A little about me: I work as an Independent Network Administrator, a SysAdmin (SIN for short) but used to import off-road vehicles a few years ago. Now I'm completely hooked on Scooters (as a user) and recently started helping my dealer (Ozooma) with their online operations (hence all the new toys ;D )!
So on with the thread...
Time for some more upgrades and a chance to evaluate a few performance parts suited to my GY6 clone (157QMJ 150cc).
Without the need to upgrade to a 250cc model, my goal was to just add a little more to the top end so that every now and then I could open her up and hit 100kph (62mph) for a minute or so, not a big deal really as most of my riding is in 80kph (49mph) zones!
Another goal was to perform this entire upgrade without removing the engine from the scooter
4 Valve Head with Racing Cam - consisting of a whole new Head, Head cover, Rubber Seal, Rocker Cover, O-ring Furrow Seal, Exhaust Gasket, Metal Head Gasket, Racing Cam, 4x longer Head bolts and longer Cam Chain.
30mm CVK Racing Carby kit - consisting of a 30mm CV Carby with Auto Choke and 30mm Alloy Intake Manifold with Gasket.
Big Bore Kit - consisting of a 61mm Piston, Cotter Pin with 2x Circlips, a set of 5 Rings, 61mm Bore ( conveniently stamped 149cm3 ) and Paper Base Gasket.
According to my converter, my existing bore/stroke which is 57.4mm x 57.8mm totals 149.63cc's (rounds up to 150). So by increasing the Bore to 61mm with the same stroke ( 57.8 ), the new cubic capacity will be: 169cc's (rounds up to 170)
Not a bad increase in displacement considering I wasn't required to do any machining!
The Head Cover was held on by 4x 8mm bolts and sealed to the Head with a rubber O-ring around it's seam. The breather hose originally ran to the Air Box but will now join up to a new Oil Catch Can (discussed later).
Next came the Valve Rocker cover - this was held in place by 4x 12mm nuts and was easy to remove.
NOTE: 2x metal dowels were holding the Rocker cover in alignment with the head.
Removing the cover exposed the Cam shaft and allowed the Cam to be lifted and tilted towards the Cam Chain.
After the Head removal, the Piston and Bore were exposed along with the metal Head Gasket.
The metal Head Gasket could easily be prised away from the Bore (but not suitable for re-use). This exposed the lower Cam Chain Runner which was removed by sliding it out of the Chain chamber.
The Bore was then gently pulled away from the engine and the Piston was allowed to slide out completely. The paper Base Gasket tore away as expected.
NOTE: The Bore was aligned to the engine base by 2 metal dowels.
On the left side of the Piston (looking from the front) the Circlip holding the Cotter pin in place was easily removed with a pair of pliers.
The Cotter pin slid out smoothly allowing the Piston to be detached from the Crank Rod.
THE 4 HEAD BOLTS (RODS)
Because of the increased height of the 4 Valve Head, 4 longer bolts were supplied. The originals were removed by double nutting them and turning anti-clockwise. A little blue lock-tight was used to secure the new bolts within the threads of the engine base.
NOTE: 2 of the bolts are slightly longer, they are placed closest to the Cam Chain chamber (same as the originals).
The most important part of re-assembly was to ensure that the gaskets and rings were correctly aligned.
The paper base gasket has a channel grooved into one corner which aligns to the same channel on the bore. This allows oil to flow up and lubricate the head and must not be blocked.
Hylomar is a gasket jointing compound available in a spray can and is perfect for giving each gasket a very light coat. This ensures a good seal and helps to prevent oil leaks.
The set of 5 rings provided with the Big Bore Kit were already pre-gapped. The 2 larger rings marked T1 & T2 were placed in the top 2 Piston grooves with the markings facing up in 1, 2 order from the top.
The lower 3 rings (none have markings) form the oil seal with the wavy ring sandwiched between the 2 flat rings. All 3 rings are fitted within the same lower groove in the Piston.
The most important part after the rings are fitted is spacing the gaps away from each other to allow even pressure from the cylinder walls. I achieved this by imagining that my Piston was divided into 3 segments (kind of like a Y drawn in the centre of the Piston).
Aligning the top ring's gap to the left point of the Y, the 2nd ring's gap to the right point of the Y and the join of the wavy ring to the bottom (tail) of the Y.
