Gt380 high idle after refurb

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Fula28
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Re: Gt380 high idle after refurb

Postby Fula28 » Sat Nov 10, 2018 8:27 pm

So used Japanese carb kits, Not keyster type! The pump arm has not been off for 26 years since new. And I'm the first to touch it since really !Its hard to state if middle pot is smoking to be fair they all smoke a lot . I've also fitted new Oem floats and rubber dust gaurds and bellows ,as though it had air leak.? I'm going to pull the motor this week and remove crank as I expect Seals are u/s somewhere if not a rust bearing too. Problem is its stood for so many years.
Oh Oil God knows it's green and came with the bike, maybe Rock mineral I'd say. Prob worth flushing and replacing to be fair as two stroke does separate after few years. Used to An little Rs250 which ran on A747 that would go lumpy after few years.
Thanks for the pointers Barney.

barney01
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Re: Gt380 high idle after refurb

Postby barney01 » Sat Nov 10, 2018 9:53 pm

The oil is possibly the cause of the smoke. I would not risk running that engine until you have emptied the oil tank and flushed the pipes. The oil if it is old mineral type did smoke more and could be contaminated. Modern semi synthetic or fully synthetic hardly smokes at all and burns much cleaner. You can check the crank seals without stripping the engine down by performing a leak down test. Another cruder method that may give you an idea is to take the carbs of and spin the motor placing the palm of your hand over the intake port to see how much suction there is, but the leak down test is the only accurate way to do it
NO SMOKE .......NO POKE

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Fula28
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Re: Gt380 high idle after refurb

Postby Fula28 » Thu Nov 15, 2018 9:51 pm

Thanks again barney , The oil tanks been drained and biggest ,Update motors stripped, and Crank Dropped of with James At BDK, for reseal there goose hard as nails and wobbly as feck So pretty sure there goosed , ready for new ethonol proof rubber and maybe odd bearing. Quite grubby in the cases.

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barney01
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Re: Gt380 high idle after refurb

Postby barney01 » Fri Nov 16, 2018 12:37 pm

Oh well sounds like it was a good job you stripped that motor! TBH if it has been sat for a long time it's a good thing to do as otherwise you are just waiting for the seals to go. Let us know when it's back together :D
NO SMOKE .......NO POKE

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Fula28
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Re: Gt380 high idle after refurb

Postby Fula28 » Sat Feb 09, 2019 8:15 pm

So update here, Rebuilt crank by BDK fitted and finally got it running today, much less smoke than before ! But have couple of issues kick start its acting weirdly kicks over but flops about? Anyways STILL have high idle problem and it won't drop without stalling. So I'm going to pull carbs tomorrow and try few things, I noticed in the book it says to start bike one cylinder running at a time and drop idle down to make 1100 rpm , but it won't start at all on one pot? Tryed all three no joy? But connect all plugs it fires up!??
Cannot get my head round it just yet. Have rebuilt carbs and ultrasonically cleaned them several times already . Is it just blocked piolet jet holes or simlar God knows , we will see tomorrow.
Oh can some one confirm needles 4DH7 /pilot 25/main/80 float height 12mm.
Thanks folks.

barney01
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Re: Gt380 high idle after refurb

Postby barney01 » Sat Feb 09, 2019 9:03 pm

http://www.ozebook.com/compendium/suzi/suzidata1.htm
Jet needle 4DH7-2
Pilot 22.5
Float height 24.25mm
Your high idle will most likely be air getting in. How old are your carb to cylinder intake rubbers? Are they still soft and not cracked? Are your clamps nice and tight?
When you say the kickstart flops about, do you mean it wont spring back upright? That will usually mean the return spring was not located in its groove before the cases were assembled. If you mean it floats about, did you remember to put the holding washer on the kickstart shaft before putting on the clutch cover
NO SMOKE .......NO POKE

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canaletto5
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Re: Gt380 high idle after refurb

Postby canaletto5 » Sat Feb 09, 2019 10:40 pm

Fula28 wrote:So update here, Rebuilt crank by BDK fitted and finally got it running today, much less smoke than before ! But have couple of issues kick start its acting weirdly kicks over but flops about? Anyways STILL have high idle problem and it won't drop without stalling. So I'm going to pull carbs tomorrow and try few things, I noticed in the book it says to start bike one cylinder running at a time and drop idle down to make 1100 rpm , but it won't start at all on one pot? Tryed all three no joy? But connect all plugs it fires up!??
Cannot get my head round it just yet. Have rebuilt carbs and ultrasonically cleaned them several times already . Is it just blocked piolet jet holes or simlar God knows , we will see tomorrow.
Oh can some one confirm needles 4DH7 /pilot 25/main/80 float height 12mm.
Thanks folks.
On the kickstart, sounds like you haven't pre-tensioned the kick start spring. Easy done. On the idle adjustment, you need to start on all three pots and run until warmed up before adjusting pot by pot/ Kev

barney01
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Re: Gt380 high idle after refurb

Postby barney01 » Sun Feb 10, 2019 7:20 am

Just had a thought which model or year 380 do you have?
NO SMOKE .......NO POKE

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Fula28
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Re: Gt380 high idle after refurb

Postby Fula28 » Sun Feb 10, 2019 8:45 am

It's 1976 A model with carbs that a linked like later 550 type, I believe ! Float height is 28.5 I've just found out too! :o

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Fula28
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Re: Gt380 high idle after refurb

Postby Fula28 » Sun Feb 10, 2019 8:47 am

Canaletto , can we pretension without opening cases? Again please tell me I can. Motor went together very quickly and I only had Clymer book (rubbish) . Anyways need to get it running better first . Never had so much hassle with idle circuits before .


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