Need some help - Yamaha YFZ450 Forum : YFZ450, YFZ450R, YFZ450X Forums

YFZ iceman · 08-05-2012, 09:16 PM

So i'm new here and a new owner of a 2008 yfz 450. So after reading the threads on here I decided to attempt the cam mod. I talked to the previous owner and he said he did not do the mod. So this morning I started pulling everything apart. I removed the valve covers and doubled checked that the mod was not done by counting the pins between the timing marks there where 14 pins so I assume the mod was not done. So I finished up the mod. I then pulled off the carb to check the jetting it had a 168 main a 42 pilot the needle was marked with ngnr no adjustment just single groove. I do have a slip on exhaust sr4 motoworks. After reading through the jetting how too and seeing that it lookes like I might be under jetted I put a 170 main a 45 pilot the needle I left it alone the air screw is 2 turns out .
So now here is my problem get everything back together. It starts right up and is idling fine I give it a little gas it seems ok. I let it warm up a little bit more give it maybe 1/4 throttle a couple of times last time giving it a little blip it was like the throttle stuck but it did not feel that way give it a couple more blips of the throttle and the idle comes back down.
I check the throttle cable and everything looks good. Take the carb back out and check everything it all looks good.
You guys have any idea as to what I should look at. Any help would be greatly appreciated. Thanks in advance.

ccole3 · 08-06-2012, 07:18 AM

Check the leak jet. If its a 40 change it to a 35 and does it have the. Ip tie mod? Also did it have this problem before? If it did then a simPle zip tie mod might fix it

ccole3 · 08-06-2012, 07:20 AM

If it does not and its more towards half throttle then you might need to look into changing the needle out. Hope this helps

YFZ iceman · 08-06-2012, 09:37 AM

No there were no issues before and It does not have the zip tie mod done I will look into doing this later. I will also check the leak jet. I'm going to order a new needle today so I will be able to check that also.

Thanks for the info

HighFlyerMN · 08-06-2012, 12:23 PM

SO if you give it gas the idle stays high and it takes a few blips of the throttle to get it to come back down to normal? It sounds like something is hanging up your throttle cable.

ccole3 · 08-06-2012, 12:26 PM

The needle will be for half throttle. If you do get a new needle feeling that thats where the issue is and not at 1/4 throttle, i would reccomend the ncvq needle over others.

darederek · 08-06-2012, 12:29 PM

if it ran fine before, and you changed jetting and this happened, why don't we just put the jetting back?

were you getting backfiring or something before?

ccole3 · 08-06-2012, 12:30 PM

After reading highflyermn post i reread your first post. I may have misunderstood your problem. If its a "blip" like a bog then my recomendations earlier will help. If the throttle is hanging and not idling back down then i agree with highflyer it sounds like a linkage issue or vaccum leak. Possibly boot come off or tore.

YFZ iceman · 08-06-2012, 10:01 PM

Ok so I put everything back the way it was all jetting back and undid the cam mod. still have the same problem. I took off the cover to the throttle cable to make sure it was not sticking and it is not. So I think in the process of changing the jets originally I must have gotten something inside one of the jets. I'm going to take the carb apart tomorrow and give it a good cleaning. Anybody have in pointers in doing this. What do you use to clean it with? Is the standard carb cleaner ok to use?

On another note when it is just idling I noticed the head pipe will turn red up to the bend is this normal? That was one of the reasons I was thinking I might be running lean.

Thanks for all the info guys

YFZ iceman · 08-06-2012, 10:19 PM

Ok did a search see the head pipe glowing red is normal

mixxer · 08-07-2012, 06:17 AM

Quote:

Originally Posted by YFZ iceman

Ok did a search see the head pipe glowing red is normal

it may be common... but it is not normal to a correctly jetted engine....

at idle there is nowhere near enough rpm and heat load to make the pipe turn red unless the afr mixture is way to the lean side..... which also sets a machine up for a bog when throttle comes off idle....

lean mix will also make an engine "hang" at higher rpms after a throttle blip.... be it from lean jetting or an air leak

ccole3 · 08-07-2012, 10:00 AM

Are you sure your two screws out on the air fuel mix? That seems way out of ordinary to be that lean at idle for the pipe to glow red.

