Tips I've learned from many builds-great newbie read.

Discussion in 'Photos & Bicycle Builds' started by Skyliner70cc, Jul 13, 2008.

  1. Skyliner70cc

    Skyliner70cc Active Member

    The statement that castor mixed with gas goes bad quick is a fallacy. If by quick you mean 2 weeks, then you are correct. 2 weeks is the max time you should store a premix made with castor. Since I mix one gallon at a time (using an empty windshield washer fluid gallon bottle), this isn't a problem. Although I currently use 100% castor oil, the average person would be best served with a blended oil containing synthetic oil mixed with castor oil (the ideal mix depends on your riding style and how hard your run the engine).

    Oil: Castor vrs Synthetic from

    After using various synthetics with excellent results, we decided to begin test Castor Oil. Typically with Synthetic, we ran 20:1 for break-in, and 28:1 for racing. Our motors have lived long lives with at these ratios.
    Castor oil seems to need a little lower ratio, 18:1 for break-in, and 24:1 for racing, according to many of the Europeans who have far more experience with Castor Oil then we did.

    For those who read their piston/exhaust outlet/spark plug, should note the differences in the decomposition of Castor vrs Synthetics as outlined in Castor Oil 101. Synthetic simply burns away, where the decomposition fractions of Castor Oil tend to leave a brownish stain of varnish.

    The proper color for mixture with Castor is more of a caramel-brown or tan then the "yellowed smokers tooth" color we see on the upper porcelain of the spark plug insulator. The piston dome should also have a dry tan appearance. Note the operative word "dry". Any sheen that could indicate liquid like oil is too rich. Inside the dome is the best place to look for any dampness. After pulling the head several times to inspect the color, we decided to use a bent Q-Tip to swab the roof of the combustion chamber for oil.

    Castor oil will leave a little more ash everywhere, including the exhaust tip. The exhaust tip will also have a tan color effect but not as pronounced - it can still be a gray color.

    Exhaust Gas Temps (EGT) will not change between Synthetic and Castor. EGT is not a reliable way to find peak power especially in water cooled motors. EGT is pretty reliable in warning of damaging temps like a stick if you have a reliable system. As Castor oil does not tend to burn like synthetic does it consumes little or no oxygen. Going from 28:1 to 24:1 also means less gasoline is being introduced. You may need to jet slightly richer with Castor then Synthetic.

    There is no discernable power difference from Castor to Synthetic. The main advantage to Castor Oil over Synthetic is it remains a better lubricant as it has decomposed. Castor Oil won't make much difference on bottom end life, but it will extend the life to the top end.

  2. Skyliner70cc

    Skyliner70cc Active Member

    Does anybody remember the day when happy time engines had a bushing wrist pin bearing instead of the roller bearing used now? Not one of my engines that I installed and sold had a failed wrist pin bushing when the new owners used Maxima 927 or Klotz castor blended 2 stroke oil. Buyers of mine who used conventional or synthetic oil would return to me within 200 miles asking for warranty repair of their engine from the worn bushing. If they didn't have proof (receipts) of using a castor oil blend the repair was on their dime. No single failure of the bushing was attributed to use of a castor blended oil.
  3. Skyliner70cc

    Skyliner70cc Active Member

    Let's compare Amsoil Dominator to Maxima 927 (a 20% castor oil blended w/ 80% syn) Dominator flashes at 198 deg F, Maxima flashes at 420 deg F. Definition of flash point: the flash point of a volatile liquid is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Since oil is a liquid, it can only do its job (lubricating an engine) when it is a liquid. Once it flashes, ITS GONE! Just 20% castor oil increases the flash point of a synthetic oil in Maxima 927 by 220 deg F! This means it is a lubricant longer. Plus, the wonderful thing about castor is that once it does flash and burn, it actually forms a dry lubricant that is actually a better lubricant than in liquid form!!!!! Unfortunately, synthetic, including AMSOIL can't say that. It also has a better viscosity at higher temperatures!

