Author Topic: 064A slow jet  (Read 950 times)

Offline Liam

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064A slow jet
« on: April 25, 2018, 07:33:43 PM »
Hi,
Nearing the end of my build...yay!!!  Just a couple of things to finish off.  Posted previously regarding dyno testing to get the fuelling right...  general advice is no which I'm more than happy about so I'm dealing with the resetting the carbs... as ver a trial and error job.  Grebbo recommend a relatively local chap that can fine tune the feeling but I'd like to get it there or there abouts...

My problem seems to be the slow jets.  when opening up the throttle the revs can dip to the point of stalling.  The original size 40 jets are 28mm long, the only jets available these days seem to be 32mm in length so it's deeper into the fuel bowl.  The length is in the main body so if required I cut the bodies down to the original 28mm.  Ive increased to number 48's but no difference and the air jet does seem to have any impact at all.  I'm hoping I just need to up the size.  carbs have been refurbed, ultrasonically cleaned etc. etc.

My question is...  How will having a longer pilot jet "body" impact on the fuelling???  is it an issue.
« Last Edit: April 25, 2018, 09:18:06 PM by Liam »

Offline Liam

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Re: 064A slow jet
« Reply #1 on: April 25, 2018, 08:04:31 PM »
oh...  and the bikes got ramair pods that replace cheap Chinese pods which were on the bike as well as a 4 into 1 straight through exhaust also inherited...
Cheers
Liam

Offline UK Pete

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Re: 064A slow jet
« Reply #2 on: April 26, 2018, 07:12:23 AM »
What bike is it

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Offline Liam

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Re: 064A slow jet
« Reply #3 on: April 26, 2018, 07:28:27 PM »
Hi Pete,

Apologies... Its a CB750F Supersport 1976 US import.

it came with 135's main jets
Ive upped the pilot jets to 48's

Cheers

Liam

Offline UK Pete

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Re: 064A slow jet
« Reply #4 on: April 27, 2018, 10:52:46 AM »
Are you sure this is a jet issue,   coils often cause these issues I chased a problem with one of my bikes for a year believing it to be a feeling problem  only for problem to disappear with a different set of could and cleaning all earthing points
Also float height set properly helps
 

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Offline royhall

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Re: 064A slow jet
« Reply #5 on: April 27, 2018, 11:32:48 AM »
Probably the pods, they don't sit well with these bikes. Can you go back to standard air box? It is possible to get them to run right on pods but it's a lot of trial and error.
Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

Offline Liam

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Re: 064A slow jet
« Reply #6 on: April 27, 2018, 04:02:32 PM »
Cheers gents. 
I think it's going to be trial and error, I don't have the original air box...  so I'll try the 58 and 68 pilot jets and try and set tick-over...
I set the floats when I cleaned and refurbed the carbs...
Watch this space 

Offline royhall

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Current bikes:
TriBsa CCM 350 Twin
Honda CB350F in Candy Bacchus Olive
Honda CB750F2 in Candy Apple Red
Triumph Trident 660 in Black/White
Triumph T100C
Suzuki GS1000HC
Honda CB450K0 Black Bomber
Honda CB750K5 in Planet Blue Metallic (Current Project)

Offline Liam

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Re: 064A slow jet
« Reply #8 on: April 28, 2018, 03:03:53 PM »
Cheers...  Appreciate the link

 

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