HighFlyerMN · 08-07-2012, 11:15 AM

Certain conditions with stock jetting will do that. The 450s really need a 45 pilot in most cases.

ccole3 · 08-07-2012, 12:28 PM

He has allready installed a 45 pilot

YFZ iceman · 08-08-2012, 09:42 AM

Ok update I'm a dumb ass....after taking the carb out again cleaning everything and putting it back in still had the same problem. After the machine warmed up I noticed it seemed like it was idling a little high. So I started turning the idle down and guess what no more throttle sticking.
I only had the carb off like 7 times did the cam mod then undid the cam mod what a waste of 2 days.
O I also jetted it back to the 170 main and 45 pilot and 2 turns out on the air fuel screw and the exhaust is not as red. I still plain on getting ncvq needle.
Thanks again guys for the help.

08-05-2012, 09:16 PM	#1 (permalink)
YFZ iceman Junior Member Join Date: Jul 2012 Posts: 5	Need some help So i'm new here and a new owner of a 2008 yfz 450. So after reading the threads on here I decided to attempt the cam mod. I talked to the previous owner and he said he did not do the mod. So this morning I started pulling everything apart. I removed the valve covers and doubled checked that the mod was not done by counting the pins between the timing marks there where 14 pins so I assume the mod was not done. So I finished up the mod. I then pulled off the carb to check the jetting it had a 168 main a 42 pilot the needle was marked with ngnr no adjustment just single groove. I do have a slip on exhaust sr4 motoworks. After reading through the jetting how too and seeing that it lookes like I might be under jetted I put a 170 main a 45 pilot the needle I left it alone the air screw is 2 turns out . So now here is my problem get everything back together. It starts right up and is idling fine I give it a little gas it seems ok. I let it warm up a little bit more give it maybe 1/4 throttle a couple of times last time giving it a little blip it was like the throttle stuck but it did not feel that way give it a couple more blips of the throttle and the idle comes back down. I check the throttle cable and everything looks good. Take the carb back out and check everything it all looks good. You guys have any idea as to what I should look at. Any help would be greatly appreciated. Thanks in advance.

08-06-2012, 12:23 PM	#5 (permalink)
HighFlyerMN Senior Member Join Date: Apr 2012 Location: Mankato, MN Posts: 586	SO if you give it gas the idle stays high and it takes a few blips of the throttle to get it to come back down to normal? It sounds like something is hanging up your throttle cable. __________________ 2007 YFZ450 - Motoworks SR4G2 full system /// CP MX Piston /// Houser Pro Bounce XC Nerfs /// Houser +2 Stem /// PRM skid plates /// FCI Intake

08-07-2012, 11:15 AM	#13 (permalink)
HighFlyerMN Senior Member Join Date: Apr 2012 Location: Mankato, MN Posts: 586	Certain conditions with stock jetting will do that. The 450s really need a 45 pilot in most cases. __________________ 2007 YFZ450 - Motoworks SR4G2 full system /// CP MX Piston /// Houser Pro Bounce XC Nerfs /// Houser +2 Stem /// PRM skid plates /// FCI Intake

08-07-2012, 12:28 PM	#14 (permalink)
ccole3 Senior Member Join Date: Jul 2012 Location: Dallas, GA Posts: 168	He has allready installed a 45 pilot __________________ 08'se lonestar, pep zps, lonestar2+2, cam mod,ported,k&n, itp's, holeshots, motoworks sr4,asv's, alba nerfs, SOLD 04/08se houser lt, tcs lt, rpm dominator, fci, full motoworks sr4, douglas and itp beads, gytr, asv's, pro taper, jansen swinger, wr rotating assembly, 06 tranny, oil mod, cam mod, 170m, 45 pilot, 3rd clip, 2 1/4 out, 35 leak.

