Earshave-to rejet or not? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 39 (permalink) Old 07-13-2013, 12:17 PM Thread Starter
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Earshave-to rejet or not?

Well I have read a lot on here and maybe I didn't read enough, (perhaps beating a dead horse or one that was already written up), anyways:
I am doing the earshave thing and don't really want to spend anymore money than I have to and I thought I read you don't have to rejet if you don't change your pipes but can't find that now. I don't think my pipes are original, PO may have taken them and the goats belly off as I don't see anything like the "goats belly" under my bike, anyways the pipes aren't original. But the bike use to run just fine so I am thinking I can do the earshave and not rejet, any thoughts?

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post #2 of 39 (permalink) Old 07-13-2013, 12:38 PM
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You will want to rejet to 42 pilots and 142 mains. Any discussion of not doing it is usually limited to 1 or 2 members who chose not to, but the majority who did the ear shave did indeed require the rejet. I don't think your exhaust is stock so just another reason to go ahead and do it. Was about 35$ in jets and shims.

1986 Kawasaki Vulcan 750
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post #3 of 39 (permalink) Old 07-13-2013, 12:42 PM
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Here is my thought...if the bike ran fine before why are your ear-shaving? Is it to get rid of the ears because you don't like the look or looking for some additional performance or because (like me) you took the carbs out and can't imagine they would go back in without removing all of that emissions crap?

Personally, I think changing the intake and exhaust should always include rejetting. Changing just the intake or the exhaust is a little more complex. A more free flowing system will need more fuel and that together is where you get the most performance impact. So a free-er intake (K&N pods for example) and a free-er exhaust (like the V&H Cruzers) would be an automatic re-jet.

But if you just change one or the other, your mileage may vary...literally. Personally I moved up to 142/42 jets with the ear shave and then changed the exhaust later and I love it.

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post #4 of 39 (permalink) Old 07-13-2013, 12:53 PM Thread Starter
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would like to do the earshave cause I have the motor out, and about ready to put it back in the bike and really don't want all that emission stuff back in. I had cracked the case and put many parts back in that got damaged due to dampers...anyways spent lots already may sit this one out as I really don't want more expense.

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Re-did the engine
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post #5 of 39 (permalink) Old 07-13-2013, 01:02 PM
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Well, I get to be odd man out.

I do not worry about jets until exhaust changes. You stated your exhaust is not OEM. I would then have to look at the jets.

I would not consider going larger than a #40 pilot w/o changing the pilot air jet also.
I would not go larger than a #140 main w/o changing the main air jet. Just me. I believe, when you increase airflow, you then need to change circuit volume not air/fuel ratio.

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post #6 of 39 (permalink) Old 07-13-2013, 01:28 PM Thread Starter
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since my pipes are not OEM perhaps PO changed jets?? How do I tell what my jet and pilot are? Are they printed with that on them? If so I will pull and look at.

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Re-did the engine
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post #7 of 39 (permalink) Old 07-13-2013, 01:29 PM
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I'm at flip side here. If you increase the flow of air you need to increase the flow of fuel to maintain the same air/fuel mixture. So, putting on less restrictive airfilters should require rejetting , where just putting on a less restrictive exhaust shouldn't.

But it's not that simple always.
But with the Vulcan, which runs fairly lean stock, and seeing how restrictive the stock air intake is, I'm pretty much in agreement that if you trash the stock "ears" and just put on some pod filters like the Emego or K+N's you should need to rejet a bit richer than stock.

Keep in mind that its possible the previous owner might have already altered the jetting..

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post #8 of 39 (permalink) Old 07-13-2013, 01:34 PM
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Quote:
Originally Posted by BeeSea View Post
since my pipes are not OEM perhaps PO changed jets?? How do I tell what my jet and pilot are? Are they printed with that on them?


Looks like we posted at the same time on this....

Uh, yes the jets do have numbers on them.
Stock jets are 138/38 .....I think...definitely both in the "30's"

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post #9 of 39 (permalink) Old 07-13-2013, 01:42 PM Thread Starter
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thanks I will check when I get home-at work now. Will let everyone know what I find out!

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1986 750 Vulcan
Coastered
Relocate R/R to side cover
Re-did the engine
from the case up.(And it runs)
YOU CAN TOO!
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post #10 of 39 (permalink) Old 07-13-2013, 03:15 PM
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Quote:
Originally Posted by BeeSea View Post
and maybe I didn't read enough, (perhaps beating a dead horse or one that was already written up)
Yes and Yes
Short search in Forum section under Carbs nad Fuel System would reveal this

Read it and put your mind at ease


Quote:
Originally Posted by Knifemaker View Post
Uh, yes the jets do have numbers on them.
Stock jets are 138/38 .....I think...definitely both in the "30's"
As usual, KM is dead on with previous comments.
FWIW: My stock jets were 132/35
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