7G Ghost Racer Kit

Discussion in '4-Stroke Engines' started by MacLotus, Jul 11, 2015.

  1. MacLotus

    MacLotus New Member

    Greetings! This is my first post.

    I recently purchased the 7G kit, which comes with the HS 49cc 4 stroke. While it runs great, one can't help but want to get a little more performance out of it.

    What aftermarket parts are available/recommended for this engine? (Exhaust pipe, carb, air-filter) Source?

    Also, I've heard about the EZ Q-Matic transmission, but not sure how it compares to the 7G? Is the 7G a recently introduced product (after the Q-Matic)? If one is better than the other... please help me understand the benefits.



  2. KCvale

    KCvale Motorized Bicycle Vendor

    Hi Ken, welcome to the forum.

    NGK 7544 (CR7HIX) Iridium spark plug.
    Adjust your valves.
    Replace the box exhaust with anything else, even a 2-stroke pipe.

    Sorry I don't have the gaps for the 2 valves, my server is down and they are in my topic there but you can search here for '142F'.

    Sadly the 7G transfer case in that kit is not not very good.
    Keep the clutch bushing well oiled and the belt tension as loose it will go to get more longevity out of it.
  3. dougsr.874

    dougsr.874 Active Member

    Valve adjustment is .004 on intake, .006 on exhaust
  4. MacLotus

    MacLotus New Member

    Thanks a bunch! Much appreciated! Is the valve adjustment needed because of poor manufacturing processes? Are they that far out of whack 'out of the box'? I'll make the adjustment.

    I appreciate hearing 'how it is' with regard to the various components out there, regardless of whether I own one or not. I'd like to find what works best, not the cheapest... but what's worth the investment, and what's not.

    The one thing I found a little disappointing about the 7G transfer case was the excessive drag when pedaling. I expected some, but not that much. I did add an upgraded spring tensioner (415# Chain) and have a 10t idler gear ordered. The spring that came with the tensioner was extremely weak for the job so I added a 30lb spring. Now tension is perfect as I go from throttle-on to engine-coasting to throttle-on. The idler gear should help too. I also just received some 1/2" vibration isolators sized to M6 1.0 for the engine mounts. We'll see how that works. This is all in an effort to minimize vibration and noise.

    I pretty much trashed everything that came with the kit opting for the best stuff I could find. I bought the Harmony Adapter Kit with 48T sprocket, which bolt directly to the hub via the 6 disc-rotor bolts (vs. clamping to the spokes). It works great. Love it! Should I change to a 41# chain?

    BikeBerry is getting ready to release a flexible Poo Poo exhaust with a flange for the HS 142F. Not sure if it will have the expansion chamber like the two stroke version. I want a pipe that takes the noise/pop and puts it behind the bike, and muffled as best possible (even at the sacrifice of a little power). That means a longer pipe.

    As for the stock air-filter... I've seen some folks recommend taking out the sponge and running nothing? Is there something better out there or do I have to engineer a solution myself?

    The last two questions are the most important to me...

    Will I appreciate the difference and benefits of the EZ Q-Matic transfer case? Subjective question... I suppose? Is it smoother, quieter, and easier to pedal 'engine-off'?

    Is the Honda GSX50 engine worth the additional money over the HS 142F? Honda is unquestionably the pinnacle of quality precision manufacturing processes, but does that transfer to the GSX50? The engine designs in photos look so similar, one can't help but think they're all the same... a horse apiece. Question is... is the Honda quality there?

    Thanks again guys! You comments are really helpful!


  5. The_Aleman

    The_Aleman Active Member

    I wrote up a valve adjustment procedure a few years ago, maybe it'll help you.
    link: http://www.motoredbikes.com/showthread.php?38514-How-to-adjust-your-GXH50-Huasheng-Titan-valves

    I'll try answering your questions the best I can. You put a lot of them in your post!

    The Huasheng is made in China by usually underpaid folks who may or may not take pride in their work, and that attitude may or may not change depending on what day of the week it is. Sounds like anywhere else, no? Anyway, valves being out of adjustment significantly alters the performance of an engine, especially one this small. Doesn't matter where it's made, best to make sure things are set right if you know the specs. Call it an enthusiastic doublecheck.

    This is to be expected when there is no freewheel mechanism on the transmission output. Pedaling with the engine off will turn the whole belt assembly and thus the freewheeling action is at the clutch drum. I don't know of a freewheel for the 7G's output shaft, but a lack of a freewheel gives you engine braking ability. Most Grubee 4G have freewheeling action and thus lack any engine braking.

