have just recently installed a jackshaft on my bicycle... Love this kit....finally received my HS motor and g4 transmission yesterday...I've mounted the motor and tranny on my bike only to find out the transmission sprocket andt the jack shaft sprocket wont line up with each other....other two sprockets are of by a quarter inch or so.....the g4 sprocket is too far inwards....I would need to move the motor over to the left to line these up but the motor mount bracket will only allow me to move it backwards and forwards....anyone have this same problem?
g4 and jack shaft alignment
- Thread starter cj5jeep80
- Start date
Just curious, what type of 4G kit is it? Is it a tapered shaft kit or the "5/8" shaft kit?
Easiest way to tell is to look at the clutch drum. If it's flat it's a "5/8", if it's domed it's a tapered.
Easiest way to tell is to look at the clutch drum. If it's flat it's a "5/8", if it's domed it's a tapered.
sounds like the same issue as i'm having (mine is the 5/8 kit) i'm having to mod the
engine mount plates 1/4 left to get the clearance i need for the jackshaft mount
this means welding up the current mounting holes an redrilling etc (so very annoying)
i've found another way if you have access to a machine shop remove the shaft on the
4g drive (this shaft http://www.bicycle-engines.com/4G-11T-Output-Shaft-5/8.html)
have them remove 1/4 (maybe a hair more) an extend the keyway to the new shoulder
this will give the clearance you need pity sick bike parts haven't thought of this 2nd idea
(or anyone else for that matter) i've messaged sick bike parts about this issue but had NO reply
engine mount plates 1/4 left to get the clearance i need for the jackshaft mount
this means welding up the current mounting holes an redrilling etc (so very annoying)
i've found another way if you have access to a machine shop remove the shaft on the
4g drive (this shaft http://www.bicycle-engines.com/4G-11T-Output-Shaft-5/8.html)
have them remove 1/4 (maybe a hair more) an extend the keyway to the new shoulder
this will give the clearance you need pity sick bike parts haven't thought of this 2nd idea
(or anyone else for that matter) i've messaged sick bike parts about this issue but had NO reply
That's too bad they aren't lining up properly anymore. Mine is a 2010 Honda-style (5/8) 4G, came with the 11T freewheel sprocket. It lined up perfectly with the SBP input.
Almost seems like Grubee changed the 4G's shaft when the 12T sprocket came out.
The early Honda-style 4Gs lined up real nice.
Almost seems like Grubee changed the 4G's shaft when the 12T sprocket came out.
The early Honda-style 4Gs lined up real nice.
Is your 4G main pulley an 80T freewheel with a solid output sprocket?
Or is your output sprocket the freewheel?
If you have the 80TFW just pull the solid output sprocket off, pull out the bushing spacer and cut it down, that will give you enough room to line up the Jackshaft with the 4G sprocket.
It's a balancing game of lengths and the new 4G's in production now have a keyed shaft and sprockets with 2 set screws to make this much easier.
Or is your output sprocket the freewheel?
If you have the 80TFW just pull the solid output sprocket off, pull out the bushing spacer and cut it down, that will give you enough room to line up the Jackshaft with the 4G sprocket.
It's a balancing game of lengths and the new 4G's in production now have a keyed shaft and sprockets with 2 set screws to make this much easier.
I wonder if it's the 12T sprocket that's causing the misalignment on the Honda-style (5/8) 4Gs. Looking at the 12T sprocket, it appears to have a flange on each side of the tooth run - like BMX freewheels. The 11T does not have a flange on the side that faces the 4G pulley. That could account for the 1/4" of misalignment between 4G output and SBP input, as the 11T is designed a bit odd for a freewheel sprocket.
I spose the only way to confirm this is for someone with a Honda-style 4G and both 11T and 12T sprockets to measure them up as mounted.
Any takers?
I spose the only way to confirm this is for someone with a Honda-style 4G and both 11T and 12T sprockets to measure them up as mounted.
Any takers?
i have no idea this is my first time doing this an sick bike parts still hasn't replied
to me going on 3+weeks now
First let me say that as our product description says our kit is designed for the 5/8 shaft engine when using the 4G transmission. We say this because it does not fit the tapered shaft version as the alignment is off. Second please let me know how you tried to contact us. We get emails from customers everyday and usually answer them within minutes so if you have sent us an email and we have not responded then for some reason we simply did not get your email. We would never ignore a customer. That is not how we do business. So please send me an email directly.
Ya, gasbike is out of 20T/80TFW/10T 4G's and shipping 20T/100T/12TFW 4G's, just built one but it wasn't jackshafted.
