74 Honda XL 350 - The Turd

cxman said:
what is it you dont understand about the air screw adjustment out is richer

stock setting is 1.5 turns

Ok that's what I thought. If I turn it all the way in (bottomed out) the bike still idles normal. So down a size or 2 on the pilot?
 
Old Rice has good data on these carbs. http://www.oldrice.com/CarbStuff.htm

If you bottom out and it still idles, then you have a leak.
 
check for vacuum leaks make sure you check the mating surface of the boot to head
 
Time to get this thing ready for Barber, wrap it up and ride it. Re routed the exhaust for the fourth or fifth time. Fitted a Supertrapp so I had to change the pipe a bit. Needs some paint but I'm happy with it.

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Got this slick billet gas cap with a recessed vent tube.

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did you find a 36 yet?
am i going to see you at barber? im in booth f&g 38 right across from the concession stands

i will be there from friday aft till sunday some time
 
trek97 said:
the gas cap is COOOL. Where did you get that?

Came from xb33bsa. He may be banned from here but he's still got a ton of great vintage MX parts lol. Need to grab some vacuum line to run up under the bars.

I actually got it for this Vesco Desert tank I traded Mr. E for at mid-o, which will go on later.

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cxman said:
did you find a 36 yet?
am i going to see you at barber? im in booth f&g 38 right across from the concession stands

i will be there from friday aft till sunday some time

Not yet. Decided to hold off on that for the moment and try and get her running right with the stock carb. I'll be at barber, hopefully I'll be able to grab a cheap one at the swap meet.


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Been a while since I've updated this thread. Been busy with other projects but still trying to get this thing on the road.

I 3D printed a bracket to mount the new TrailTech Vapor speedo. It mounts to the stock gauge bracket and the Vapor bolts on to the bracket from underneath. Eventually I’ll have one printed in metal, but I printed this one at high fill so it should hold up for a while.

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Ran the wires as cleanly as I could and used a band clamp to hold a bracket for the speedo sensor. I drilled a shallow hole and epoxied the magnet between two of the spokes. It seems to pick up pretty well although I have yet to get the thing calibrated.

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I got the bike running well enough and had it out around the neighborhood a couple times. The last time I had it out, I romped on it a bit in the sandy stuff down by the creek and something went amiss. I was able to limp it home but it seemed to be misfiring like crazy and hard to start. I bought a set of OEM Honda points to replace the crappy ND ones I had originally installed and re-set the timing but still hard to start. I plan to go back and check the tappet clearances again to make sure nothing loosened up, and I'll go back and clean the carb again just to be 100% certain the pilot isnt blocked.
 
Ok I got the old girl running again today and changed out the oil. The pilot and main were partially blocked. Bike idles sporadically and barely wants to stay running without running in the idle screw a bit. and the plugs still look fouled even after a ride.

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Have you ridden it enough to break in the rings- Lots of full throttle, no throttle, up hills then down hills dropping the gears to create back pressure, etc etc? Worn rings will cause a 4 stroke to foul plugs, but in your case this motor is a fresh rebuild, so if the rings haven't broken in the same results may apply. You also mentioned way back that you didn't remember the needle position, so you put it in the middle. That should be fine, but have you messed with the needle since and have you changed any jets since rebuilding the carb? I assume you pulled it apart again and blew cleaner through all the ports and jets to insure everything is free and clear. I would also make sure you have fresh ignition and perfect timing. Weak spark and retarded timing will also cause this.
 
yup to breaking in the rings mine smoked like crazy started letting off as i broke it in

i now have probably 150 miles on it im still not using wide open but its clear of even a whisp of smoke till i get

it hot and over 6500 so its coming along nice
 
Yep I have been working on breaking in the rings, haven’t had it up over 3/4 throttle and varying RPMs, always keeping load on the motor.

As far as the carb goes, it’s been cleaned over and over. I rebuilt the ACV as I had it blocked off before. I haven’t messed with any of the jets or the needle at all.

I just replaced points with OEM Honda points and the timing is right on.


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advCo said:
Yep I have been working on breaking in the rings, haven’t had it up over 3/4 throttle and varying RPMs, always keeping load on the motor.

As far as the carb goes, it’s been cleaned over and over. I rebuilt the ACV as I had it blocked off before. I haven’t messed with any of the jets or the needle at all.

I just replaced points with OEM Honda points and the timing is right on.


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It's not keeping loading on the motor, it's putting it on, then taking it off then putting it back on. Full throttle, off throttle, decel and downshift- basically putting pressure on both sides of the rings. That said, if everything else checks out and you can get it to stay running fine, then put some miles on it and see if it improves. Do some proper plug chops. Get on a road with a pocket full of plugs and the necessary tools and get it to top speed- cut it off. Pull the plug and check. Do it in varying ranges of the throttle. Also, what is your air cleaner situation?
 
irk miller said:
It's not keeping loading on the motor, it's putting it on, then taking it off then putting it back on. Full throttle, off throttle, decel and downshift- basically putting pressure on both sides of the rings. That said, if everything else checks out and you can get it to stay running fine, then put some miles on it and see if it improves. Do some proper plug chops. Get on a road with a pocket full of plugs and the necessary tools and get it to top speed- cut it off. Pull the plug and check. Do it in varying ranges of the throttle. Also, what is your air cleaner situation?

Yeah I’ve been keeping varying RPMs and all that. Been pretty meticulous about it since the rebuild.

I’m using the stock airbox with a UNI foam element.
 
advCo said:
Yeah I’ve been keeping varying RPMs and all that. Been pretty meticulous about it since the rebuild.

I’m using the stock airbox with a UNI foam element.
Do you have something you remove the airbox and install to see if that changes things?
 
irk miller said:
Do you have something you remove the airbox and install to see if that changes things?

Like a K&N filter? I don’t. I wanted to keep the intake all stock. I want to put a VM36 on it so I’ll change the intake then.
 
advCo said:
Like a K&N filter? I don’t. I wanted to keep the intake all stock. I want to put a VM36 on it so I’ll change the intake then.
Can be a Uni, just something to run it and see if it fixes the situation. Not suggesting a permanent fix. Could be that your Uni in the stock box is the issue. If it's not getting enough air, then your plugs will foul the same as if you have the fuel mix to high. Speaking of which, where's the fuel mix screw set?
 
irk miller said:
Can be a Uni, just something to run it and see if it fixes the situation. Not suggesting a permanent fix. Could be that your Uni in the stock box is the issue. If it's not getting enough air, then your plugs will foul the same as if you have the fuel mix to high. Speaking of which, where's the fuel mix screw set?

A/F is about 3/4-7/8 turns out. I’m using the stock cage in the airbox, just UNI foam to replace the original element.
 
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