    If you want to minimize vibration, use a quality mount and make sure it's tight. Rubber mounts will often exacerbate any vibration.
    A single cylinder engine is by nature unbalanced harmonically, so there will always be some NVH somewhere.

    If your chain run is perfectly straight, a standard BMX-sized 410 should work. If you want a little peace of mind, use heavy duty 410 like KMC's 710.
    If you want even more peace of mind, use 415, which is a little wider (3/16" vs 1/8"). #41 will also work, but IMHO is unnecessary.
    You will get better performance with a lighter chain.

    It shouldn't have the expansion chamber. From my experience, BikeBerry is a joke for 4-stroke stuff. They don't seem to know what they are doing.
    Get the Whizzer flexpipe from Memory Lane Classics for $22 and their tailpipe tip if you like. If you want a snarly muffled sound, use a large Briggs cigar muffler.
    They are <$10 at Ace Hardware. On my setup I don't use a muffler anymore, I just bend the end of the flexpipe slightly downward.

    Keep the sponge, but drill a bunch of 1/2" holes in the air filter cover. It will work just fine. You can upgrade the filter to something better.
    It may not win anything in the looks department, but it will work just fine. Or you can change the whole intake and carb and use Venice Motor Bike's kit.
    His kit will eliminate any problems you will likely end up having with the stock carburetor, and it also will improve performance a bit.

    The Q-Matic is an excellent cruising system. It's is smoother, about as loud and about the same difficulty in pedaling with the engine off.
    It's much slower on take-off from a dead stop than a 4G/7G and doesn't like slow cruising speed (clutch can burn up prematurely).
    But on the straights, it's perhaps the best system. You can blip the throttle all you like and the system is easy on the bike.

    The GXH50 is not worth the extra money over the Huasheng. All said and done, the GXH50 costs over twice as much, it's only slightly better in the end.
    It does have very slightly more power (~5-10%) and it's a little quieter. It also comes with a governor and low oil shutoff, which get in the way.

    It will not necessarily last longer than a Huasheng. Either engine can break when over-revved for extended periods. Primitive oiling system.
    My brother has had a GXH50 and Q-matic for over 5 years. He's had to rebuild his engine once already, has about 2K miles on his setup. He runs hard.

    I've had a Huasheng and a 4G on SBP shift kit for 5 years. I'm approaching 10K miles and my engine still starts in 3 pulls or less and runs like new.
    I use 15w40 Rotella T oil and every 2 tanks of gas, I put a capful of Marvel in the gas as an upper cylinder lube.
    Change oil every 2-4 months, adjust valves the same time, don't rev it over 7500. Change fuel filter every 8-10 months.

    It should last you a long time.
    Dustmonkey likes this.
  6. LR Jerry

    LR Jerry Well-Known Member

    Consider a shift kit.
  7. MacLotus

    MacLotus New Member

    Wow! Great information! I can't thank you enough for taking the time to help me better understand these machines. There is no substitute for those who have 'tried and true' experience. Thank you.

    I do appreciate the engine braking, and with the engine running at idle, it seems easy enough to pedal... With a little 'power-assistance' when needed.

    Regarding the carb, I looked at that but it appeared he's out of stock for now. I mentioned it to the guy at BikeBerry and he scoffed at the thought of a two-stroke carb on a 4s. I'm curious if it had to be re-jetted for 4s use? Like you, I wasn't terribly impressed by his knowledge... Or lack thereof. ;-)

    I'll order those exhaust parts today. That sounds like some great options.

    Lastly, the transfer case. I personally don't use the bike for transportation, but for low & slow speed exploration (15 mph or so). I agree the single cylinder engines don't last long at higher rpm's, but since I'm not a speed demon and more of a cruiser, that shouldn't be a problem. Since I'm a slower cruiser-type, would the Q-matic burn clutches faster than my 7g?
    You mentioned its smoother, but slower on take-off. Does it have more torque as a trade-off?

    It may be an issue for me, but currently I have a 48t rear sprocket (Harmony Adapter Kit) with monster disc brakes. I really like the direct-bolt mount to the hub and the disc brake set-up... Stops on a dime! The downside.... I'm limited in the size of the rear sprocket or I'll lose the rear disc brake set-up. I could fit a 52t or maybe a 54t, but not any larger. The q-matic requires a 56t minimum. Question is, would I really lose 'umph' on take-off vs the 7g I have?

    Regarding a shift kit, I took the Shimano 7-speed system off the bike and installed an upgraded cassette hub, surly spacers, and 22t single speed cog with surly tensioner. Works great! Again, I prefer low speed cruising... and the current set-up easily goes faster than I need/want. I wish I could go 60t, but I'll lose the rear brake. I like (make that LOVE) good brakes! ;-)

    Thanks again. You're experience is saving me huge time & money on experimentation! Much appreciated!