    DOMINATOR™ Synthetic 2-Cycle Racing Oil
    Kinematic Viscosity @ 100°C, cSt (ASTM D-445)
    Kinematic Viscosity @ 40°C, cSt (ASTM D-445)
    Viscosity Index (ASTM D-2270) 157
    Pour Point °C (°F) (ASTM D 97)
    -46 (-51)
    Flash Point °C (°F) (ASTM D 92)
    92 (198)
    Fire Point °C (°F) (ASTM D 92) 92 (198)

    Maxima 927
    Viscosity SUS @ 100°F 617

    Viscosity SUS @ 210°F 73

    Viscosity cSt @ 40°C 133.1

    Viscosity cSt @ 100°C 13.79

    Pour Point °F -5

    Flash Point °F 420

    Fire Point °F 480

    Viscosity Index 99

    SAE Viscosity 40
    Last edited by a moderator: Dec 18, 2015
  4. Skyliner70cc

    Skyliner70cc Active Member

    I will however state, that for 4 strokes, a nice Group IV base stock synthetic oil is your best bet. I use nothing but synthetics in 2 of my 3 vehicles (the 3rd is a rotary engine and I use a low ash, ESP (emission system protection) Group III basestock oil that burns clean in the rotary-no castor needed since the engine is water cooled and won't exceed 200 deg F water temp. Synthetic oil in my 4 stroke vehicles allows me a minimum of 10,000 miles between oil changes with oil analysis by Black Stone laboratories confirming the oil is easily capable of 10k miles and often more.

    Polyalphaolefin (PAO) = American Petroleum Institute (API) Group IV base oil

    Synthetic esters, etc = API Group V base oils (non-PAO synthetics, including diesters, polyolesters, alklylated napthlenes, alkyklated benzenes, etc.)

    Hydrocracked/Hydroisomerized = API Group III base oils. Chevron, Shell, and other petrochemical companies developed processes involving catalytic conversion of feed stocks under pressure in the presence of hydrogen into high quality mineral lubricating oil. In 2005, production of GTL (gas-to-liquid) Group III base stocks began, the best of which perform much like polyalphaolefin. Group III base stocks are considered synthetic motor oil only in the United States; elsewhere they are not allowed to be marketed as "synthetic".
  5. shell shock

    shell shock Member

    well then.. i know what my next purchase is. thanks skyliner.
  6. axel

    axel New Member

    syn. oil

    Dear Skyliner70cc Good info on syn. oil for 4 stroke cars & trucks. The oil I use is good way, way beyond 10000 mi. With syn. fiber filters, AMSOIL EA or Donaldson endurance, oil and air, it is in the 20000 + range. With bypass system, like on my gravel truck, incredible. mineral base stock oil cant do this. Isodewaxed/hydrocracked group three oils, which are good, wont give that kind of performance. They have less shear strength, lower tbn#, are somewhat more volatile, and will not withstand nearly as many cycles( repeated heating and cooling) according to Lake Speed Jr. at Joe Gibbs racing(oil div.) mineral oil starts to burn (coke) at 320 degrees where as syn. goes to 554 before this occurs. Syn. oil is also heat activated, it gets better as it warms up. Synthetic oil was created in early 1940s for use in jet engines, mineral oil burns off, motor stops, plane crashes! But you already know all of this. I did not realize you thought I was trying to start a oil war here. I also did not know that you consider my posts as POLLUTION. am truly sorry! I will not post on this subject again. Thank you for the information, I learned alot! axel
  7. ToxicAZ520

    ToxicAZ520 New Member

    Does any one kno or have a list of all the screws,nuts,studs and bolt sizes so i can just go the store once and not have to take one out at a time dnt have a ride down there. Thanks.
  8. Stan4d

    Stan4d New Member

    If there are some that you need that are not listed, just ask.
    Last edited: Mar 19, 2011
  9. A-TownTX

    A-TownTX Member

    new tip

    Today my bike was bogging out and I went through all the technics to fix the problem. thought I'd pull off the bottom of carb to see if anything was clogged up and didnt realize the fuel jet valve wiggled off so now when I have the problem agian i know to check the valve with all new builds .:D
  10. Skyliner70cc

    Skyliner70cc Active Member

    yep, i had that happen to me recently on a new speed carb i installed. i was too eager to see if it would help my engine run better and didn't check the main jet to ensure it was wasn't.
  11. lsoult

    lsoult Member

    Thanks for the tips. I just finished (and reworking) my first build. I'm gonna re-do a few things and use the suggestions on your list because I can see where thay would eliminate some of the issues I'm having. Like the tank moving. How many bikes have you built?.. I wanna keep building... I really enjoy it!
  12. Skyliner70cc

    Skyliner70cc Active Member

    Isoult, sorry to hear you were having issues. Glad to have you onboard of a member and hope your experience with motorbikes allows your to share your knowledge with us too.

