Top end replacement on my BMW/Kymco 450 engine.

[Big Timmy]

I got the top end of my original G450X engine back together. While waiting for parts, gaskets, valve seals, etc. I did some light porting, cleanup and valve bowl work on both the Intake and Exhaust side with a good polish on the exhaust side, to keep any carbon from sticking. This engine only had 112 hours on it and the factory ring end gap was nearly 3 times what the acceptable clearance specification calls for. This is 1 of the reasons these engines commonly have top-end blow by issues. So a good breather mod is a good idea. I installed a DMD breather on this engine.

The Husky TC 449 engine in my bike now has a ZipTy breather set up with a one of a kind baffled breather tank and recovery system of my own design. The new Piston I installed here is a ProX "A".
I will probably re-install this engine back into the bike very soon and then freshen up the 449 engine next. It's running just fine but I want to go back to the wide ratio 5 spd. in the BMW engine.

The TC 449 close ratio 5 spd. engine only has about 80 total hours on it.

I put together a quick engine stand to mount the engine on that elevates it up in the air and if you notice it has a length of rectangular tube welded perpendicular to the base plate that allows it to rotated 180 degrees and still be clamped firmly into the wheel clamp on my motorcycle lift. This made it a lot easier to work on and when it came time to torque all of the cylinder head studs, I had no problem with it moving around since I was doing this on a bench and table in my garage and not at my shop 6 blocks away.

 

[Big Timmy]

A few more pictures.

 

[jpdog]

Nice headwork

 

[Big Timmy]

Thank you JP.
The bikes all back together with the original fresh rebuilt engine now that I installed last weekend. I've heat cycled it a few times and rode it a few miles for initial break in.

I swapped the heavier and thicker G450X clutch out to run the lighter and narrower Husky449 clutch and am still using the Hydraulic actuated clutch cover. It has instant throttle response and really revs up quickly.

Now that the Husky TC 449 engine is out and on the bench in the engine stand it will get the same treatment and then some. It has an estimated 85 hours on it.

I just bought a BMW G450 X complete wide ratio 5 spd transmission gear set from Ebay along with all the other associated parts, shafts, shift forks, shift drum. I'll split the cases and use all the best parts between the 2 transmissions shift components to restack the transmission in it with the wide ratio gear set from the more desirable BMW transmission. I'll be swapping out the TC449 close ratio 5 spd. gear set all together. I don't need the close ratio set up any more for what I do with the bike. Since its been my loaner bike the last few years I don't need it being able to wheelie in all 5 gears either.