Mike Daborn

[Mike Daborn]

Hi,

Manifold repaired and all air leaks stopped. New filter fitted. Bike starts, idles, revs and goes as it should and MOT passed. Success!

Thank you for all the help.

[Mike Daborn]

I ordered a fuel tap for a GT125 and received it within ten days and nothing extra to pay. However what they sent was incorrect and although they said they will refund me if I return it the postage cost is the same as the item value. The only confirm refund of the item, nothing else so not worth bothering. They tell me the tap I ordered is out of stick yet they still show it as available. No idea what tap they have sent me.

[Mike Daborn]

Hello,

I now know what the issue is: the rear manifold has delaminated from the metal base plate and was moving when the engine was revved. I have separated it from the plate and hope that I can rejoin them.

I also need to place an order for the screws that hold the needle jet base in place as one sheared in half tonight.

[Mike Daborn]

Hi,
One further clean of the carbs and the bike runs fine without the airbox fitted. Revs well, idles well and response is snappy. I fitted the upgraded K&N filter plus jets and all good without the airbox fitted so filter not being used at this point. Fitted airbox and it will idle and rev but not so well. Will sometimes die after hard revving. Sometimes the revs take a few  seconds to drop.  All the connections between manifolds and carbs and carbs to airbox are all tight. If I remove the air filter it seems  to idle better. After a few revs it starts to increase revs on its own.

I did notice that the rear cylinder took much longer to warm up than the front one.

I don’t know where to go from here. Totally lost and a bit fed up.

[Mike Daborn]

Hi,

Fuel pump checked and works fine.

Last part will be to fit the K&N filter and bigger jets.

[Mike Daborn]

Hi,

I have stripped and clean the carbs again. I installed the pilot air screws and opted for 2 1/2 and 2 3/4 turns front to rear. The pump appears to work but when I attach the pump to the carbs the bike dies. If I go direct from a mobile fuel unit to the carbs the bike idles and revs  like a dream without the airbox fitted or the carbs clamped to the manifolds. I checked the plugs and both are very sooty so I guess I need to later the pilot screws maybe a quarter to half a turn each?

I don’t understand why the pump appears to work but the engine dies when it is connected.

[Mike Daborn]

Hi Marcel,

i will test the fuel pump tomorrow.

i removed the pilot air screw and it was set at  3 turns front and 3 1/4 at the back. Should these be 2 1/4 – 2 1/2 front and 2 3/4 back?

i have attached a photo of the new pilot jet  next to the old one. The holes in the new one are much smaller. Will this be a problem? I also attached a photo of the new and the old needles and the new ones are much fatter do is it the fact that the old ones are worn?

[Mike Daborn]

Further update. Both plugs sooty. Carb bowls contain fuel. Bike won’t start. I have started to strip the carb again and this time will remove the mixture screw. I noticed that the rubber manifolds were wet with fuel.

i want to remove and dismantle the fuel pump but the fixings are difficult to access so no luck so far.

[Mike Daborn]

Hi,

i removed as much as possible from the carbs except the pilot screws. Everything was cleaned. I fitted the carb rebuild kit, pilot jets and needle jets and float needles. Floats set at 7mm.  I fitted the carbs to the airbox to get a tight seal using the new stainless clamps and then fitted the carbs to the manifold rubbers, again with new clamps plus o rings on the manifolds. Everything was airtight as far as I could tell. Actually the best fit I have achieved to date. I fitted the Laser Iridium Plugs, new coils and leads.

The bike would turn over but wouldn’t start. There were healthy sparks to both plugs but no fuel. I checked the obvious and then bypassed the fuel pump using a mobile fuel line and the bike started. It idles but dies when revved. I suspect there may be an issue with the pump but clearly I have not solved the carb issues.

I don’t know where to go from here.

 

[Mike Daborn]

Hi Marcel,

Thank you for the speedy reply. I have also fitted new needle valves. I will let you know how the bike runs asap

[Mike Daborn]

Hi,

I finally found time to fit the parts ordered as advised above.  The final check is float height. Am I correct that this should be 7mm with the floats resting on the needles as in the attached photo?

i have followed the advice given so far and will do the same for the final assembly. I will let you know the result.

Many thanks

Mike

 

[Mike Daborn]

Thank you Marcel.

I have ordered parts according to your first recommendations below and will see how this goes before going further

[Mike Daborn]

Hi Marcel,

Thank you for your comprehensive reply. I have posted a photo of the fuel tap that I need as requested.

From your suggestions I have a plan and a list of things that I need to check and to buy. I will start with the more essential fuel related parts and then review. I have some questions:

1.The manual says not to touch the mixture CO screw so does this definitely have to be left alone?

2. How do you remove the pilot jet?

3.How many turns is recommended for the pilot screw?

Thank you again and I now feel that I have a more methodical approach following your advice

 

 

[Mike Daborn]

[Mike Daborn]

Thank you

[Mike Daborn]

Hi,

Thank you for the reply. The fuel pipes from the tank go to the fuel tap and then to the pump and carb. So my question is related to which of the two pipes goes to the reserve connection on the fuel tap?.

i have attached a photo.

Many thanks

Mike

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