News:

This forum is run by RPM and donations from members.

It is the donations of the members that help offset the operating cost of the forum. The secondary benefit of being a contributing member is the ability to save big during RPM Holiday sales. For more information please check out this link: Membership has its privileges 

Thank you for your support of the all mighty FJ.

Main Menu

pod filters and jets

Started by scarylarry, March 19, 2012, 01:29:12 PM

Previous topic - Next topic

scarylarry

gents,
i did a search and i think i have this right:
i have an '87 fj1200 with stock everything and want to change to the pod filters offered at rpm.
i should run 125 main jet, 40 pilot jet and shim needle with 5mm washer, is this correct?
i'd like to know this is correct before i order from rpm.

thanks,
larry

SlowOldGuy

That main jet will be way too large for just pods.  You could use the stock main, or go up to a 115.

Shimming the needles is far more critical than changing the main jet.

DavidR.

Dads_FJ

Quote from: scarylarry on March 19, 2012, 01:29:12 PM
gents,
i did a search and i think i have this right:
i have an '87 fj1200 with stock everything and want to change to the pod filters offered at rpm.
i should run 125 main jet, 40 pilot jet and shim needle with 5mm washer, is this correct?
i'd like to know this is correct before i order from rpm.

thanks,
larry

Don't forget to purchase a crank-case breather filter.  And ear plugs.  The intake howl was too much for me so I ditched the UNI pods and reinstalled the air box.  just my .02 of course.
John S.

'84 Yamaha FJ1100
'89 Yamaha FJ1200
'94 Yamaha WR250
'80 BMW R100S/Sidecar
'39 BSA WM20

andyb

Depending a bit on the air where you are, a 125 is still hilariously too much for stock exhaust.  David's right on there.  Jets are cheap, I'd probably buy a set of 115's and shim the needles slightly, and experiment from there.

Nah, let's be honest.  I'd get 122.5's and try to make them work.  By buying a pipe.  :)

1tinindian

Quote from: Dads_FJ on March 19, 2012, 02:53:52 PM

 And ear plugs.  The intake howl was too much for me so I ditched the UNI pods and reinstalled the air box.  just my .02 of course.

Damn, you must have great hearing.
I can't hardly tell the differance on my bike. At least not to the point of having to change back to an airbox.

Leon
"I want to be free to ride my machine without being hassled by the "man"!
91 FJ1200

racerrad8

Quote from: 1tinindian on March 19, 2012, 04:50:42 PM
Damn, you must have great hearing.
I can't hardly tell the difference on my bike. At least not to the point of having to change back to an airbox.

Leon

Speaking of that, how does it run?

Randy - RPM
Randy - RPM

scarylarry

so i should just keep the the stock main jet, go to a 40 pilot and shim the needle with a 5mm washer?
...and the crank case breather.

larry


andyb

A 5mm washer would give you interesting results. Try a 0.5mm washer to start perhaps?

Slow down, read a bit more carefully. 

Dads_FJ

I think jetting threads can be as bad as oil threads or worse yet, which oil do I use on my chain threads!  My opinion, and everybody has one... is that because you'll have more air entering across the board, that is throughout the whole rpm range, then you'll have to compensate by adding more fuel across the whole range as well - by increasing the main main jet as well as the pilot jet.  When I went from air-box to sans-air box and back to air-box, the only jetting change I made was with the main jet.  I don't recall which size jets I used with the pods, they went with the filters when I sold them.  I should also add that the loudness I referred to earlier was when I was in the kookaloo zone above 5-6K RPM.  Also... (don't worry, I'll stop soon!), although there was a bigger hit at higher RPMs, the loss in low end power conflicted with my 18 tooth front sprocket, 'nother reason I switched back.   your results may vary.
John S.

'84 Yamaha FJ1100
'89 Yamaha FJ1200
'94 Yamaha WR250
'80 BMW R100S/Sidecar
'39 BSA WM20

andyb

In part, and in defense of those without airboxes, not mildly enrichening the midrange would have meant you were leaner than prior, and you likely lost some torque because of it, not just the lack of airbox.

In truth, the best way by a long shot is to put it on a dyno and see what's what, but that's an expensive proposition unless you're quite certain that you're done upgrading airflow into and outof the engine.  Suggested jetting changes are just that, suggestions as a place to start.  Nothing will ever take the place of fine tuning either via dyno time or careful chopped plug reads.

scarylarry

Quote from: andyb on March 20, 2012, 08:24:40 AM
A 5mm washer would give you interesting results. Try a 0.5mm washer to start perhaps?

Slow down, read a bit more carefully. 

i was always decimally challenged!   :dash2: 

thanks, I'll start from there.

1tinindian

Quote from: racerrad8 on March 19, 2012, 07:14:53 PM
Quote from: 1tinindian on March 19, 2012, 04:50:42 PM
Damn, you must have great hearing.
I can't hardly tell the difference on my bike. At least not to the point of having to change back to an airbox.

Leon

Speaking of that, how does it run?

Randy - RPM

As of right now, I only have a little over 30 miles on it since getting it back together, but from what I have been able to tell, it runs great, and the top end sounds good. The pods can be heard at WFO, but hell, I love that sound!

Thanks for getting me through this Randy!

Leon
"I want to be free to ride my machine without being hassled by the "man"!
91 FJ1200

rktmanfj

Quote from: 1tinindian on March 19, 2012, 04:50:42 PM

Damn, you must have great hearing.

Leon

If he's riding an FJ sans earplugs (airbox or not), he probably won't for long.

Dads_FJ

Quote from: rktmanfj on March 20, 2012, 11:07:50 AM
Quote from: 1tinindian on March 19, 2012, 04:50:42 PM

Damn, you must have great hearing.

Leon

If he's riding an FJ sans earplugs (airbox or not), he probably won't for long.

I was waiting for an earplug thread!  I am a firm believer in them, I use the the yellow cylindrical ones, gotta save what hearing I have left.  I attest that my bad hearing is from rock concerts of the 70s & 80s.
John S.

'84 Yamaha FJ1100
'89 Yamaha FJ1200
'94 Yamaha WR250
'80 BMW R100S/Sidecar
'39 BSA WM20

rktmanfj

Quote from: Dads_FJ on March 20, 2012, 11:16:59 AM
Quote from: rktmanfj on March 20, 2012, 11:07:50 AM
Quote from: 1tinindian on March 19, 2012, 04:50:42 PM

Damn, you must have great hearing.

Leon

If he's riding an FJ sans earplugs (airbox or not), he probably won't for long.

I was waiting for an earplug thread!  I am a firm believer in them, I use the the yellow cylindrical ones, gotta save what hearing I have left.  I attest that my bad hearing is from rock concerts of the 70s & 80s.

Well, why didn't ya start one?     :biggrin:

I'm having a new set of customs made up soon... lost one of the originals, and the custom earbuds got chewed up by the (now ex) GF's Pekingese.   :diablo:

There are some good generic 'plugs out there, but, IMO, none of those compare to custom-made ones.