Trouble after changing cylinder head..

FZR600 Forum

Moderators: Site Director, FZR Forum Moderators

Post Reply
User avatar
fzraudun
50+ Posts
50+ Posts
Posts: 52
Joined: Fri May 30, 2008 2:20 pm
Location: Trondheim, Norway

Trouble after changing cylinder head..

Post by fzraudun »

I recently changed my cylinder head on my 1990 FZR600 to a newer head from a 98 model. It started fine and idled great but when taking it on a spin i noticed the rpm couldnt go higher than about 5k and it runs like poo. When I changed the head I noticed I have some sort of emisson tubing going from the exhaust port to the airbox and cyl #1. This is something the cali model has, but I don't think I have a cali model, theres no exup at least.
I decided to dismantle this tubing and plug the hole in the airbox and change the rubber boot on cyl #1 (so theres no hole there).
I'm running the 98 head with my 90 (cali model?) cams.... I've checked my CDI and it does not have the wire that the cali cdi has.
Could it be possible my fzr used to be a cali model and the old cams wont work with the 98 head? Remember, it runs fine in neutral, when I rev it and everything, but when I ride it it runs badly.


Update: Ran the bike today and it seems better (might be the fuel hose was kinked previously), but it sounds differebt. A little deeper and it feels lazier...
User avatar
haunter
2000+ Posts
2000+ Posts
Posts: 2266
Joined: Fri May 09, 2008 9:17 am
Location: Urbana, Il USA
Contact:

Re: Trouble after changing cylinder head..

Post by haunter »

jetting?

a bike runs easier in N as it has no real load........


I cant imagine the cams would be differnet enough to make it like a whole crappier bike
User avatar
ragedigital
4000+ Posts
4000+ Posts
Posts: 4153
Joined: Wed May 07, 2008 9:30 am
Location: Northwest St. Louis

Re: Trouble after changing cylinder head..

Post by ragedigital »

haunter wrote:I cant imagine the cams would be differnet enough to make it like a whole crappier bike
+1

Sounds like a carb issue. Either they're not on all the way or air is getting in through a loose carb boot.
Thanks for joining and participating in the most "active" FZR Community on the internet!
User avatar
fzraudun
50+ Posts
50+ Posts
Posts: 52
Joined: Fri May 30, 2008 2:20 pm
Location: Trondheim, Norway

Re: Trouble after changing cylinder head..

Post by fzraudun »

The stuttering around 5k was due to a kinked fuel hose... :whistle


It now runs okay, but I'm pretty sure it's lacking some power and it sounds richer. does anyone know I removing the emission tubing Image makes the carbs require readjustment?
User avatar
haunter
2000+ Posts
2000+ Posts
Posts: 2266
Joined: Fri May 09, 2008 9:17 am
Location: Urbana, Il USA
Contact:

Re: Trouble after changing cylinder head..

Post by haunter »

never dealt with that cali stuff before....

if you give it a bunch of choke does it run even worse?
User avatar
megaloxana
2000+ Posts
2000+ Posts
Posts: 2282
Joined: Thu May 15, 2008 5:05 pm
Location: Hanover, PA 17331
Contact:

Re: Trouble after changing cylinder head..

Post by megaloxana »

Your new heads may be more efficient in the way of valves sealing, etc. Therefore its a good chance you might need jetting. I went with from a 38k mile motor to a 3k mile motor, but I still used same jetting setup and the 3k motor was running really lean.
'92 FZR 600
Airtech R1 kit \*/ 520 conversion \*/ 14F-47R gearing
K&N pod filters \*/ Stage 3 jet kit \*/ Factory Pro shift kit \*/ Full V&H SS exhaust
Custom '02 R6 undertail \*/ YZF gas tank \*/ Raised via dogbones \*/ custom flush turnsignals
Full R6 brake set-up \*/ SS lines \*/ Progressive fork springs \*/ ZX2 coilpack


ADD YOURSELF TO THE OFFICIAL FZRONLINE GOOGLE EARTH MAP :bunny :banjoman
Post Reply