  8. KCvale

    KCvale Motorized Bicycle Vendor

    The Almen summed up everything extremely well (Nice work A).

    I will just add this...

    Not only does the 7G not have any freewheel, the clutch bell is on a bushing so it makes it even harder to pedal.
    The Q-matic is good but also has no freewheel and it is really wide due to the outer bearing support for the Secondary pulley.


    That is the Q's cover next to a 4G cover on the ground.
    That's a 79cc build in the bay right now so a different engine but the same Q system.
    The wider it is, the wider the pedal spacing has to be.

    The 4G's use a freewheel output sprocket for easy pedaling, but they have to be at least 12T and considering their small size, not that reliable.

    I think the 10G KCK is the best system to date, it has a much larger freewheel bearing inside the 100T secondary pulley, and the clutch bell is isolated from the engine shaft on a set of bearings of it's own.
    That means you can go with as small as a 9T solid output sprocket and comes with a 9 and 10T.

    Bummer for you is, you have the wrong engine.
    Like the 4G, the 10G was developed for the HS 142F-1G engine with the tapered shaft and clutch attached.
    You have the HS 142FS engine with long straight shaft and separate clutch, all of which ride on the engine shaft like the 7G.

    To change your transfer case options to better ones, you have to change engines.

    Note there are also HS 144F-1G engines.
    Same engine as the 142 49cc, it just has a slightly wider bore for 53cc and a bit more power.

    Hope that helps.
  9. KCvale

    KCvale Motorized Bicycle Vendor

    You must have been posting when I was so I will address your last post.

    I had a customer with the same needs as you last year.
    He wanted a Mule. All torque, light, and ~15mph top speed.
    Great disc brakes and enough torque to climb a telephone pole without gears so I built him this.


    The whole bike is Surly and better stuff.
    He shipped me a couple of big boxes of parts and said 'use these'.
    Had to be $2K worth and it is so nice to work with great parts!

    Jackshafted it so I didn't have to mess with the brakes and gained a bunch of gear reduction in the process.
    Like you, I replaced 7-speed with a perfectly aligned big single sprocket on the hub via the spacers.


    I just talked to him a couple months ago, too funny...

    He was apparently trying to climb a near vertical cliff and flipped it over backwards and broke a couple parts and wanted to know about replacements, but the too funny (or maybe really cool) part was him going on and on and on... about how perfect the machine was for his needs and this wasn't my fault.

    Who doesn't like kudo's like that?

    Anyway, the point is
    you can get what you what though I'd suggest replacing the back hub with a 3-speed disc hub but what you have will work dandy.

    Geared right, with a 3S you can creep along 8mph at WOT full power up hill, or get up to some real speeds or a quitter (lower rpm) slow ride up-shifting, yet the chain line remains true and fixed.

    Just examples what can be done, hope it helps you.
    Last edited: Jul 13, 2015
  10. MacLotus

    MacLotus New Member

    Those are some great suggestions. Thank you! Are the 10g engines available? Source?

    I'd like to learn more about 'jack shafting' and what engines you can do that to. Any links?

    Thanks again!
  11. The_Aleman

    The_Aleman Active Member

    My 2010 model 4G has an 11T and it works fine with a SBP shift kit. Freewheel outputs work great with shift kits because they don't freewheel while coasting
    with engine running, they only freewheel when pedaling with engine off. While coasting with engine on, the freewheel action is done by the rear hub.

    You can run an SBP shift kit on your existing setup. You say you're interested in low-speed cruising, I think a shift kit will be the best option for that.

    You'll still have the problem of added resistance while pedaling engine-off, tho. In fact it may be worse because an extra chain will be thrown into the equation.

    It's possible to modify the jackshaft input with a reverse freewheeling gear however, this will eliminate most of the added resistance.
  12. MacLotus

    MacLotus New Member


    That 'mule' is pretty cool! How big is that single speed rear cog? I have a 22t, but would like a bigger one.

    Thanks again!
  13. MacLotus

    MacLotus New Member

    Is this the 4G you're referring to? http://www.bicycle-engines.com/4G-T-Belt-Transmission-Only.html

    It looks similar to the 7G I have. What is the major difference between the 4G and the 7G? Does one offer less resistance while pedaling 'engine-off'?

    So if I understand you correctly, your saying that 'tapping in' to the bike's drive system (with an SBP Shift Kit), the torque will be significantly better than the what I have (415# Chain, Tensioner, and 48T sprocket)? But there will still be pedal resistance 'engine off' (similar to what I currently have now).

