Topic: How much does rejetting cost?

[jamesv220820]

i have a 350f im restoring and some parts i am going to order say that the bike will most liekly have to be rejetted
still new to restoring how much should that cost?
and should i rebuild the carbs before i get the rejetting done?

[moham]

What parts require re-jetting? If you are serious about restoring, then rebuilding carbs will be at the top of the list. Plan to spend a minimum of $50 to rebuild carbs.

[TwoTired]

A "restoration" to stock should only require the stock components, including the jets in the carbs.

[jamesv220820]

aftermarket exhaust and K&N air filters say rejetting might be required

[TwoTired]

aftermarket exhaust and K&N air filters say rejetting might be required

Then you aren't restoring the bike.  You're just returning it to operating condition.  Nothing wrong with that, though.
Open exhaust and filtration that raises the carb throat pressure, usually means larger metering orifices/adjustments int the carbs.
If the carbs are gunked up, then they need cleaning.  If they are clean, then it's just adjusting and jet size changes.  Look inside to determine the cleaning needs.
Most likely you'll have to richen up the idle, to get descent throttle response from down low (perhaps only with the idle bleed screws), possibly raise the slides needles, and maybe a larger main jet.
If you aren't using a dyno and getting a fuel map, then find a test track, some extra spark plugs, and learn to read spark deposits for combustion conditions.  Then test and try, till it works as you wish it to.  Takes patience and perseverance.

Cheers,

[333]

+1 on the reading of the plugs.  And you are going to have a harder time of it because of where you live.  The higher altitudes compound the issue.  Less air will affect the jetting.  But if the bike has spent it's whole life in your area, it may not still be stock.  The jets have numbers on them, so it will be easy to tell.

[jamesv220820]

cool thanks for all the help

james

[cb650]

You can do it yourself for the price of jets.  Or you can take it to a shop that charges a bunch for a semi good job. 
Also for the altitude here regetting would be better.  Regardles of what was stock.  Dont let the "experts" tell you bigger at our altitude either.

[TwoTired]

You can do it yourself for the price of jets.  Or you can take it to a shop that charges a bunch for a semi good job. 
Also for the altitude here regetting would be better.  Regardles of what was stock.  Dont let the "experts" tell you bigger at our altitude either.

The only caveate I have about this, is that ideal jetting for altitude usually means the engine runs lean at sea level.  No issue around town, but if you take a trip...  You might wind up with a hot, melted motor.

Cheers,

[cb650]

If you look at his location he is in denver colorado.    Mile high+++++   lowest part of the state is 3500.   Less air less fuel = smaller jets.  Stock jets are for sea level.

[masonryman]

I am getting ready to try this myself, I just bought 5 sets of jets and 2 sets of exhaust gaskets from Z1 I put pods and a custom exhaust on a build project and have not even started it yet.

The jets are just a little of $1.00 each at z1

Good luck

[friedfish80]

You got a link for where you picked up your jets? 

Does anyone have any experence with the glass sighted spark plug for tuneing. The site that sells the Morgan carb tune sells this sparkplug that's glass so you can see in the combustion chamber and "tune" by the color of the fire in the chamber. Is there any truth to this method?

[jamesv220820]

If you look at his location he is in denver colorado.    Mile high+++++   lowest part of the state is 3500.   Less air less fuel = smaller jets.  Stock jets are for sea level.

cool ya the bike will stay in denver for awhile probably 6 months then ill send it down to tampa florida or ride it down there not sure yet so i guess i would have to get it rejet again but for now ill rejet it for best performance in a high altitude

[jamesv220820]

If you look at his location he is in denver colorado.    Mile high+++++   lowest part of the state is 3500.   Less air less fuel = smaller jets.  Stock jets are for sea level.

smaller huh, well i was just was gonna order a keyster carb rebuild kit so are you saying those jets are gonna be a waste of money ?

http://cgi.ebay.com/ebaymotors/FOUR-Honda-CB350-F-Carb-Rebuild-Kits-Keyster-Kit-CB350F_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem110348966273QQitemZ110348966273QQptZMotorcyclesQ5fPartsQ5fAccessories

thanks

[mrbreeze]

If you look at his location he is in denver colorado.    Mile high+++++   lowest part of the state is 3500.   Less air less fuel = smaller jets.  Stock jets are for sea level.

Stock jets are for sea level...............so when you take a stock bike with stock jets up to the mountains......just how high can you go before you have probs. with air/fuel mixture?
Oh.......and the main question.........How much does it cost to jet?
My experience tells me its alot less if you know what you're doing.The expense of working on these bikes comes two fold.....Parts and Time!!!!

