Kohler 7000 series engine build

I'm going detail some of the 7000 series Kohler engine build ideas I have here starting off with cylinder head modification. For one the ports are fairly open requiring only some minor port work for optimum flow. Pics will be posted once I get a clear shot on the original heads. I've already modified the second set.

Cool! Looking forward to the pictures of this one. Is it a KT Series 1 or 2?

I think I need to change the title of my post just a bit. So this is not a kt17 which is apparently the kt series. Also happens to be an opposed. This build is the newer kt735 model number which I realized is called a 7000 series despite it having kt in the model number. My bad.

Ah, so it's a V-twin then.

Cool, I love a good engine build.

Yes it is a v-twin. Not even one of the bigger ones in that line of engines. Although it is fairly big at 725cc which is right about 44cubic inches. The way it's built leaves lots of room for really dragging the power out of it.

Sounds like it has potential to be a real powerhouse!

I'm hoping so. I've got new valve springs new rocker arms with a better ratio coming that aren't here yet. I'll detail it all as I start posting up the pics. I'm waiting on the rocker arms. So I can start tearing into it and show everyone what I've learned and how I figured it all out.

So here's some stock engine specs. 735 cc or 44ci, 9.1:1 compression ratio. .343 intake lift at the valve and .307 exhaust lift at the valve. Stock rocker arm ratio is 1.5. so I figured I can cheat the factory cam with a 1.6 ratio rocker arm to get a little more lift and duration of the cam. No aftermarket cam exists yet for this block. Making a new can the way this camshaft is made wouldn't be impossible. I'll detail that in another post. So my initial thoughts have been better carb, better valvetrain, and some minor port work on the heads. What I have done so far is found a beehive valve spring that is a near drop in upgrade. It's .260in longer than the stock spring with a higher spring rate so I'm order for it to work I either need to make a .250in deep spring pocket or source a longer valve. Still researching a possible valve. Another upgrade I want to do is increase the pushrod diameter from 3/16 to 5/16 so I don't bend one. As far as the carb I got a 34mm flat slide I mocked up on the stock block. Better for here with no other changes will wake this engine up all by itself.

Would be easier to cut the springs to size with a cut off wheel and a jig to hold it. Be easier then redoing the valvetrain geometry or cutting the head up. Springs are definately stronger then stock.

Cutting is not the best option here cause you loose the flat end and increase your spring rate. These will have 40lbs of seat pressure. Which is a lot more than the stock spring. I disassembled the stock ones rather easily by hand. As far as increasing the valve height is a simple fix to keep the geometry the same by just adjusting the pushrod the same length. It just moved all upward meaning if need to make a space for the valve cover. Which I will likely need to do any way with the new rockers.

Update got my valve spring pickets cut and the springs installed. Also took some pics of the mild porting I did. I'll get pics of the before from the other heads when I get to it.

Here's a trick to removing the engine flywheel I learned a few years ago. First you need to remove the bolt or nut depending on the engine. Second thing is you will need a pry bar and a hammer. So on the ones with a bolt you'll run the bolt back in against the crank minus any washer. This will protect the threads from any damage as well as the crank end. On ones with a nut you'll want to install the nut till the threads are flush with the top of the nut. I recommend using a dead blow or other heavy but soft faced mallet on this style. The next step is easy find a suitable position to pry upward that won't damage anything and then start giving swift blows to the nut or bolt. Believe it or not after a few good strikes the flywheel will pop free from the tapered seat on the crank. No puller needed and works good in a pinch.

Well I'll call it phase 1 at this point. Due to the pandemic parts and progress on my build have been on hold. However I've installed the carb on my other motor that's stock. It's very lively. Carb is a Chinese pwk keihn knock off 34mm carb that's $28 of of Amazon. Ran rather fat at first after adjusting the needle and the isle air mix it seems very happy. Slide does not always return to the same resting point off throttle so adjusting the cable is a bit tricky. Otherwise I'd say I'm happy with it.

Very cool. One of these days I'll try one of those cheap slide carbs on something.

Final decided to get back into this motor after being out of the game for almost a year due to a shoulder injury followed by surgery and recovery after I quit from not getting parts I ordered. The rocker arms are crane cams sbc 1.5 roller rockers. I had to move the pivot point back in the head about half a hole diameter to get the proper contact on the valve stem. So I milled the old bosses off and machine up a new boss I need to tig weld in place still. I got some new rocker arm studs as well. I believe they are for a windsor Ford but I can't remember. Also needed to get longer 5/16 chromoly pushrods which are a lot beefier than the stick 3/16 high carbon steel stock jobs. More to come as I get into it. Last pic is the mock up where you can see the roller tip is to far forward on the valve stem