Topic: Ordering jets, need advice

[Scott S]

 I have a set of 087A carbs that are going on a "built" CB550 engine.

 That engine always got poor mileage, ran a little rich and would foul the #3 plug, but I think those were all symptoms of a tired engine and not the carbs.
 The carbs are clean....for sure....new O-rings, drilled emulsion tubes. Stock jetting and needle heights.

 The engine will have 1.00 over, high compression Yoshimura pistons, mild P&P, CB650 cam and a Kerker 4-1 with baffle.

 Stock mains are #100. Should I order #105's and #110's? Or even bigger?

 I know I'll have to experiment once the engine is done and running, but think the stock needle clip setting is good enough?

[Don R]

 I'd try one step on the jet and one step on the needle jet. Double check the float levels on a  bike that gets poor mileage. It made a large difference on my 750F1.

[Scott S]

I'd try one step on the jet and one step on the needle jet.

 By "one step on the needle jet", you mean the clip on the needle? One step richer, I assume?

[Scott S]

 Any other thoughts or opinions?

[harisuluv]

110 mains and lowering the needle clip one position (same as raising the needle by one position) would be a good start

[bwaller]

110 mains and lowering the needle clip one position (same as raising the needle by one position) would be a good start

Agreed. A nice tight engine with better intake vacuum doesn't usually need a huge change in mains.

[Scott S]

110 mains and lowering the needle clip one position (same as raising the needle by one position) would be a good start

Agreed. A nice tight engine with better intake vacuum doesn't usually need a huge change in mains.

 I found this to be true on the "lean burn" PD carbs and a very similar engine build, minus the high CR pistons (but still overbored). I ended up with nearly stock jetting, slightly bigger on the mains, excellent power and mid-40's to 50 MPG.

 Thanks, guys. I'll order some jets tomorrow.

 One thing I forgot to mention: I'll be using the stock plenum, but one of the K&N cone type filters that bolts to it.

[Scott S]

 4into1.com is out of the 110's, of course. They have 105 and 115 in stock.
 They're cheap; only $2.50 each, but they're Keyster.

 JetsRus has the 110's and I *think* they sell genuine Keihin jets. But they're also $6 each.

 How's the quality of the Keyster main jets? I can get three different sizes from 4into1 for less that $40, whereas that would cost me close to $85 from JetsRus.

 EDIT: It looks like 4into1 has more than one option for the mains.....what's the consensus on Keihin vs. Kesyter vs. replica for main jets?

http://4into1.com/replica-keihin-press-fit-secondary-main-jets/#

http://4into1.com/keyster-keihin-press-fit-secondary-main-jets/

[evanphi]

Get the Keihin. Guaranteed to be correct for all of them. 

[Scott S]

 I'll see when 4into1 gets them back in stock. Even their Keihin is much cheaper than JetsRus.

[flybox1]

I'll see when 4into1 gets them back in stock. Even their Keihin is much cheaper than JetsRus.

ive ordered the 'OEM equivalent' main jets from jetsrus in the past and run them without tuning issue. 
I would not hesitate to order again.
its the really small ID, pilot jets with the emulsion holes that become questionable in spec quality.  I wll order only OEM pilots

[Scott S]

 I was searching eBay and found some jets that 4into1 has listed. Contacted them through eBay and asked about the two different jets and the quality.

 Here's the reply I got:

"If I gave you a handful of jets, you probably wouldn't be able to pick out the replicas.
The quality is good, they will work just fine!
But if you want to wait for the Keyster version, it will probably be about a week.

Cheers,
Trevor
4into1"

[Scott S]

 And since I'm actually going bigger, and not trying to match an OEM measurement, I guess I'll give them a try.