Mega torque from my 1000?

Can my 78 kz1000 be built to make crazy torque? Like effortless wheelies and burnouts at around 4000 rpm?

Kinda V twin power from a 4. just wondering...

Sure, it just takes $$$.

OK let me rephrase... HOW to do it? Cams for sure, what else? Which cams? Cam timing?

Nelson wrote:

OK let me rephrase... HOW to do it? Cams for sure, what else? Which cams? Cam timing?

This is a good goal for a street bike and if you achive it, you'll be VERY happy. Here are some opinions in order of priority:

V&H exhaust WITH performance baffle. A kerker may also work but has a much larger collector which might push the power band higher (more top end power). You want mid range so go with a smaller collector. V&H collector is 2" Kerker is 2.5". BIG difference.

Keep high velocity through the intake port. This is the cheapest, easiest modification you can make. It requires no work at all. Stock intake ports work great in the range you are talking about up to 8000rpm. Don't hog them out. It's ok to port match to the carb and clean up some casting flash if it'll make you feel better but it's not necessary and don't open the throat of the port. It will reduce velocity and midrange torque. There may be a chorus of boos at this advice but I have yet to find anyone who has found increased midrange torque from opening up a KZ intake port. I've personally found the opposite.

29mm carbs have a good reputation but are expensive and hard to find. BS34s are great street carbs and will work as good as any if the rest of the engine is set up properly.

10.5:1 pistons. If you're running stock 8.5:1 pistons it's going to be difficult to make big midrange torque numbers. Just not enough compression.

0.365 Web drop-in cam or APE 0.410. Something with decent lift and short duration. Cam timing will affect power in the mid range a little. Start with the factory reommended install numbers and go from there.

Plan to spend lots of time tuning and testing. Many hours of fun to be had with ignition timing and carb jetting. And a day at the dyno will be useful.

Do this and you'll be looking at 60+ lbft in the mid range and 100hp peak.

btw No guarantee on "effortless wheelies" with a 550lb bike.

Great info! I spose I should say what I got now. BS34's with port matching and no air filters. V&H Sidewinder drag pipe. Recent valve adj, tune, etc. Runs VERY well now I just want more oomph! When i put on the BS34s (and jetted) I noticed a significant boost in low rpm power - nice! I'm a low budget guy so if I only picked one other mod... what? I'm guessing just the hi comp pistons alone would be a very significant boost. yes? Still run OK on pump gas?

also - I made a baffle for the drag pipe to quiet in just a tad and add some back pressure. Sounds Great!

I haven't used the sidewinder but I know it's a drag pipe so it might be designed for more upper RPM performance. What's the size of the baffle? Did you notice an increase in midrange when you installed it? The V&H street pipe with a performance baffle is a good mid-range setup.

I'd say that 10.5:1 pistons will do more for mid range then a cam at this point. If you go that route, while the head is off, inspect the valves and seats. If work is necessary, have a multi angle valve job done by a reputable shop, upgrade the springs and clearence the head and cam cover for a 0.410 cam. This way, a future cam upgrade will just be a matter of popping off the valve cover.

I seem to recall member roy-b-boy-b running solidly into the 11's with a stock cam, 10:1 pistons and 29mm carbs. His avitar showed a nice wheelie launch. Maybe he can elaborate on his mods and experience.

The pipe has a 4" opening with no baffle - huge! definitely a hi rpm pipe. Baffle i made is about 2" I noticed a slight loss of the hi rpm free revving sort of feel. Not sure about mid range, but the bike seems to run a little better in general with the baffle. The pipe is just too much for the stock internals i think. I'm keeping the pipe. with or without baffle it sounds absolutely wicked and I love the angled head pipes.

Nelson wrote:

The pipe has a 4" opening with no baffle - huge!

What size is the collector? - where the 4 header pipes come together.

about 2 1/8 at the narrowest spot, maybe only 2

Nelson wrote:

about 2 1/8 at the narrowest spot, maybe only 2

Ok. Good. Make sure the collector transistions smoothly to your homemade baffle. If there are any gaps or misalgnement, spend the time to correct them. Also, use fibeglass packing between the perforated tubing of the baffle and megaphone. You don't want the baffle to create back pressure. Ideally, you want to ensure the exhaust is not restricted and the gasses maintain a high velocity through the megaphone. That's what the 2" baffle will do if properly installed and mated to the collector junction. This should aid in scavaging/cylinder filling and boost mid-range torque without hurting top end power.

Here's an image of my 2" baffle for the V&H street megaphone. Big difference in low-end and mid-range performance with the baffle installed.


In these engines, and most other high performance engines, a well designed exhaust is greatly repsonsible for cylinder filling through scavaging.

cool, looks almost identical to the one i made