[masonryman]

www.z1enterprises.com


You need to clean your carbs and see how it runs, and find out what size jets are in it

[jamesv220820]

www.z1enterprises.com


You need to clean your carbs and see how it runs, and find out what size jets are in it

very nice site thanks masonryman i was wondering where i could find the decals theyve got alot of stuff for em

thanks

james

[TwoTired]

Stock jets are for sea level.

What makes you say that?  Do you have a Honda directive for that statement?

Given the ideal mixture ratio changes with temperature, altitude, and humidity, and Honda sold to everywhere in the world, why would they set up the stock bike for ideal operation at only sea level altitudes?

I always thought they set up stock ratios for about 2000 Ft as a reasonable compromise.  So, it runs a little leaner at lower altitudes, and a bit richer at higher altitudes.

Is there a Honda directive I missed?

[333]

It seems to me that the early micro fiche actually stated something about altitude regarding the "optional" jets.

[dummkauf]

I haven't seen anyone respond with prices yet, but jets should cost you about $20.  I've seen jet kits running upwards of $100, however if you know what size you need, just go to a honda dealer and get just the sizes you need and skip the kit.

I just picked up a main and a primary for my Buell this afternoon and it only cost me $5.36 for both, and that was Harley dealer prices, probly could've gotten them for $3 online somewhere .....note that this is a thumper so I only needed one set as opposed to 4 for a CB.

[heffay]

Stock jets are for sea level.

What makes you say that?  Do you have a Honda directive for that statement?

Given the ideal mixture ratio changes with temperature, altitude, and humidity, and Honda sold to everywhere in the world, why would they set up the stock bike for ideal operation at only sea level altitudes?

I always thought they set up stock ratios for about 2000 Ft as a reasonable compromise.  So, it runs a little leaner at lower altitudes, and a bit richer at higher altitudes.

Is there a Honda directive I missed?

no... but there is a class on tact that you missed.   

and yes... i would agree that if you live at or in the rockies and intend to ride in them... you must constrict the flow of fuel in order to match the restricted air.  its a simple formula.  i've never read a directive for anything, i don't think... although, i have read many manuals and suggested carb settings for dealing w/ altitude.

also, 2000 feet above sea level isn't even close to how high we are!!!   

[TwoTired]

no... but there is a class on tact that you missed.   

Attending class, and absorbing covered material are two different things... as is clear you've experienced.

and yes... i would agree that if you live at or in the rockies and intend to ride in them... you must constrict the flow of fuel in order to match the restricted air.  its a simple formula.  i've never read a directive for anything, i don't think... although, i have read many manuals and suggested carb settings for dealing w/ altitude.

also, 2000 feet above sea level isn't even close to how high we are!!!   

 My airplane is carbureted, and normally aspirated, as is the SOHC4.  It has a mixture control knob in the cockpit that is pilot operated.    The operator's manual clearly states that mixture control leaning procedures begin above 5000 feet.  More importantly, it stipulates full rich setting for decent below 5000 ft.
The Cessna 152, favored as a primary trainer to develop operational habits of pilots, uses 3000 Ft as the point when mixture control becomes significant, above; lean for peak RPM, below; full rich.

Forgetting this control on descent (leaving it leaned while landing) has danger in the event of a go around.  Landing approaches are made with little or no power.  A Go-around requires full power, and if the engine is still leaned for 7000 ft altitude, you get no power.  (BT,DT) There are quite a few dented dashboards where the pilot has rammed the mixture control full forward, to regain engine power.  And then, a permanently etched action made into the mental checklist of the pilot for decent procedures. (Brown pants are advised during pilot training.)

Anyway, despite the extremist aura that you wish to project, 5000 ft isn't extreme for thousands of airplanes that routinely fly above that altitude, albeit WITH a mixture control.

The point is, unless you absolutely must have maximum power, altitude effects don't really become interesting until 4000-5000 ft altitudes are achieved.  And as I pointed out, ideal mixtures at or above 5000 are NOT good for lowland hot operation.
So, if you tune your bike for high altitudes, just remember to keep it there.  And, don't be surprised if a bike that's peak tuned for altitude suddenly stops working ($) while driving toward Florida.  A bike tuned for Florida, will likely tend to foul plugs in Denver or above.  But, replacement plugs are way less $.

Do what you want.  Just be aware of what you are doing.

Cheers,

[heffay]

but you didn't say that in the beginning two tired.  not at all.


oh, here, sory... i almost forgot. 

[friedfish80]

Ok let's play nice around her

[heffay]

just banter... maybe 2tyred knows that by now.
if not he's a lost cause. 

either way he disburses valuable information like its, well, valuable.   

choke levers work well in the mountains... as does rejetting.

i would pay someone 50 bucks to do it for me as i looked over their shoulder... if they really needed the money.   otherwise, i'd just save myself the trouble and money.

