opting not to drill slides- dynojet???? - Suzuki GSX-R Motorcycle Forums Gixxer.com
 
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post #1 of 14 (permalink) Old 05-03-2010, 08:26 PM Thread Starter
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opting not to drill slides- dynojet????

In the dynojet kit it states to drill and tap the slides and insert these little plastic threaded restrictors in the tapped holes. It also states that for "track or hard street use the holes may be left stock". In my particular kit, there are 2 plastic restrictors that don't have holes in them and 2 that do???? is this right? If I choose not to drill the slides and not put in the restrictors what kind of headache am I setting myself up for, if any? Anyone have some insight/ experience in this?
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post #2 of 14 (permalink) Old 05-03-2010, 08:54 PM
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Re: opting not to drill slides- dynojet????

The size of the holes affects the rate of rise of the slides. If it were me, I'd call Dynojet and get them to talk to you a little about your specific application.

JR
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post #3 of 14 (permalink) Old 05-04-2010, 12:45 AM
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Re: opting not to drill slides- dynojet????

give it a shot. the worst that will happen is you might have a flat spot here or there. With this kind of CV carb, the rate of slide lift controls the amount of accel enrichment you get, that's why there is no accelerator pump. So by changing the slide lift speed you're changing the 'size' of the accel pump hit, faster = leaner but the engine can rev up faster. Slower = richer but the engine might bog or accelerate slowly.

Like everything else it's a tradeoff. Me personally I would give it a shot without drilling them. You could also call Dynojet but don't expect to get an especially helpful answer.

Factory pro, incidentally, leaves the slides stock but tailors the speed with a different spring.

Gives you something to think about - if you have a spare set of springs you could stretch them for more preload or cut them down to get different slide opening/enrichment curves.

good luck...
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post #4 of 14 (permalink) Old 05-04-2010, 01:48 AM
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Re: opting not to drill slides- dynojet????

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Originally Posted by robertob View Post
give it a shot. the worst that will happen is you might have a flat spot here or there. With this kind of CV carb, the rate of slide lift controls the amount of accel enrichment you get, that's why there is no accelerator pump. So by changing the slide lift speed you're changing the 'size' of the accel pump hit, faster = leaner but the engine can rev up faster. Slower = richer but the engine might bog or accelerate slowly.

Like everything else it's a tradeoff. Me personally I would give it a shot without drilling them. You could also call Dynojet but don't expect to get an especially helpful answer.

Factory pro, incidentally, leaves the slides stock but tailors the speed with a different spring.

Gives you something to think about - if you have a spare set of springs you could stretch them for more preload or cut them down to get different slide opening/enrichment curves.

good luck...
In My opinion:
1) Is better don't stretch springs for more preload: isn't easy to stretch 4 springs at the same rate (eventually you can cut them at the same rate).If you need spring strongest.. you have to buy others..2)
2) about the sliders: If you drill the holes they become faster, and I think you enrich the mixture, because you open completely the main jet at the bottom of the carb earlier.
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post #5 of 14 (permalink) Old 05-04-2010, 05:57 AM Thread Starter
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Re: opting not to drill slides- dynojet????

Yeah, I understand how the hole size affects the slide lift rate. W/ the Dynojet kit the little plastic inserts they give you have a smaller hole than stock meaning they want a slower lift rate?? I may give it a try w/o drilling first and see how it acts. Hopefully i won't end up w/ a flat spot. I may also have to give Dynojet a call and ask why I have 2 POS inserts w/ no hole in them.
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post #6 of 14 (permalink) Old 05-04-2010, 05:01 PM
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Re: opting not to drill slides- dynojet????

Quote:
Originally Posted by robertob View Post
give it a shot. the worst that will happen is you might have a flat spot here or there. With this kind of CV carb, the rate of slide lift controls the amount of accel enrichment you get, that's why there is no accelerator pump. So by changing the slide lift speed you're changing the 'size' of the accel pump hit, faster = leaner but the engine can rev up faster. Slower = richer but the engine might bog or accelerate slowly.

Like everything else it's a tradeoff. Me personally I would give it a shot without drilling them. You could also call Dynojet but don't expect to get an especially helpful answer.

Factory pro, incidentally, leaves the slides stock but tailors the speed with a different spring.

Gives you something to think about - if you have a spare set of springs you could stretch them for more preload or cut them down to get different slide opening/enrichment curves.

good luck...


Good carb info.
Pieces like this could be added somehow to the "Carb sticky".
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post #7 of 14 (permalink) Old 05-05-2010, 01:36 AM
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Re: opting not to drill slides- dynojet????

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Originally Posted by nikos1400 View Post


Good carb info.
Pieces like this could be added somehow to the "Carb sticky".
man take care : is the opposite.
needle up:rich
needple down: lean
Therefore:
slide faster (big holes): enrich
slide slower (small holes): leaner
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post #8 of 14 (permalink) Old 05-05-2010, 05:21 AM
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Re: opting not to drill slides- dynojet????

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Originally Posted by robertob View Post

Factory pro, incidentally, leaves the slides stock but tailors the speed with a different spring.
who else got springs in their fp kits? . . . 'cause i didn't!!!
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post #9 of 14 (permalink) Old 05-05-2010, 11:44 AM
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Re: opting not to drill slides- dynojet????

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Originally Posted by fulviogsx View Post
man take care : is the opposite.
needle up:rich
needple down: lean
Therefore:
slide faster (big holes): enrich
slide slower (small holes): leaner
Yes I agree but you are forgetting that the holes affect TRANSITION, not steady. With changes to the springs you are absolutely correct. With changes to the holes it is opposite because you're just adjusting the speed of lift not the amount.
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post #10 of 14 (permalink) Old 05-05-2010, 11:45 AM
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Re: opting not to drill slides- dynojet????

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Originally Posted by mark_E View Post
who else got springs in their fp kits? . . . 'cause i didn't!!!
For bandit 1200, sorry I just assumed it was for all. Must depend on the kit.
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post #11 of 14 (permalink) Old 05-05-2010, 11:53 AM
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Re: opting not to drill slides- dynojet????

Quote:
Originally Posted by fulviogsx View Post
In My opinion:
1) Is better don't stretch springs for more preload: isn't easy to stretch 4 springs at the same rate (eventually you can cut them at the same rate).If you need spring strongest.. you have to buy others..2)
2) about the sliders: If you drill the holes they become faster, and I think you enrich the mixture, because you open completely the main jet at the bottom of the carb earlier.
You are right about the springs for sure. But on #2 think about it - the slide rises to a certain level depending on the vacuum differential between the back and front of the slide. This determines needle position and richness. This modifies enrichment for engine load.

HOWEVER, the slide POSITION does not change with bigger or smaller holes. Only the rate of change of position. So it only affects transitions (getting on the throttle during accel), not steady state (like full throttle). The slower it rises, the more vacuum is at the main jet (like a choke) so the richer.

The SPRING changes slide position by the way, but the holes do not.
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post #12 of 14 (permalink) Old 05-05-2010, 12:01 PM
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Re: opting not to drill slides- dynojet????

I didn't get springs in my FP kit
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post #13 of 14 (permalink) Old 05-05-2010, 12:01 PM
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Re: opting not to drill slides- dynojet????

oh yeah also what happens when you remove the airbox is you increase the pressure differential (delta P) between the mouth of the carb and the engine, so the slide will rise faster anyway. That may be why dynojet slows it down.
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post #14 of 14 (permalink) Old 05-05-2010, 01:27 PM
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Re: opting not to drill slides- dynojet????

No springs with my fp kit
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