb body that feeds fuel in on the cold start cycle cannot be removed. Take your time finding the right size wire, sometimes those plastic/wire ties you get when you buy an electronic item can fit when the plastic is stripped off.

[Bob the B]

Kev - Maybe I'm being a bit thick but do you mean second from the top?

Bob

[Kev]

No Bob other way 2nd slot up from the sharp end, incidentally if you have the carb apart still and you are a bit of a newbie you might want to clean the jets and the emulsion tube to save problems later, get some cheap lemon juice and 50/50 mix of juice and water in an old pan on the hob, drop the bits in and boil them up for a few mins. Also check the 0 ring on the float needle holder if there is no resistance when you push the unit back in the carb body it will cause flooding. More you do now the less grief later. Regards.

[Bob the B]

Ah! in that case the needles in my carbs are in the wrong position, they are second from the top at the mo.

What's the emulsion tube? the plastic extension on the pilot jet?

Bob