I have the big bore high compression piston and stage 2 cam along with a Dyna muffler and a larger main jet in the stock carb with original airbox and filter. I also had the carb tuned by somebody who really knows his business with carbs. I am really happy with the powerband of the bike now. The cam alone seems to be the biggest single improvement to the engine performance.

But as others said you'll want to do something about the suspension and brakes in addition to these mods. I have better shocks and it's a huge help. I'm saving up for the bigger brake now because it needs it more than ever.

The rear tire doesn't have to be bumped up in size for twisties - there are good 130/90-15 tires that are grippy and handle well.  Going to a larger 140/90-15 will slow the handling down a little bit....the stock 140/80-15 size has very poor tire choices.

Getting a little longer rear shocks (stock is 10.5") will help with the bumps as the longer rear shocks will have more travel that the 1.5" that the stock shocks provide, and it will steepen up the fork angle a bit.  Shocks in the 11.5" - 12" look OK with the stock fender - if you get taller than that it starts to look like a dirt bike in the back.

When I am riding the curves in my area of KY - I use very little HP and cruise along at 45 - 50 mph on the straight sections, and try not to slow down too much in the corners.  My modified engine makes a good bit more power than a stock engine - but I don't use it much on my local rides.  When we go to ride the areas in TN/NC and are in the mountains - I really like the extra power when coming out of the uphill turns!

I also don't use high gear of my very tall (double Kawasaki pulley) gearing while in the curves - but when I need to get home in a hurry I can ride over to the 4 lane highway and make good time on the way home......a sustained 75 mph is not a strain as my engine is only turning 4,200 rpm!

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PhilthyMike,the single biggest change for torque/horsepower, is your larger/higher compression piston,it pulls in a larger volume of F/A mix,and compresses it to a higher degree, increasing  Hp(9.5% @ peak torque)and   throughout the entire RPM range.The after market cam is very mild, in our bikes and is merely frosting on the cake.

batman wrote on 03/28/17 at 21:01:13:


I don't believe the goal is performance....the goal is to reduce the rpm at highway speeds so that the engine is not turning 4,342 rpm at 65 mph or 4,676 rpm at 70 mph .  The stock engine can handle a modest gearing change fine, and it makes the bike a lot more relaxing to ride on the highway.  Several of the forum members have made a gearing change and are happy with the results.

The Kawasaki front pulley change makes an 8.7% reduction in rpm at cruise, and owners report the change doesn't make any noticeable "seat of the pants" difference in the acceleration.  You could do a similar 9%-10% change using sprockets and get a bike that is nicer to ride when you have to do the 60-70 mph highway speeds.

When you make the gearing change - you most likely will use the bottom 4 gears when riding the twisties.....and the taller 5th gear will become the overdrive gear for use over 60 mph.  And when you want to see how fast you can go - it may well be that 4th gear will get you the highest top speed.

batman wrote on 03/28/17 at 20:40:56:


Thanks for the explanation, I had it in my head that the cam was mostly responsible for the improved powerband.

As for the shocks I'm really happy with the 2nd hand 11" progressive 412's I'm running. Overall handling is much improved and on the highway I'm not airborn over every nasty bump anymore.

I thought that the head and cylinder could be removed without removal of the engine. I seem to remember reading in the FSM that in order to remove the engine that the head has to be removed.

When I was doing the conversion of my bike I tried in vein to remove the engine while it was in tact so I could paint the frame. In the end I just painted around it (I was doing more damage trying to remove the engine).

Yep, the engine can be removed if all the engine mounts are removed, the belt/chain disconnected, and a few other things, and the engine tilted forward and to the right side.  However, after going to all that trouble you might as well pull it the rest of the way out and put it on the bench.  It is much easier to work on that way.