1100 Spectre cams?

My '83 1100 Spectre is running great now. Starts with a small amount of choke from cold and idles nice always. But it seems flat after 5500 rpm or so. Don't get me wrong, it does pull pretty hard, but seems like the motor signs off over 5000 rpm. It's not carb mixture, runs clean always. It likes to be short shifted and you are in 5th gear by 40 mph or so. I think the gearing is too low, but it's a shaft drive so not a lot I can do about that. Last 1100 I had ridden was a long time ago and it was an '81 GPZ1100, which seemed to have a LOT more top end from memory. But looking at specs it would have been a 108 HP motor, this Spectre should have 100 HP. So, is it the cams on the Spectre that suck, or is my memory of the GPZ faded that much or? BTW, the GPZ had dead fuel injection so we put carbs on it.

The problem you describe is not the difference between cams. Did you adjust the valves and/or is the bike modified and if so, did you rejet the carbs properly?

Are you sure the jetting is right at that 5k range, just when the main jet is fully kicking in. On my GPz11 it was like Dr Jekyll and Mr Hyde, almost 2 stroke type powerband (300 degree zx1100 cams)

I guess with a shaft drive and non GPz spec you will be down 20 percent plus anyway.

www.kzrider.com/forum/2-engine/590239-stock-j-model-cam-options

Seems like your cams are 270 degrees duration, like the earler twin shock 550 and 750 GPz, good midrange and a strong top end rpm power rush. I have some hotter zx cams for my 750 but I like the earlier grind.

Are you sure the valve timing is right, on some of these they can be incorrectly set a tooth out without interference.

What kind of carbs? Pics?
Steve

No pics needed, it's a totally stock bike. The carbs are nice, runs clean, plugs look good, very slight tan, will wind up to maybe 8000 rpm, just no real pull getting there, and re read my original post, it DOES pull but the midrange is where the torque is at. Valve timing is right, checked that when I shimmed the valves. Main jets are 125. I have raised the needles the same as two notches if it had needle notches LOL, and that worked as the midrange is stronger now. Pilot jets are 40 and screws are at three turns, those made the bottom stronger too, and not need so much choke from cold. Does not smoke or use oil. Wondering if the stock exhaust is really restrictive, hurting the top end. I'm just disappointed I guess, I was hoping for some real power, and it's ok, but not what I thought it would be like. Maybe I need to trade up to a mid eighties GPZ1100.

What about ignition fully advancing, have you strobe checked it?

You are seeing improvements as the you richen the mix, why not continue more until it gets fluffy, to eliminate mix problems?

Maybe a WOT full power plug chop? I know you think the mix is right...

DGA wrote: No pics needed, it's a totally stock bike. The carbs are nice, runs clean, plugs look good, very slight tan, will wind up to maybe 8000 rpm, just no real pull getting there, and re read my original post, it DOES pull but the midrange is where the torque is at. Valve timing is right, checked that when I shimmed the valves. Main jets are 125. I have raised the needles the same as two notches if it had needle notches LOL, and that worked as the midrange is stronger now. Pilot jets are 40 and screws are at three turns, those made the bottom stronger too, and not need so much choke from cold. Does not smoke or use oil. Wondering if the stock exhaust is really restrictive, hurting the top end. I'm just disappointed I guess, I was hoping for some real power, and it's ok, but not what I thought it would be like. Maybe I need to trade up to a mid eighties GPZ1100.

If the bike set up has the original BS34 carburetors, air box and 4 into 2 stock exhaust, your main jets may be a step or two rich. If I recall correctly, the FSM spec for the stock setup is 120 main, and 37.5 pilot jetting.

Have not checked if the timing is advancing, no. I did oil the weights etc and they look nice, no rust etc, guessing I would have to strobe it and rev the crap out of it sitting there? I could try a WOT plug chop but I live in a busy city and it's hard to find a place to do that around here, and to load it hard enough it seems to need to be around 100 mph or more.
I just rode it again and noticed something screwy with the throttle cable, it seems to have a lot of play, and now I'm wondering if it's actually getting full throttle. Will check that later today and try again.

daveo wrote:

DGA wrote: No pics needed, it's a totally stock bike. The carbs are nice, runs clean, plugs look good, very slight tan, will wind up to maybe 8000 rpm, just no real pull getting there, and re read my original post, it DOES pull but the midrange is where the torque is at. Valve timing is right, checked that when I shimmed the valves. Main jets are 125. I have raised the needles the same as two notches if it had needle notches LOL, and that worked as the midrange is stronger now. Pilot jets are 40 and screws are at three turns, those made the bottom stronger too, and not need so much choke from cold. Does not smoke or use oil. Wondering if the stock exhaust is really restrictive, hurting the top end. I'm just disappointed I guess, I was hoping for some real power, and it's ok, but not what I thought it would be like. Maybe I need to trade up to a mid eighties GPZ1100.

If the bike set up has the original BS34 carburetors, air box and 4 into 2 stock exhaust, your main jets may be a step or two rich. If I recall correctly, the FSM spec for the stock setup is 120 main, and 37.5 pilot jetting.

I bought the bike with 125 mains in it, it certainly does not burble or make me think it is rich, but I could get some 122.5 and try it. It fair screams over 6000 rpm, sounds good (too quiet though), but just does not stretch my arms out like I figure it should. It had 37.5 pilots in it but it was a mess and they were so f***ed up I had to LH drill them out, the 40 pilots are not too rich as I had to go to 3 turns out on the screws and it made more power and ran cleaner at that. Everything I have done to the carbs has improved both the rideability and the power.

Full advance on these is only about 2500 rpm, no need to put a rod through the cases. Sticky advancers and fatigued springs has been discussed here recently...also check you have the tiny rubber damper pads fitted.

Full power WOT plug chop is scary enough on a 550 let alone an 1100 I know, maybe do it on a dyno -last when you have eliminated all other possible problems.

I worked on a 80 LTD this spring that was lean on the top end/ wide open. It would just jump in the midrange low end then take forever to hit 8k rpm. Had stock exhaust and air box, stock jetting. Ending up finding that the air box snorkel made all the difference in the world. The midrange punch went away a bit but it would pull al the way to 9 grand. I think you have a jetting issue.

Good advice. I will put a timing light on it then and see if it moves the marks around.
I have not had the airbox open to be honest, from what I can see the air filter element is stock looking, and is in there, will pull it and look for obvious airflow problems. The Virago you see in my sig pic was like that, the airbox had a snorkel that was smaller than ONE of the carbs, when I opened that up it needed 6 jet sizes richer on the mains.