2017 Rps hawk 250 red hot header help

Robertk · 08-05-2017, 01:32 AM

I need help. I dont do much with the internet an took me an hour to figure out how to post on here............

But I have a 2017 hawk 250 with 190 miles on it.

I just installed..... mikuni vm26 with (120) jet, NGK iridum, full exhaust and did the air box mod.

When i start it up it only takes 20 seconds or so and the header gets CHERRY RED HOT. So i shut it off.

What is causing this?? I tried puting a 125 main jet in it and playing with the air/fuel screw, tried using the old spark plug, checked valve lash, ect ect....

Im afraid to run it long enough to get the air/fuel mix set so it will idle at lower rpms. (Pry 1500-200rpms now)

Is it super lean or does this exhaust pipe just get that hot cas its cheap and thin?
I dont want to drop a valve or anything

BARLOW · 08-05-2017, 02:51 AM

sounds like the exhaust is clogged, or the timing is off ... i would not run it ... i run a 115/40 setup and it is rich, not lean ... i would start with the back half of the exhaust, because it is easy to get off of the bike, and you can run it without it, unlike the header ... but my best guess is the cat is going to be clogged/smashed inside ... if you or a buddy can weld good, i would cut the guts out of the cat asap anyway

Robertk · 08-05-2017, 03:17 AM

The exhaust is not clogged its the ebay race exhaust, not the factory exhaust

How do i check the timing?

pete · 08-05-2017, 04:18 AM

Ok.... 20 seconds is pretty dam quick..
a bike will glow the header if it is sitting
idleing for a while..theres no airflow to cool it
both my bikes do it.. but it takes longer than 20
seconds..A lot longer..
do you have any idea what the wall thickness of the header is ?
stainless steel heats up alot faster/easyer than steel..

can't give you any jetting help... don't have a hawk .. anything would only be
second hand info you can find here..
But I assume it is doing it at idle... so if it is jetting it's most lightly to be the pilot jet..

also check for a air leak at the motor/exhaust join...

.

ben2go · 08-05-2017, 10:51 AM

Hot exhaust is caused by a lean condition or valves being out of adjustment.

pistolclass · 08-05-2017, 11:08 AM

Did it do this before the mods? If not, i' m suspect of the new exhaust or plug. Try putting some of the old stuff back on then mod 1 thing at a time.

Robertk · 08-05-2017, 01:43 PM

Valves adjusted correctly. I dont think it was hot before the mods. Im going to try modding the factory carb and see if it still does it

ben2go · 08-05-2017, 05:05 PM

If the new exhaust's tubing is thinner than the original exhaust, it will get hot faster.

Robertk · 08-05-2017, 05:15 PM

Well i took the mikuni off. and opened the factory carb up. Put a 120jet and 2 3/4 turns on the air/fuel needle also 2 washers under the main jet needle and put it on the bike. It now runs great. The problem was the mikuni vm26.

pistolclass · 08-05-2017, 06:58 PM

What slot was the VM26 groove set to?

08-05-2017, 01:32 AM	#1
Robertk Join Date: Aug 2017 Location: Iowa Posts: 5	2017 Rps hawk 250 red hot header help I need help. I dont do much with the internet an took me an hour to figure out how to post on here............ But I have a 2017 hawk 250 with 190 miles on it. I just installed..... mikuni vm26 with (120) jet, NGK iridum, full exhaust and did the air box mod. When i start it up it only takes 20 seconds or so and the header gets CHERRY RED HOT. So i shut it off. What is causing this?? I tried puting a 125 main jet in it and playing with the air/fuel screw, tried using the old spark plug, checked valve lash, ect ect.... Im afraid to run it long enough to get the air/fuel mix set so it will idle at lower rpms. (Pry 1500-200rpms now) Is it super lean or does this exhaust pipe just get that hot cas its cheap and thin? I dont want to drop a valve or anything
	0

08-05-2017, 04:18 AM	#4
pete Join Date: Jan 2012 Location: ChCh , NZ Posts: 2,266	Ok.... 20 seconds is pretty dam quick.. a bike will glow the header if it is sitting idleing for a while..theres no airflow to cool it both my bikes do it.. but it takes longer than 20 seconds..A lot longer.. do you have any idea what the wall thickness of the header is ? stainless steel heats up alot faster/easyer than steel.. can't give you any jetting help... don't have a hawk .. anything would only be second hand info you can find here.. But I assume it is doing it at idle... so if it is jetting it's most lightly to be the pilot jet.. also check for a air leak at the motor/exhaust join... . __________________ 09 XT660R ... 06 TTR250 ... 80 Montesa H6 125 Enduro... 77 Montesa Cota 348 MRR "Malcom Rathnell Replica"... Current resto projects.. 81 Honda CT110... 80 Kawasaki KL250A1... 11 Husaburg TE125 enduro... "sold" along with another 31... Lifan 125 Pitbike.. "stolen" ... KIWI BIKER FORUM...... http://www.kiwibiker.co.nz/forums/content.php All the best offroad rides in NZ... http://www.remotemoto.com/ E-mail... xtpete1@gmail.com
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08-05-2017, 02:51 AM	#2
BARLOW Join Date: Jan 2016 Location: central illinois Posts: 362	sounds like the exhaust is clogged, or the timing is off ... i would not run it ... i run a 115/40 setup and it is rich, not lean ... i would start with the back half of the exhaust, because it is easy to get off of the bike, and you can run it without it, unlike the header ... but my best guess is the cat is going to be clogged/smashed inside ... if you or a buddy can weld good, i would cut the guts out of the cat asap anyway
	0

08-05-2017, 03:17 AM	#3
Robertk Join Date: Aug 2017 Location: Iowa Posts: 5	The exhaust is not clogged its the ebay race exhaust, not the factory exhaust How do i check the timing?
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08-05-2017, 10:51 AM	#5
ben2go Join Date: Jun 2011 Posts: 1,335	Hot exhaust is caused by a lean condition or valves being out of adjustment.
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08-05-2017, 11:08 AM	#6
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 980	Did it do this before the mods? If not, i' m suspect of the new exhaust or plug. Try putting some of the old stuff back on then mod 1 thing at a time.
	0

08-05-2017, 01:43 PM	#7
Robertk Join Date: Aug 2017 Location: Iowa Posts: 5	Valves adjusted correctly. I dont think it was hot before the mods. Im going to try modding the factory carb and see if it still does it
	0

08-05-2017, 05:05 PM	#8
ben2go Join Date: Jun 2011 Posts: 1,335	If the new exhaust's tubing is thinner than the original exhaust, it will get hot faster.
	0

08-05-2017, 05:15 PM	#9
Robertk Join Date: Aug 2017 Location: Iowa Posts: 5	Well i took the mikuni off. and opened the factory carb up. Put a 120jet and 2 3/4 turns on the air/fuel needle also 2 washers under the main jet needle and put it on the bike. It now runs great. The problem was the mikuni vm26.
	2

08-05-2017, 06:58 PM	#10
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 980	What slot was the VM26 groove set to?
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