What's the deal with performance cams?

[Anonymous]

I'm thinking of trying to get some more power out of my 1150 project bike. Right now it's pretty much in stock form, minus a V&H exhaust. So, I was checking out Ape's website looking for some stuff (upgraded clutch, camchain tensioner etc..) and I noticed that they sold higher performance cams. I don't really want to rebuild my motor (too much $$$ for an overbore) but cams and springs seems relatively cheap.

So, what's the deal with switching cams? What other mods are needed to make them work to their potential? What would the benifits be? How much added HP can be expected? the only one that Ape is offering that seems appropriate for my non-overbored engine is the WGS348 cams.

Waht about getting my current cams ground to a different profile? I have no idea what all the lift/duration/degree numbers mean but I've heard people talking about changing their existing cams to get better power, is this an option too?

[cbxchris]

A 355 lift is about right for the street. Maybe a 370 if not riden a great deal. Don`t go to the trouble without putting in a piston kit. There are many things that you need do if you start toying with the 1150 engine. Go see someone that knows the engines. If you can tell us your budget I can get you in the ball park what you need the most. For starters you need the crank welded,then personally the tranny undercut,manual cam chain tensioner,adjustable sprockets,cams,new adjusters and rockers, springs with retainers(set to the proper spring hieght and rate), 1mm over valves don`t hurt with porting,new ignition,studs (case and cylinder),at least a billet hub with the heli gears,clutch springs,pistons,then you need all the normal gaskets and new parts like timing chain. Do it right or don`t start. Sorry to be so blunt but I`ve messed with these engines for 25 years and have seen to many make way to many mistakes. Good luck.

[SqDancerLynn1]

If you want to spend some money go for the clutch basket and the tensioner upgrade. then after that maybe some slotted cam gears

http://www.gsx1100.com/motor/gtips.htm

[Motorcyclemodeller]

I have to agree, when you redesign a motor it must be complete. The head, pistons, cams, carbs and exhaust all must work together. Basically everything must be done for a final result. Mind you this final result will be outstanding; but not cheap at all.

When people come to me with your situation, I tell them this: Leave the motor stock and get the following.

Carbs- Flat Slides 36 for an 1150
Exhaust- 4 into 1
Cam sprockets- have them degreed
Coils + Wires
Manual Cam chain tensioner
Street & Strip Clutch + springs + welded clutch basket

This is enough to really wake the bike up, with out spending 6 or 7 grand on a motor.

Unfortunatly these bikes are money pits, you can spend 15,000 grand easily to upgrade everything. I did........would I do it again.....no! I would spend 8 grand on a new Hyabusa that runs 9.8 1/4's and 200 mph, and handles like a race bike. Don't get me wrong, I love my GS but engine building and parts are super expensive.

Dr. Dre

[Anonymous]

Hey, Dr. Dre
What would you suggest for the '79 750E? Pretty much the same thing except carb size? Which carbs? This is a 2 valve/cylinder bike and uses the VM carbs.

Harrison

[gsbill]

Dr Dre offers some good advice..

[Motorcyclemodeller]

Mikuni 34 RS flatslides are perfect for 750's. This is the one part that makes the biggest difference. Once you go mechanical carbs you will never go back to CV's. I think VM's are mechanical round slides, but RS's are the way to go.


Dr. Dre

[Anonymous]

Very good imfo from Dr Dre

[RacingJake]

I run G4's cams in my bike and really like them. They have a good sound when the bike is idling too. Heard G3 are good too.

This site has info on different cams,

http://members.accesstoledo.com/fastlarry1/cams.htm

[scotty]

Mikuni 34 RS flatslides are perfect for 750's. This is the one part that makes the biggest difference. Once you go mechanical carbs you will never go back to CV's. I think VM's are mechanical round slides, but RS's are the way to go.


Dr. Dre

What is the reason you say that once one changes to mechanicals they wont go back to CVs??

Aren't mechanical carbs, although more quick to respond a little more dificult to operate when giving full throttle and may not be for a person who does not want an all out performance carb??

[oldschoolGS]

You can mildly uptune your motor without going all out. A starting point could be CV flatslides off an aircooled GSXR1100. Compared to $600 for RS carbs, these are better than your stock carbs and can be had for about $200 used with pods- most already have been jetted. Next, true drop-in cams (.330 lift) will wake up the motor and do not require extensive head work. I would go with the manual cam chain tensioner and slotted sprokets also. Unless you are drag racing or the clutch is already worn out, it should handle these mods fine. Dyna coils and a 5 degree advancer will complete the package nicely along with your V+H pipe. Total investment about $800. The bike will be much stronger thru midrange, more responsive and will still run fine on pump gas. Yoshimura used to sell a complete Stage 1 kit for the GSXR750/1100 that basically included these same mods. Good Luck, Ed.

[RacingJake]

Well I'm just a drag racer gs1100e with GSXR 750 38mm CV carbs with 160 mains, G4 cams I've have'nt even dailed in yet and 13.5-1 1166cc motor (it's a ture 1100 now) and this thing is going faster every time out. Check out e-bay, stripbike.com and dragbike.com for cams you should be able to find a good set for $150 and cv 38mm carbs for around $75.

[Motorcyclemodeller]

Mechanical carbs are just more sensitive and responsive that CV's, true they are more oriented towards a performance motor and rider. But that is where the original post was going.........I think. Snapping open a set of slides at 5000 rpm, and feeling all the power come on in a fraction of a second is a feeling like no other. Where CV's will slowely open as vaccuum in the motor increases. Replacing CV's with RS's on the same motor can be a totally different ride. Driving a machine with mechanical carbs will allow you to experience the difference, I will never go back.

Dr. Dre

[Billy Ricks]

I couldn't agree more with the Doc. RS flatslides will make a clutch that was fine with CVs slip to the point where you have to back off the throttle a bit when letting it rip so the clutch can grab again. I need to rebuild my clutch for that very reason. But I'm going to wait until I do the bottom end with a 750 crank and rods. Below about 5,000 rpm you have to roll the throttle a bit to keep from bogging the engine. But once you get in the powerband the power is instant. Whack them open and off you go.

[lhanscom]

Not sure if you can run the rs34's on a bike originally equipped with the VM carbs. The intake boots were a lot smaller I think. I thought the hot set up for the vm bikes was the 29mm smoothbores. The RS carbs are great thou, I have the 38's, but that's with the piston kit, and a couple other things. I also love the G4 Cams, but I don't think you can just drop those in. Have fun.