The Honda XL (and other vintage singles) thread!

[Mr. Ray]

Originally Posted by jitterymonkey

Should start & run with a dead battery.
headlight/tail light should also work with a dead battery... after it's running.

It never has in the time i've owned it. As far as I know a 1974 xl175 (and maybe all the 175s) need a battery to start and run.

If I'm wrong maybe there is another method to starting these once the battery is dead or there is some tip someone can offer.

[396]

Yup, it needs a battery to run. Might try a 6v lantern battery to get her going.

[Snr Moment]

Is anyone running a 32mm Mikuni flat side carb on an XL250? I'm looking at getting one, but need some jet/needle info.

[dorkpunch]

Here's a list of carb adaptations I compiled on the xl board... Might give you a good idea of where to start.

link to original post- http://www.oldrice.com/CarbStuff.htm

K, so here's the deal. Every other day someone asks for the stock specs or what carb people have adapted to their XL.
I had some time to kill so I searched the forum for pretty much everything and anything to do with the 250 and 350 carbs, and this is what i came up with. I know there's more people out there with mikuni carbs on their XLs (myself included) and more advice on setting up the stock carb. Lets here it!

Honda XL250/350 Carb Conversions

The general consensus is that the stock carb, when set up properly, is very adequate for every day use. There are, however, some of us that like that teensy bit of extra zip.
Setting up the Stock Carb
The stock settings are as follows:

Item	XL250	XL350
Model (Keihn)	'72-75; 645B'76, '78; 074A	'74-'75; 699A'76; 075A '77-'78; PD01A
Main Jet	'72-75; 120'76, '78; 125	'74-'75; 130'76; 125 '77-'78; 115
Air Jet	N.A.	N.A.
Slow Jet	45	'74-'76; 48'77-'78; 45
Initial Pilot Screw Setting	1 1/4	'74-'76; 1 1/4'77-'78; 1
Needle Jet Clip Position	3rd Groove	'74-'76; 3rd Groove'77-'78; 4th Groove
Float Level	24mm (.945 in.)	'74-'76; 18mm (.709 in.)'77-'78; 14.5 mm (.571 in.)
Idle Speed	1,200 rpm	1200 rpm

For the most part, these settings are very accurate. The only thing that is commonly changed would be the Needle Jet Clip Position. The setting was fairly rich from the factory. To cure the rich setting the needle clip is RAISED one position, to the fourth slot (lowering the needle).
If you are having issues with carburation, be sure the tank, petcock, and carb are all clean and make sure that all of the jets/settings are correct. If you're still having problems or you want a little more oomph, read on!
Adapting a Mikuni Carb to the XL
The most common choice for an aftermarket carb on the XL is the Mikuni VM, usually a 36mm or 38mm for the 350 and a 32mm or 34mm for the 250, although some have used as big as 44mm carbs on modified engines. The following is a compilation of what different people have ended up using on their XL's and how they set them up.
Carb: 36mm Mikuni
Name: smokndav
Engine: cammed 412cc with Xlint exhaust
q6 needle jet
6fj40 needle
35 pilot
for some reason did not get the main (220-230 range?)

Carb: 38mm Mikuni
Name: nh141
Engine: Stock 350 with 1.75 in OD header
Slide 3.5
6F8 needle - clip in the middle position
P5 needle jet
30 pilot jet (35 might be a better choice)
180 main jet - this will probably change when I get my 85mm bored and Web cam engine done.

Carb: 36mm Mikuni
Name: aircanjk
Engine: Stock '75 350
3.0 slide
P5-159 needle jet
230 main
6F8 needle
40 pilot

Carb: 38mm Mikuni
Name: overbore
Engine: 412cc w/megacycle AB cam. Pipe is open w/reverse cone meg
Series 159 P-5 Needle Jet
6F 9 needle
30 pilot
280 main jet
3.0 slide.
clip on needle is in richest position.

