My new project YZF450

Absolutely awesome build, I've always wanted to do something like this. Keep the updates coming!

Its back together and running but not 100%. It seems to have an air leak.....:thumbsup:.... will not idle and backfiring bad. I am trying to get it going 100% to take to FL riding this week but I dont know........might have to just ride the smoker.

I still have a lot to finalize like taking it back apart and painting the frame & swingarm black and get new plastic & custom graphics.





Your air leak could be in the exhaust too. Make sure you have a new crush gasket in the head and at the midpipe joint to be safe.

It has a new header/head gasket and I just found the corect muffler clamp......I had a good large hose clamp on it.

Idle screw does nothing so it makes me think its intake.

I used Yamabond #4 on the boot to the head surface so I dont think its there. The little metal tab on the carb is about 1mm away from the boot notch and I have tried using long tire irons to carefully pry it in but it wont go any further.

Should the tab be all the way against the boot?

Pulled the carb & intake boot off and cleaned the yamabond off. Cleaned the carb again since I was there and checked the jets. 160 main, 45 pilot, 3rd clip from top, Air screw 2 3/8........not sure what the other jet in the float bowl is but it is a 72.

Was able to get the idle to adjust but idle drop was not right......hanging up. Opened air screw another 1/2 turn and it was better. Good enough to break it in.

Went to TNT and rode it easy for a couple more heat cycles. Idle drop was still hanging bad so I opened the air screw up about another 3/4-1 turn. Guessing its now its about 4 turns open......meaning I need to go down on the pilot jet.

Bike is working well but forks are really stiff. My guess is since this was an AX practice bike the forks have been made much stiffer. If I have time I will pull them apart before heading to FL on Wed for the Jacksonville SX. I will be riding at Jax for a couple days before heading to the stadium on Friday to rep our Moto Hose products.

Bike looks awesome great work!

Although, I think it would have looked better if you had not painted the radiators and whole engine black.

Now to get graphics going........



When you say you opened the "air screw" up, are you meaning the fuel screw, or pilot screw, as Yamaha calls them? :thumbsup: I'm fairly certain the "fuel screw ", as I call it (coming up though the front of the float bowl, kinda vertically, into the carb's main casting body, basically...) controls fuel rather than air..... If so, it sorta sounds like maybe you're needing a #48 pilot jet, or like you said, figure out if there's an air leak.

At any rate, I like your project! :bonk:


Edited by Diesel Goober

I had the air boot tear where it meets the carb, might want to check that area. Basically underneath the clamp.

How much did you get the bike for if you don't mind me asking...

It looks like it's coming together nicely, great job!

By the time I am done I will Probably have around $2600 into it

Wow ! I have never seen a "basket case" that was only 3 years old except for back in the early 2 stroke days when bikes were literally obsolete from year to year (early 80's)

But it looks like one man's serious lack of wrenching skill is your gain !

Awesome project.

After running good at TNT for break in............Still chasing air leak but acted up after driving to Florida. Rode 1 lap at Pax back track easy checking the track out then got on it.......and it revved then backfired and stalled out.....then was a bitch to start. Back to the pits and put in the richer 48 pilot but still having the same problem.

Feels electrical. The flywheel key way was cut down and screwed up like someone did not have it in the groove when they tightened it. Might have spun........I have a new key way and will pop it in and put in a new sparkplug.

Pulled the plug and no spark. The end of the coil/plug cap seems to be crooked and melted as it does not plug straight on the sparkplug. Hopefully the new one will arrive tomorro as my local LL qualifier is this weekend.

The new coil did not re-spark it. The stator was also a question as it took a whack from a piece of aluminum between the rotor & stator when the clutch basket came apart. I used 2 part epoxy over the cracks in the windings when I built it and it had spark for about 2 hours of riding. :thumbsup:

Hopefully the replacement stator should get here today or tomorrow. Thinking about driving up to Buds Creek of Friday so.......

Good luck, Lumpy!!!

It sounds like you'll get it sorted out. Would've been nice if it was before your races, though......


I still got 2nd at my LL qualifier on the faithful 10 year old 2 stroke so its all good.

One thing for sure is in breaking the 450 in I know I will be faster on it and shaving seconds off my lap times on the thumper.

Nice project, Im actually trying to do the same with a 2007 around here if the guy will trade +cash for my 125.

Popped a new stator in and sparky is back! TNT should be perfect tomorrow with the rain we had this week!

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