Diaphragm hole diameter question

[Dads_FJ]

Quick question... Does anybody know the correct factory size of this hole?  Mine measures .140" or 9/64" but I believe it was drilled out as part of a 'jet-kit' installation by the PO.  I've struggled with cold bloodlessness and a flat spot/hiccup off idle for the entire time I've owned it, almost 20 years...  I've replaced all the jets to factory but went with a larger pilot (I forget what the value).  It deserves better...

[Flynt]

Mine are about the same size as the hole in the backing plate (that retains the little spring and needle assy)...  Not precise I know, but should be close enough unless the backing plate has been drilled out as well?

Frank

[racerrad8]

Those have definitely been drilled out the stock hole I measured is  0.085" (for the flat slide)

Robert

[Dads_FJ]

Thanks Randy, much appreciated.   

[racerrad8]

Thanks Randy, much appreciated.   

John, I can't take the credit for that info, I'm away from the shop until next week.

That's all Robert.

Randy - RPM

[Dads_FJ]

Duh, thanks and cudos to Robert! 

[racerrad8]

John,

Robert and I were talking this morning and he recalled one other thing. You used those JBM(?) replacement diaphragms on your carbs. If the needle is not in the design position for the RPM/fuel range that might be the cause of the stumble.

Randy - RPM

[Dads_FJ]

John,

Robert and I were talking this morning and he recalled one other thing. You used those JBM(?) replacement diaphragms on your carbs. If the needle is not in the design position for the RPM/fuel range that might be the cause of the stumble.

Randy - RPM

Thanks for the info Randy - I do use the JBM diaphragms and did secure them in place on the slide.  I verified they did not rotate and the hole is facing toward the engine.

With that:  I'm in the market for a set of four slides - even if the rubber diaphragms are worn and have holes etc...

Thanks - John

[racerrad8]

John,

Robert and I were talking this morning and he recalled one other thing. You used those JBM(?) replacement diaphragms on your carbs. If the needle is not in the design position for the RPM/fuel range that might be the cause of the stumble.

Randy - RPM

Thanks for the info Randy - I do use the JBM diaphragms and did secure them in place on the slide.  I verified they did not rotate and the hole is facing toward the engine.

With that:  I'm in the market for a set of four slides - even if the rubber diaphragms are worn and have holes etc...

Thanks - John

John,

We need to get your carbs changed over to curved slides and shrouded e-tubes.

Randy - RPM

[Dads_FJ]

John,

Robert and I were talking this morning and he recalled one other thing. You used those JBM(?) replacement diaphragms on your carbs. If the needle is not in the design position for the RPM/fuel range that might be the cause of the stumble.

Randy - RPM

Thanks for the info Randy - I do use the JBM diaphragms and did secure them in place on the slide.  I verified they did not rotate and the hole is facing toward the engine.

With that:  I'm in the market for a set of four slides - even if the rubber diaphragms are worn and have holes etc...

Thanks - John

John,

We need to get your carbs changed over to curved slides and shrouded e-tubes.

Randy - RPM

You lost me I'm afraid.  The slides are factory OEM and I've replaced all the jets and emulsion tubes which I believe were purchased from RPM.  If I sink any more $$ in these carbs I might consider sending my bike to Kansas for an EFI upgrade

[FJmonkey]

You lost me I'm afraid.  The slides are factory OEM and I've replaced all the jets and emulsion tubes which I believe were purchased from RPM.  If I sink any more $$ in these carbs I might consider sending my bike to Kansas for an EFI upgrade

If you are getting new slides anyway then get the modern round bottom slides with shrouded e-tubes. They will work with your carb bodies.

[Dads_FJ]

I have these e-tubes.

http://rpmracingca.com/proddetail.asp?prod=Carb%3A50H-14941-92-00&cat=24

Are these the shrouded type?

[racerrad8]

Not according to my records.

The carb kits you purchased will have the non-shrouded e-tubes.

Randy - RPM