    BTW, I lost count of how many bikes I built. For about 4 1/2 years I was building 3-4 a month and selling them. I knew we were in trouble in our economy when I sold my last build in late 2008 but Ill be honest, I don't put much effort in selling them anymore either as I did before.
  13. lsoult

    lsoult Member

    I've seen all the posting you do. A BIG Thanks- to you and everyone else that likes to help the new guys.
  14. gia

    gia New Member

    Thanks to everyone, especially Skyliner, for the great lists & tips. I do have to admit, you all lost me on the oil debate, so I hope that buying a good quality 2 cycle (non-marine) oil will suffice.

    With all of this great information and the fact my memory isn't as good as it once was, I've now started a Word document to keep it all together, along with my other info about prices, websites, companies with bad reviews, companies with good ones...and the 1001 other tidbits of advice I've found here in the past month I've been lurking.

    All of you are providing a HUGE service to the newbies that come along in search of information about how to build themselves a motorized bicycle!
  15. adrian101

    adrian101 Member

    may i add: remove clutch cover (drive cog side) and check that the nut holding the drive cog on is correctly tight.

    I have had the nut on my new engine come off causing my wheel to lock up. I now need a new rear wheel and chain.

    Make sure to double check everything on the drive cog side. I can't stress that enough. Don't end up face down on the ground due to that drive cog. It hurts! lol
  16. cdevidal

    cdevidal New Member

    Where's the best place(s) to source the parts listed in the first/followup posts? I'm not sure where to begin.
  17. spmspeeder

    spmspeeder New Member

    Great tips for a first timer

    Wow, thanks for posting this information. It will become part of my build procedure.

    Great stuff,
  18. danlandberg

    danlandberg Member

    Adrian: How did you run your clutch cable on the blue bike? Did you use a roller set up? I have had to run a roller set up when using the billet intake. And have had to run the x-chamber down under the bike. But I mostly build using mountain bike style frames. The next build I'll be trying one of the new frames w/built in tank. (Have you seen those? and if so what do you think?) I do like the X-chamber being an up pipe instead of a down pipe. Good looking bikes you've got!
  19. jeffuehrer

    jeffuehrer Member

    Mounting an engine on a bike without a 75° angle.

    I recently had my engine's rear mounting bolts snap off at the casting. I successfully extracted the left bolt but I had to drill and tap the right side - For some reason all the bolts on the right side of most of my engines have needed to be double nutted. (more vibration?) - I used the stock size (6mm) of the left bolt except in Grade 8 steel. (Ace IS the place). The optimal size for this bike is 3" but as you can see in the photo it is considerably longer. For the right side I (some friends from work and I) tapped it out with a 1/4" - 20 and I found the perfect size bolt at you know where. I applied blue loc-tite to the threads then let it sit for a few hours then I threw some washers and lock nuts to the base to reinforce it. (not really sure if it will help or hurt but thought I'd give it a try) I let it sit overnight and mounted everything (see pictures). I used two back mounting plates so that the swivel and position of the plates would cup the frame. I took it out and it performed well with less vibration then the stock set-up. I reset the trip setting so I'll see if it lasts longer than the stock set-up of 400 miles. If this set-up works it will make life a lot easier for those of us with bikes that don't have a 75° angle.

    Attached Files:

    Last edited by a moderator: Dec 18, 2015
  20. toojung2die

    toojung2die Member

    You are not square to the seat tube. I see an angle off the 90 degrees required between the engine mount and the tube. That's the most important connection to the bike frame. Mount the engine on the seat tube so there's no gaps. Modify the front mount to adjust for the difference in tube angle. Get the back mount square and tight to the frame first.