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D
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Discussion Starter · #1 ·
Hi Guys

I have just taken my bike for a spin (with no seat, as im waiting for a sattler to have time to do it), after a nice line of upgrades. I have given it a new (huge) lithium battery, dyna coils, new ignition cables, and new NGK sparkplug caps. I should also inform you that I run the stock Mikuni BST40, with a Dynajet kit stage 3, open filters and an aftermarked exhaust.

It springs to life instantly, so thats nice. But I have noticed two things, it pops a little more (I think) than before when deaccelerating. The motor runs nice in idle speed, no pops, and fairly consistent.
The other thing is that It is a little slow to reduce the revs, when the gas is cut. Is this just because the slides are vacuum controlled, or is there something that can be done? (not including in investing in Mikuni RS flatslides :fu:)

All advice is greatly appreciated :)
 
G

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Popping shutting the throttle can be an indication of it running a little weak or an air/vac leak this can also cause the throttle to hang

having said that its usually because the carbs are balanced slightly too far up the adjustment range, with pods on these you need to balance at the lowest reliable idle you can get & it may take 2 or 3 attempts to get sub 1000 revs but 6 to 800 revs is achievable, then you can pick the revs up to a normal idle & ride, don't let the bike overheat while doing it
 

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D
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187 Posts
Discussion Starter · #3 ·
Popping shutting the throttle can be an indication of it running a little weak or an air/vac leak this can also cause the throttle to hang

Having said that its usually because the carbs are balanced slightly too far up the adjustment range, with pods on these you need to balance at the lowest reliable idle you can get & it may take 2 or 3 attempts to get sub 1000 revs but 6 to 800 revs is achievable, then you can pick the revs up to a normal idle & ride, don't let the bike overheat while doing it
Ok, thanks! I will check the rubber for cracks, first.
When you write that the carbs are balanced sligtly too far up the adjustment range, do you mean the idle screws themselves on each carburettor or the main common idle set thumb screw that basically works like the chocker? (It might be a stupid question - but Im not a carburettor expert, but I did manage to clean & jet them myself)

Thanks!
 
G

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No worries I am glad to be able to help :)

By balance I mean a carb sync using the adjusting screws between carbs 1&2 ...3&4 & finally 2&3 in that order to get them all working together, it is common for the adjusters to be too far in when going over to pods & that can cause the hanging throttle

The sync should be done with a manometer such as Morgan Carbtune & is pretty easy to do, a quick search here should help you see what I mean & if you can get the tools there are a few of us here who can talk you through it

The only thing that does concern me a little is your jetting as that can cause problems, if you post up the exact year & model + the jetting & clip position on the needle you are on that may help in determining if its purely a balance problem or not, I suspect it will be purely down to sync (balance) but its always worth checking :)
 

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D
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187 Posts
Discussion Starter · #5 ·
The jetkit I have used it this.
http://www.ebay.co.uk/itm/DYNO-JET-...832?pt=LH_DefaultDomain_3&hash=item5b0dbd2638

The bike is a gsxr 1100 from 92.
I did sync the carbs after installing the jetkit, but before changing coils/ignition wire & caps. But I am unsure if there is something I am missing. I dont remember the clip position, but I was following the instructions. If I can find them, Ill know. I have found a manual for the same kit but for American models only (36mm carbs), it says 3rd grove from the top. I suspect it is the same.
 
G

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Ok I just went through your build thread & the first thing I notice is that exhaust TBH its never going to run as good as it could with that on there like that ;) but .....

I will still try & help out, you have made changes to ignition after carb sync & that will have an effect & I guess from your first post its not really been run on the road since the carbs were sorted, so I stand by the first comments I put up here, sync again at the lowest idle you can get..... you will find you have to adjust the idle as the carbs come into sync but try to keep it sub 1000 revs & don't let it overheat

Then you can try it & do a plug chop for an indication of how the mixture is :)

Any more problems I will definitely need to know which size jets you used & the clip position to help more
 

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OLD GUY's RULE
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4,642 Posts
I could never get the Stage 3 to work on My 89 1100.
Best plugs I every had in it were Denso Iradium.
Bloody thing woke right up.
 

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D
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187 Posts
Discussion Starter · #8 ·
Ok I just went through your build thread & the first thing I notice is that exhaust TBH its never going to run as good as it could with that on there like that ;) but .....

I will still try & help out, you have made changes to ignition after carb sync & that will have an effect & I guess from your first post its not really been run on the road since the carbs were sorted, so I stand by the first comments I put up here, sync again at the lowest idle you can get..... you will find you have to adjust the idle as the carbs come into sync but try to keep it sub 1000 revs & don't let it overheat

Then you can try it & do a plug chop for an indication of how the mixture is :)

Any more problems I will definitely need to know which size jets you used & the clip position to help more
Thanks a lot! I will give it a shot and re-sync the carbs :)
 

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D
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Discussion Starter · #9 ·
I could never get the Stage 3 to work on My 89 1100.
Best plugs I every had in it were Denso Iradium.
Bloody thing woke right up.
The stage 3 kit works well for me and has improved the middle-area imensly! :rock:
I dont think, there is a problem w. my plugs, but I will definetly try those Denso Iradium next time they need to be replaced. Thanks for you input.
 
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