If you pull the 12TFW sprocket off then pull out that spacer and cut it down the freewheel sprocket will go back in farther.
The other option is to just drill yourself some new mount slots.
Also note the SBP kits comes with a bunch of spacer washers, little black ones and big brass ones, all you NEED is at least one thin black washer against the bearing on each side.
Last edited:
my engine is the 5/8 with 4G trans. i tried contacting you via your "contact us" link on your site i WASN'T!! after a refund or return i was only contacting you at sick bike parts to let you know about the issue as everything else from you at sick bike parts has been awesome hence why i got a second kit plus parts from you.
i just thought i would of got a "thanks for letting us know" but you say you didn't get a message from me so i'll take your word for it.
i'm not trying to be rude or an ass just trying to help
I have done a lot of business with SBP over the years and both Jim and Paul are pretty darn good guys that always answer mail, and Jim has even contacted me about this problem and I am helping them figure out a better design for the engine mount base to accommodate the ever changing combinations of small 4-stroke engines and transfer cases.
Jim is a pretty smart cookie, you can bet he'll come up something a little easier to work with.
Jim is a pretty smart cookie, you can bet he'll come up something a little easier to work with.
i don't doubt it KC.
one of the easiest ways i can workout is a modified drive shaft off the 4G that holds both the chain drive an 80? an 100 tooth pulley (80 i'm unsure of as i haven't used one) anyway by removing 1/4' off the shaft an machining a longer keyway would keep the mounts as is an move the chain sprocket to where it needs to be
note this 1/4' is measured from the left edge of the mounting slot not the middle of the mounting slot
by doing it this way it keeps the engine centered where it is instead of moving the engine closer to the left leg etc
I have the china girl with the 4g tranny and sbp shift kit and i noticed the same issue. all i did was put another washer behind the left gear and perfecto..... now the problem i ran into was pedal clearance . im using the bottom bracket adapters and the mm crank (came with kit and the arms are 170s which hit the tranny. Any have this set up also (o the bike is a walmat schwinn)
FYI, when we use the term "china girl" here we refer to the common 2-stroke engine, not the 4-stroke Honda clone that you obviously have. That is a Huasheng or "HS".
Pedal clearance can be tricky with the 4G. If you have a Honda-style 4G (aka the 5/8" keyed shaft version) then modifying the 4G cover bolt holes so it mounts closer to the pulleys might take care of it. Not running the cover helps too of course. I have this version of 4G with SBP kit and had to modify the cover. My pedal clears the cover by a millimeter or two.
If you have the tapered shaft 4G (the one with a domed clutch bell) then you really only have 2 choices: bend the cranks/replace the SBP crank arms with dog-legged versions, or run shorter crank arms. This version of 4G is a bit wider than the other, enough that crank clearance can be a real problem.
I use the funky curved pedal arms from the 4-stroke kit if I get pedal clearance issues, it don't matter to the jackshaft, the freewheel is mounted to the pedal shaft not the right pedal itself.
well what i ended up doing was cutting the crank arm (the one from motor kit) and welding it back together and had another arm from another build so they match except height of course. I thought pedaling would be funny (not that i do any) but i took for a non motorized ride around the block and its not bad. possibly due to how far your out to clear the engine to begin with. sometimes K.I.S.S is the answer
time for me to eat crow be a man an admit i was wrong
Ghost0 (i'm guessing you're the sickbikeparts man) let me say i'm so very sorry
for what i said about the 4stroke shifter jack shaft kit i finally work out my
problem was with the shifter kit but the chain i was using i was using the chain
that came with the engine kit
damn i feel dumb i didn't realize this mistake untill i read The Aleman say something
about "bmx" or "single speed" bike chain is the same pitch as 415 when it clicked
that's what the install manual was pointing at (as it doesn't exactly say still my fault)
anyway i just wanted to stand up an admit my mistake an say sorry sick bike parts
Ghost0 (i'm guessing you're the sickbikeparts man) let me say i'm so very sorry
for what i said about the 4stroke shifter jack shaft kit i finally work out my
problem was with the shifter kit but the chain i was using i was using the chain
that came with the engine kit
damn i feel dumb i didn't realize this mistake untill i read The Aleman say something
about "bmx" or "single speed" bike chain is the same pitch as 415 when it clicked
that's what the install manual was pointing at (as it doesn't exactly say still my fault)
anyway i just wanted to stand up an admit my mistake an say sorry sick bike parts
