1983 Honda XR 350 Jetting


19 replies to this topic
  • hitech515

Posted June 26, 2010 - 04:49 PM

#1

Greetings,

I just picked up a 1983 Honda XR350 that is stock and in mint condition. I changed the oil and put fresh 91 octane fuel in it and rode it. I noticed that mid to top-end that there is a bit of hesitation. Also the motor seemed to run too hot. I knew that it was time to clean the carbs. I removed them stripped them down and cleaned them very carefully, reassembled set everything back to stock. The bike runs prefectly now and has a nice smooth throttle repsonse in all positions, but it still runs too hot!!! I pulled the spark plug to analyze the color and its just prefectly clean no real color to it. That would indicate that its running a bit lean.

Can anyone recommend how to properly jet this bike based on the following factors? Thanks for your support.

I live in the California Central Valley area
0 to 3000 ft.
Temp 60 to 90 F

Its has dual carbs
- Primary Carb Main Jet is a #112
- Secondary Carb Main Jet is a #105
- Primary Carb Slow Jet is a #45

Air screw opening = 1-1/4

Oil type and weight used:
Castrol GTX 20/50 (non synthetic)

Spark Plug information:
Standard NGK DPR8EA-9

Edited by hitech515, June 26, 2010 - 06:13 PM.


  • dholland17

Posted February 23, 2011 - 08:35 AM

#2

did you ever figure this out? I need to do the same on my 83 xr350. Thanks

  • Kah Ran Nee

Posted February 23, 2011 - 03:28 PM

#3

All the XR and XL350R;s ran very very hot. They come exceptionally lean from the factory. Uncork the intake and exhaust, and up the primary and secondary main jets to 135/110.

  • dholland17

Posted February 24, 2011 - 06:28 AM

#4

What do you mean by uncork the the intake and exhaust? Is there something in the airbox and is the exhaust the baffle?
this being a dual carb model, should I pop the 135/110 in both carbs?
Also, I have an 84 XR250R as well. Any suggestions on the jetting for this dual carb model too to keep her cool.
Thanks a lot!

  • Kah Ran Nee

Posted February 24, 2011 - 11:59 PM

#5

What do you mean by uncork the the intake and exhaust? Is there something in the airbox and is the exhaust the baffle?
this being a dual carb model, should I pop the 135/110 in both carbs?
Also, I have an 84 XR250R as well. Any suggestions on the jetting for this dual carb model too to keep her cool.
Thanks a lot!


Well, it's common knowledge that ALL dual sport motorcycles sold in the USA come highly restricted from the factory. They reduce the amount of air coming in, exhaust coming out, and fuel consumption, to create a quiet, hard to start, hot running, poor running EPA compliant motorcycle.

Remove the airbox snorkle, remove the exhaust plug, re jet to 135 primary 110 secondary, raise the pilot jet up one size, and raise the needle up one clip.

The bike will run better, cooler, and faster. And a bit louder, but not too much.


http://www.google.co...8e4c0cc530c3619

  • dholland17

Posted February 25, 2011 - 08:24 AM

#6

Please excuse my ignorance but what is the pilot jet inthis diagram?
http://www.cheapcycl...assemblies/4703

Also, what are the primary and secondary jets int he diagram? I see the main jet is #44 in the diagram. I assume that's the primary jet. Just not sure what the secondary is.

As for the airbox, which parts should I rip out to let it breathe: 12 and 13:
http://www.cheapcycl...assemblies/4699


Lastly, the muffler. Removing part #7 all that's needed:
http://www.cheapcycl...assemblies/4723

Can't thank you enough!

  • Kah Ran Nee

Posted February 26, 2011 - 08:58 AM

#7

Please excuse my ignorance but what is the pilot jet inthis diagram?
http://www.cheapcycl...assemblies/4703

# 46

Also, what are the primary and secondary jets int he diagram? I see the main jet is #44 in the diagram. I assume that's the primary jet. Just not sure what the secondary is.

It doesn't show it. It's in the same place on the other carb.

As for the airbox, which parts should I rip out to let it breathe: 12 and 13:
http://www.cheapcycl...assemblies/4699

You need to have a minimum 3" x 3" opening in the top of the airbox.


Lastly, the muffler. Removing part #7 all that's needed:
http://www.cheapcycl...assemblies/4723

Yes, #7. Remember, the stock headers may have a 'restriction band' welded inside at the inlet, and that should be ground out, as well.

