Author Topic: Correct jets  (Read 731 times)

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Offline Davlea

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Correct jets
« on: June 10, 2021, 05:00:50 PM »
Just put a Yambits carb kit on my 250f and I just wanted to check they are best, the bike seems to be getting too much fuel
Kit contains 5L1 needle, 22.5 pilot jet, 115 main jet. Thanks

Offline paul n

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Re: Correct jets
« Reply #1 on: June 10, 2021, 05:08:58 PM »
Many people have had problems with aftermarket carb kits but here is the spec table link (second post down)

https://www.aircooledrdclub.com/smf/index.php?topic=43267.msg458097#msg458097


you can still get oem jets from http://www.motocarb.com/ or https://www.allensperformance.co.uk/
« Last Edit: June 10, 2021, 05:14:22 PM by paul n »
No garage is large enough!
Nottingham

Online Gr8uncleal

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Re: Correct jets
« Reply #2 on: June 10, 2021, 05:38:12 PM »
Many people have had problems with aftermarket carb kits but here is the spec table link (second post down)

https://www.aircooledrdclub.com/smf/index.php?topic=43267.msg458097#msg458097


you can still get oem jets from http://www.motocarb.com/ or https://www.allensperformance.co.uk/


+1

Ditch the aftermarket brassware and order original Mikuni, either from a dealer or a retailer such as the one that Paul provided a link to.
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Offline tony2stroke

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Re: Correct jets
« Reply #3 on: June 10, 2021, 05:53:39 PM »
+2

Offline Barnett

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Re: Correct jets
« Reply #4 on: June 10, 2021, 06:33:55 PM »
+3!

Offline Davlea

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Re: Correct jets
« Reply #5 on: June 11, 2021, 04:51:07 PM »
Could someone please tell me the symptoms for leaking Crankcase seals, could it be the cause of the excess fuel problem I have.
« Last Edit: June 11, 2021, 09:57:31 PM by Davlea »

Offline Richard S

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Re: Correct jets
« Reply #6 on: June 11, 2021, 05:59:07 PM »

Offline ajh

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Re: Correct jets
« Reply #7 on: June 11, 2021, 06:56:09 PM »
Could someone please tell me the symptoms for leaking Crankshaft seals, could it be the cause of the excess fuel problem I have.

Weak mixture so you could get surging and high rpm on idle. Possibly excessive smoke if the right seal has gone (due to gearbox oil escaping into the combustion side). Taking the left hand case off you may see mixture below the rotor where the seal has leaked
in Chiswick, West London

77 RD250d, 80 DT175mx, 81 4L0 350LC

Offline Davlea

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Re: Correct jets
« Reply #8 on: June 13, 2021, 08:09:19 AM »
Thanks guys I will try a new Mikuni set

Offline 5port

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Re: Correct jets
« Reply #9 on: June 13, 2021, 08:24:34 AM »
Another point is the Main Jet washer.  This gets dished in use and can allow fuel past the main jet. It is worth fitting new ones. Allens supply them.  Don't try an ordinary brass washer, the correct Mikuni part is thicker (about 1.5mm thick) and it has a sharp square edge on one side that should fit against the small shoulder on the alloy housing of the carb to seal. 
Cheers

5port
5port

Offline c50

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Re: Correct jets
« Reply #10 on: June 13, 2021, 09:58:03 AM »
Are your air correction passageways/jets  all clear and functioning? One of the most important checks.

Offline Davlea

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Re: Correct jets
« Reply #11 on: June 15, 2021, 12:40:55 PM »
Thanks I did fit new main jet washers, I blew out every hole I could see I have not taken out the brass balls.

Offline mts

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Re: Correct jets
« Reply #12 on: June 15, 2021, 01:13:31 PM »
my 400 was overfueling on the carb side ,,,recheck your float heights and that the fuel cut off valves are sealing off correctly
Silver black 250 DX  pure
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Online betty foRD

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Re: Correct jets
« Reply #13 on: June 15, 2021, 03:26:11 PM »
All the above but also check the choke valve is shutting off fully. The runner seal hardens and takes a set with time.
Rev 'em till they rattle

Offline Davlea

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Re: Correct jets
« Reply #14 on: June 15, 2021, 07:42:22 PM »
Choke checked and cleaned looked fine, float heights checked and valves are ok sealing. My patience is starting to run out with this bike. I am waiting for new Mikuni brassware so fingers crossed.