"Jetting Kits" from back in the day (thanks Swiss!)
Carb: 36mm Mikuni
Engine: Stock 350
Bill Bell: 3.5 slide
6F8 needle
220 main jet
P5-159 needle jet
35 pilot jet
2.0 air jet.
Jerry Branch:
3.0 slide
6F5 needle
230 main jet
P4-? needle jet
30 pilot
no air jet.
White Bros.: 3.0 slide
6DH3 needle
220 main jet
P8-166* needle jet
35 pilot
no air jet.
Powroll:
3.5 slide
6F8 needle
230-26- main jets
P5-159 needle jet
20 pilot
no air jet.
WB
166 cut to 5mm height (2-stroke style needle jet)

STILL WAITING ON THE SPECS ON PATS 44mm MIK!!!!

[Snr Moment]

Thanks for the info. The jetting problem is that I have yet to see any specs for the 32mm other than what the seller's of the product have them set up with: 200 or 250 main and 45 pilot. The needle specs are Greek to me and I have no idea as to how they match up with the jets themselves.

I've explained to a couple of the vendors that it's going on a 1976 Honda XL250 ridden at 3k feet to 8k feet. 4-5k would be about most of the riding. I'd have to buy a bucket full of jets & needles and play test pilot for a week to sort it out. To add to the confusion, I'm ordering a custom header pipe from XLint and will most likely be putting on a pod filter and an FMF muffler of some sort, so my airflow will be changing quite a bit.

My uneducated guess is that the 200/45 jet combo would work with the air/fuel set up I'm planning on. Maybe even a 200/35 from the looks of the chart.

[neilios]

Ask XLint what they think, they must have had the question asked before?

[Snr Moment]

Rather awkward since they sell a Mikuni VM kit that's jetted to specs, includes extra jets, filter, cables, & throttle. I'm getting a flat slide from another vendor.

[Mr. Ray]

I got it running again! It turns out the brake light switch was shorted out.

I found that out by disconnecting the Magneto and running the bike on battery alone. When the brake switch wires started to melt I realized why fuses were blowing over and over again.

So I disconnected the brake switch on the rear brake and no more issue .

I have ridden it about 20 miles so far and i rode it to work today.

I need to sort out some carb issues now but it does run pretty well.


QUESTIONS:

What is popping on deceleration indicative of?

Shoud the elevation change from PA (800-1900ft) to MA (25-250ft) necessitate different Jetting?

[dorkpunch]

Popping on decel- lean mixture... fairly normal unless it pops A LOT.

[Mr. Ray]

Originally Posted by dorkpunch

Popping on decel- lean mixture... fairly normal unless it pops A LOT.

It's definitely significant. Not one or two pops.....more like the whole time the throttle is closed during the approach to a stop. No backfiring though. Maybe I should richen it up a tad? Don't want to ruin any parts. I'd rather foul plugs.

Off to check stick needle and jet settings and then I'll make adjustments after work.

I'm also going to check the valves today. I am looking forward to that.

[bpeckm]

I don't know about your carbs specifically, but the general "knowledge" on carbs is that, on deceleration, the throttle plate is closed and therefore the only fuel feed is through the idle jets. Therefore the remedy is to "richen" your idle circuit, either through the idle mixture adjustment or through the jet itself....

[Mr. Ray]

Originally Posted by bpeckm

I don't know about your carbs specifically, but the general "knowledge" on carbs is that, on deceleration, the throttle plate is closed and therefore the only fuel feed is through the idle jets. Therefore the remedy is to "richen" your idle circuit, either through the idle mixture adjustment or through the jet itself....

Thanks for the input. I think I am headed for a thorough carb rebuild soon.

I have more questions.

What are you guys who own 175's doing for sprockets? I am having a tough time finding them.

Also,

Does anyone know of a good cable supplier? I need brake, throttle, and clutch cables.

Thanks

[396]

Ray,
I e-bay or bikebandit most everything. That being said, PBISPROCKETS.COM lists 11-15 front & 28-60 rear sprockets for the 175. Likely special order, I don't know what they stock.

[jake28]

Originally Posted by Mr. Ray

Does anyone know of a good cable supplier? I need brake, throttle, and clutch cables.

Thanks

Motionpro.com

[Mr. Ray]

Thanks guys.

I appreciate the help.

Let's start an Xl rally for all of us to ride to.


I vote for one in PA.