12:1 Pistons and fuel?

Shop deals on ebay
shop deals on amazon
Advertise with us
Yamaha Raptor 350 & Warrior Forum

Help Support Yamaha Raptor 350 & Warrior Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
G

griff

Well-Known Member
Joined
Oct 9, 2006
Messages
478
Reaction score
0
Location
Sacramento, CA
Heya everyone,

Is anyone running the JE 12:1 piston on their Raptor 350?

I'm getting some mixed info on it.... some of my sources are saying its OK with 91 or 92 pump gas, and some are saying race/pump gas mix. Anyone confirm either way?

Anyone know what the stock timing curve is on the Rap350? i.e. how much advance at how many degrees?

Thanks,
 
What i've heard more than anything else, both from the local shop's advice and over the net, is that 12:1 it will RUN on 93, but not very well. Not very well means pretty much any kind of potential performance you would gain from the higher compression is lost because it's not running right anyways. I think 11:1 or a little less is the best way to go unless you are actually willing to spend all that extra $$$ on fuel just to gain a little more hp.
 
My opinion is the 12.1 compression on a aircooled motor would lose power over time during a hard fast ride due to the extream heat its going to produce. The only example I can come up with would be Suzuki switching from the old SACS motor to the water cooled version in 1994 on the gixxer 750, because the old motor would lose power during a race due to high heat which also caused accelerated wear, am I right Griff???????
 
Yes and no..... The SACS engine is/was an excellent design, even during Suzuka 24hr Endurance, they had no power loss issues, though they ran a secondary oil cooler developed by Yoshimura and Suzuki. All SACS engines to this day still have the same oil galleys and plugs, and you can plug in a variety of extra oil cooling systems to them.

My 86 GSXR runs a +1 overbore (771cc), and 13:1 compression, and has no detonation on 91 pump gas. Before that I had a +5* timing advancer, which worked great with stock compression 10.5:1 IIRC, but at 13:1 it was too much advance, and it ping'd here and there. So the stock advancer went back on.

Suzuki went to a water cooled design in 91/92 (there was a weird half-year model made with the SACS design in late 91). The main reason was the GSXR was get'n real porky, as they kept strengthening the frame and swing-arm, it got heavier for obvious reasons (more metal!), they had to make up the difference, and the water-cooled engine design is lighter.

As far as the 12:1 on the Raptor 350, it may or may not run well on high octane pump gas, theres a variety of factors that will determine that. The timing advance curve can give ya a decent clue. Sometimes only a minor tweak is needed, for example going 1 step colder on the spark plug, or say retarding the timing slightly to make the higher CR work with pump gas, things like that.

The problem is right now, I dont know anyone running a 12:1 setup on this engine, and I cant find enough facts to substantiate it either way. Its all speculation or hearsay.
 
I am running a 12:1


It will run on 94 however if you get it hot it runs worse and worse....... running full race gas will keep it cool and performing good all day long however mix works too.
 
A buddy of mine (finally) got back to me a little while ago, regarding this. Basically its crap shoot on the 12:1 CR with pump gas. Some parts of the country that have better fuel formulation (and 93+ oct) work fine with this engine with 12:1. In California, the fuel is pretty crappy, poor formulation and lower oct (91), the engine can be temperamental at times starts pinging. A little octane boost will fix it (which I dont want to add or mix anything myself).

He indicated that an oil-cooler is a must with 12:1, it keeps the piston temp down enough to keep it from pinging like crazy (assuming you are using good fuel).
 
I am running a 12:1


It will run on 94 however if you get it hot it runs worse and worse....... running full race gas will keep it cool and performing good all day long however mix works too.
Click to expand...

Thanks DSW :)

Are you running an oil-cooler?

Have you tried a 1 step colder spark plug?
 
When you guys are talking about race gas, is it unleaded 100 octane gas or leaded 110 octane like Cam2. Which would be better, I can get both at the race track, of course 100 is like $4.75 gallon and 110 is like $6.00 a gallon, they also have 114, and 118 octanes available.
 