Can't thank you enough!



You should go and post on the VINTAGE forum for more details

  • dholland17

Posted March 15, 2011 - 06:11 AM

#8

Is # 27 in this diagram th epilot jet? Thanks
Just sent my 84 XR350 out for a bore with a Wiseco piston (.5 oveR) and want to grab the right jets at the dealer too. I'll grab the 135/110 mains but not sure hwat to ask for regarding the pilot size?? thanks

http://www.cheapcycl...assemblies/4703

  • XRMD

Posted March 17, 2011 - 08:32 AM

#9

Well, it's common knowledge that ALL dual sport motorcycles sold in the USA come highly restricted from the factory. They reduce the amount of air coming in, exhaust coming out, and fuel consumption, to create a quiet, hard to start, hot running, poor running EPA compliant motorcycle.

Remove the airbox snorkle, remove the exhaust plug, re jet to 135 primary 110 secondary, raise the pilot jet up one size, and raise the needle up one clip.

The bike will run better, cooler, and faster. And a bit louder, but not too much.


http://www.google.co...8e4c0cc530c3619

how can i tell which jet goes in which carb? iIcurrently have the 112 with the 'brand symbol "on the left side and the other on the right. I put the jet with the brand symbol on the left. but when i took the carbs off i noticed that the right exhaust out-put from the engine has more carbon build in it (Blackened) is that the side the bigger jet should be on?

my direction is me on the bike so my right would have the exhaust`

Thanks!

  • dholland17

Posted March 18, 2011 - 05:39 AM

#10

The left carb is the main so the larger jet goes in that one. For a 350 the suggested rejetting is to 135 left and 110 right. I need to buy some jets myself. Looks like if i ordered the jet for the XR500 it would suit my needs.

  • XRMD

Posted March 18, 2011 - 11:47 AM

#11

The left carb is the main so the larger jet goes in that one. For a 350 the suggested rejetting is to 135 left and 110 right. I need to buy some jets myself. Looks like if i ordered the jet for the XR500 it would suit my needs.

The bike whole top end has been rebuilt recently and has ran perfect till now. i cleaned the carb and it runs a lil better but now there's a resistance when it gets to the middle it takes off.
And it doesn't start as easy as it did before
Any Ideas?

  • XRMD

Posted March 18, 2011 - 02:59 PM

#12

The left carb is the main so the larger jet goes in that one. For a 350 the suggested rejetting is to 135 left and 110 right. I need to buy some jets myself. Looks like if i ordered the jet for the XR500 it would suit my needs.




so the one facing the fuel-cock side is the main? and thhe other one on the exhaust side is secoundary?

  • dholland17

Posted March 21, 2011 - 09:30 AM

#13

correct

  • JeemboNC

Posted May 31, 2011 - 08:29 AM

#14

Just bought a stock '84 XL350R to run around (70 mpg!) and carry on my boat (at 300# it can be lifted by my dinghy davit) for transport when cruising. Fairly crisp and I have put another 700 miles on it (had 4700 when bought) with and oil change and other light maintenance. Experienced dirt biker (enduros w/in New England Trail Riders Assoc (NETRA) on an IT175 (still have it) with the Minutemen Trail Riders north of Boston in the '80s), but not much experience with thumpers. Been searching and lurking and have several questions to put to this group for some much appreciated help advice:

1. valve noise seems high. local Honda shop manager said seemed a little noisy, but not bad (I don't think he was calibrated on a bike of this vintage). Checked and reset to .002" and .003" and sounds the same. Somebody suggested 20W50 oil - good idea? Cam chain slap does not appear to be the problem.
2. Re oil, I seem to be consuming it. No smoke, so maybe blowing it out? Typical?
3. Air filter crumbling, cleaned it but needs a new one. Stock or aftermarket? Source? I will probably use only 10% off road. I'll open up the air box, but do not want any more noise and would prefer to leave the exhaust core intact.
4. Stock Yokohama tires work surprisingly well, but I am thinking more street oriented tires. They buzz a bit at some speeds and have some sidewall cracking (age). Suggestions? I'm not a tire snob - value-priced is okay for me. Do NOT want to relace front wheel - will stick with stock 21". I do not ride hard (bad accident on my now-gone VFR keeps me cautious).
5. I feel 'surging' at 60 mph (guessing ~half throttle). Cannot tell if engine is missing (valves and wind too noisy). Does not appear to be buffeting. Rejet? I'll do after a filter change. Apparently raising the needle and Apparently 130/110 jets are the hot setup (I don't know squat about Keihan carbs (Mikuni guy))? Much loss of fuel economy? This things seems to run way hot, too.
6. Somewhere I found that the plug wire has a resistor in the cap (for TV/radio interference)? Should I remove it?
7. to cut down on the buzziness am considering upping from 14t to a 15t front sprocket (same chain and rear - both in good shape). Should reduce ~300 rpm at 60. Good idea? Is there case clearance? Competitively priced source? Top gear roll-ons are NOT arm stretching, so I might have to drop to fifth in a passing situation (kinda do now).

