Carb Adjustment 99 450ES - Honda Foreman Forums : Rubicon, Rincon, Rancher and Recon Forum

99trx450es · 12-03-2011, 09:54 PM

99 TRX 450 ES

I just overhauled the carb with a new Moose Kit - 130 Main / 45 Slow jet / Needle at 3rd etc.

Can someone provide me some basic carb tuning instructions ? I have played with the Slow jet starting at 2.75 turns and going in an out and it's not running well in the 25-50% range with an ocational backfire through the carb.

What all can I try ? This machine is new to me --- so I would not rule anything out ... valve adjustment needed etc....

Thanks

scottl1346 · 12-03-2011, 10:02 PM

the air/fuel mixture screw should be 2 5/8 turns out.

rich450es · 12-03-2011, 10:14 PM

yup base line is 2 5/8 turns out but i think the carb is still dirty . how did you clean it ? with just carb clean ? did you blow all the pasages with compressed air ?
look at this thred
Home Brewed Carb Cleaning

99trx450es · 12-03-2011, 11:13 PM

The Carb was clean when I got it from ebay. I still dunked it in carb cleaner -- the gallon can from autozone, and then ran Gumout through it, and used compressed air. The I added all the new brass from the kit with all new jet needles, jets, seals, ect.

This puppy (carb) is clean ---- still backfires thou.

Should I move the Jet Needle setting to one more richer ?

Thanks.

**toodeep** · 12-03-2011, 11:52 PM

Does it run better if you apply the choke some? If so raise the needle a notch and see what it does.

scottl1346 · 12-04-2011, 02:51 AM

are you sure the problem is with the carb and not a loose header nut, bad header gasket, crack in the pipe or loose/rotted baffles in the exhaust?

99trx450es · 12-04-2011, 08:40 AM

The exhaust does sound louder than normal like it needs "repacked". It does push alot of air through it if you stand behind the muffler.

What can I try to be sure I need the muffler fixed / replaced ?

Why would a restrictive muffler cause a backfire through the rear of the carb ?

scottl1346 · 12-04-2011, 01:43 PM

are you running a stock or aftermarket exhaust. take a small hammer and tap the outside of the exhaust if you hear thing moving around or rattling then its bad. stock exhausts cant be repacked theres nothing in there but baffles. it causes backfiring because there no back pressure and it makes it run really lean condition

Relheok · 12-05-2011, 04:02 PM

All foremans push lots of air out the back. I'd do the exhaust check but a lot more gremlins to be found by trouble shooting the carb

99trx450es · 12-10-2011, 05:36 PM

Here's where I am. I ran the bike until warm and kept the choke on 100%. The Bike runs great with no backfire in carb or exhaust upon acceleration or deceleration. I can hold it full throttle and it appears to be hitting a rev limiter, if it has one. At full throttle is appears to be "bogging" a bit. The bike idles fine with full choke. I probaby could easily have a great ride using it in this condition.

When I take the choke off, I get the backfires starting in the carb and exhaust. Every minute or so at idle -- the engine dies like it was starving for air/gas.

Should I clean this carb once again and place the old "Honda" Brass back in afterward ? I am not sure how good the new Moose Carb kit is ?

Shoudl I raise the needle one notch first ?

12-03-2011, 09:54 PM	#1 (permalink)
99trx450es Honda Rider Join Date: Nov 2011 Posts: 28	Carb Adjustment 99 450ES 99 TRX 450 ES I just overhauled the carb with a new Moose Kit - 130 Main / 45 Slow jet / Needle at 3rd etc. Can someone provide me some basic carb tuning instructions ? I have played with the Slow jet starting at 2.75 turns and going in an out and it's not running well in the 25-50% range with an ocational backfire through the carb. What all can I try ? This machine is new to me --- so I would not rule anything out ... valve adjustment needed etc.... Thanks

12-03-2011, 10:02 PM	#2 (permalink)
scottl1346 Honda Red Wing Rider Join Date: Apr 2009 Location: mass Posts: 2,219	the air/fuel mixture screw should be 2 5/8 turns out. __________________ 02 foreman 450 ES 2 inch HL lift kit super ATV front disk brake conversion 27" zillas on OEM wheels 14% gear reduction HMF ECO system exhaust diamond plate bash plate and cv boot guards Super-winch 2500lb custom LED brake lights

12-03-2011, 10:14 PM	#3 (permalink)
rich450es Honda Red Wing Rider Join Date: Nov 2010 Location: tooele, utah Posts: 15,256	yup base line is 2 5/8 turns out but i think the carb is still dirty . how did you clean it ? with just carb clean ? did you blow all the pasages with compressed air ? look at this thred Home Brewed Carb Cleaning __________________ 2000 foreman 450 es-s the f**king pig SOLD! honda forum.com stickers for sale .....pm me for details !

