TOPIC:

I was discussing that with a co-worker this morning. It's exactly the sort of part that we make all the time in our shop.

this is gonna be a cool thread!

i can't wait to watch you rehab these turds into the polished jewels that i know you will have.

leon

As long as I can get the mechanical issues sorted, I will spend some time polishing on these carbs. They are worth the effort, unlike those dang VM26's that are on there right now.

BTW I forgot to mention that I did the valve clearance checkup, adjusted the timing chain tensioner, and went over all the nuts and bolts on the bike. I also pulled the carbs and re-did all the passages, and I still can't find anything plugged there. Stuck it all back together and I also installed the straight through baffle that I built so long ago.

Still has the hiccup just off idle, but not as bad. The small vibration changed, but still there. However, on the bright side, that new baffle made a world of difference. I had to step up a pilot jet size to 17.5 and the bike has a ton more midrange power now. Not to mention that it was engine braking so hard before that it felt like I had a Jake Brake on the bike. Now that's gone. I guess that the previous baffle was too restrictive.

Phase one of the carburetor repairs is done. I got those dumb ez-outs and the remains of the two pilot jets drilled out from the carbs. Here's how I went about it. First I clamped the carb body in a mill vise and indicated the ID of the counterbore above the pilot jet. This ensures that the drilling is on the centerline of the jet. That's important because you don't want to drill out the threads in the carb body.



Next, I needed to use a carbide endmill to drill out the hardened tool steel ez-out. I had a worn 1/8" ballnose so I used that and drilled down until I couldn't see any more of the ez-out. You can just see the endmill above my indicator in this picture:



Now the next trick is to find a left hand twist drill bit. Sometimes you get lucky and the bit grabs the broken screw or jet and just unscrews it. I didn't get so lucky this time.



I had to keep drilling to just under the size of the minor diameter of the threads. I measured the minor diameter with a gauge pin at 0.163". I drilled up to 0.161" and then I carefully picked out the last slivers of brass. After I thought all of the brass was gone, I made up a small brass bolt to screw into the carb. This bolt has a slit cut in the end to clean out any remaining junk. The correct thread is M5x0.8 by the way. The end of the jet fell out when I drilled through it:

that looks fancier than my milwaukee 18v cordless drill press!

I also got one of the jet blocks repaired today. First I was concerned that I may smash the jet block since it is very thin aluminum. So I made up an aluminum slug that fit tightly inside the jet block to support it. You can see the slug in the jet block in the following picture. Notice that I indicated the boss where the jet needle screws into.



Now I used a 5/16" endmill to mill out the messed up threads. This particular mill has a little play in the spindle bearings, so the hole actually came out to 0.317" but was round to within 0.0002" so I called it good.



Next I made up a brass insert on the lathe. This insert must be precisely sized to produce a light press fit into the bore in the jet block. I cut the insert to 0.3174" and drilled and tapped it for the M6x0.75 threads that are supposed to be there. Here's the insert before I installed it:



Finally, I just pressed the insert into the jet block. I just used a small precision vise since this is a light press fit, no need for the 50 ton press. This is the part where I felt the need for that aluminum slug. I was concerned that I may distort the jet block when pressing the insert in place.



Now I just have to do the other three..

show off!

wireman wrote: show off!

Hey, I'm not showing off. This is my application for the new machine shop foreman at Zmax!

the "press" in my milwaukee cordless drill press comes from me pushing on it!
hopefully ill here something back tomorrow about the building down the street,then ill have some room to spread out and buy some bigger tools for shop.

Nice work Josh! Thats what I like some real detailed work keep them pics coming.

Yikes! Those pilot jets were stuck in there really tight!

Kudos for a job well done on removing them.

Just curious as to whether it might be beneficial to "heat" the jet block and "freeze" the new brass insert immediately before putting them together, with a view toward eliminating the need for any pressure (akin to method for bearing fitment).

Once assembly is completed and temperatures normalize to tighten the fit, they should remain tight during service where temperature of both remains equal.

No doubt you will soon deserve your very own parking spot.

Good Fortune!

Well , i guess u can do it that way.


i would have just done it with my grinder. lol

Marks fingers after cutting his nails with his grinder:

Patton, you are right in that it would be marginally easier to install the inserts if I had done the freeze one, heat one trick. However, if I had made the insert too big and the temperature normalized, then it could have split the boss on the thread block. This method allows some "feel" so I could abort if I felt that I was going to crack the aluminum. Now I wouldn't necessarily suggest this repair for just about anybody. I have a lot of experience assembling thin walled aluminum parts, and have learned the hard way what will give and what won't. That jet block is a very fragile aluminum part. I was surprised at the amount of porosity in the aluminum when I milled out the threads.

It really didn't require that much force to install that insert. It's a very small vice that I used to press it in with. I was able to press it in with only finger pressure on the small vice handle. Here's a picture of the vice that I used:



The vice is only 2 3/8" wide and maybe 6" long.

oh yeah!







way to go josh.

you saved some carbs that probably did not have much of a chance any where else.

so now when you are done with them there will be no doubt in your mind that they are right.

very inspiring.

leon

p.s. this is awesome,i get my kz fix and
MACHINING PORN!!

Well I wasn't able to get to the mill today so I had to settle for getting the nasty Heli-coil out from the one jet block and I stripped the black paint from the caps and started to polish them. I started by sandblasting off the black paint:



Then sanded them starting with 80 grit since there were some heavy scratches under that paint. Then 180, 240, and finally 600 grit before I hit it with some rouge on buffing wheel.



I got the new pilot jets, needle jets, and jet needles today from Z1E. Thanks again Jeff! I shold have these carbs back to life in short order.

Looking good bro.

Agh ha ha ha ha hah ahahah ah ah ahah ha hhhahhh. I finally got it. Finally figured it out. I can't believe it. Ha ha hah ah ahahahahaha!

What an idiot I have been! Hahahahahaah!

That stupid vibration. I finally got it. Sometimes revving your bike like an idiot is useful. After I finished changing the oil, I started the bike and was listening all over the place for that stupid vibration and I found it. The damned license plate. Hahahaha! I never bolted down the lower two holes in the license plate, and it was vibrating against the aluminum backing plate. How dumb is that? Been sweating that little vibration for two months now.

Had to take the exhaust off to get the oil filter out. Gained an exhaust leak for my efforts, and I could care less. Guess I need some new exhaust gaskets.