Dorothy, Heald VT-7 (anything goes) project ...

Mini Bike & Go-Kart Parts

#41
You need a 125 or 130 main jet. you are too lean with stock jetting. I have both if you like pm me your address and ill send them just pay return postage and return them when done. you can get them from isky but this way you can see which works best. Or look on AGK website and he has drill sizes to drill out your stock jet to get it to 125 to 130 size.
 
#42
ole4
Interesting read in drilling jets ...
I don't know that the nelson exhaust will be the final one .. I'm guessing exhaust will affect jetting ..
difference between stock and 130 about .011 ... should I drill it out with say a #56 (119 jet size) for now and tune later when I come up with an exhaust I like?
 
#43
I have open headers on all my motors. the hs50 is night and day different than the tuned clones yet the jetting works for all. I think it has more to do with displacement than tuning. the original carb is jetted for the lifan horizontal Honda z50 to 125cc motors.
 
#44
Thinking on this more I think your approcach is better. When drilling jets its not as exact as when you buy a sized jet so if you go up to the 119 size you should still be able to tell if it has improved the issue you are having. then keep going up gradually till it stops improving. (if lean condition is your issue).
 
#45
Thinking on this more I think your approcach is better. When drilling jets its not as exact as when you buy a sized jet so if you go up to the 119 size you should still be able to tell if it has improved the issue you are having. then keep going up gradually till it stops improving. (if lean condition is your issue).
WOW WOW WOW!!!
I took a new #56 bit and grabbed my hand air drill (I'm arrogant enough to think I can do this without a drill press!).
Put the jet gently in a vice horizontally and quickly ran it in and out once. Took my air blast and blew it out.
Put it all back together, couple of pulls and she was running but like CRAP!! Chug chug, stutter stutter.
I'm thinking I just smoked a jet, maybe left some slivers behind and smoked the carb.
Last thin to do was pull the "kit" air filter off ... so I did and the first thing I see is gas around the seal ... hmmm ....
toss it aside and pull the rip cord ... VAROOM!!!!
WOW!! I'm not sure there is a top end but I didn't find it going down my street ... opening that jet brought that engine to life ...
I did a couple hot laps at hi RPM and shut the motor off while it was at hi RPM and coasted into my garage ...
The plug was pulled and looks like this ...


That looks damn near perfect to me!!

ole4, you nailed it again!!
Thanks amigo!

I pulled the plug boot and this stayed on the plug ...
It's always something!
 
#46
I put a #40 sprocket on the 3D clutch ... after the 25 min break in I found this ...


Its metal shavings from the New chain hitting the New #40 sprocket ...




As mentioned earlier the gearing is way to tall with the #40 set up ...
I had the original #35 sprocket, an 18t #35 jack shaft sprocket and some new #35 Extreme chain so I put those on, gearing is not as tall but still way too tall ...
However I see the same metal shaving trail on my mounting plate that I had with the #40 set up ... I didn't take it apart but for all the world it looks like the chain is hitting the 3D sprocket.
Yes the alignment is correct ... I am that anal.

Here is a pic of the oil after the first 25 min break in ....
 
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#47
Kinda hard to see the oil picture but on my rebuilds I usually see a fine metallic sheen on the first and sometimes second oil change. I also put a magnet in the drain plug.
 
#48
Well the air filter has proven to be a problem ... I thought it might be a ledge molded into the rubber covering the holes in the back of the carb so I jury rigged an aspirin bottle to act as an smooth intake that covers only the outside of the carb ....



That didn't work either ... without question the air demands of this motor are more that this air filter can deliver.

What air filter do I need?
 
#49
Rip cord getting ripped out of my hand!!! OUCH!!!

A real problem is one I did not anticipate ...
Pull the rope and sometimes it will rip it out of your hands weather your prepared for it or not ... I have 2-handed it and had it ripped out ...

The cam does not have the compression release bump on it .. is there another way to add compression release?
 
#56
sixpac440, try pulling on the cord slow. you should have a spot where the cord will pull real easy and then it gets hard. at that point still pull it slow and you will feel it come off that hard spot and another one will be there...stop. at that point pull it reel fast and make sure you bring your hand back down with the recoil(quickly) just try it and see if that works. i should almost do a video starting my ohh-tecumseh with a dyno-255 cam,milled head,hot coil(advance timing) and yes a mikuni carb....142.5 jet
something else you may have to dail in is your pilot. drive the bike at a low speed cruise and if it stumbles you may have to go to a larger pilot.....:thumbsup:
 
#57
you know that bike was originally setup for electric start. you might have to boot that blue cover and go with a electric start setup.........no that would be to easy and wouldn't look cool anymore without the blue performance cover......:scooter:
 
#58
you know that bike was originally setup for electric start. you might have to boot that blue cover and go with a electric start setup.........no that would be to easy and wouldn't look cool anymore without the blue performance cover......:scooter:
I put it on the compression stroke to pull ... I will check it a bit closer ...

Electric start may be an option ...
 
#59
sixpac440, try pulling on the cord slow. you should have a spot where the cord will pull real easy and then it gets hard. at that point still pull it slow and you will feel it come off that hard spot and another one will be there...stop. at that point pull it reel fast and make sure you bring your hand back down with the recoil(quickly) just try it and see if that works. i should almost do a video starting my ohh-tecumseh with a dyno-255 cam,milled head,hot coil(advance timing) and yes a mikuni carb....142.5 jet
something else you may have to dail in is your pilot. drive the bike at a low speed cruise and if it stumbles you may have to go to a larger pilot.....:thumbsup:
I tried your method and indeed it starts without pulling tendons!
The gearing is way to tall so I don't know how low speed really is and if I need to adjust the pilot jet size.

I ordered a #40 24t plate sprocket for the jackshaft, that will improve the gearing ...
The air filter needs rethinking and that may affect low speed too ..

The shock rubbers are worn and it causes the seat to wiggle left to right, not very confidence inspiring!

There are a few other small things ... I'll update as I go ....
 
#60
The shock rubbers are worn and it causes the seat to wiggle left to right, not very confidence inspiring!

The shock rubbers are not the determining factor in seat movement right to left. The hinge is loose and you can tighten it to the pin to help or even eliminate the wiggle.

You will heed to remove the seat and turn the hinge straight up. Use the biggest hammer you can find, 5 or 6 pounds, as a backer under the hinge. Use a good punch and a 2 or 3 pound hammer to roll the hinge back tight to the pin. Easy to do as long as you have help.

Doug
 

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