700S Jet kit help wanted

[Willie]

Having read through the various ads for jet kits, I'd like to know who has tried what vendor's product and their opinion of the results. I couldn't help but notice the 6 Sigma kits are a LOT less expensive than all the others. Considering that few, if any, come with needles, I'd like to know what fellow members think of their mods.
Thanks in advance.
Willie

[Bob H]

I followed Pete's lead and got jets from carbjetkits.com earlier this year.

When I got my OEM gasket set for carbs from Partzilla they were labeled for 700s and I learned that the bikes share the same carbs after fairly extensive review of carbs on 700s and the late model 750 (91-2003)

As a California bike it was very lean with 110 main jets. I followed the carbjetkits.com recommended 115 main, and although the low speed jets looked fine I took their recommendation and replaced them (stock size).

My needles were fine, but I found small "slits" (tears) in 2 diaphragms. I had to hold them up to a light, didn't see them at a glance. Paid out the nose for OEM ones from Partzilla because the diaphragms were still available.

Bike runs MUCH better above 5,000 to redline, where it was kind of lazy in that range before.

[Pete in PA]

I've done 3 bikes now with carbjetkits.com all work great. Instead of $100+ you can do a 4 cylinder for $25.

No drilling of the slide (bad idea)

Even if the bike is stock, it's still lean from the factory due to emissions. Lots of room for improvement.

[Willie]

Thanks Pete! JUST the info I was hoping for. Having looked at the choices in their jet kits, I noticed that for another $30 or so, you can purchase the "Ultimate Jet Kit" that includes larger pilots as well. Am I correct that you went with the standard kit and didn't replace the pilots? Also, is your 750(?) bone stock like mine is?

[Bob H]

...I noticed that for another $30 or so, you can purchase the "Ultimate Jet Kit" that includes larger pilots as well.

Not Pete here - but I wanted to point something out.
If you go on the carbjetkits site, enter your Honda 700s, there is an "Ultimate" jet kit that mentions larger pilot jets.

BUT IF YOU DO THE JET CALCULATOR, and everything is STOCK, it will tell you to use the stock size pilot jet (which is what I did personally, just so they would be immaculate). If you had aftermarket exhaust and intake, that is what the worksheet - calculator takes into consideration.

To put it another way, I paid the price for the "Ultimate" Jet kit @ $55 and got 4 mains, 4 pilot, but the pilot jets were stock size. You can spend less and just get the main jets.

Here are the results of telling the carbjet site calculator you have a stock 700s

[Willie]

I meant to edit my post to state that the pilots in the Ultimate kit were that same size but didn't. Fwiw, I emailed  carbjetkits.com last night asking why they recommended replacing the stock pilots with the same size but have not heard back from them. It's not like the jets wear out.
I'll update this post with their response if I get one. If not, I'll be ordering the regular kit and go with that.

[Bob H]

It's not like the jets wear out.

Agreed. I ultrasonic'ed all parts, and when it came to replacing those smaller jets I felt like I really didn't "need" them.

If you were in the business of providing jets to others, and had to answer the phones from people who bought old non-running bikes, or just stored over the winter without running or draining fuel... you may not want to assume that every customer will have an ultrasonic cleaner and the jets are cheap enough to just replace them.



The Carbjetkits.com parts are made by Keihin, same mfg as original.
When I was sourcing my parts in March 2023, initially I bought the cheap stuff on Ebay.
The rebuild kits had tons of gaskets & O-rings and jets.

Between the time I ordered the cheap kits and their arrival, I was reading about how some people found that the fuel rail O-rings were the wrong size - and that was one of the reasons I was redoing my carbs again after doing them 10 years ago. The would leak if I drained the carbs and stored the bike while out of town, upon my return. When I would put in new fuel to the dry system, the old "shrunken" fuel rail O-rings would leak for a few days, then stop.

So I ordered OEM gasket sets, and alternate jet kits. When the cheap junk arrived, the jets had zero branding on them. They "looked" OK but after lots of hours of labor I was not about to put some unbranded garbage into my carbs.

When I researched Keihen, confirming their logo, I checked out what they have been doing since the world has moved on from Carburetors https://www.keihin-na.com/

They make a lot of fuel injection systems, bikes and cars. Just yesterday in a parking lot I was admiring a newish Triumph Bonneville, noticed the Keihen logo on what appeared to be carburetors. Looked closer, it was an injection system (wires going to them) designed to look just like old school carbs. My point is that I trust replacement parts from Keihin, they are not asleep at the wheel.

[Pete in PA]

I suspect they want you to get new pilots because it can be hard to clean that tiny hole without making it bigger.
Heck, it's hard to even look through or get anything through to know it's clean.

My 92 750 NH is bone stock except rejetted. 1 size bigger mains and 1 washer under each needle.
BIG improvement in cold starting and overall power. No more header bluing.

[Willie]

Very informative responses, guys, and very much appreciated. I took delivery of my '85 700S yesterday and, as is my routine, made a list of items to attend to. I think the sensible thing to do, with regard to the carbs, is to see how it runs to begin with. Always nice to have a baseline to compare with.
So, after performing all the routine maintenance, I think the 1st upgrade will be to replace the brake lines with braided SS.

[mollusc]

Replacing the brakes lines (and clutch too -- it's hydraulic) is definitely a big improvement.  I'd recommend new plugs and wires as the next step.  Wires are often overlooked, and they made a HUGE difference on my own 700S.

[Willie]

Hadn't thought about replacing the wires but that's a good idea. What brand wires did you go with and were they made to size or did you make up a set yourself?
Speaking of ignition, I'll be comparing voltage at the coils with the voltage across the battery terminals in case a coil relay mod is needed.

[Larry Fine]

Speaking of ignition, I'll be comparing voltage at the coils with the voltage across the battery terminals in case a coil relay mod is needed.

Instead of making two separate measurements, just measure from battery + to coil + with the engine running.

[mollusc]

I just used a set off eBay.  I got 'em in red since that matches my bike.  The coil end is unfinished and screws into the existing caps.

[Willie]

Instead of making two separate measurements, just measure from battery + to coil + with the engine running.

Never thought of that. I'll do both and see if there's a difference. If there is a difference, I'll know what it's getting during start up.

[Larry Fine]

It's what we electricians call a fall-of-potential measurement.

You're measuring the voltage drop along the circuit under load.

It's also a troubleshooting method across fuses and switches.