[quote:iwsz9dea]I am running a 12:1


It will run on 94 however if you get it hot it runs worse and worse....... running full race gas will keep it cool and performing good all day long however mix works too.
Click to expand...

Thanks DSW :)

Are you running an oil-cooler?

Have you tried a 1 step colder spark plug?[/quote:iwsz9dea]



I do not have an oil cooler..

With Race gas the motor runs no hotter than it did when i had a wiseco... in fact it runs cooler from what i can tell.

And no i have not tried changing plugs... im running a splitfire crossover of the D8ea stock number.

Ive never had any problems with mine so far and with the cam and piston combo i have (.430 webcam) I have way more torque than stock and the top end is insane.
 
When you guys are talking about race gas, is it unleaded 100 octane gas or leaded 110 octane like Cam2. Which would be better, I can get both at the race track, of course 100 is like $4.75 gallon and 110 is like $6.00 a gallon, they also have 114, and 118 octanes available.
Click to expand...

I'm refering to unleaded only. I do not run leaded fuels of any kind.

My big reason is the additional deposits created in the engine using leaded fuels. I've torn down a couple engines where the rider used leaded race fuel in notable quantity, and it every case the valves were a mess, as well as the piston tops.

You can get away with it more in 2-strokes, but I still dont recommend it.

With that said, if you are a racer, and you tear down the engine 2-3 times a year, then its not a big deal.
 
I do not have an oil cooler..

With Race gas the motor runs no hotter than it did when i had a wiseco... in fact it runs cooler from what i can tell.

And no i have not tried changing plugs... im running a splitfire crossover of the D8ea stock number.

Ive never had any problems with mine so far and with the cam and piston combo i have (.430 webcam) I have way more torque than stock and the top end is insane.
Click to expand...

Hmmm, it really shouldnt run cooler with race gas, unless youre getting a shitload of detonation wthout it. Higher octane will definitely not allow detonation, but race gas usually has higher energy potential (i.e. will make more heat). Theres only 2 way to tell realistically, oil-temp gauge, or laser temp-reader. All my motorcycles have always run hotter running race gas, anywhere from 10 to 25*, but they made kick ass power to ;)

Betcha if ya tried a plug one step colder heat range, in this case a NGK D9EA, you might find a couple hp, and cool it down slightly. If you want that engine to live a long time at that CR, you may want to seriously consider getting an oil cooler setup. That in itself may also be worth another couple hp, and you may not need to run race gas at all.

Interestingly enough, my GSXR and my Bandit both use D8EA's stock, though I currently run the Champion Powersports 8809 (which works nicely in the Rap350), theyre reliable and can be found pretty inexpensively.

Just a suggestion to everyone, dont by the over-priced bling spark plugs, they will not make a damn bit a difference for HP (regardless of what the manufacturer says). In all my years dyno'ing motorcycles, I have never once seen a spark plug provide a real HP gain. The only time it ever made a difference, was when the plugs were swapped for OLD plugs that were spent, and not quite arc'ing properly anymore.
 
[quote:z6d53rss].
Click to expand...

I'm refering to unleaded only. I do not run leaded fuels of any kind.

My big reason is the additional deposits created in the engine using leaded fuels. I've torn down a couple engines where the rider used leaded race fuel in notable quantity, and it every case the valves were a mess, as well as the piston tops.

You can get away with it more in 2-strokes, but I still dont recommend it.

With that said, if you are a racer, and you tear down the engine 2-3 times a year, then its not a big deal.[/quote:z6d53rss]

Oh alright I guess that would make sense, were does the lead have to go. Also I bought some D8ES plugs what are they and will they work, or should I just get the D9?????
 
Oh alright I guess that would make sense, were does the lead have to go. Also I bought some D8ES plugs what are they and will they work, or should I just get the D9?????
Click to expand...

Whats the CR on your engine setup? What fuel do you run normally? Does it ping at all now?
 
I got the stroker motor, and the compression is 11.1 and no no pinging that I know of, and I run 93 octane.
 
You must log in or register to reply here.

Latest posts

Back
Top