Thanks to everyone. I'll kick in when I can to help others. Jim

  • dholland17

Posted June 01, 2011 - 05:29 AM

#15

My 84 XR350 is noisy too and the 20W50 oil didn't really help much. It's only noticeable at idle so I'm not too concerned at this point.
If you uncork your exhaust it will flow quicker and keep the head on your bike cooler. The rejetting will help too. I went with the 130/110 when I bored my piston out .50 over and used a Wiseco piston kit and I love it. Bike rips!
I'm in New England too. Have you heard of the King Philip Trail Riders out of Wrentham?

  • JeemboNC

Posted June 01, 2011 - 08:37 AM

#16

Sure, I remember the KPTRs. There were some very active clubs back then (early '80s) - the Minutemen claimed North Reading, I think. I lived in Marblehead. VERY different riding from the open California riders that were in all the bike rags (except Dirt Rider tried to be more East Coast oriented). Will never forget Kevin Hines whoop-whooping and then blowing past me in the rocks like I was walking - very demoralizing! Fun time in my life.

I'm gonna do a trial with the exhaust opened up, but as I ride mostly on the street I don't want to be too loud. I also think I'll shim the needle to see what it does (told there are no circlip options on the XL carbs) before I rejet. Jim

  • JeemboNC

Posted August 02, 2012 - 07:11 AM

#17

update - I now have a 38T rear that I ordered with new 14t front and o-ring chain. Knocks ~300rpm out of revs at 60 mph. but still cannot pull top gear to redline. Actually, just as fast in 5th as 6th. I expected that.
Bike ran great until it gets hot (stall at high power rollon, detonation and likely cooking the oil). Changed my left carb jet to 127.5 (they did not have a 130). This has cooled the engine considerably and reducing the pinging but at ~5% loss of fuel economy (expected). BUT - when I open the throttle too fast (not a snap) at higher speeds/power - it burps. Too lean or too rich? Opening the choke/enrichment does not help. I did not change the needle position, still has stock air filter, stock exhaust but took off the cover used to blow out carbon, right carb stock (110 jet). Any advice from the gurus? Thanks, Jeembo
BTW - I get stopped a lot (only guys, dammit!) about this bike - everybody seems to want it!

  • ohio rusty spokes

Posted December 04, 2012 - 02:22 PM

#18

Ooops wrong fourm

Edited by Ohio Rusty Spokes, December 04, 2012 - 02:27 PM.


  • hitech515

Posted December 29, 2013 - 11:59 AM

#19

Greetings,

 

 I know it has been quit some time since I posted my original question in regards to jetting for the dual carb XR350. I have created an informational video series for rebuilding, cleaning, and jetting these bikes. I posted these videos on YouTube. I hope you all find this information useful. Please feel free to comment. I value your feedback. Thanks. 

 

http://www.youtube.c...aHB65qhLMG96lwQ

 

-Jason



  • Michel

Posted April 19, 2014 - 07:32 PM

#20

Here we go another XR350, slow and main jet mods with data, swapped the 45 to a 48 slow jet, still hard to start when hot, but instant cold start.... Aaaack, the engine was in the 250F temp after a few hours ride in the sierras 60-70F day.... Installed the 50 slow jet and 128 main to replace the 112 on the primary carb.... same ride today... and start anytime on first kick cold or hot... and the best the crankcase and cylinder temp is a cozy 205F.

I did not deal with needle height, this is a camping trip, nor did I bother with the secondary carb....

Forgot, this is from 3 to 6000' ride.


Edited by Michel, April 20, 2014 - 07:57 AM.





 
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