First Generation Ascots > Tech Section

Jetting recommendation

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patrino:
Well, I ended up with a #145 main and a #58 pilot.

Here's the play-by-play, for the intake-through-exhaust story:

Bought the bike back in ~August 2017, got it running September or so.  Intake was filthy, so scrapped the stock filter and adapted a large Uni pod filter to work in the stock airbox.  Stock pipe, stock carb, stock jetting, stock ignition.

October 2017, read the "FT500 Essentials" and installed a #145 main and #58 pilot from ThumperStuff. 

July 2018, installed the full Kerker system.  Kept the #58 pilot, threw in a #165 main to see what happened.  Saw that someone had already installed two shims under the needle.  Off-throttle to mid-throttle there was noticeably more power.  At WFO from about 3000 it blubbered, wouldn't rev out.  I haven't jetted too many four-strokes, but it felt like it was eight-stroking.

A couple days later, got the Six Sigma jet kit.  They recommended a #145 main, with a #140 or #150 option.  They also recommended a #72 pilot jet (!), plus a couple shims under the needle.  I installed the #150 and the #72 pilot, and kept the two shims under the needle.  Started OK cold but died as soon as I choked it.  The bike was pretty "fluffy" off-throttle and mid-throttle.  At WFO it would pull up to redline (2nd, 3rd, 4th) but would still eight-stroke every now and then.  Much improved WFO operation compared to the #165, but still not good. 

Returned to the garage.  Installed the #145 main and the #58 pilot.  Less fluffy off-throttle, and revved out very cleanly (2nd, 3rd, 4th) at WFO.

I'll take it on a cruise this week or next, and peep the plug for a double-check.

Pretty happy!!!  Hope the info above helps someone.

triguyracer:
Sounds like to many or too thick of a shim under the needle there is from what I understand a lot of overlap between the main jet and the needle on a cv carb,have to admit almost all my jetting has been with round slide or flat slide carbs.Very important for the needle to be abile to drop all the way down. Make sure the outside dia of the shim is not larger than the outside dia of the top part of the needle as that is the part that bottoms out in the slide or it will hold it up and cause a rich condition in the mid range.I have no experience with the carb kit you are using but a pilot jet of that size sounds way rich unless they are using a diff way to calibrate fuel flow, lol

triguyracer:
Try the 165 with one shim under the needle and stay with the 58 pilot.are you are using the stock needle?

triguyracer:
You can drop the main a little if you are using the air box, forgot you mentioned that in your reply lol

patrino:
Update on jetting ...

I removed a shim from the needle (so am now running one shim only).  Bike running well.

Checked the plug twice, once after zipping around town, once after a ~70mph 40-mile freeway schlep (~1/2+ throttle).  Plug looked good both times, nice even milk-chocolate.

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