    I get that folks would use a shift kit to get speed, but can it be used to get major torque? I'd prefer not to have gears, but rather one gear... the right gear... a 'mule' as KC said. I want to power through sand. Top speed would be about as fast as you could probably pedal a single speed bike manually. Lastly, it's a fat tire beach cruiser, so the bracket and the hubs are a little wider than typical bikes. Would that pose a problem -or- is it irrelevant? I'm not familiar with its installation, that's why I ask. Maybe there are some posts here? I'll have to look.

    Would it ride smoother and function better than having sprockets on both sides? How would it perform with my single rear 22T cog?

    Is this the kit? http://www.sickbikeparts.com/catalo...ucts_id=110&osCsid=5bt31dro1pra7r51kfnomirne3

    Again... New to all this stuff, so I appreciate the education here guys. I can't thank you enough!
    Last edited: Jul 14, 2015
  14. KCvale

    KCvale Motorized Bicycle Vendor

    Well.. Since you asked...
    The KC's 10G Long Shaft is not an engine, it is a transfer case that bolts to the engine like your 7G.
    Unfortunately, you have a different engine output so irrelevant to what your options are with that engine but here is the scoop...

    I worked with Don Grube (Grubee, Skyhawk) for the last year on a new transfer case that fits the HS 142/144F-1G engines that have an output shaft that reaches the right site on it's own....


    I developed a base with a carrier bearing for the right side shaft end for support, and the only tensioner needed in the whole system is on the base so you never have to move your engine or the base to keep that right side chain tight.



    With an SBP freewheel bottom bracket freewheel pedal assembly you are 'jackshafted' without the need for an additional shaft, bearing, mount base, sprocket or chain.

    There is no link to buy one yet but since you asked, you can reserve one with a despot here.

    He asked and you have to admit it is one heck of a 4-stroke better solution...
    When I actually have them here I'll do a vendor post, or should I just make a post there now and reefer people to that topic?
    Just trying to play by the rules ;-}
  15. MacLotus

    MacLotus New Member

    Thanks for posting pictures. Cool set-up!! Freewheel is kind of a new term to the bicycle newb... such as myself, so please forgive my ignorance. Is freewheel like a directional ratcheting effect (like my rear hub)? So does the bottom bracket freewheel when under power? Or is the freewheeling done on the the countershaft?

    Do you have to raise the engine up and forward (than normal) to make room for the countershaft assy? I ask because, if I'm gauging scale effectively, the countershaft would be right where my vertical seat-post/frame post is. I have my engine mounted further down to fit a fuel tank.

    I'd certainly be interested in learning more when you're ready to ship the units. Thanks!

  16. MacLotus

    MacLotus New Member

    After a lot of research, it would appear because of my 'odd-sized' Chinese bottom bracket... changing to the SBP is not an option for me. My fat tire bottom bracket is wide, 120mm with a 40mm BB shell. So the KCK 10G solution may need to wait for my next bike.

    I also looked into a freewheeling rear hub/sprocket assembly, but again, the width of the rear hub on my bike is 170mm, much wider than the freewheeling hub in that kit.

    I did manage to find a 4G that fits the 5/8" keyed shaft I currently have. Supposedly it has the 12t freewheeling gear that may help a little to reduce drag.

    I also ordered a 60t rear sprocket. I'll lose my rear disc brake, but maybe it won't be needed with the slower speed and increased torque.

    Anyhow, I continue to absorb and evaluate what's available out there. Thanks again for your comments. Very helpful.
  17. KCvale

    KCvale Motorized Bicycle Vendor

    On a shifter you have 2 input power sources to the same sprocket connected to the back wheel...
    Your pedals, and the engine, and they don't play well together.

    You need a freewheel on the engine power side so you don't have engine drag when pedaling...
    This can be the output sprocket, in the secondary transfer pulley, or just the clutch bell.

    And you need a pedal crank arm freewheel so your pedals don't beat you to death when the engine is turning the drive sprocket.
    It is like a socket wrench and the handle is your crank arm.
    The socket has 2 sprockets, one to drive your back wheel, and another for the engine to turn it.

    Like a socket wrench you can turn it one way with the handle, but your can also just turn it the same way with your hand and the wrench does not move.

    The downside to this is you can't back pedal for a coaster brake like some 3-speed hubs have.

    What 'Fat Tire' bike are you working with?
    I don't even consider direct driving builds with actual outside tire width over ~2.75", they all get shift kits because the pedal side is always setup to clear the tire.

    You seen the Fito's, here some even fatter tired bikes, a couple with 120mm BB's, and all have the SBP BB freewheel.




    My electrics use the same BB system as gas, and the electrics have a freewheel drive sprocket.