Gt380 high idle after refurb

Post your problems / information on the smaller GT Models here
User avatar
Fula28
Posts: 27
Joined: Mon Oct 22, 2018 8:35 am
Location: Nwi

Re: Gt380 high idle after refurb

Postby Fula28 » Sun Feb 10, 2019 8:10 pm

Thanks Barney, will get reading those in a bit! So using today's info about kickstart resetting I have not successfully sorted that! I thank you guys for that pearl of info.So with no1 cylinder at TDC and with words to ref set about checking timing set up, The Boyer mag pickup was 180' out and I've learned How to make TDC stop out if an old spark plug too.So still need to set up back plate with timing gun.
Carb rubbers are soaking in the winter green oil/thinners mix! It's cheap option of softning rubbers I guess, My clamps are good but I'm not 100% on them .Will replace those for sure.
Once rubbers are nice playable I will reassemble and see, what's what.
Float heights are all Cock on same , filled off bike drained bowls and there pretty bloody good.
Attachments
image.jpeg
image.jpeg

Kettletimes3
Posts: 1478
Joined: Thu May 03, 2012 12:58 am
Location: Sunny Wales

Re: Gt380 high idle after refurb

Postby Kettletimes3 » Sun Feb 10, 2019 9:20 pm

I think those carb kits you have used are going to be your problem.

barney01
Posts: 2405
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Gt380 high idle after refurb

Postby barney01 » Mon Feb 11, 2019 7:01 am

Me too :? I always always go genuine Mikuni. Have read so many posts over the years about faulty aftermarket jets. It's a critical part to whether the bike runs well or crap.
NO SMOKE .......NO POKE

User avatar
Fula28
Posts: 27
Joined: Mon Oct 22, 2018 8:35 am
Location: Nwi

Re: Gt380 high idle after refurb

Postby Fula28 » Mon Feb 11, 2019 9:56 am

Ok guys fair enough! Are we saying whole kit needles/ piolet /main jet/float needle valve.? This sounds like more cashola to me! B****x indeed , Tourmax kits? Japanese or genuine mikuni all the way ,? Just asking guys.
Guess I should have gone Oem mikuni from start really.

User avatar
Alan H
Posts: 9229
Joined: Fri Aug 05, 2011 6:38 am
Location: Wombwell, Republic of South Yorkshire

Re: Gt380 high idle after refurb

Postby Alan H » Mon Feb 11, 2019 10:01 am

Fula28 wrote:
Guess I should have gone Oem mikuni from start really.


Yup.
Proof that four strokes are over complicated

barney01
Posts: 2405
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Gt380 high idle after refurb

Postby barney01 » Mon Feb 11, 2019 11:50 am

I would perhaps try replacing bit by bit until the problem you have is solved. First I would get the Mikuni pilot jets as you have a low engine speed issue. See how that works out.
NO SMOKE .......NO POKE

User avatar
Fula28
Posts: 27
Joined: Mon Oct 22, 2018 8:35 am
Location: Nwi

Re: Gt380 high idle after refurb

Postby Fula28 » Mon Feb 11, 2019 12:31 pm

So barney ! I've ordered new mikuni #25 pilots and very carefully gone through carbs and the passageways with carb cleaner and tiny pipe cleaner and also flushed with isopropyl they had been ultrasonically cleaned at least 3 times when I stripped them ! It's super super clean and clear ! No issues with flow or blockages anywhere , emulsion tubes are not ovaled or badly worn , well should be perfect 651 miles on it, plus they don't come into play until 1/4" throttle anyways.
:roll:
See what happens with this small change!

teazer
Posts: 563
Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: Gt380 high idle after refurb

Postby teazer » Mon Feb 11, 2019 2:59 pm

High idle is usually caused by one of two things. First is if the throttles are actually open slightly because of the idle screw or cables. Sometimes a cable end is not seated deeply because it's too thick or an aftermarket cable is too short etc. That's easy to check if the airbox is removed.

Second is an air leak somewhere. I would do a leakdown test to be sure. It is possible that a seal was damaged - unlikely but possible. The best way is with a simple leakdown tester one cylinder at a time. Get a squirt bottle with soapy water to spray to find out where it's leaking. Had an RD350 a few weeks ago that bubbled like mad around the reed cages even though one side had a gasket and the other side was plastered in gasket goo and the owner refused to believe it until I showed him the evidence.

In your case I would suspect the intake rubbers.

If you are lucky, it will be those pilot jets, but if not, you might want to think about a leakdown test.

barney01
Posts: 2405
Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Gt380 high idle after refurb

Postby barney01 » Mon Feb 11, 2019 8:34 pm

NO SMOKE .......NO POKE

User avatar
Fula28
Posts: 27
Joined: Mon Oct 22, 2018 8:35 am
Location: Nwi

Re: Gt380 high idle after refurb

Postby Fula28 » Tue Feb 12, 2019 7:22 pm

Thanks for the info guys, just waiting on mikuni pilots at present? I have band aided the inlet rubbers By xylene and winter green oil, There so supple and soft now! Amazed it worked anyways this is only temp fix! As I feel they need replacing.1976 there old as hills, in rubber terms. Keep you posted when I get jets tomorrow! :roll: :tw


Return to “GT 250 380 550 GT500 SECTION”

Who is online

Users browsing this forum: No registered users and 2 guests