Quick question, is the front pulley on the qmatic supposed to be pretty snug to get on the 99cc shaft? Im sure i can tap it on with a mallet but wanted to make sure i didn't need to have anything machined.
99cc Predator HF Build
- Thread starter cory151
- Start date
Oops, hey Quinton, I made a mistake in my previous post. I am using 3/4" conduit on my exhaust, mainly because it was available and it fits snugly over the stock exhaust manifold after the muffler flange is removed.
Thanks Q, for posting your experiments data.
I haven't done extensive or accurate speed tests, but I can't tell any difference in feel or speed on my cheapo speedo with or without the large hotdog muff.
Thanks Q, for posting your experiments data.
I haven't done extensive or accurate speed tests, but I can't tell any difference in feel or speed on my cheapo speedo with or without the large hotdog muff.
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Sorry I'm not Q, but yes, it should be rather snug. Just be sure not to damage the belt and it will stretch after it's run for a while.Quick question, is the front pulley on the qmatic supposed to be pretty snug to get on the 99cc shaft? Im sure i can tap it on with a mallet but wanted to make sure i didn't need to have anything machined.
I've installed belts that were really tight on the q-matics and there was no slop at all for the idler pulley. It all broke-in fine after the belt relaxes a bit.
I have noticed that the 99cc's shaft is slightly oversize from 5/8". Both mine measure at .630". I just used a mallet and carefully knocked on a die cast pully on one. It shaved out a little of the pully's bore as it was driven on.
For a steel pully, I would try heating the pully to about 200 degrees f. or more to expand it some then quickly slip/tap it into place.
For a steel pully, I would try heating the pully to about 200 degrees f. or more to expand it some then quickly slip/tap it into place.
Like all Chinese products, the measurments will vary. I checked the shaft on the 79 CC and it is very close to 5/8" [.625"]. The HS 142 with the "5/8" shaft is actually 15.8 MM or .622". After checking the 99 CC I found it to be .626" and the pulley needed to be "tapped" on. It is so close, maybe a little sanding inside the pulley will allow it to fit more easily.
Have fun,
Have fun,
OK, shaft is too large.....yeah, don't force it as they crack rather easily (cast iron). The aluminum-like congress pulleys will shave rather than crack, but they can crack too. Light sanding as Q suggested.
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Sanding is a good idea, prolly more than lightly to get it done though.
I would try the heat method first though. The heated pully's bore will expand several thousands. This is a common method for installing bearings in industrial applicatons, they are heated to about 250-275 deg and installed with thick gloves for handeling.
Sanding is a good option though. I would try it with a steel dowel, slightly smaller than the pully bore, in a drill press, with rather coarse emery paper glued to it. Work it around the bore methodicly and evenly, and skip pressure over the keyway.
With the potmetal pullies you will need a coarser grit, like 80-100 to keep the paper from clogging.
With a steel pully or clutch hub, the paper dulls quickly and you will prolly have to change the paper a few times before enough material is removed.
Keep stopping and trying the fit. You don't want any looseness at all, need enough interference that it needs some tapping with a light hammer. The torsional vibration from a 4 stroke engine power pulses will wallow out the key and bore eventualy or soon, if there isn't some interference in the fit
Just my conclusions from my lifetime experiences, hope it helps someone, YMMV
I would try the heat method first though. The heated pully's bore will expand several thousands. This is a common method for installing bearings in industrial applicatons, they are heated to about 250-275 deg and installed with thick gloves for handeling.
Sanding is a good option though. I would try it with a steel dowel, slightly smaller than the pully bore, in a drill press, with rather coarse emery paper glued to it. Work it around the bore methodicly and evenly, and skip pressure over the keyway.
With the potmetal pullies you will need a coarser grit, like 80-100 to keep the paper from clogging.
With a steel pully or clutch hub, the paper dulls quickly and you will prolly have to change the paper a few times before enough material is removed.
Keep stopping and trying the fit. You don't want any looseness at all, need enough interference that it needs some tapping with a light hammer. The torsional vibration from a 4 stroke engine power pulses will wallow out the key and bore eventualy or soon, if there isn't some interference in the fit
Just my conclusions from my lifetime experiences, hope it helps someone, YMMV
I would use a Dremel grinder and sanding drums to increase the I.D. of the pulley. The only issue with using heat is removing the pulley at a later date [if needed]. It also very important to install a large flat washer [fender washer] at the end of the crankshaft to stop the pulley from ever sliding off the crankshaft.
Have fun,
Have fun,
LOL, no you wouldn't want to use heat to remove it, and you wouldn't have to.
Back in my petrochem millwright days, we always heated bearings and sheaves to install them. This was called a shrink fit. Very tight and reliable. We used conventional pullers or a hyd press,depending on the job, to remove them with no problem.
Back in my petrochem millwright days, we always heated bearings and sheaves to install them. This was called a shrink fit. Very tight and reliable. We used conventional pullers or a hyd press,depending on the job, to remove them with no problem.
Hi Wayne Z,
I used the "heat" method hundreds of times during my racing days with Ducati & HD to install sleeves in the cylinders. We put the sleeves in the freezer and heated the cylinder, and the sleeve would just slide into the cylinder. Of course the sleeves were impossible to remove once they were installed and required cutting them out to replace. I remember you could move the sleeve around for a short period of time and once it cooled it was forever. We didn't use heat on any gears or bearings as it would either dry out the lubricant in the bearings or change the temper of the gears.
Sadly the crankshaft in the Chinese motors isn't made of really hard steel and several times during gear removal [on the early "Hoot" drives] the puller managed to flare the end of the crankshaft.
Have fun,
I used the "heat" method hundreds of times during my racing days with Ducati & HD to install sleeves in the cylinders. We put the sleeves in the freezer and heated the cylinder, and the sleeve would just slide into the cylinder. Of course the sleeves were impossible to remove once they were installed and required cutting them out to replace. I remember you could move the sleeve around for a short period of time and once it cooled it was forever. We didn't use heat on any gears or bearings as it would either dry out the lubricant in the bearings or change the temper of the gears.
Sadly the crankshaft in the Chinese motors isn't made of really hard steel and several times during gear removal [on the early "Hoot" drives] the puller managed to flare the end of the crankshaft.
Have fun,
Cory,
I asked AZbill to post some Pix of my HF99 and the Q-Matic mount technique on JBcruzin's Pred99 build thread, I'm bad on posting here on the board, If you send me your E-mail I will email them direct to you.
[email protected]
R/Mac
I asked AZbill to post some Pix of my HF99 and the Q-Matic mount technique on JBcruzin's Pred99 build thread, I'm bad on posting here on the board, If you send me your E-mail I will email them direct to you.
[email protected]
R/Mac
How long is the mount plate from the inside of each tube cutout? Need to know to measure my frame...
frozen,
I used the HS49 mount plate that came with the HS kit, I modified it to fit the large down tube of my OYNX, so I didn't want to do all the weld and grinding to get a comfy fit to the frame(if I used a new mount), I believe AGK has an adjustable one, take a look at their site
R/Mac
I used the HS49 mount plate that came with the HS kit, I modified it to fit the large down tube of my OYNX, so I didn't want to do all the weld and grinding to get a comfy fit to the frame(if I used a new mount), I believe AGK has an adjustable one, take a look at their site
R/Mac
here is the link for the plate for the HF79/99
affordablegokarts: Motor Plate for 79cc &99cc HF Engines
affordablegokarts: Motor Plate for 79cc &99cc HF Engines