does anyone know what compression a motor with a ct racing kit should have? also what compression do you need to start running racing fuel.. i know on my ski im running 93 and the ski has 170 compression.. any info would be great..
CT racing kit
- Thread starter mr_3_0_5
- Start date
the ct should be around 165/175 depending on the set up.
theres 2 factors at play when deciding upon raced gas..
1. static 170 psi is a good reference to start upping the octane, but it isn;y the whole story. your actual compression varies significantly as your motor runs, that is the whole concept behind a good pipe as the return pulse ads to the scavanging and compression. so how the bike runs is just as important, does it get hot?? knock or ping??
2. octane doesn't make power. it's actually the opposite. octane slows the flame front and resists detonation. but it does allow for more timing and compression which can improve power. Too much octane will actually make your bike slower. if you think you need race gas, start at a 50/50 mix of race gas and pump.. race gas does burn slightly cooler so if it's a long race or very hot out it would also be a benefit. remember to check jetting when changing fuels or oils. one of the single best power increases is an EGT and proper jetting. being off1 or 2 jet sizes richer or leaner can make a huge impact on power.
theres 2 factors at play when deciding upon raced gas..
1. static 170 psi is a good reference to start upping the octane, but it isn;y the whole story. your actual compression varies significantly as your motor runs, that is the whole concept behind a good pipe as the return pulse ads to the scavanging and compression. so how the bike runs is just as important, does it get hot?? knock or ping??
2. octane doesn't make power. it's actually the opposite. octane slows the flame front and resists detonation. but it does allow for more timing and compression which can improve power. Too much octane will actually make your bike slower. if you think you need race gas, start at a 50/50 mix of race gas and pump.. race gas does burn slightly cooler so if it's a long race or very hot out it would also be a benefit. remember to check jetting when changing fuels or oils. one of the single best power increases is an EGT and proper jetting. being off1 or 2 jet sizes richer or leaner can make a huge impact on power.
im running em rich.. and im running 2 parts av gas to 1 part 93 the av gas is 110 octane it still will give me a ping if i really get on it.. why is that??
also im runnng 32 to 1 klotz..
they are running rick at idle but that doesnt mean they are running rich at top end right???
i think my pilot is wrong but my main is right.. i think.. causse if i plug chop it its nice and broen but at idle its blackish..
also im runnng 32 to 1 klotz..
they are running rick at idle but that doesnt mean they are running rich at top end right???
i think my pilot is wrong but my main is right.. i think.. causse if i plug chop it its nice and broen but at idle its blackish..
i dont think it is.. im thinking my timming may be a little to far advanced..
im not sure.. i only get a ping here and there and only at full throttle in 6th..
one of the best investments you can make as far as tuning and diagnostics are concerned are a leakdown tester and an EGT. these 2 things will eliminate over 90% of tuning difficulties.
running AV gas with pump gas or half gas is a joke...AV gas's octane level is rated differently than our pump gas. I have heard this from many different engine builders and from my local shop. When you run half gas you actually end up burning a lower octane gas than regular 89 octane pump gas.
so your calling av gas half gas... and hpw can it be a lower octane if its 110..
im asking cause your not the first to mention that av gas can be a lower octane then 89. but i will say if i put stright 93 octane then it will ping almost at a constant at high rpm and useing the av gas improved that 95% so im lost..
im asking cause your not the first to mention that av gas can be a lower octane then 89. but i will say if i put stright 93 octane then it will ping almost at a constant at high rpm and useing the av gas improved that 95% so im lost..
just do a search on av gas properties, it has several additives such as anit-icers etc. and was designed to run a moderate sustained rpm at lower air densities. there is a LOT more to fuel than octane ratings.
have you tried running straight race fuel trick, vp etc to see what effect it has? you had mentioned timing, that can make it ping to and if to far advanced can require some major octane. advanced timing helps bottom end, to much advance will take away from top end.
Well I call it half gas because most people run half AV gas that is "110 octane" and half pump gas normally 93 octane or here in cali 91 octane and then they "average" it out and think they are running something like 102 octane. but really they are not.
That is about all I know about it. I have just had many people tell me that it really lowers the over all octane of the gas you are burning. It has something to do with what RPM airplanes run at and what RPMS bikes and cars run at.
If you really want to burn a higher octane gas in your bike than pump gas then I would get the race gas at your local shop or dealer. Even then your still not getting the advertised octane.
This is just the small amount of information that I know about mixing gas. And because of what I have heard about mixing gas when i do my 240 build I am going to make sure my engine can still run at tip top on pump gas only!
Best bet is to run half race gas and half pump gas but even then i have heard that your not getting that high of an octane boost. If you can afford it and can access it i would run straight race gas if you are really want to run that high of an octane of gas.
That is about all I know about it. I have just had many people tell me that it really lowers the over all octane of the gas you are burning. It has something to do with what RPM airplanes run at and what RPMS bikes and cars run at.
If you really want to burn a higher octane gas in your bike than pump gas then I would get the race gas at your local shop or dealer. Even then your still not getting the advertised octane.
This is just the small amount of information that I know about mixing gas. And because of what I have heard about mixing gas when i do my 240 build I am going to make sure my engine can still run at tip top on pump gas only!
Best bet is to run half race gas and half pump gas but even then i have heard that your not getting that high of an octane boost. If you can afford it and can access it i would run straight race gas if you are really want to run that high of an octane of gas.
Last edited:
ok that would make sense cause my bike loves to run at a constant rpm.. as for the pinging i kinda know when to expect it to ping by now and that when i am really slamming on it and reaming it out..
as for stright race gas havent tried it im in the middle of the booneys and its not so easy to come by i will run up to the race track and pick some up..
also how long of a shelf life will av gas have??
i havent ridding in a week or two is that long enought for the octane to drop?
ok... to clear up misconceptions.. the octane of avgas is measured differently, but it is still higher than pump gas. mixing will NOT lower it below the lowest rating to start with. there is a calculator http://www.bazellracefuels.com/Calcs/OC1.htm which will help you figure out what your ending up with. mixing ligit fuels will have a blending effect so your octane will definitly go up. what is worthless is the 104 octane type over the counter octane booster in a can. it moves the actual octane very little, we are talking 93.00 to 93.2 that little.
sweet the calculator thing tell me i need more 110 then im mixing at now
i should be mixing 4 gal av to 1 gal 93 then ill have 107 . im doing it 3 av 2gal 93
4 to 1 will give me 106.5 thats the min i need.. thanks..
exactly ,jsut ru nit straight and watch your plug may need to rejet to compensate .theres so much misconcpetion about avgas on the net ,most people over octane a motor .its excellent fuel to run so many have tried it and realized its benefits not a miracle fuel but for most its definitly leaps and bounds ahead of premium pump and it will ward off detonation it has lead and has oxygen added thats a definite increase in power regardless of the rating doesnt matter if your motor warrants/needs it or not its superior to unregualted watery ethanol plagued pump gas .try a search on here and everything2stroke on people who actually have used it .
hey sorry im off topic here but how can i tell if i need to run race gas i asked my local shop and they said i should but coming from them its usally there wrong. with my mods listed below and timming advaced 4 degrees should i or not?
