1972 450 engine questions

Its my understanding that a lean condition due to an air leak can suddenly worsen when the throttle is closed during de-acceleration just like when you were going into that tight corner. When fuel/air is ultra lean its not uncommon for two strokes to diesel leading to that motor running with the kill switch depressed, backfiring, and I would guess running backward.

Cool idea, I like that it allows the motor to be rotated. I agree that 2X4's can be a pain in the a$$.

Hi guys this thing kicked my butt few weekends ago my foot is still hurting. I want to upgrade the carburetor to a Mikuni what, size would I use I'm also going to get external flywheel electronic ignition, but at $500 that's going to have to wait.

38mm VM Mikuni carb. Be sure the idle and air screws are are on the left side so they're accessible when the air cleaner is in place.

I don't recall the jetting but be sure and buy from a vendor that will include correct jetting for your bike.

I have looked for a carb with the adjuster and idle screw on the left and cannot find one. My Sudco book and the newest Mikuni book say that the VM38mm is available but not with whose adjusters on the left side. Are there older carbs with the adjusters on the left?

I wasn't aware that new carbs didn't have an option of adjustments on the left. It seems the original Husky Mikuni from the late 70s early 80s had the idle screw on the left but fuel air mix was on the right.

So I bought a used carb from Motomwo on ebay, he says it is in good condition. My books say the 38mm round slide is only available with the adjusters on the right. I never called around either, just lazy. I missed the post office today to pick it up, they close at 12. But when I got home I found this in the mail!!
So I am still pretty stoked!!

cool...

So I went upstate and worked on the bike, and found the kill switch is really touchy..as in micro touchy. So I removed it. Kicked with plug removed from head and still on ignition wire. Marginal spark, blue but very tiny. Cut the raja off and installed a new one that crushes the HT lead inside, still marginal. Checked the points, they look new and clean and at .038. They were recently replaced with the condenser. OK. I'm tired of effing with this beautiful bike, so I will start from scratch when I get the time. All grounding points paint free, moving the condenser to the coil. ohming everything out, ignition and HT coils. I mean there is not that much here. Unless the rotor mags are played out, but they hold a wrench pretty good. I mean this thing ran before!! But like Sun-Tzu says "If you are far from the enemy, make him believe you are near." So I will see if it is a fuel problem first!

Points gapped at .038?

Did you mean 0.38 mm (or ~0.015 inches?)

(If gapped at 0.038" that could definitely be a cause for weak spark.)

Yeah I mean MM. Hahah!

is the plug wet after a few kicks? ol mate has a trick when he is looking at an old bike to buy. He takes some "start ya bastard"..(aerostart) and pulls the filter, blasts a heap in and gives her a few kicks. if it runs, he knows the spark isnt the issue. give it a try

So I got the Vape Ignition Thursday. And Got a 38mm Mikuni, and with an old adaptor and mount. She started with a flick of the choke! Sitting and with my left leg!! My right ankle has a couple of torn ligaments and i'm in a boot until New Years. No fuel all over the motor, and lighting too. Though I have not checked it, and will add a battery, lights and ignition switch. Cause it's plated!! I am so happy to be able to start this bike pretty easily. I tried to install a compression release, but the binding set screw for the cable was not tapped correctly leaving it stripped. I'll weld a nut to the outside and tap the next size up. Then the staring should be even easier! Looks like I finally ironed out the staring problems. I'll tune the carb in the spring, then I can enjoy this 2yr project.

Finished the basic wiring, and made brackets for the lights and license plate. Still need to make a place for the battery and horn. Also need to find a switch for the bars that will run the kill, horn and lights. And she started on the second kick today!! OH YEAH!!

bike is looking good man..cant wait to hear how some rides go

I am stoked that she starts! I think the testing proved everything ok, but the combination of a less than enjoyable spark with an air bleeding old Bing was too much for my ability to remedy the situation. I think I've done what anyone would, considering the circumstances. Plus I have a bunch of extra power for lights and such. I'll keep you updated, and I have the Others. You all have been there for me and my questions, so hats off the bunch of you! AND Merry Christmas! Did I use enough emoji?

not the slightest bit wrong putting the vm on there and ditching the bing..easy to tune and get parts for.

I was running the bike and thought it was pretty loud, on inspection found oil on the head. Pulled the exhaust and found some holes! So I welded some sheet metal to cover them.

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