I then aligned the gaps of the remaining 2 rings (the ones above and below the wavy ring) to opposite ends of the Piston, roughly in line with the centre of the Cotter pin holes that run straight through the Piston (left to right).
The main thing was to ensure that none of the gaps ended up aligning with the gap of another ring above or below it!
The inner edge of the Bore's collar is slightly tapered which greatly assists with pre-inserting the Piston (now with rings) into the Bore prior to fitting to the engine.
By tilting the piston and inserting at a slight angle to the bore, I found that the 1st 2 rings could slide in with minimum effort. The trick was to allow the gapped end to make contact last so that the pressure would close the gap thus narrowing the ring.
Surprisingly the sandwiched 3 rings slid in without requiring too great an angle. Only a few light taps with the palm of my hand on the Piston base were needed, all the while being careful not to pinch the rings against the Bore's collar.
TIP: Lubricate the rings and the walls of the Bore with a little machine oil.
With the paper gasket lightly coated with Hylomar and allowed to dry for 30mins, I aligned it correctly onto the base of the Bore and then inserted the 2 metal dowels into their groves.
Next came the Cotter pin which required that the Piston had enough sleeve exposed (just a fraction before the base ring is again exposed). The Cotter pin was only slightly inserted, leaving enough room for the Crank Rod to be aligned.
I then slid the completed Bore with Piston down the 4 Bolts/Rods.
Once the Bore with Piston attached was aligned with the Crank Rod, I pushed the Cotter pin right through to butt up against the Circlip on the other side of the Piston.
Then with a set of pliers, I gave a newly inserted Circlip a slightly inward twist until it snapped into it's groove within the Piston.
I physically and visually checked that the Circlips securely attached the Crank Rod within the Piston - no point in taking chances here!
Once completely sure everything was aligned, I pulled the Cam chain through it's chamber and slid the Bore collar into the base of the engine allowing the Piston to slide up through the Bore.
NOTE: Make sure that the collar of the Bore fits freely into the engine base, i.e without being forced or rocked from side to side. Otherwise use some fine sandpaper and polish until this is achieved. If the Bore's collar is too tight, it will force apart the engine base, potentially causing an oil leak.
Now with a longer Head, the Cam chain needed replacing. Luckily a longer replacement chain was provided in the kit!
I dreaded the idea of removing and splitting the engine for such a simple upgrade so with a bit of research, I read that the Cam chain can be fitted via a joining link. Unlike traditional chains, there is no obvious joining link but upon closer inspection, there is a brass coloured link that can be forced open with either a small chain breaker or if you're as lucky as I was, a small flat blade screwdriver and a hammer with a good aim ;D
I decided to do this after the Bore was fitted to minimise any debris entering the engine. Using my trusty chain breaker (a large set of bulk cutters), I cut the original chain. Using my alternative chain breaker (flat blade screwdriver & hammer on the bench) I gently split the new chain on the brass link.
After taping the new split chain to the end of the old cut chain (still on the crank), I slowly rotated the flywheel and pulled the new chain through. Untaped them and joined the link back together on the new chain, applying some very nervous pressure with my "chain joining tool" (bulk cutters) until I heard a pop - opened my eyes and all was good
Unlike the original head, the manufacturer of this 4 Valve head cast it with a sand furrow within the lower right bolt shaft. This furrow drains out the sand during the casting process next to the exhaust manifold.
Provided in the kit is a small O-ring that slips over the lower right bolt once the Head and Rocker cover are in place to prevent oil leaking into the shaft when the engine is running.
In addition to this, I chose to seal up the furrow opening at the exhaust end with some high temperature silicone gasket compound prior to placing the Head onto the engine.
Once this had cured (8hrs), it was time to assemble the Head.
First, I re-inserted the lower Cam chain guide into the Bore, then aligned the lightly Hylomar coated metal Head gasket and placed the metal dowels into position.
NOTE: Hylomar was allowed to dry for 30 mins and a seal of high temperature silicone gasket compound was applied around the lower right bolt.
Finally, I slid the Head down onto the gasket whilst the Cam chain and guides were eased through their chamber.
