performance question
 

Hey everyone, I am new here. I just purchase my superhawk last friday from a salvage auction. it has 25k miles over all in decent condition. it starts, runs, rides. It has manual timing chain adjuster, two bros slip ons, and sonic fork springs. other than that it seems stock.

I have had several bikes in the past. I just came off of a 600 katana, I have an 06 zzr600 before that. I have worked at a couple different bike shops through the years and have ridden a wide variety of bikes.

My question is: How should this thing perform? It really seems to just level off and stop making power at about 5500rpm. According to the dyno sheets I have found online this thing should pull hard through the whole rpm range. I don't expect it to be a screamer like an inline 4, but I don't think it runs correctly. It Starts and idles fine. It is nice and torquey on bottom. I just falls on its face if you try to rev it out.

I have checked the carbs, they are nice and clean, everything is clear and seems correct. The air filter is ok, not the cleanest but not bad by any means. It has 155psi compression (cranking cold at WOT) My front plug looks significantly cleaner than my rear plug. ( I have new ones on order )

I have ridden sv650's and TL1000's in the past and they would both eat this thing alive as it is right now. I worked at a Honda shop in the late 90's and I can remember one of the other techs there riding a hawk that came in for service and just being absolutely amazed with how it ran. I must same I am currently very let down.


Any thaughts would be appreciated.

It should pull hard up to ~9500 rpm and have peak torque at around 6.5-7k (rev limiter is at 10.3k IIRC)

So something is definitely off. Is the choke working right? (sometimes one carb gets stuck on) is the petcock hooked up right? lots of things to check.. Perhaps the rear's choke is stuck on.

Choke seems to be working correctly, approximately how far should the know pull out? mine pulls exactly 1/2". Seems short... But it idles fine ( about 1000rpm. ) when choked it does the high idle and everything like an enrichener should.

be sure the slides are both operating correctly on the carbs and that neither diaphragm is torn. soemthing definitely not right.

it should not be soft on the bottom and peaky up top; nor good on the bottom and lackluster up top... mine scares me held open on tight stuff! not a screamer like my ex - ZX-7, but some top end rush is there... neighbors know when i get on it above 5500 rpm lol! you've got some sort of issue...

Under jetted. Landshark, landshark - feed it!

A bike you don't know, yet go with the basics. Change the oil, filter, air filter, and the plugs. Sounds like you have descent compression. After changing those items -suggest spraying some Seafoam Deep Creep on the moving choke and butterflies in the carbs. Crank the bike up with the choke -let it get warm- remove the choke -LITELY spray around the engine with ether for vaccum leaks- then the fine tuning can began- You'll have to get that from the" ELDERS of KNOWLEDGE"

spark plugs are on order, no one in town had them.

Anyone know what stock size the main jets should be and what size is reccomended for use with slip on's?? ( I have two bros slip on's)

The diaphrams looked good. I inspected them thoroughly. The slides move freely with no binding.

thanks
Cale

175f / 178 r....

i run 178f / 180r with slip-ons but some run larger.

tim

Sounds like a vacuum leak.

+1 sounds like it was never rejetted for slipons. You may have an aftermkt air filter too...

You can check both:

The needles...aftermkt needles are adjustable but OEMs IIRC are not

The filter...aftermkt filters wont have the air dam

air filter is stock, honda part. I will pull the carbs and check the mains to see what size they are.

Anyone have a link to a valve adjustment procedure?? I just want to check them being I don't know how well this bike has been maintained.

yeah, I was wondering that. All the lines look good, but it never hurts to check anyhow.

https://www.superhawkforum.com/forum...ad.php?t=11365

Here's the svs manual...just pull the valve covers and check the gaps. If they aren't in spec you'll need to pull the cams and reshim, otherwise reinstall covers and ride:)

I'm with cliby on this one.

I would pull the carbs and remove the caps for the slide actuator diaphrams and make sure the lip is seated in the groove and no tears in the diaphragm.

Also drain and remove the float bowls and determine what you have for main jets. Go with trinc's recommended jets, if you have a stock air filter. Install a stock air filter, if you don't, IMO. If you have the stock jets installed, you will still in the ballpark and it should pull hard and be quite satisfying above 5500 RPM.

Cam timing?

yeah I have never had a bike run this poorly just due to stock jetting w/slip ons. Atleast not without pod filters/ open air box etc.

its all better, for some reason the front slide wasn't working right. took it apart, put it back together, wow! much better. this thing really gets with the program!

by the way, my jetting is 175/178

Power will usually start to decrease around 10500rpm.

yay!

ummm ok. too bad the rev limiter cuts in at 10.3K ;)

He said "around" 10500, okay??:p

Well if you want to get technical the power starts to drop off at 9K as you are on the back side of the HP peak. You actually start to feel it at around 9.5K but as most never rev the motor that high...... the only reason I said anything is unless you have a HRC ecu you can never make it to 10.5K

Um... Well... Yes you can, but it requires you having a degree in electrical engineering... So the HRC ECU is probably an easier option...

Why would you want to rev it above 9500 RPM, with stock cams?

http://i33.tinypic.com/2eevbrk.jpg

Well that's why I would need someone like you....... I'm pretty good with the mechanical stuff but when it comes to the electrical, it's all FM (fookin' magic) to me ;)

Well that is why I said you really feel the power go away after 9.5K The only reason I've been to a higher RPM is that I don't have a 7th gear. ;)

I know what you mean. I keep trying for 7th gear with my RC51 at THill. I'm going to have to drop a tooth on the rear chainring.

Now that I've thought abut it some more, I think I have the gearing just right. I'm just hitting redline at the end of the front straight. I just need to stop trying to shift.

Anyway - I posted the dyno chart for a couple of reasons. One being a refernce for shift points. The other is that there is some good jetting info from Dan Kyle, which brings us back to the original subject.

my dyno
 

That Dyno run with just slip-ons seems strong compared to my run with full Erion system and jetting. May just be the difference in freshness as mine had 30K miles on it at the time...