Need more powa!!??

devinzz1

devinzz1

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Oct 25, 2010
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Looking to see what my options power wise are with the redhead 700 engine. i want to keep it a single pipe setup but anything else im up for. What are my options as far as porting/big bores/heads go keeping the stock pipe? Im gona start building on the sled this fall and want to know for then. I know a few guys on the site did some engine work but cant remember their usernames.
 

Heelclicker clutching. You will need a tall cover and I recommend 15 mm or larger rollers. You'll need another helix too. If you haven't got transfer rods, get them.
 
Well, can't make much more power then I guess, without going to triple pipes and maybe a bigbore.
 
Get it ported. What gears do you have? I really liked the 20/40 or 21/40 setup. They respond well to the lower gearing. I understand that they like it when you ceramic coat the pipe and muffler, makes it able to run more optimally.
 
trail port the cylinders,window the pistons, lightweight wristpins, port the case top and install larger srx/viper reed blocks, reed spacers and peel the head gasket. It will make quite a bit more power and still run good with the stock single pipe. They move alot more air= more power because with all that youll need to bump the jetting up to 152.5-155 mains depending on your elevation and temp where you live.

I cant tell you how much more power over stock because i never spent the money on dyno time for that engine,but they will throw around 55 grams of clutch weight as well when done so its a big increase in power! That engine is one of the most under tuned engines from yamaha, they left alot of gain in those.
 
get your clutching spot on. 8ca weights, around a 52/42 cam, reed spacers and the head gasket mod. this sled will fly. i have played with many red head triples. might be best motor yamaha ever made. 3:16 (yammie tony)
 
I thought it was the pipe that was at least partially responsible for the low power. Add pipes, and it's up 20 hp at once. Do you mean with a single piped sx, you have to take your jetting from say.. 142,5 and 143,8 all the way up to 152,5-155?
 
norwegian said:
I thought it was the pipe that was at least partially responsible for the low power. Add pipes, and it's up 20 hp at once. Do you mean with a single piped sx, you have to take your jetting from say.. 142,5 and 143,8 all the way up to 152,5-155?
Click to expand...

yes sir! The low output hp like 112-114hp stock is from very low compression, a case that blocks the rear boost port, cylinder skirts that block off the rear port. By opening up the rear of the case,and adding ;larger reed blocks with spacers it allows the engine to pump more air. Along with more aggressive port timing, added compression from a headgasket peel, it bumps the power up quite a bit, even with the stock pipe.

yes, of course triple pipes add 20hp right off the bat but they are not an option for some guys who ride where theres strict exhaust laws in place.

I call these engines the "super singles", even if you ride in warmer climates your jetting will still be 148.8-150, when you add that much jet to an engine it means its moving ALOT more air. An engine is nothing but a air pump, more it pumps, more power it makes.
 
Thank you, this was very informative. One more question, you said it pulls 55 grams of weight, how much did it pull before the porting? Is the clutch set up close otherwise? same spring/helix/wrap? (probably not, but you see what I mean)?
 
sx engines come with like 42 grams of weight in them going off my head, we both know the stock stuff wasnt optimum at all but its no where near 55 grams no matter what you use. I use a fairly big helix, its not the same set up as stock by far.
Loaded up 8dn20's(4.5 in both holes) will work good with a light primary spring ,big helix. I almost always try keep the gearing around a 1.8 ratio in them they seem to really like it with the shorter stroke engine.

If you run heel clickers in them, around a 50/40 helix with the super single engine they will almost pull as much weight as a stock srx will!

if set up right, they are the little over achiever engine, is it the best engine ever made......I am not sure about that because of the design flaws. The srx engine has alot better bore to stroke ratio, 59.6mm vs 64mm ,better cylinders, better case and it came with triple pipes and powervalves...lol, its just yamaha didnt leave as much on the table for "gain in hp" for the aftermarket world as they did the redhead engines.

The redheads are indeed a good engine with tons of potential in the right hands!
 
Right now it has 8t drivers. Minor clutching and jetting. Carbon reeds/spacers. Gutted airbox. And ive been swapping between the stock bored, slp, and sno stuff silencers. I like the lightweight compact single pipe and like the thought of it looking stock, plus i like the sound of the single better. Engine needs to be gone through anyways.
 
Sled runs absolutely crisp setup as it is and ive taken 800etecs and rx-1s off the line up to a few hundred feet. In my class in a local sled drag i was only beat by an srx which got me at the last few feet. How much would i be looking at for a basic trail port that will work with the stock pipe?
 
we run three 700 sx red heads on the asphalt. one is a pro stock, 9.95 best. everything done possible. and very lite. sled made 163 @ c&h, next one a 700 sx improver. 10.11 best. 5.46 on grass. third ones a box stocker 700 sx single pipe. 11.20,s. 6.20,s on grass in trail class. all 700 cc. this motor is amazeing, totally bullet proof and still gets my vote for best triple yamaha made. and i am a srx and vmax 4 guy. in 1998 i bought a 97 sx brand new. i beat more 98/ 99 srx,s with that sled than i can remember. all i did was clutching. i traded it in on my 2000 srx lol 3:16 (yammie tony)
 
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