[mlinder]

If I remember correctly (from reading a couple things, though couldn't point you to said articles now), the first SOHC's were, in fact, jetted for sea level, Jetted for the roads near where they were built.

The k0 and k1 750's do run a tad rich, even a few hundred feet above sea level.
I can't say, and wouldn't know, if later jetting changes were made at the factory to be better for the higher altitudes that the bikes would be sold at, or for some other reason.

General rule of thumb, at least to start at, is about half (5) to three quarters (7.5) of a step down in size per 5000ft (for main jets. I'll talk about pilot jets a bit later), with erring on quater (2.5) to half (5) as the jet sizes get smaller (smaller than about 110's)
That is, if you have 98's, and are going up 5000 feet, 93's would be a good place to start.
However, you are running pods and an open(ish) exhaust. This makes things more difficult. There are also some rules of thumb for jetting for these. I posted one at some point on this forum, lemme see if I can find it...

Eh, something like this:

up 2.5 jet size for pod (K&N, Uni, generic) filter (single inside the air box)
up 2.5 jet size for drilling the airbox
up 2.5 jet size for both single K&N and drilled air box
up 5 on jet size for individual pod filters
up 5 on jet size for 4 into 1 exhaust

up 2.5 pilot jet size for every 3 (7.5) main jet size increase

Add up jet sizes and subtract 2.5

so, lets say individual pods (5) + a 4 into 1 (5) and subtract 2.5. That means a good place to start is 7.5 up

Again, depends on the bike, but this is just for starters.
But what this means is that pods and 4 into 1 may give a very close to correct jettings setting without changing your jets. Or if they arent right, they are very close (within 2.5, probably.. )

Now, I can't remember offhand, but I thought the cb350f stock main jets were 98's? (97.5, I guess..)

If so, that means 97.5 - 5 (for altitude) + 7.5 (pods and 4 into 1) = 100.00

As far as pilots go, it's been different for every damned bike I've worked on. Some bikes don't want any change on jet size, and don't need any air-screw adjustment. Some need minor enriching at the air-screw (and by minor, I mean 1/16 to 1/8th turn). Some may need just the next size up in pilot, but I've only seen this happen on bikes with larger displacement cylinders and much larger carbs.

Good luck.

[mrbreeze]

OK class..................so what have we learned?........Carbs suck a$$!!!!!!!!........Right? So......anyone got any bright a$$ed ideas how we can incorporate FI to our bikes??
It is a bit of trial & error getting things right when there are so many varialbles but like Lloyd said.............it does take a fair amount of patience.........hang in there and when you get it right.........you won't be able to wipe the smile off your mug!!!!!!!

[jamesv220820]

wow this is a little confusing well i guess what im gonna do is just buy a carb rebuild kit and do that then install all the other parts (K&N air filer system, & new exhaust) then take it somewhere and get new jets then save the brand new ones that i got in the rebuild kit and put them back in if the bike goes down south

good idea right i think so

cuz now i know the parts for rejetting aren't expensive (or no that expensive) but the labor at a bike shop i probably shouldnt ask

[mrbreeze]

The labor will knock your d#@% in the dirt and probably will be done by someone that doesn't really know WTF they are doing. I have 3 or 4 different sized jets that were $7 a pop(X4).You are better off doing them yourself.Plan to rebuild the carbs.......see what you have to start with.I wouldn't even worry about the pilots.The KN's & exhaust are gonna force you to go to fatter jets.You will have to change your needle settings to get your mid range throttle straightened out.Plug chops and a good ear will tell you if you are getting farther away or closer to where you wanna be.
I should be the poster boy of this sh!t!!!!!!!!.......I have had my bike with so many different configurations at different altitudes...........Keep at it my friend..........or just give up and send me your bike!!!!!!

[754]

IMO almost any bike jetted for sea level, should never foul the plugs being run at 5000 f..

[OakBehringer]

I'm surprised that no one has mentioned how short on luck people typically are when trying to re-jet after going to pods on a 350F. Search around our forum, you'll find that it's almost always a losing scenario with this bike and the 400F (same carbs). I was going to go to pods on my own, because I HATE trying to get that damn air-box between the stock carbs and filter, but after doing researched I decided against it.

[TwoTired]

IMO almost any bike jetted for sea level, should never foul the plugs being run at 5000 f..

I tend to agree. (although the word never is a bit extreme)

But, if you look at Colorado topology, and go west of Denver, where the winding roads are...

Cheers,