Finding Top Dead Center on the Flywheel was a no brainier, it could be both visualised and felt as the flywheel was turned. It was just at the point that the Piston wanted to drop and where the marker on the Flywheel was between the arrow and the line before the T.
I tilted the Cam shaft into the chamber and turned it until the larger of the 3 holes in the Cam sprocket was at top center. The 2 smaller holes were even with the lip of the head enclosure. When I let go of the Flywheel and allowed the piston to drop very slightly, I turned the sprocket anti-clockwise by 1 tooth and pulled the Cam chain on.
To confirm that I had it right, I advanced the Flywheel by 2 revolutions until I was back to the point just before the Piston was ready to drop (between the arrow and line) and then checked the Cam sprocket. The large hole was top dead centre with the 2 smaller outer holes perfectly in line with the lip.
Time to place the Rocker cover on. I inserted the 2 metal dowels and also squeezed a seal of high temperature gasket compound around the lower right bolt. After centering the Cam shaft sprocket within the chamber and aligning it's bearings onto the Head, I slid on the Rocker cover.
3 of the 12mm nuts with washers (top left & right + bottom left) were hand tightened whilst I rolled on the rubber O-ring to the lower right bolt and coated it in a little high temperature gasket compound then also placed on a washer and tightened the 12mm nut over it.
The 2 8mm side bolts (outside of the Cam chain chamber) were tightened and then the head nuts tightened in a diagonal order.
After applying a little Hylomar to the Cam Chain Tensioner's Gasket and letting it set for 30mins, I unscrewed the top screw from it and inserted a small flat blade screw driver. Turning clockwise until it's shaft had completely raised and then inserted it into the Bore - tightened it's 2 8mm bolts before releasing the flat blade screwdriver to let the tension take hold.
Finally capping off the Cam Chain Tensioner with it's centre screw to avoid compression loss and oil leaks.
NOTE: Without first raising the tensioner shaft, damage can occur to the Cam chain and Guide from too much tension.
Returning the Flywheel/Cam Sprocket to Top Dead Center, grabbing a set of Metric Feeler Gauges and 9mm spanner, it was time to check and set all 4 of my shiny new Valves to .004
In brief, I loosened the 9mm locking nut on each of my Valves, inserted a .004 feeler gauge into the gap loosening or tightening the screw by hand until the gauge was clasped relatively firmly and then tightened each of the 9mm nuts. I then checked each Valve first with a .005 to confirm that it was too tight and then the .004 to confirm that it still fit after tightening.
After all was completed, it was just a matter of putting on the head cover and tightening the 4x 8mm bolts.
One thing I noted was that my NGK C7HSA spark plug was now a few mm too short within the Valve and the manufacturer recommended a longer spark plug of the same spec.
The one I chose that fit perfectly was an NGK Iridium IV CR8EIX and was a slightly colder plug - better suited to the extra anticipated compression whilst still being compatible with the 98 octane fuel I use. (BP Premium Unleaded)
After re-installing a new Exhaust Gasket, Exhaust Pipe, Plastic Engine Covers & Carby, it was time to address where the head cover oil vent would lead to, especially now that the I eliminated the Air Box that the original Head cover was vented to.
Introducing my new Oil Catch Can, with it's poor English stickers proclaiming "High Accelerative" amongst it's many attributes ;D
Attached by Cable Ties to the frame where the Air Box once was, the Head vents to the Oil Catch Can's base via 1/4" fuel hose. From there, the Oil Catch Can has an overflow hose that I cable tied to hang below the bottom fairing in front of the engine bay. A 3rd hose runs from the Catch Can and replaces the Dip Stick so that it can return oil vapour back to the Sump.
The whole unit fits nicely behind the front plastic fairing near the riders feet and can be accessed when the seat is raised.
One of the annoying things about poor quality rubber, especially when it's on the intake manifold is it's ability to split causing an air leak.
Mine only lasted an hour whilst I tried to make my new larger Carby fit within the same space the old one was. Unfortunately the accelerator pump at the base of the new Carby was the real culprit but was easily remedied by gaining a little height away from the top of the engine.
The solution to both problems was to replace the rigid black rubber intake manifold rubber with a slightly longer length of fibre re-enforced clear 32mm industrial hose and a couple of new ring clamps.