08-06-2012, 07:18 AM	#2 (permalink)
ccole3 Senior Member Join Date: Jul 2012 Location: Dallas, GA Posts: 168	Check the leak jet. If its a 40 change it to a 35 and does it have the. Ip tie mod? Also did it have this problem before? If it did then a simPle zip tie mod might fix it

08-06-2012, 07:20 AM	#3 (permalink)
ccole3 Senior Member Join Date: Jul 2012 Location: Dallas, GA Posts: 168	If it does not and its more towards half throttle then you might need to look into changing the needle out. Hope this helps

08-06-2012, 09:37 AM	#4 (permalink)
YFZ iceman Junior Member Join Date: Jul 2012 Posts: 5	No there were no issues before and It does not have the zip tie mod done I will look into doing this later. I will also check the leak jet. I'm going to order a new needle today so I will be able to check that also. Thanks for the info

08-06-2012, 12:26 PM	#6 (permalink)
ccole3 Senior Member Join Date: Jul 2012 Location: Dallas, GA Posts: 168	The needle will be for half throttle. If you do get a new needle feeling that thats where the issue is and not at 1/4 throttle, i would reccomend the ncvq needle over others.

08-06-2012, 12:29 PM	#7 (permalink)
darederek Member Join Date: Mar 2011 Posts: 33	if it ran fine before, and you changed jetting and this happened, why don't we just put the jetting back? were you getting backfiring or something before?

08-06-2012, 12:30 PM	#8 (permalink)
ccole3 Senior Member Join Date: Jul 2012 Location: Dallas, GA Posts: 168	After reading highflyermn post i reread your first post. I may have misunderstood your problem. If its a "blip" like a bog then my recomendations earlier will help. If the throttle is hanging and not idling back down then i agree with highflyer it sounds like a linkage issue or vaccum leak. Possibly boot come off or tore.

08-06-2012, 10:01 PM	#9 (permalink)
YFZ iceman Junior Member Join Date: Jul 2012 Posts: 5	Ok so I put everything back the way it was all jetting back and undid the cam mod. still have the same problem. I took off the cover to the throttle cable to make sure it was not sticking and it is not. So I think in the process of changing the jets originally I must have gotten something inside one of the jets. I'm going to take the carb apart tomorrow and give it a good cleaning. Anybody have in pointers in doing this. What do you use to clean it with? Is the standard carb cleaner ok to use? On another note when it is just idling I noticed the head pipe will turn red up to the bend is this normal? That was one of the reasons I was thinking I might be running lean. Thanks for all the info guys

08-06-2012, 10:19 PM	#10 (permalink)
YFZ iceman Junior Member Join Date: Jul 2012 Posts: 5	Ok did a search see the head pipe glowing red is normal

08-07-2012, 10:00 AM	#12 (permalink)
ccole3 Senior Member Join Date: Jul 2012 Location: Dallas, GA Posts: 168	Are you sure your two screws out on the air fuel mix? That seems way out of ordinary to be that lean at idle for the pipe to glow red.

08-08-2012, 09:42 AM	#15 (permalink)
YFZ iceman Junior Member Join Date: Jul 2012 Posts: 5	Ok update I'm a dumb ass....after taking the carb out again cleaning everything and putting it back in still had the same problem. After the machine warmed up I noticed it seemed like it was idling a little high. So I started turning the idle down and guess what no more throttle sticking. I only had the carb off like 7 times did the cam mod then undid the cam mod what a waste of 2 days. O I also jetted it back to the 170 main and 45 pilot and 2 turns out on the air fuel screw and the exhaust is not as red. I still plain on getting ncvq needle. Thanks again guys for the help.

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