12-03-2011, 11:13 PM	#4 (permalink)
99trx450es Honda Rider Join Date: Nov 2011 Posts: 28	Carb The Carb was clean when I got it from ebay. I still dunked it in carb cleaner -- the gallon can from autozone, and then ran Gumout through it, and used compressed air. The I added all the new brass from the kit with all new jet needles, jets, seals, ect. This puppy (carb) is clean ---- still backfires thou. Should I move the Jet Needle setting to one more richer ? Thanks.

12-03-2011, 11:52 PM	#5 (permalink)
toodeep Administrator Join Date: Aug 2007 Location: south dakota Posts: 8,636	Does it run better if you apply the choke some? If so raise the needle a notch and see what it does. __________________ A 420 and 300 with some stuff...

12-04-2011, 02:51 AM	#6 (permalink)
scottl1346 Honda Red Wing Rider Join Date: Apr 2009 Location: mass Posts: 2,219	are you sure the problem is with the carb and not a loose header nut, bad header gasket, crack in the pipe or loose/rotted baffles in the exhaust? __________________ 02 foreman 450 ES 2 inch HL lift kit super ATV front disk brake conversion 27" zillas on OEM wheels 14% gear reduction HMF ECO system exhaust diamond plate bash plate and cv boot guards Super-winch 2500lb custom LED brake lights

12-04-2011, 08:40 AM	#7 (permalink)
99trx450es Honda Rider Join Date: Nov 2011 Posts: 28	Carb The exhaust does sound louder than normal like it needs "repacked". It does push alot of air through it if you stand behind the muffler. What can I try to be sure I need the muffler fixed / replaced ? Why would a restrictive muffler cause a backfire through the rear of the carb ?

12-04-2011, 01:43 PM	#8 (permalink)
scottl1346 Honda Red Wing Rider Join Date: Apr 2009 Location: mass Posts: 2,219	are you running a stock or aftermarket exhaust. take a small hammer and tap the outside of the exhaust if you hear thing moving around or rattling then its bad. stock exhausts cant be repacked theres nothing in there but baffles. it causes backfiring because there no back pressure and it makes it run really lean condition __________________ 02 foreman 450 ES 2 inch HL lift kit super ATV front disk brake conversion 27" zillas on OEM wheels 14% gear reduction HMF ECO system exhaust diamond plate bash plate and cv boot guards Super-winch 2500lb custom LED brake lights

12-05-2011, 04:02 PM	#9 (permalink)
Relheok Honda Red Wing Rider Join Date: May 2010 Location: Northeast Kingdom, VT Posts: 763	All foremans push lots of air out the back. I'd do the exhaust check but a lot more gremlins to be found by trouble shooting the carb __________________ 2002 Foreman 450ES - 2" HL Lift - 27" Dirt Devil XT - LT2000 Superwinch - Moose Utility Seat - K&N Air Filter - 5582 Miles and counting! 2003 Rincon 650 - Warn Winch - 26" Interco Swamp Lights - 3412 Miles and counting! 2003 Recon 250ES SOLD

12-10-2011, 05:36 PM	#10 (permalink)
99trx450es Honda Rider Join Date: Nov 2011 Posts: 28	Here's where I am. I ran the bike until warm and kept the choke on 100%. The Bike runs great with no backfire in carb or exhaust upon acceleration or deceleration. I can hold it full throttle and it appears to be hitting a rev limiter, if it has one. At full throttle is appears to be "bogging" a bit. The bike idles fine with full choke. I probaby could easily have a great ride using it in this condition. When I take the choke off, I get the backfires starting in the carb and exhaust. Every minute or so at idle -- the engine dies like it was starving for air/gas. Should I clean this carb once again and place the old "Honda" Brass back in afterward ? I am not sure how good the new Moose Carb kit is ? Shoudl I raise the needle one notch first ?

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