On the air intake end, an extension was also needed to allow the 38mm UniFilter to clear the frame. For this, I used a 42mm to 42mm rubber pipe commonly found in swimming pool retailers (Clark Rubber in my case) and a couple of new ring clamps.
It sounded nice and smooth starting her up and a little meaner when the throttle was cracked open!
To properly seat the rings, I went with a medium to hard run in.
Briefly: 5min run at 40-60% revs, then a 15min cool down. 10min run at 60-80% revs, then a 15min cool down. 15min run at 70-90% revs, then a 1 hour cool down.
Each time checking for oil leaks during cool down and happy to report she's bone dry ;D
After this run in, I did a top speed check. Prior to the upgrade, I was maxing out at 88kph (54mph) and that was after I upgraded the Belt to a Gates PowerLink 835 20 and matched the 60grams of mixed rollers I had with 6x 10 gram rollers (same total, smoother delivery).
Without pushing too hard before run-in is complete, I can now max her out on a quarter mile straight (level ground) at 95kph (59mph)!
That gives me more than enough headroom in an 80kph (49mph) zone to get me out of a mess and I suspect that after run-in, it will improve even a little more
There are still 2 more performance components I'm keen to utilise, a race mapped no rev limit CDI and a performance exhaust - I'll keep you posted!
2007 Roketa Fiji 150 2007 Roketa MC54-250B 1992 Harley Sportster 1200 ----------------------------------- "Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming -- WOW--What a ride!!!"
How much better is your acceleration? Any loss of fuel economy?
Yes definately a noticable difference in acceleration. First noticed it after the initial run-in, I was cruising back towards home and got to the 3/4 throttle mark - when I cracked her open it was like - Wow, where did that come from!
Fuel economy, can't really comment yet but it still looks like I'll get at least 200k's out of the 6 litre tank. I'll pay more attention over the next few weeks!
how much did it cost you to do everything you did to the scooter from when you got it bone stock in the box?
Thanks Adnan, great question...
These are in AUD $ (so shave around 10c off each $)
The Inferno Ignition Coil cost around $199 from PBU, originally bought it for my 250 Dirt Bike but I think the scooter needed it more!
The new Chrome Hand Grips with rubber inlays cost $120 but definately worth it, adds a whole new feel to the bike - seriously!
The 61mm Big Bore Kit cost $120 (a friend of mine imports performance parts and did this kit wholesale for me)
The 4 Valve head with racing cam cost $180 - from same friend!
The 30mm CVK carb with intake $100 (as above)
The Oil Catch Can cost $40 & UniFilter $20, both from a mate who owns a dirt bike shop. He also provided the Bling 1/4" fuel filter for $10
Incidentals such as ring clamps and 1/4" fuel hose, Gates 835 Belt & 6x 10g rollers - probably another $100
So that's roughly $890 (USD$800)
After just getting back from an awesome ride this afternoon, I have to say I'd spend it all again, my scooter's definately worth it! ;D
Absolutely incredible thread! The time and effort you put in with all the pictures thru-out the process, clarity of pictures and description is top notch! You are quite the teacher and wanted to say THANK YOU! By the way, what size are the grips? I have been wanting to change my grips for quite some time now, and I love the Harley type ones you have installed. I am just not sure what size mine are. Thanks again.
Thanks so much for the compliment, the grips I got were made by Kuryakyn. They're called ISO grips and can be seen here. The model was 6241 (not shown on that page) but fits my scooters' 7/8" bars nicely.
Thanks again! I have found the exact ones on Ebay from you help.
2009 CFMOTO GLORY 2006 CUSTOM AVANTI BETA
wereed: HOw can I start a thread?
Jun 1, 2013 10:55:49 GMT -5
wereed: or respond to a thread I started three years ago...
Jun 1, 2013 10:56:07 GMT -5
marklorenzi: I just bought one of the Fleetwoods. They look like a clone of the Honda XRM's they sell overseas. It is in transit now and I should get it this week. I will try to post my experience here. Call me the guinea pig hahaha.
Jun 2, 2013 20:29:11 GMT -5
flyangler: wereed, this forum is read only the new forum is on the banner above. Dan
Jun 5, 2013 7:35:29 GMT -5
silkyg1973: can someone please tell me how to post
Jun 10, 2013 12:08:46 GMT -5